                             aptitude user's manual

Version 0.8.12

  Daniel Burrows

   Main author of the document. <dburrows@debian.org>

  Manuel A. Fernandez Montecelo

   Main maintainer after Daniel Burrows, documentation about new features,
   corrections and formatting. <mafm@debian.org>

   Copyright © 2004-2011, 2012-2016 Daniel Burrows, Manuel A. Fernandez
   Montecelo

   This manual is free software; you can redistribute it and/or modify it
   under the terms of the GNU General Public License as published by the Free
   Software Foundation; either version 2 of the License, or (at your option)
   any later version.

   This manual is distributed in the hope that it will be useful, but WITHOUT
   ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
   more details.

   You should have received a copy of the GNU General Public License along
   with this manual; if not, write to the Free Software Foundation, Inc., 51
   Franklin St, Fifth Floor, Boston, MA 02110-1301 USA

   ══════════════════════════════════════════════════════════════════════════

   Table of Contents

   Introduction

   What is this aptitude thing, anyway?

   What is a package manager?

   What is the apt system?

   How can I get aptitude?

   Pre-built aptitude packages, or, “what 99% of users should do”

   Building aptitude from source code

   Tracking and participating in aptitude development

   1. Getting started

   Using aptitude

   aptitude basics

   Navigating the aptitude package list

   Finding packages by name

   Managing packages

   Updating the package list and installing packages

   Using aptitude from the command line

   2. aptitude reference guide

   The aptitude terminal user interface

   Using the menus

   Menu commands

   Working with multiple views

   Becoming root

   Managing packages

   Managing the package list

   Accessing package information

   Modifying package states

   Downloading, installing, and removing packages

   Understanding and managing package trust

   Managing automatically installed packages

   Resolving package dependencies

   Dependency resolution in aptitude

   Immediate dependency resolution

   Resolving Dependencies Interactively

   Costs in the interactive dependency resolver

   Configuring the interactive dependency resolver

   Search patterns

   Searching for strings

   Shorthand for search terms

   Searches and versions

   Explicit search targets

   Search term reference

   Customizing aptitude

   Customizing the package list

   Customizing keybindings

   Customizing text colors and styles

   Customizing the display layout

   Configuration file reference

   Themes

   Playing Minesweeper

   3. aptitude frequently asked questions

   4. Credits

   I. Command-line reference

   aptitude — high-level interface to the package manager

   aptitude-create-state-bundle — bundle the current aptitude state

   aptitude-run-state-bundle — unpack an aptitude state bundle and invoke
   aptitude on it

   List of Figures

   2.1. Commands available in the Actions menu

   2.2. Commands available in the Undo menu

   2.3. Commands available in the Package menu

   2.4. Commands available in the Resolver menu

   2.5. Commands available in the Search menu

   2.6. Commands available in the Options menu

   2.7. Commands available in the Views menu

   2.8. Commands available in the Help menu

   2.9. Values of the “current state” flag

   2.10. Values of the “action” flag

   2.11. Syntax of compound cost components

   2.12. Safety cost levels

   2.13. Syntax of the ?for term

   2.14. Customizable styles in aptitude

   List of Tables

   2.1. Basic cost components

   2.2. Default safety cost levels

   2.3. Quick guide to search terms

   List of Examples

   2.1. Sample resolver costs

   2.2. Use of the ?= term.

   2.3. Use of the ?bind term

   2.4. Use of the ?exact-name term

   2.5. Use of the ?for term

   2.6. Use of the ?term-prefix term

   2.7. Grouping policy firstchar or firstchar(binary)

   2.8. Grouping policy firstchar(source)

   2.9. Use of pattern to group packages by their maintainer

   2.10. Use of pattern with some packages placed at the top level

   2.11. Use of the pattern grouping policy with sub-policies

   12. Usage of --show-summary

                                  Introduction

   Table of Contents

   What is this aptitude thing, anyway?

   What is a package manager?

   What is the apt system?

   How can I get aptitude?

   Pre-built aptitude packages, or, “what 99% of users should do”

   Building aptitude from source code

   Tracking and participating in aptitude development

     “Master, does Emacs possess the Buddha nature?” the novice asked.       

     “I don't see why not,” replied the master. “It's got bloody well
     everything else.” Several years later, the novice suddenly achieved
     enlightenment.
                                                                -- John Fouhy

   Hello, and welcome to the aptitude user's manual! This introductory
   section explains what aptitude is and how to get your hands on it; for
   information on actually using it, please proceed to Chapter 1, Getting
   started.

What is this aptitude thing, anyway?

   aptitude is a featureful package manager for Debian GNU/Linux systems,
   based on the renowned apt package management infrastructure. aptitude
   provides the functionality of dselect and apt-get, as well as many
   additional features not found in either program.

What is a package manager?

   A package manager keeps track of what software is installed on your
   computer, and allows you to easily install new software, upgrade software
   to newer versions, or remove software that you previously installed. As
   the name suggests, package managers deal with packages: collections of
   files that are bundled together and can be installed and removed as a
   group.

   Often, a package is just a particular program. For instance, the instant
   messaging client gaim is contained in the Debian package of the same name.
   On the other hand, it is common for programs to consist of several
   interrelated packages. For instance, the gimp image editor consists not
   only of the gimp package, but also of the gimp-data package; in addition,
   several optional add-on packages (containing esoteric data, documentation,
   and so on) are also available. It is also possible for several small,
   related programs to be contained in a single package: for instance, the
   fileutils package contains several common Unix commands, such as ls, cp,
   etc.

   Some packages require other packages in order to function. In Debian,
   packages can depend upon, recommend, suggest, break, or conflict with
   other packages.

     • If a package A depends upon another package B, then B is required for
       A to operate properly. For instance, the gimp package depends upon the
       gimp-data package in order to ensure that the GIMP graphics editor can
       access its critical data files.

     • If a package A recommends another package B, then B provides important
       additional functionality to A that will be desired in most
       circumstances. For instance, the mozilla-browser package recommends
       the mozilla-psm package, which adds support for secure data transfers
       to the Mozilla Web browser. While mozilla-psm is not strictly required
       for Mozilla to function, most users will want Mozilla to support the
       secure transmission of confidential data (such as credit card
       numbers).

     • If a package A suggests another package B, then package B provides
       functionality that may enhance A, but is not needed in most cases. For
       instance, the kmail package suggests the gnupg package, which contains
       encryption software that can be used by KMail.

     • If a package A conflicts with another package B, then the two packages
       cannot be installed at the same time. For instance, fb-music-hi
       conflicts with fb-music-low because they provide alternate sets of
       music for the game Frozen Bubble.

   The job of a package manager is to present an interface which assists the
   user in managing the collection of packages installed on his or her
   system. aptitude provides such an interface by building on the apt package
   management system.

What is the apt system?

   Being able to install and remove packages is great, but the basic software
   for doing this (known as dpkg) does exactly that and nothing more. This is
   fine if you download one or two packages by hand, but quickly becomes
   cumbersome when you are trying to manage a large number of packages.
   Furthermore, if your shiny new package requires software you haven't yet
   installed, you have to download the newly required software by hand. And
   if you later decide to remove the no-longer-shiny package, these extra
   packages will linger on your system, consuming hard drive space, unless
   you manually remove them.

   Obviously, all of this manual labor is a tedious chore, and so most
   package management systems come with software which takes care of some or
   all of it for you. apt is a common base on which to build these programs:
   in addition to aptitude, programs such as synaptic and apt-watch make use
   of apt.

   apt works by keeping a list of the packages that can be downloaded from
   Debian on your computer. This list is used to find packages that need to
   be upgraded and to install new packages. apt can also solve many
   dependency problems automatically: for instance, when you choose to
   install a package, it will find any additional required packages and
   install those as well.

   When working with a package manager based on apt, such as aptitude, you
   will typically perform three basic tasks: you will update the list of
   packages that are available by downloading new lists from the Debian
   servers, you will select which packages should be installed, upgraded, or
   removed, and finally, you will commit your selections by actually
   performing the installations, removals, etc.

   apt-based package managers read the list of “sources” -- repositories of
   Debian packages -- from the file /etc/apt/sources.list. The format and
   contents of this file are beyond the scope of this document, but are
   described in the manual page sources.list(5).

How can I get aptitude?

   In case you are reading this manual but aptitude is not yet installed on
   your system, this section explains how to correct this unfortunate
   situation. Most people should head straight for the section on binary
   packages.

  Pre-built aptitude packages, or, “what 99% of users should do”

   Pre-built, or “binary” packages are the easiest and most common way to
   install aptitude. You should only attempt a source install if binary
   packages are not available for some reason, or if you have unusual needs
   that are not met by binary packages.

   If you are using a Debian system, execute the following command as root:
   apt-get install aptitude. If you are not using a Debian system, your
   system provider might have created a pre-built package of aptitude; if you
   are not sure, you can contact them for further suggestions.

  Building aptitude from source code

   You also can build aptitude from source; however, this is probably not a
   useful exercise unless apt is already available on your system. If it is,
   you can install aptitude from source with the following steps:

    1. Install the following pieces of software:

          • A C++ compiler, such as g++.

          • The development files for apt, typically available in a package
            with a name like libapt-pkg-dev.

          • The libsigc++-2.0 library, available in the package
            libsigc++-2.0-dev or from http://libsigc.sourceforge.net.

          • The cwidget library, available in the package libcwidget-dev or
            from http://cwidget.alioth.debian.org.

          • The gettext program, which should be included with your Linux
            distribution.

          • A make tool, such as GNU make.

    2. Last but not least, download the most recent aptitude source code,
       available from http://packages.debian.org/unstable/admin/aptitude.
       (scroll to the bottom of the page and download the “.orig.tar.gz”
       file)

   Once all the required components are available, open a terminal and
   execute the command tar zxf aptitude-0.8.12.tar.gz to unpack the source
   code. Once the source code is unpacked, type cd aptitude-0.8.12 &&
   ./configure && make to compile aptitude. If this succeeds, make sure you
   are the root user (by using su, for instance), then type make install to
   install aptitude on your computer. Once aptitude is successfully
   installed, typing aptitude at a command prompt should start the program.

  Tracking and participating in aptitude development

    Getting the aptitude development source tree

   If you want to test the latest bleeding-edge source code for aptitude, you
   can download unreleased aptitude source code using Git. Install Git
   (available from http://git-scm.com/) and execute the command git clone
   git://anonscm.debian.org/aptitude/aptitude.git to retrieve the most recent
   source code.

   [Warning] Warning
             The aptitude Git repository is an active development tree; it
             will change as bugs are fixed and features are added, and there
             is absolutely no guarantee that it will even compile, let alone
             run properly! Bug reports are welcome, but be aware that you use
             development code entirely at your own risk!^[1]

    Mailing list

   The primary mailing list for aptitude development is
   <aptitude-devel@lists.alioth.debian.org>. Archives of the list are located
   at http://lists.alioth.debian.org/pipermail/aptitude-devel/. To subscribe,
   visit the Web page
   http://lists.alioth.debian.org/mailman/listinfo/aptitude-devel.

    Submitting patches

   Ideally, patches should be submitted to the aptitude mailing list,
   <aptitude-devel@lists.alioth.debian.org>. But if you prefer sending them
   by private email, you may email them to <aptitude@packages.debian.org> or
   <dburrows@debian.org>. A brief description of the motivation behind your
   patch, and an explanation of how it works, are greatly appreciated.

    Tracking changes to the aptitude source tree

   The aptitude source tree is regularly updated with new features, bugfixes,
   and new bugs. Once the source code is available on your computer (see the
   previous section), you can cd into it and type git pull to update it with
   any changes made to the main repository.

   To automatically receive notifications when changes are made to the
   aptitude codebase, subscribe to the Atom feed available at
   http://anonscm.debian.org/gitweb/?p=aptitude/aptitude.git;a=atom or RSS
   feed available at
   http://anonscm.debian.org/gitweb/?p=aptitude/aptitude.git;a=rss.

    Building aptitude from the development tree

   To build aptitude from the Git repository, you must have the programs
   autoconf and automake installed. Type sh ./autogen.sh && ./configure to
   generate the files needed to compile aptitude, then execute make and make
   install.

   ══════════════════════════════════════════════════════════════════════════

   ^[1] Of course, all free software is used at your own risk, but the risk
   involved in using an active development tree is much higher.

                           Chapter 1. Getting started

   Table of Contents

   Using aptitude

   aptitude basics

   Navigating the aptitude package list

   Finding packages by name

   Managing packages

   Updating the package list and installing packages

   Using aptitude from the command line

          A journey of a thousand miles must begin with a single step.  
                                                                   -- Lao Tsu

   aptitude is a sizeable program with many features, and it can be a bit
   overwhelming for new users to get acquainted with it. This chapter does
   not exhaustively describe the features of aptitude (see Chapter 2,
   aptitude reference guide for that), but it does provide a walk-through of
   the basic and most commonly used features of the program.

Using aptitude

   This section describes how to use the visual interface of aptitude. For
   information on using aptitude's command-line interface, see the section
   called “Using aptitude from the command line”.

  aptitude basics

   To run aptitude, open your favorite text terminal, and at the command
   line, type:

 foobar$ aptitude

   Once the cache is loaded (this may take some time on slower machines), the
   main aptitude screen should appear:

  Actions  Undo  Package  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
 aptitude 0.2.14.1
 --- Installed Packages
 --- Not Installed Packages
 --- Obsolete and Locally Created Packages
 --- Virtual Packages
 --- Tasks






 These packages are currently installed on your computer.









   As you can see, the main screen of aptitude is divided into several
   regions. The blue line at the top of the terminal is the menu bar, and the
   blue lines below it are informational messages describing some important
   commands. The black space that follows is the list of all available
   packages, in which some groups of packages are listed. The currently
   selected group (“Installed Packages”) is highlighted, and its description
   is shown in the lower black space.

   As the top line of the screen suggests, you can access aptitude's menus by
   pressing Control+t (also valid: Control+Space and F10); you can also click
   the mouse on a menu title if your system supports it. Pressing Control+t
   will open the Actions menu:

  Actions  Undo  Package  Search  Options  Views  Help
 +-------------------------+  u: Update  g: Download/Install/Remove Pkgs
 |Install/remove packages g|
 |Update package list     u|
 |Forget new packages     f|
 |Clean package cache      |eated Packages
 |Clean obsolete files     |
 |Mark Upgradable         U|
 |Play Minesweeper         |
 |Become root              |
 +-------------------------+
 |Quit                    Q|
 +-------------------------+
 These packages are currently installed on your computer.









 Perform all pending installs and removals

   Use the arrow keys and Enter to select menu items (or, if your system
   supports it, click on them with a mouse); to close the menu without
   selecting anything, press Control+t again. The currently highlighted menu
   item is explained at the bottom of the screen. If a menu item can be
   activated using a keyboard shortcut, the shortcut is displayed in the
   menu: for instance, the command “Update package list” can be activated by
   pressing u.

   At any time, you can press ? to display an on-line reference to the
   available keyboard shortcuts.

  Navigating the aptitude package list

   The list of packages is the primary interface to aptitude. When aptitude
   starts, the list is organized into a number of groups, as can be seen in
   the following screen shot:

  Actions  Undo  Package  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
 aptitude 0.2.14.1
 --- Installed Packages
 --- Not Installed Packages
 --- Obsolete and Locally Created Packages
 --- Virtual Packages
 --- Tasks






 These packages are currently installed on your computer.









   [Note] Note
          Empty groups of packages are automatically hidden by aptitude, so
          you may see more or less groups than appear in this screen shot.

   In the screen shot above, the first group (“Installed Packages”) is
   highlighted to indicate that it is currently selected. You can move the
   selection up and down with the arrow keys; note that the description below
   the package list changes as you do so. To “expand” a group, press Enter
   while the group is selected:

  Actions  Undo  Package  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
 aptitude 0.2.14.1
 --\ Installed Packages
   --- admin - Administrative utilities (install software, manage users, etc)
   --- base - The Debian base system
   --- devel - Utilities and programs for software development
   --- doc - Documentation and specialized programs for viewing documentation
   --- editors - Text editors and word processors
   --- electronics - Programs for working with circuits and electronics
   --- games - Games, toys, and fun programs
   --- gnome - The GNOME Desktop System
   --- graphics - Utilities to create, view, and edit graphics files

 These packages are currently installed on your computer.









   As you can see, the “Installed Packages” group has been expanded to reveal
   its contents: it contains a number of subgroups, loosely defined by what
   types of software they contain. Expanding the “admin” section by selecting
   it and pressing Enter, we see:

  Actions  Undo  Package  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
 aptitude 0.2.14.1
 --\ Installed Packages
   --\ admin - Administrative utilities (install software, manage users, etc)
     --- main - The main Debian archive
   --- base - The Debian base system
   --- devel - Utilities and programs for software development
   --- doc - Documentation and specialized programs for viewing documentation
   --- editors - Text editors and word processors
   --- electronics - Programs for working with circuits and electronics
   --- games - Games, toys, and fun programs
   --- gnome - The GNOME Desktop System

 Packages in the 'admin' section allow you to perform administrative tasks such
 as installing software, managing users, configuring and monitoring your system,
 examining network traffic, and so on.







   The “admin” group contains a single subgroup, the “main” Debian archive.
   Expanding this group reveals some packages!

   [Tip] Tip
         To save time, you can use the [ key to expand all the subgroups of a
         group at once. Selecting “Installed Packages” and pressing [ would
         have immediately revealed the packages in the screenshot below.

  Actions  Undo  Package  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
 aptitude 0.2.14.1
 --\ Installed Packages
   --\ admin - Administrative utilities (install software, manage users, etc)
     --\ main - The main Debian archive
 i     acpid                                                1.0.3-19   1.0.3-19
 i     alien                                                8.44       8.44
 i     anacron                                              2.3-9      2.3-9
 i     apt-show-versions                                    0.07       0.07
 i A   apt-utils                                            0.5.25     0.5.25
 i     apt-watch                                            0.3.2-2    0.3.2-2
 i     aptitude                                             0.2.14.1-2 0.2.14.1-2

 The Debian distribution consists of packages from the 'main' section. Every
 package in 'main' is Free Software.

 For more information about what Debian considers to be Free Software, see
 http://www.debian.org/social_contract#guidelines





   In addition to the arrow keys, you can move the selection through the
   package list by a page of information at a time using the Page Up and Page
   Down keys.

   [Tip] Tip
         When there is more information in the lower half of the display than
         fits into the available space, the a and z keys can be used to
         scroll through it.

  Finding packages by name

   To quickly find a package whose name you know, press / to open a search
   dialog:

  Actions  Undo  Package  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
 aptitude 0.2.14.1
 i     frozen-bubble                                        1.0.0-5    1.0.0-5
 i A   frozen-bubble-data                                   1.0.0-5    1.0.0-5
 i     geekcode                                             1.7.3-1    1.7.3-1
 i     gfpoken                                              0.25-3     0.25-3
 i     ggz-gnome-client                                     0.0.7-2    0.0.7-2
 i     ggz-gtk-client                                       0.0.7-1    0.0.7-1
 i     ggz-gtk-game-data                                    0.0.7-2    0.0.7-2
 i +--------------------------------------------------------------------------+
 i |Search for:                                                               |
 i |froz                                                                      |
 Po|                             [ Ok ]                             [ Cancel ]|
 Fr+--------------------------------------------------------------------------+
 attempt to shoot bubbles into groups of the same color to cause them to pop. It
 features 100 single-player levels, a two-player mode, music and striking
 graphics.

 This game is widely rumored to be responsible for delaying the Woody release.

 URL: http://www.frozen-bubble.org/


   As you can see in the above screen shot, a search for froz finds the
   frozen-bubble package. Using aptitude's powerful search language,
   described in the section called “Search patterns”, it is possible to find
   packages based on many complex criteria.

   [Tip] Tip
         You can search backwards in the package list by pressing \, and you
         can repeat the last search by pressing n after closing the search
         window.

   Sometimes it is useful to hide all packages except those which meet some
   particular criterion. To do this, press l:

  Actions  Undo  Package  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
 aptitude 0.2.14.1
 --- Installed Packages
 --- Not Installed Packages
 --- Obsolete and Locally Created Packages
 --- Virtual Packages
 --- Tasks


   +--------------------------------------------------------------------------+
   |Enter the new package tree limit:                                         |
   |apti                                                                      |
   |                             [ Ok ]                             [ Cancel ]|
 Th+--------------------------------------------------------------------------+ a









   This dialog works exactly like the search dialog, except that instead of
   highlighting the next package that matches what you typed into the dialog
   box, it hides all packages which don't match. For instance, typing apti
   into this dialog box and pressing Enter will hide all packages except
   those whose names contain “apti”:

  Actions  Undo  Package  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
 aptitude 0.2.14.1
 --\ Installed Packages
   --\ admin - Administrative utilities (install software, manage users, etc)
     --\ main - The main Debian archive
 i     aptitude                                             0.2.14.1-2 0.2.14.1-2
 i A   synaptic                                             0.51-1     0.51-1
   --\ x11 - The X window system and related software
     --\ main - The main Debian archive
 i     xfree86-driver-synaptics                             0.13.3-1   0.13.3-1
 --- Not Installed Packages
 --- Virtual Packages

 These packages are currently installed on your computer.









  Managing packages

   Now that you can move about the list of packages, it's time to start using
   aptitude to install and remove packages. In this section you will learn
   how to flag packages for installation, deletion, and upgrade.

   [Tip] Tip
         You can only change your system's setup as the root user. If you
         want to experiment with aptitude, you can safely run it as any user
         other than root without damaging your system in any way. aptitude
         will tell you when you try to do something that only root can do,
         and if you want to continue, you must type root's password.

   All changes to a package are performed by first highlighting it in the
   package list, then pressing a key corresponding to the action which should
   be performed. The basic action keys ^[2] are + to install or upgrade a
   package, - to remove a package, and = to prevent a package from being
   automatically upgraded (this is known as holding the package). These
   actions are not performed immediately; aptitude will simply update the
   package list to show the change that has been requested.

   For instance, in the screen shot below, the kaffeine-mozilla package was
   selected and + was pushed. The package is now highlighted in green and the
   letter “i” has appeared to the left of its name, to indicate that it will
   be installed; in addition, an estimate of the amount of space that the
   package will use is displayed.

  Actions  Undo  Package  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
 aptitude 0.2.14.1                  Will use 2925kB of disk space  DL Size: 1375kB
   --\ kde - The KDE Desktop System
     --\ main - The main Debian archive
 p     bibletime-i18n                                        <none>     1.4.1-1
 p     education-desktop-kde                                 <none>     0.771
 p     junior-kde                                            <none>     1.4
 piA   kaffeine                                      +2843kB <none>     0.4.3-1
 pi    kaffeine-mozilla                              +81.9kB <none>     0.4.3-1
 p     karamba                                               <none>     0.17-5
 p     kde-devel                                             <none>     4:3.1.2
 p     kde-devel-extras                                      <none>     4:3.1.2
 The K Desktop Environment (development files)
 A metapackage containing dependencies for the core development suite of KDE
 including kdesdk, qt3-designer, and all core KDE -dev packages.








   [Tip] Tip
         At any time, you can use Undo → Undo (Control+u) to “undo” any
         change to one or more packages. This is very useful if an action has
         unforeseen consequences and you want to “take it back”.

   In addition to actions that affect individual packages, another important
   action is available: typing U will attempt to upgrade any packages that
   can be upgraded. You should use this command on a regular basis to keep
   your system up-to-date.

    Managing broken packages

   Sometimes, changing a package's state will cause dependency relationships
   to become unfulfilled; packages with unfulfilled dependencies are said to
   be broken. aptitude will warn you when this happens, and explain why it
   occured. For instance, here is what happens if I attempt to remove
   sound-juicer:

  Actions  Undo  Package  Resolver  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
 aptitude 0.3.3       #Broken: 1   Will free 48.6MB of disk space
 i A   nautilus                                             2.10.1-4   2.10.1-4
 i     nautilus-cd-burner                                   2.10.2-1.1 2.10.2-1.1
 i A   nautilus-data                                        2.10.1-4   2.10.1-4
 i     netspeed                                             0.12.1-1   0.12.1-1
 i A   oaf                                                  0.6.10-3   0.6.10-3
 i     pybliographer                                        1.2.6.2-1  1.2.6.2-1
 i     rhythmbox                                            0.8.8-13   0.8.8-13
 i     shermans-aquarium                                    3.0.1-1    3.0.1-1
 idA   sound-juicer                                 -1733kB 2.10.1-3   2.10.1-3
 GNOME 2 CD Ripper
 sound-juicer will be removed.


 The following packages depend on sound-juicer and will be broken by its
 removal:


   * gnome-desktop-environment depends on sound-juicer

 [1(1)/...] Suggest 2 keeps
 e: Examine  !: Apply  .: Next  ,: Previous

   As you can see, aptitude displays three indicators that something has gone
   wrong: first, the number of broken packages is displayed in the upper blue
   area; second, the lower half of the display changes to describe broken
   packages that are related to the currently highlighted package; third, a
   bar appears at the bottom of the screen with a suggestion on how to solve
   the problem. To quickly find broken packages in the package list, you can
   press b or search for ?broken.

   [Note] Note
          The text [1(1)/...] indicates the progress of aptitude's dependency
          resolver. The first number is the solution that you have currently
          selected, and the second one is the number of solutions that
          aptitude has already generated. The presence of the text “...”
          indicates that there may be additional solutions beyond the ones
          generated; if aptitude knew for certain that it had generated the
          only possible solution, this indicator would read [1/1].

   To see more information about how aptitude thinks you can solve this
   problem, press e. A screen similar to the following will appear:

  Actions  Undo  Package  Resolver  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
                 Packages                          Resolve Dependencies
   --\ Keep the following packages at their current version:
     gstreamer0.8-cdparanoia                           [0.8.10-1 (unstable, now)]
     sound-juicer                                                [2.10.1-2 (now)]
















 [1(1)/...] Suggest 2 keeps
 e: Examine  !: Apply  .: Next  ,: Previous

   From here, you can see more solutions by pressing . or return to solutions
   that you previously examined by pressing ,. To apply the current solution
   and return to the package list, press !. For instance, pressing . while
   the above screen is displayed results in the following solution being
   presented:

  Actions  Undo  Package  Resolver  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
                 Packages                          Resolve Dependencies
   --\ Keep the following packages at their current version:
     sound-juicer                                      [2.10.1-3 (unstable, now)]
   --\ Downgrade the following packages:
     gstreamer0.8-cdparanoia          [0.8.11-1 unstable, now -> 0.8.8-3 testing]















 [2(2)/...] Suggest 1 keep,1 downgrade
 e: Examine  !: Apply  .: Next  ,: Previous

   In addition to the basic solution navigation commands, you can press r to
   “reject” actions of which you disapprove. For instance, the first solution
   will cancel the removal of sound-juicer -- the very action we were trying
   to perform! By pressing r on the item corresponding to this action, we can
   tell aptitude that it should not cancel the removal of sound-juicer in
   this way.

  Actions  Undo  Package  Resolver  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
                 Packages                          Resolve Dependencies
   --\ Keep the following packages at their current version:
     gstreamer0.8-cdparanoia                           [0.8.11-1 (unstable, now)]
 R   sound-juicer                                      [2.10.1-3 (unstable, now)]






 GNOME 2 CD Ripper
 gnome-desktop-environment depends upon sound-juicer
 --\ The following actions will resolve this dependency:
   -> Remove gnome-desktop-environment [1:2.10.2.3 (unstable, testing, now)]
 R -> Cancel the removal of sound-juicer
   -> Downgrade sound-juicer [2.10.1-3 (unstable, now) -> 0.6.1-2 (testing)]




 [1(1)/...] Suggest 2 keeps
 e: Examine  !: Apply  .: Next  ,: Previous

   As you can see, the list item corresponding to keeping sound-juicer at its
   current version has turned red and been marked with an “R”, indicating
   that it has been rejected. Solutions that you generate in the future (that
   is, any solution that you have not yet viewed) will not include this
   action, although solutions that were already generated and contain this
   action will be available.

   [Note] Note
          In the above screen image, a description of sound-juicer is
          displayed in the middle of the screen; below it, you can see the
          dependency that caused sound-juicer to be kept at its current
          version, along with all the ways to resolve this dependency that
          aptitude knows about.

   For instance, if this rejection is imposed immediately after attempting to
   remove sound-juicer, pressing . retrieves the following solution, skipping
   the solution that cancels the installation of sound-juicer and downgrades
   gstreamer0.8-cdparanoia.

  Actions  Undo  Package  Resolver  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
                 Packages                          Resolve Dependencies
   --\ Remove the following packages:
     gnome-desktop-environment              [1:2.10.2.3 (unstable, testing, now)]

















 [2(2)/...] Suggest 1 removal
 e: Examine  !: Apply  .: Next  ,: Previous

   Rejections are only applied to newly generated solutions: that is,
   solutions that are generated when you press . while viewing the last
   generated solution. Previously generated solutions can still contain
   rejections. You can cancel a rejection at any time by once again selecting
   the rejected action and pressing r; this will permit solutions containing
   the action to be generated again, including any solutions that were
   previously “skipped”.

   The opposite of rejecting an action is approving it. To approve an action,
   just select it and press a; this forces the problem resolver to choose the
   action whenever possible^[3]. Approved actions will turn green and will be
   marked with “A”, as in the following screenshot:

  Actions  Undo  Package  Resolver  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
                 Packages                          Resolve Dependencies
   --\ Remove the following packages:
 A   gnome-desktop-environment              [1:2.10.2.3 (unstable, testing, now)]

















 [2(2)/...] Suggest 1 removal
 e: Examine  !: Apply  .: Next  ,: Previous

   [Important] Important
               If you do not resolve any broken dependencies, aptitude will
               automatically implement its current suggestion when you commit
               your selections by pressing g. However, it is hard to
               automatically solve dependency problems, and you may not be
               happy with the results, so it is generally better to look at
               what aptitude plans to do before committing your selections.

  Updating the package list and installing packages

   At this point, you know enough about aptitude to actually make
   modifications to your system.

   You should periodically update your list of available packages from the
   Debian servers, to keep track of new packages and new versions of
   packages. To do this, press u. At any time during the download, you can
   press q to abort it.

   Once you have fresh lists of packages, you can choose the packages to
   upgrade, install, or remove as described in the previous section. To
   review the actions you have requested, press g once. When installing the
   kaffeine-mozilla package (from the previous example), the following screen
   appears:

  Actions  Undo  Package  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
 aptitude 0.2.14.1                  Will use 2925kB of disk space  DL Size: 1375kB
 --\ Packages being automatically installed to satisfy dependencies
 piA kaffeine                                        +2843kB <none>     0.4.3-1
 --\ Packages to be installed
 pi  kaffeine-mozilla                                +81.9kB <none>     0.4.3-1







 These packages are being installed because they are required by another package
 you have chosen for installation.

 If you select a package, an explanation of its current state will appear in this
 space.





   As you can see, aptitude automatically decided to install kaffeine for me
   because kaffeine-mozilla requires it. At this point, I have the choice of
   either continuing with the installation by pressing g, or aborting it by
   pressing q.

Using aptitude from the command line

   In addition to its “visual” interface described in the previous section,
   aptitude can be used to manage packages directly from the command-line in
   the same way that you would use apt-get. This section covers the most
   common aptitude command-line actions; for more information, see the
   aptitude command-line reference.

   In general, a command-line invocation of aptitude will look like this:

   aptitude action [arguments...]

   action tells aptitude what action it is to take; the remaining arguments
   are used in an option-specific fashion. Typically they will consist of
   package names and command-line switches^[4].

   The most important actions are:

   aptitude update

   This command updates the package lists, as if you had entered the visual
   interface and pressed u.

   aptitude safe-upgrade

   This command will upgrade as many packages as it can upgrade without
   removing existing packages.

   It is sometimes necessary to remove one package in order to upgrade
   another; this command is not able to upgrade packages in such situations.
   Use the full-upgrade command to upgrade those packages as well.

   aptitude full-upgrade

   Like safe-upgrade, this command will attempt to upgrade packages, but it
   is more aggressive about solving dependency problems: it will install and
   remove packages until all dependencies are satisfied. Because of the
   nature of this command, it is possible that it will do undesirable things,
   and so you should be careful when using it.

   [Note] Note
          For historical reasons, this command was originally named
          dist-upgrade, and that name is still recognized by aptitude.

   aptitude [ install | remove | purge ] pkg1 [pkg2...]

   These commands install, remove, or purge^[5] the specified packages.
   “Installing” a package which is already installed but can be upgraded will
   cause it to be upgraded.

   aptitude search pattern1 [pattern2...]

   This command searches for packages whose name contains any of the given
   patterns, printing the result to the terminal. In addition to just being a
   string of text, each pattern can be a search pattern as described in the
   section called “Search patterns”. ^[6] For instance, “aptitude search
   gnome kde” will list all packages whose name contains either “gnome” or
   “kde”.

   aptitude show pkg1 [pkg2...]

   Prints information about each pkg to the terminal.

   The commands that install, upgrade, and remove packages all accept the
   parameter -s, which stands for “simulate”. When -s is passed on the
   command line, the program performs all the actions it would normally
   perform, but does not actually download or install/remove any files.

   aptitude will sometimes present a prompt like this:

 The following NEW packages will be automatically installed:
   space-orbit-common
 The following NEW packages will be installed:
   space-orbit space-orbit-common
 0 packages upgraded, 2 newly installed, 0 to remove and 0 not upgraded.
 Need to get 3200kB of archives. After unpacking 8413kB will be used.
 Do you want to continue? [Y/n/?]

   In addition to the obvious options of “Yes” and “No”, a number of commands
   are available which can be used to change the information displayed at the
   prompt, or to specify further actions. For instance, typing s will display
   or hide information about how much space each package will use:

 Do you want to continue? [Y/n/?] s

 Size changes will be shown.

 The following NEW packages will be automatically installed:
   space-orbit-common <+8020kB>
 The following NEW packages will be installed:
   space-orbit <+393kB> space-orbit-common <+8020kB>
 0 packages upgraded, 2 newly installed, 0 to remove and 0 not upgraded.
 Need to get 3200kB of archives. After unpacking 8413kB will be used.
 Do you want to continue? [Y/n/?]

   Similarly, typing d will display information about automatically installed
   or removed packages:

 The following NEW packages will be automatically installed:
   space-orbit-common (D: space-orbit)
 The following NEW packages will be installed:
   space-orbit space-orbit-common
 0 packages upgraded, 2 newly installed, 0 to remove and 0 not upgraded.
 Need to get 3200kB of archives. After unpacking 8413kB will be used.

   This shows that space-orbit-common is being installed because space-orbit
   depends on it. You can see the entire list of possible entries by entering
   ? at the prompt.

   If your request violates dependencies in a way that cannot be trivially
   resolved, aptitude will ask you what to do:

 The following packages are BROKEN:
   libsdl1.2debian
 The following packages will be REMOVED:
   libsdl1.2debian-alsa
 .
 .
 .
 The following actions will resolve these dependencies:

 Install the following packages:
 libsdl1.2debian-all [1.2.12-1 (unstable)]

 Score is 41

 Accept this solution? [Y/n/q/?]

   Typing y (or simply pressing enter) will accept the proposed solution.
   Typing n will display the “next best” solution:

 Accept this solution? [Y/n/q/?] n
 The following actions will resolve these dependencies:

 Install the following packages:
 libsdl1.2debian-esd [1.2.12-1 (unstable)]

 Score is 19

 Accept this solution? [Y/n/q/?]

   As with the main command-line prompt, you can perform a number of
   additional actions, including manually altering the states of packages,
   from the dependency resolution prompt. Type ? to see a complete list.

   Typing q will abort the automatic resolver and allow you to resolve the
   dependencies manually:

 Accept this solution? [Y/n/q/?] q
 aptitude failed to find a solution to these dependencies.  You can solve them yourself by hand or type 'n' to quit.
 The following packages have unmet dependencies:
   libsdl1.2debian: Depends: libsdl1.2debian-alsa (= 1.2.12-1) but it is not installable or
                             libsdl1.2debian-all (= 1.2.12-1) but it is not installable or
                             libsdl1.2debian-esd (= 1.2.12-1) but it is not installable or
                             libsdl1.2debian-arts (= 1.2.12-1) but it is not installable or
                             libsdl1.2debian-oss (= 1.2.12-1) but it is not installable or
                             libsdl1.2debian-nas (= 1.2.12-1) but it is not installable or
                             libsdl1.2debian-pulseaudio (= 1.2.12-1) but it is not installable
 Resolve these dependencies by hand? [N/+/-/_/:/?]

   You can use any of the package manipulation commands to resolve the broken
   dependencies (type ? for a full list of the available commands). Type n or
   press enter to quit aptitude:

 Resolve these dependencies by hand? [N/+/-/_/:/?] n
 Abort.

   For complete documentation of the command-line features of aptitude, see
   Command-line reference.

   ══════════════════════════════════════════════════════════════════════════

   ^[2] You can also change packages using the Package menu; see the section
   called “The Package menu” for details.

   ^[3] Approving an action is slightly different from requiring all
   solutions to contain the action; what it means is that given a choice
   between an approved action and a non-approved action, the resolver will
   always pick the approved action. If there are several possible approved
   actions, all of them will be candidates to be placed into the solution.

   ^[4] A “switch” is a letter preceded by a hyphen: for instance, “-a”,
   “-v”, etc.

   ^[5] Purging a package removes the package, as well as all its
   configuration files.

   ^[6] In fact, the same is true of the commands that take packages as
   arguments, such as install or show.

                      Chapter 2. aptitude reference guide

   Table of Contents

   The aptitude terminal user interface

   Using the menus

   Menu commands

   Working with multiple views

   Becoming root

   Managing packages

   Managing the package list

   Accessing package information

   Modifying package states

   Downloading, installing, and removing packages

   Understanding and managing package trust

   Managing automatically installed packages

   Resolving package dependencies

   Dependency resolution in aptitude

   Immediate dependency resolution

   Resolving Dependencies Interactively

   Costs in the interactive dependency resolver

   Configuring the interactive dependency resolver

   Search patterns

   Searching for strings

   Shorthand for search terms

   Searches and versions

   Explicit search targets

   Search term reference

   Customizing aptitude

   Customizing the package list

   Customizing keybindings

   Customizing text colors and styles

   Customizing the display layout

   Configuration file reference

   Themes

   Playing Minesweeper

     The White Rabbit put on his spectacles. 'Where shall I begin, please    
     your Majesty?' he asked.

     'Begin at the beginning,' the King said gravely, 'and go on till you
     come to the end: then stop.'
                                         -- Lewis Carrol, Alice in Wonderland

   aptitude is a large program with many features, and it is sometimes
   difficult to remember how to do something, or even to remember whether
   that something is even possible. Indeed, many feature requests received by
   the author describe features which are already present but are difficult
   to find.^[7]

   In an attempt to combat this obscurity, this reference guide describes
   every feature and configuration parameter of aptitude. For a more gentle
   guide to the important features of aptitude, see Chapter 1, Getting
   started.

   [Note] Note
          aptitude's behavior and appearance can be configured in a number of
          ways. This manual describes how the program works with the default
          settings; descriptions of how various settings affect behavior are
          given in the section called “Customizing aptitude”.

The aptitude terminal user interface

   This section describes the parts of the terminal-based user interface of
   aptitude that do not deal with managing packages.

  Using the menus

   The menu bar at the top of the screen lists the most important commands in
   aptitude. To activate the menu bar, press Control+t (also valid:
   Control+Space and F10); you can then navigate it using the arrow keys and
   select a menu item using Enter.

   Some menu items also have “hotkeys”: letters or numbers that can be used
   to select the item while the menu is active. These hotkeys are displayed
   in a brighter shade of white than the rest of the menu.

   In addition, some menu items have “shortcuts”: keystrokes that perform the
   same action as the menu item while the menu is not active. These
   keystrokes are listed on the right-hand side of the menu.

   In the remainder of the manual, menu commands will be written like this:
   Menu → Item (key). This indicates that you should choose Item from the
   Menu menu, and that key is the shortcut for this command.

  Menu commands

    The Actions menu

   Figure 2.1. Commands available in the Actions menu

   ┌────────────────────────────┬───────────────────────────────────────────┐
   │          Command           │                Description                │
   ├────────────────────────────┼───────────────────────────────────────────┤
   │                            │ If an installation preview is not         │
   │ Actions → Install/remove   │ visible, display one; otherwise, perform  │
   │ packages (g)               │ an install run as described in the        │
   │                            │ section called “Downloading, installing,  │
   │                            │ and removing packages”.                   │
   ├────────────────────────────┼───────────────────────────────────────────┤
   │ Actions → Update package   │ Bring the package list up-to-date.        │
   │ list (u)                   │                                           │
   ├────────────────────────────┼───────────────────────────────────────────┤
   │ Actions → Mark Upgradable  │ Flag all upgradable packages, except      │
   │ (U)                        │ those which are held or forbidden from    │
   │                            │ upgrading, for upgrade.                   │
   ├────────────────────────────┼───────────────────────────────────────────┤
   │ Actions → Forget new       │ Discard all information about what        │
   │ packages (f)               │ packages are “new” (empty the “New        │
   │                            │ Packages” tree).                          │
   ├────────────────────────────┼───────────────────────────────────────────┤
   │                            │ Cancel all pending actions from this      │
   │                            │ session (including installations,         │
   │ Actions → Cancel pending   │ removals, upgrades, holds, marking as     │
   │ actions                    │ automatically installed...). This is      │
   │                            │ roughly equivalent to restart the         │
   │                            │ program.                                  │
   ├────────────────────────────┼───────────────────────────────────────────┤
   │ Actions → Clean package    │ Delete all the compressed packages that   │
   │ cache                      │ were downloaded by aptitude ^[a].         │
   ├────────────────────────────┼───────────────────────────────────────────┤
   │                            │ Delete any compressed packages that were  │
   │                            │ downloaded by aptitude ^[a] and are no    │
   │ Actions → Clean obsolete   │ longer available. These are presumed to   │
   │ files                      │ be packages which are obsolete, and can   │
   │                            │ be deleted to save disk space without     │
   │                            │ requiring an otherwise unnecessary        │
   │                            │ download.                                 │
   ├────────────────────────────┼───────────────────────────────────────────┤
   │                            │ Play a game of Minesweeper, as described  │
   │ Actions → Play Minesweeper │ in the section called “Playing            │
   │                            │ Minesweeper”.                             │
   ├────────────────────────────┼───────────────────────────────────────────┤
   │ Actions → Become root      │ Continue working as the root user; see    │
   │                            │ the section called “Becoming root”.       │
   ├────────────────────────────┼───────────────────────────────────────────┤
   │ Actions → Quit (Q)         │ Quit aptitude, saving any changes to      │
   │                            │ package states.                           │
   ├────────────────────────────┴───────────────────────────────────────────┤
   │ ^[a] Or any other apt utility.                                         │
   └────────────────────────────────────────────────────────────────────────┘

    The Undo menu

   Figure 2.2. Commands available in the Undo menu

   ┌─────────────────────────┬──────────────────────────────────────────────┐
   │         Command         │                 Description                  │
   ├─────────────────────────┼──────────────────────────────────────────────┤
   │                         │ Cancel the effect of the last change to a    │
   │ Undo → Undo (Control+u) │ package's state, up to the last time         │
   │                         │ aptitude was started, the package list was   │
   │                         │ updated, or an install run was performed.    │
   └─────────────────────────┴──────────────────────────────────────────────┘

    The Package menu

   Figure 2.3. Commands available in the Package menu

   ┌───────────────────────┬────────────────────────────────────────────────┐
   │        Command        │                  Description                   │
   ├───────────────────────┼────────────────────────────────────────────────┤
   │ Package → Install (+) │ Flag the currently selected package for        │
   │                       │ installation.                                  │
   ├───────────────────────┼────────────────────────────────────────────────┤
   │ Package → Reinstall   │ Flag the currently selected package for        │
   │ (L)                   │ reinstallation.                                │
   ├───────────────────────┼────────────────────────────────────────────────┤
   │ Package → Remove (-)  │ Flag the currently selected package for        │
   │                       │ removal.                                       │
   ├───────────────────────┼────────────────────────────────────────────────┤
   │ Package → Purge (_)   │ Flag the currently selected package to be      │
   │                       │ purged.                                        │
   ├───────────────────────┼────────────────────────────────────────────────┤
   │                       │ Cancel any pending installation, upgrade, or   │
   │ Package → Keep (:)    │ removal of the currently selected package, and │
   │                       │ remove any hold that was set on the package.   │
   ├───────────────────────┼────────────────────────────────────────────────┤
   │ Package → Hold (=)    │ Hold the currently selected package back.      │
   ├───────────────────────┼────────────────────────────────────────────────┤
   │                       │ Mark the currently selected package as an      │
   │ Package → Mark Auto   │ “automatically installed” package. For more    │
   │ (M)                   │ information on manually and automatically      │
   │                       │ installed packages, see the section called     │
   │                       │ “Managing automatically installed packages”.   │
   ├───────────────────────┼────────────────────────────────────────────────┤
   │                       │ Mark the currently selected package as a       │
   │ Package → Mark Manual │ “manually installed” package. For more         │
   │ (m)                   │ information on manually and automatically      │
   │                       │ installed packages, see the section called     │
   │                       │ “Managing automatically installed packages”.   │
   ├───────────────────────┼────────────────────────────────────────────────┤
   │                       │ If a package that can be upgraded is selected, │
   │ Package → Forbid      │ forbid it from being upgraded to the currently │
   │ Version (F)           │ available version. If a version of a package   │
   │                       │ is selected, forbid the package from being     │
   │                       │ upgraded to that version.                      │
   ├───────────────────────┼────────────────────────────────────────────────┤
   │                       │ Display a screen containing information about  │
   │ Package → Information │ the currently selected package, such as the    │
   │ (enter)               │ packages it depends upon, the packages which   │
   │                       │ depend upon it, and its available versions.    │
   ├───────────────────────┼────────────────────────────────────────────────┤
   │                       │ When browsing the package list, cycles through │
   │                       │ the information that can be displayed in the   │
   │                       │ information area (the lower half of the        │
   │ Package → Cycle       │ display). The information area can display the │
   │ Information (i)       │ long description of the selected package (its  │
   │                       │ default behavior), a summary of the            │
   │                       │ dependencies related to the package, or an     │
   │                       │ analysis of which other packages require or    │
   │                       │ suggest the selected package.                  │
   ├───────────────────────┼────────────────────────────────────────────────┤
   │                       │ Display the currently selected package's       │
   │ package → Changelog   │ Debian changelog. To see the changelog of a    │
   │ (C)                   │ particular version, select that version and    │
   │                       │ execute this command.                          │
   └───────────────────────┴────────────────────────────────────────────────┘

    The Resolver menu

   Figure 2.4. Commands available in the Resolver menu

   ┌───────────────┬────────────────────────────────────────────────────────┐
   │    Command    │                      Description                       │
   ├───────────────┼────────────────────────────────────────────────────────┤
   │ Resolver →    │ Display a detailed description of the problem          │
   │ Examine       │ resolver's current suggestion (see the section called  │
   │ Solution (e)  │ “Resolving Dependencies Interactively”).               │
   ├───────────────┼────────────────────────────────────────────────────────┤
   │ Resolver →    │ Carry out the actions that the problem resolver is     │
   │ Apply         │ currently suggesting.                                  │
   │ Solution (!)  │                                                        │
   ├───────────────┼────────────────────────────────────────────────────────┤
   │ Resolver →    │                                                        │
   │ Next Solution │ Select the problem resolver's next suggestion.         │
   │ (.)           │                                                        │
   ├───────────────┼────────────────────────────────────────────────────────┤
   │ Resolver →    │                                                        │
   │ Previous      │ Select the problem resolver's previous suggestion.     │
   │ Solution (,)  │                                                        │
   ├───────────────┼────────────────────────────────────────────────────────┤
   │ Resolver →    │                                                        │
   │ First         │ Select the problem resolver's first suggestion.        │
   │ Solution (<)  │                                                        │
   ├───────────────┼────────────────────────────────────────────────────────┤
   │ Resolver →    │ Select the problem resolver's most recently generated  │
   │ Last Solution │ solution (see the section called “Resolving            │
   │ (>)           │ Dependencies Interactively”).                          │
   ├───────────────┼────────────────────────────────────────────────────────┤
   │               │ When examining a solution, toggle whether the          │
   │ Resolver →    │ currently selected action is rejected and move to the  │
   │ Toggle        │ next action (see the section called “Resolving         │
   │ Rejected (r)  │ Dependencies Interactively”). If the action is         │
   │               │ currently approved, its approval will be cancelled.    │
   ├───────────────┼────────────────────────────────────────────────────────┤
   │               │ When examining a solution, toggle whether the          │
   │ Resolver →    │ currently selected action is approved and move to the  │
   │ Toggle        │ next action (see the section called “Resolving         │
   │ Approved (a)  │ Dependencies Interactively”). If the action is         │
   │               │ currently rejected, its rejection will be cancelled.   │
   ├───────────────┼────────────────────────────────────────────────────────┤
   │ Resolver →    │ When examining a solution, view detailed information   │
   │ View Target   │ about the package which is affected by the currently   │
   │ (Enter)       │ selected action (see the section called “Resolving     │
   │               │ Dependencies Interactively”).                          │
   ├───────────────┼────────────────────────────────────────────────────────┤
   │               │ Reject (as if with Resolver → Toggle Rejected (r)) all │
   │ Resolver →    │ actions that would break a hold on a package or        │
   │ Reject        │ install a forbidden version. These actions are         │
   │ Breaking      │ rejected by default unless                             │
   │ Holds         │ Aptitude::ProblemResolver::Allow-Break-Holds is set to │
   │               │ true, but this menu item allows you to reject them     │
   │               │ manually at any time.                                  │
   └───────────────┴────────────────────────────────────────────────────────┘

    The Search menu

   Figure 2.5. Commands available in the Search menu

   ┌──────────────────────────┬─────────────────────────────────────────────┐
   │         Command          │                 Description                 │
   ├──────────────────────────┼─────────────────────────────────────────────┤
   │                          │ Find the next package in the package list   │
   │ Search → Find (/)        │ that matches a search pattern (see the      │
   │                          │ section called “Search patterns”).          │
   ├──────────────────────────┼─────────────────────────────────────────────┤
   │ Search → Find Backwards  │ Find the previous package in the package    │
   │ (\)                      │ list that matches a search pattern (see the │
   │                          │ section called “Search patterns”).          │
   ├──────────────────────────┼─────────────────────────────────────────────┤
   │ Search → Find Again (n)  │ Repeat the last Find command.               │
   ├──────────────────────────┼─────────────────────────────────────────────┤
   │                          │ Repeat the last Find command, but in the    │
   │ Search → Find Again      │ opposite direction. If the last Find        │
   │ Backwards (N)            │ command was Find Backwards, this will       │
   │                          │ perform a forwards search, and vice versa.  │
   ├──────────────────────────┼─────────────────────────────────────────────┤
   │                          │ Filter the current package list by removing │
   │ Search → Limit Display   │ any packages which do not match a search    │
   │ (l)                      │ pattern (see the section called “Search     │
   │                          │ patterns”).                                 │
   ├──────────────────────────┼─────────────────────────────────────────────┤
   │ Search → Un-Limit        │ Un-filter the current package list (all     │
   │ Display                  │ packages will be shown).                    │
   ├──────────────────────────┼─────────────────────────────────────────────┤
   │ Search → Find Broken (b) │ Find the next broken package. This is       │
   │                          │ equivalent to searching for ?broken.        │
   └──────────────────────────┴─────────────────────────────────────────────┘

    The Options menu

   Figure 2.6. Commands available in the Options menu

   ┌───────────────────────┬────────────────────────────────────────────────┐
   │        Command        │                  Description                   │
   ├───────────────────────┼────────────────────────────────────────────────┤
   │                       │ Open a new top-level view in which you can     │
   │                       │ modify aptitude's settings. Configuration      │
   │                       │ options are displayed in a tree similar to the │
   │ Options → Preferences │ tree of packages; to enable or disable an      │
   │                       │ option, select it and press Space or Enter.    │
   │                       │ Configuration options are saved to             │
   │                       │ ~/.aptitude/config immediately upon being      │
   │                       │ selected.                                      │
   ├───────────────────────┼────────────────────────────────────────────────┤
   │ Options → Revert      │ Reset all options to their default values.     │
   │ options               │                                                │
   └───────────────────────┴────────────────────────────────────────────────┘

    The Views menu

   [Note] Note
          For an overview of how views work, see the section called “Working
          with multiple views”.

   Figure 2.7. Commands available in the Views menu

   ┌─────────────────────────────┬──────────────────────────────────────────┐
   │           Command           │               Description                │
   ├─────────────────────────────┼──────────────────────────────────────────┤
   │ Views → Next (F6)           │ Change to the next active view.          │
   ├─────────────────────────────┼──────────────────────────────────────────┤
   │ Views → Prev (F7)           │ Change to the previous active view.      │
   ├─────────────────────────────┼──────────────────────────────────────────┤
   │ Views → Close (q)           │ Close the current view.                  │
   ├─────────────────────────────┼──────────────────────────────────────────┤
   │ Views → New Package View    │ Create a new view of the package list.   │
   ├─────────────────────────────┼──────────────────────────────────────────┤
   │                             │ Create a view that displays packages     │
   │ Views → Audit               │ which are not installed, and which a     │
   │ Recommendations             │ package installed on your system         │
   │                             │ Recommends.                              │
   ├─────────────────────────────┼──────────────────────────────────────────┤
   │ Views → New Flat Package    │ Create a new view of the package list in │
   │ List                        │ which packages are not categorized.      │
   ├─────────────────────────────┼──────────────────────────────────────────┤
   │                             │ Create a new view of the package list in │
   │ Views → New Debtags Browser │ which packages are categorized according │
   │                             │ to their debtags entries.                │
   ├─────────────────────────────┼──────────────────────────────────────────┤
   │                             │ A number of additional menu items        │
   │                             │ appear; these correspond to the          │
   │ Additional items            │ currently active views. To switch        │
   │                             │ directly to a view, select it from the   │
   │                             │ menu.                                    │
   └─────────────────────────────┴──────────────────────────────────────────┘

    The Help menu

   Figure 2.8. Commands available in the Help menu

   ┌──────────────────────┬─────────────────────────────────────────────────┐
   │       Command        │                   Description                   │
   ├──────────────────────┼─────────────────────────────────────────────────┤
   │ Help → About         │ Display some copyright information.             │
   ├──────────────────────┼─────────────────────────────────────────────────┤
   │ Help → Help (?)      │ Display the on-line help page.                  │
   ├──────────────────────┼─────────────────────────────────────────────────┤
   │ Help → User's Manual │ Display the User's Manual (this document).      │
   ├──────────────────────┼─────────────────────────────────────────────────┤
   │ Help → FAQ           │ Display the aptitude FAQ.                       │
   ├──────────────────────┼─────────────────────────────────────────────────┤
   │ Help → ChangeLog     │ Display a history of the major changes made to  │
   │                      │ aptitude.                                       │
   ├──────────────────────┼─────────────────────────────────────────────────┤
   │ Help → License       │ Display the terms under which you may copy,     │
   │                      │ modify, and distribute aptitude.                │
   └──────────────────────┴─────────────────────────────────────────────────┘

  Working with multiple views

   aptitude allows you to work with several “views” at once. A “view”
   (sometimes called a “screen”) is simply something that can appear in the
   area of the screen below the menu bar. The most common view is the package
   list, but download views are also common.

   When several views are open at once, a bar listing all the active views
   will appear at the top of the screen. For instance, if I examine apt by
   pressing Enter, then examine libc6, the screen will look something like
   this:

  Actions  Undo  Package  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
          Packages                  apt info                  libc6 info
 aptitude 0.3.1
 i A  --\ libc6                                             2.3.2.ds1- 2.3.2.ds1-
   Description: GNU C Library: Shared libraries and Timezone data
     Contains the standard libraries that are used by nearly all programs on the
     system. This package includes shared versions of the standard C library and
     the standard math library, as well as many others. Timezone data is also
     included.
   Priority: required
   Section: base
   Maintainer: GNU Libc Maintainers <debian-glibc@lists.debian.org>
   Compressed size: 4901k
   Uncompressed size: 15.9M
   Source Package: glibc
   --\ Depends
     --- libdb1-compat
   --\ Suggests
     --- locales
     --- glibc-doc
   --\ Conflicts
 GNU C Library: Shared libraries and Timezone data

   You can close the current view using Views → Close (q). To switch to the
   next or previous view, use Views → Next (F6) and Views → Prev (F7), or
   click on the view's name at the top of the screen; you can also find a
   list of all active views in the Views menu.

   As shown above, some commands (for instance, viewing information about a
   package) will create new views automatically; you can also explicitly
   create a new view using Views → New Package View.

  Becoming root

   Some actions, such as updating the package lists, can only be performed as
   root. If you are not root and you try to update the package lists,
   aptitude will ask if you want to become root:

  Actions  Undo  Package  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
 aptitude 0.2.14.1
 --- Installed Packages
 --- Not Installed Packages
 --- Obsolete and Locally Created Packages
 --- Virtual Packages
 --- Tasks

   +-------------------------------------------------------------------------+
   |Updating the package lists requires administrative privileges, which     |
   |you currently do not have.  Would you like to change to the root account?|
   |                                                                         |
   |         [ Become root ]                  [ Don't become root ]          |
 Th+-------------------------------------------------------------------------+









   If you select “Become root”, aptitude will prompt you for root's password;
   when you have correctly entered it, aptitude will perform the action that
   required root privileges. You will still be root after the action
   completes.

   You can switch to the root account at any time using the command Actions →
   Become root. Any changes you have made to package states will be preserved
   (but will not be saved until you quit aptitude).

   By default, aptitude will use the command su to gain root privileges. If
   you would like it to use some other command (such as sudo), set the
   configuration option Aptitude::Get-Root-Command.

Managing packages

   This section describes how to manipulate the list of packages, how to
   install new packages on your system, and how to remove old packages.

  Managing the package list

   To keep the list of packages up-to-date, it is recommended that you
   periodically update it. You can do this using the Actions → Update package
   list (u) command.

  Accessing package information

   Information about packages is presented in several locations in aptitude:
   the package list gives a quick overview of the state of each package, and
   additional views providing detailed information about a package are also
   available.

    The package list

   The package list displays an “at-a-glance” synopsis of a package's state.
   For instance, the package webmin might have the following synopsis:

 piAU  webmin                                        +5837kB <none>     1.160-2

   The four characters on the left-hand side of the synopsis show that the
   package is not installed (“p”), that it is going to be installed (“i”),
   that it was automatically chosen to be installed (“A”), and that it is
   untrusted (“U”). On the right-hand side of the synopsis, the current
   version and the most recent available version are displayed, along with an
   indication of how much space will be used by the upgrade.

   [Tip] Tip
         You can customize how package synopses are displayed; see the
         section called “Customizing how packages are displayed” for details.

   The four status flags on the left-hand side of the screen give the basic
   information about a package's state. The first character is the package's
   current state. The second character is the action which will be taken on
   the package. The third character indicates whether the package was
   automatically installed (see the section called “Managing automatically
   installed packages”), and the fourth character indicates whether the
   package is trusted (see the section called “Understanding and managing
   package trust”).

   The possible values of the “current state” flag are given in Figure 2.9,
   “Values of the “current state” flag” and the possible values of the
   “action” flag are given in Figure 2.10, “Values of the “action” flag”.

   Figure 2.9. Values of the “current state” flag

   i - the package is installed and all its dependencies are satisfied.
   c - the package was removed, but its configuration files are still
       present.
   p - the package and all its configuration files were removed, or the
       package was never installed.
   v - the package is virtual.
   B - the package has broken dependencies.
   u - the package has been unpacked but not configured.
   C - half-configured: the package's configuration was interrupted.
   H - half-installed: the package's installation was interrupted.
   W - triggers-awaited: the package awaits trigger processing by another
       package.
   T - triggers-pending: The package has had an update triggered due to
       changes in another package.

   Figure 2.10. Values of the “action” flag

   i - the package will be installed.
   u - the package will be upgraded.
   w - the package will be downgraded.
   d - the package will be deleted: it will be removed, but its configuration
       files will remain on the system.
   p - the package will be purged: it and its configuration files will be
       removed.
       the package will be held back: it will be kept at its current version,
   h - even if a newer version becomes available, until the hold is
       cancelled.
   F - An upgrade of the package has been forbidden.
   r - the package will be reinstalled.
       the package is “broken”: some of its dependencies will not be
   B - satisfied. aptitude will not allow you to install, remove, or upgrade
       anything while you have broken packages.

   In addition, aptitude will use colors to indicate package state if your
   terminal supports it. State distinctions are mainly displayed using the
   background color:

   Black

   The package cannot be upgraded (or is not going to be installed), and it
   has no dependency problems. If the package is installed, its name will be
   highlighted.

   Green

   The package is going to be installed.

   Blue

   The package is currently installed, and it will be upgraded.

   Brown

   The package is currently installed, and it will be downgraded.

   Magenta

   The package is currently installed, but it will be removed.

   White

   The package is currently installed, and it is “held” at its current
   version: automatic upgrades will ignore it.

   Red

   This package is broken: some of its dependencies will not be satisfied.

   Finally, the lower half of the screen displays the long description.
   aptitude will attempt to detect whether the package is involved in a
   dependency problem; if so, information regarding the dependency problem
   will be displayed here. To cycle between dependency information and the
   package description, press i.

    Detailed package information

   Pressing Enter while a package is highlighted will display the package
   information screen:

  Actions  Undo  Package  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
 aptitude 0.2.14.1
 i A --\ apt                                                0.5.25     0.5.25
   Description: Advanced front-end for dpkg
     This is Debian's next generation front-end for the dpkg package manager. It
     provides the apt-get utility and APT dselect method that provides a simpler,
     safer way to install and upgrade packages.

     APT features complete installation ordering, multiple source capability and
     several other unique features, see the Users Guide in apt-doc.
   Essential: yes
   Priority: important
   Section: base
   Maintainer: APT Development Team <deity@lists.debian.org>
   Compressed size: 970k
   Uncompressed size: 2961k
   Source Package: apt
   --\ Depends
     --- libc6 (>= 2.3.2.ds1-4)
     --- libgcc1 (>= 1:3.3.3-1)
     --- libstdc++5 (>= 1:3.3.3-1)
   --\ Suggests
     --- aptitude | synaptic | gnome-apt | wajig
     --- dpkg-dev
     --\ apt-doc (UNSATISFIED)
 p     0.6.25
 p     0.5.25
   --\ Replaces
     --- libapt-pkg-doc (< 0.3.7)
     --- libapt-pkg-dev (< 0.3.7)
   --- Package names provided by apt
   --- Packages which depend on apt
   --\ Versions
 p A 0.6.25
 i A 0.5.25


   This display can be navigated in a manner similar to the package list: for
   instance, in the screenshot above, I expanded the dependency on apt-doc,
   revealing the available versions of apt-doc which will fulfill the
   dependency. These versions can be manipulated in the same way that
   packages can: for instance, to install version 0.5.25 of apt-doc, you
   would highlight it and press +.

   [Tip] Tip
         To quickly satisfy a dependency, select the dependency and press +;
         aptitude will attempt to automatically satisfy it.

   In addition to the dependencies of a package, you can view the package
   names that it Provides, the packages which depend upon it, and the
   available versions of the package (including any other packages that
   Provide it).

   As usual, you can dismiss this screen and return to the main view by
   pressing q. For convenience, a few other information screens (which only
   display some commonly-used information, hiding the rest) are available:
   press v to view the versions of a package, d to view the dependencies of a
   package, and r to view the “reverse dependencies” of a package (packages
   which depend upon it).

  Modifying package states

   The following commands are available to modify the states of packages.
   Commands take effect the next time you perform an install run; until you
   do, all of these commands can be reversed using Undo → Undo (Control+u).

   To apply a command to a package, simply select the package in a package
   list and issue the command. These commands can also be applied to groups
   of packages by selecting the group header (for instance, “Upgradable
   Packages”) and issuing the command.

   ┌────────────────────────┬───────────────────────────────────────────────┐
   │        Command         │                  Description                  │
   ├────────────────────────┼───────────────────────────────────────────────┤
   │                        │ Flag the current package for installation.    │
   │                        │                                               │
   │ Install: Package →     │ If the package is not installed, it will be   │
   │ Install (+)            │ installed. If it is already installed, it     │
   │                        │ will be upgraded if possible and any sticky   │
   │                        │ upgrade prevention that is in effect (eg,     │
   │                        │ Hold) will be cancelled.                      │
   ├────────────────────────┼───────────────────────────────────────────────┤
   │                        │ Flag the currently selected package for       │
   │ Remove: Package →      │ removal.                                      │
   │ Remove (-)             │                                               │
   │                        │ If the package is installed, it will be       │
   │                        │ removed.                                      │
   ├────────────────────────┼───────────────────────────────────────────────┤
   │                        │ Flag the current package to be purged.        │
   │                        │                                               │
   │ Purge: Package → Purge │ If the package is installed, it will be       │
   │ (_)                    │ removed. Furthermore, even if it is removed,  │
   │                        │ any remaining files (such as configuration    │
   │                        │ files) related to the package will be removed │
   │                        │ from the system.                              │
   ├────────────────────────┼───────────────────────────────────────────────┤
   │                        │ Flag the current package to be kept at its    │
   │                        │ current version.                              │
   │ Keep: Package → Keep   │                                               │
   │ (:)                    │ Any action that was to be performed on the    │
   │                        │ package -- installation, removal, or upgrade  │
   │                        │ -- is cancelled, and any persistent hold that │
   │                        │ was set on the package is removed.            │
   ├────────────────────────┼───────────────────────────────────────────────┤
   │                        │ Set a persistent hold on the package.         │
   │                        │                                               │
   │                        │ As with Keep, any action that was to be       │
   │ Hold: Package → Hold   │ performed on the package is cancelled. In     │
   │ (=)                    │ addition, the package will not be             │
   │                        │ automatically upgraded ^[a] until the hold is │
   │                        │ removed. You may cancel a hold by issuing the │
   │                        │ Install command.                              │
   ├────────────────────────┼───────────────────────────────────────────────┤
   │                        │ The package will not be automatically         │
   │                        │ upgraded^[a] to the version it would          │
   │                        │ currently be upgraded to. If it was going to  │
   │                        │ be upgraded, the upgrade will be cancelled.   │
   │                        │                                               │
   │                        │ If you issue this command on a particular     │
   │ Package → Forbid       │ version of a package, the package will not be │
   │ Version (F)            │ upgraded to the selected version. Note that   │
   │                        │ only one version can be forbidden at once.    │
   │                        │                                               │
   │                        │ This functionality is largely provided as a   │
   │                        │ convenience for users of the “unstable”       │
   │                        │ distribution, so they can avoid known-bad     │
   │                        │ versions of packages.                         │
   ├────────────────────────┼───────────────────────────────────────────────┤
   │                        │ Flag the current package for reinstallation.  │
   │                        │                                               │
   │                        │ Note that the reinstallation will not be      │
   │ Reinstall: Package →   │ saved when you quit aptitude or perform an    │
   │ Reinstall (L)          │ install run, for technical reasons            │
   │                        │ (essentially, the underlying software layers  │
   │                        │ (dpkg and apt) do not provide any way to find │
   │                        │ out whether a reinstallation was successful   │
   │                        │ or not).                                      │
   ├────────────────────────┼───────────────────────────────────────────────┤
   │                        │ Sets whether the package is treated as having │
   │ Package → Mark Auto    │ been automatically installed; automatically   │
   │ (M), Package → Mark    │ installed packages will be removed when no    │
   │ Manual (m)             │ other package requires them. For more         │
   │                        │ information, see the section called “Managing │
   │                        │ automatically installed packages”.            │
   ├────────────────────────┴───────────────────────────────────────────────┤
   │ ^[a] That is, it will be unaffected by Actions → Mark Upgradable (U)   │
   │ or the full-upgrade or safe-upgrade command-line actions.              │
   └────────────────────────────────────────────────────────────────────────┘

   In addition to these commands that affect the selected package, there are
   two commands that affect large numbers of packages at once regardless of
   what is selected. Actions → Forget new packages (f) clears the “new”
   status of all packages in the package list, and Actions → Mark Upgradable
   (U) flags every package which can be upgraded for upgrade, except for
   packages that are held back or would be upgraded to a forbidden version.

   [Note] Note
          All changes to package states are saved when you quit aptitude,
          update the package list, or perform an install run. If you do not
          wish to save your changes, you can always abort aptitude by
          pressing Ctrl-C.

  Downloading, installing, and removing packages

   Changing package states as described in the previous section does not
   actually affect what is installed on your system. Thus, you can adjust the
   state of packages without affecting your system until you are happy with
   what you see; once you are, you can “commit” the changes by actually
   installing and removing packages.^[8]

   To commit your changes, use the Actions → Install/remove packages (g)
   command. Selecting this command will display a preview screen describing
   the changes that will be performed. This screen is just a package list,
   and you can manipulate the packages (for instance, cancelling unwanted
   removals) in the same way that you could in the main list.

   When you are done, use Views → Close (q) to cancel the installation, or
   use Actions → Install/remove packages (g) to proceed. aptitude will
   download any files that need to be downloaded, then prompt you to continue
   with the installation. When you select “Continue”, the installations and
   removals will commence.

   Packages that are downloaded by aptitude are placed in a cache directory
   (typically /var/cache/apt/archives). Normally, they are just left in this
   directory ad infinitum. To delete all the files in this directory, use
   Actions → Clean package cache; to delete only files which cannot be
   downloaded again (ie, obsolete packages), use Actions → Clean obsolete
   files.

  Understanding and managing package trust

   apt's ability to access multiple package sources leads to a potential
   security vulnerability. Suppose you add an archive of packages published
   by Joe Random Hacker to your sources.list file in order to install Joe's
   gargleblast package. It is possible, however, that -- unbeknownst to you
   -- Joe's archive also contains his own “customized” versions of packages
   such as libc6 and ssh...versions that steal your private information or
   open backdoors on your system! If these packages have higher version
   numbers than the legitimate Debian packages, apt will blithely install
   them on your system during your next upgrade, allowing Joe to do his dirty
   work undetected. Joe could also break into your mirror of the Debian
   archives and replace the legitimate software with his doctored version.

   Luckily, newer versions of apt and aptitude, such as the version
   documented in this manual, have built-in safeguards to help defeat this
   type of attack. apt uses strong security mechanisms based on the popular
   GPG encryption software to verify that the packages being distributed from
   the official Debian mirrors are the same packages that were uploaded by
   the Debian developers. aptitude will then warn you if you attempt to
   install a package from a non-Debian source, or if you attempt to upgrade a
   package that was installed from a Debian source to a version that came
   from a non-Debian source.

   [Warning] Warning
             The security mechanisms in apt provide a near-perfect guarantee
             that the contents of your archive mirror are identical to the
             contents of the master Debian archive. However, they are not a
             panacea: for instance, there are many ways that a tampered
             package could theoretically find its way into the master Debian
             archive.

             Ensuring that you only install software from a trusted source
             will give you an important degree of protection against
             malicious packages, but it cannot eliminate all the risks
             inherent in installing software.

    Understanding trust

   apt allows the administrator of an archive to provide a signature of the
   archive's index. This signature, which (for all practical purposes) cannot
   be forged, indicates that the package files listed in the index are the
   same files that the administrator intended to place in the archive: ie,
   that the contents of the archive have not been tampered with since it was
   created.^[9] The signature can be validated by checking that it
   corresponds to the administrator's public key. The public key of the
   Debian archive is distributed with apt, typically on your Debian CD.

   When aptitude downloads an archive index, it will check whether the index
   is properly signed. If it is unsigned, aptitude will not trust package
   files from that archive. (see below for information on what this means) If
   it has a signature but the signature is incorrect or cannot be verified, a
   warning will be printed and aptitude will refuse to trust packages from
   that archive.

   Later, when you perform an install run, aptitude will check whether the
   packages are from trusted sources. If an untrusted package is being
   installed, or a package is being upgraded from a trusted to an untrusted
   version, a warning will be displayed and you will have the opportunity to
   abort the download:

  Actions  Undo  Package  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
 aptitude 0.3.0                    Will use 831kB of disk space   DL Size: 30.4MB
 --\ Packages to be upgraded
 iu U wesnoth                                       -98.3kB 0.8.7-1    0.8.8-1.0w
 iuAU wesnoth-data                                  +930kB  0.8.7-1    0.8.8-1.0w
 +------------------------------------------------------------------------------+
 |WARNING: untrusted versions of the following packages will be installed!     #|
 |                                                                             #|
 |Untrusted packages could compromise your system's security.  You should only #|
 |proceed with the installation if you are certain that this is what you want  #|
 |to do.                                                                       #|
 |                                                                             #|
 |  * wesnoth [version 0.8.8-1.0wesnoth.org]                                   #|
 |  * wesnoth-data [version 0.8.8-1.0wesnoth.org]                              #|
 |  * wesnoth-music [version 0.8.8-1.0wesnoth.org]                             #|
 |         [ Really Continue ]                  [ Abort Installation ]          |
 +------------------------------------------------------------------------------+
                                                                                #
                                                                                #
                                                                                #
                                                                                #
                                                                                #
                                                                                #

    Trusting additional keys

   You might find it useful to allow apt to trust additional archives,
   besides the main Debian archive. For each archive that you want to trust,
   you will have to acquire the public key that is used to sign the archive's
   package index. This is typically a text file whose name ends in .asc; it
   might be provided by the site administrator or downloadable from a public
   keyserver. For more information on what public keys are and how to get
   them, see the GPG web page.

   The list of keys that apt will trust is stored in the keyring file
   /etc/apt/trusted.gpg. Once you have the GPG key, you can add it to this
   file by executing the command gpg --no-default-keyring --keyring
   /etc/apt/trusted.gpg --import newkey.asc. aptitude will then trust any
   archive that is signed with the key contained in newkey.asc.

   [Warning] Warning
             Once an archive's key has been added to the APT keyring, it will
             be trusted just as much as the main Debian mirrors themselves!
             You should only do this if you are very confident that the key
             you are adding is correct and that the person who holds the key
             is trustworthy and competent.

  Managing automatically installed packages

   To install one package, it is often necessary to install several others
   (to fulfill its dependencies). For instance, if you wish to install the
   clanbomber package, you must also install the package libclanlib2. If you
   remove clanbomber again, you probably no longer need the libclanlib2
   package; aptitude will attempt to detect this and automatically remove the
   libclanlib2 package.

   It works like this: when you install a package, aptitude will
   automatically install any other packages on which it depends. These
   packages are marked as having been “automatically installed”; aptitude
   will monitor them and remove them when they are no longer depended upon by
   any manually installed package ^[10] . They will appear in the preview as
   “packages being removed because they are no longer used.”

   As with any automatic process, there is a potential for things to go
   haywire. For instance, even if a package was automatically installed to
   start with, it might turn out to be useful in its own right. You can
   cancel the “automatic” flag at any time by pressing m; if the package is
   already being removed, you can use Package → Install (+) to cancel the
   removal and clear the “automatic” flag.

Resolving package dependencies

  Dependency resolution in aptitude

   There are two main dependency resolution algorithms in aptitude.

   The first is an algorithm that is also used by programs such as apt-get
   and synaptic; I will call it “immediate resolution”. It is invoked
   whenever you select a package for installation interactively, and
   immediately after one or more packages are marked for installation at the
   command-line. Immediate resolution is fast and will solve most dependency
   problems, but it is sometimes unable to find any solution.

   The second algorithm, which I will call “interactive resolution”, is
   invoked when packages have broken dependencies even after immediate
   resolution^[11]. It can resolve more dependencies, it allows you to review
   a solution before applying it, and it allows you to provide feedback to
   the resolver, guiding it towards a better solution.

  Immediate dependency resolution

   Whenever you choose to install or upgrade a package in aptitude, aptitude
   makes an immediate attempt to resolve any of its dependencies that are not
   fulfilled. For each unsatisfied dependency (either a “Depends”, a
   “Recommends”, or a “Conflicts”), it performs the following steps:

    1. If the dependency is a recommendation, aptitude tries to guess whether
       it is a “new” recommendation or a “previously satisfied”
       recommendation. aptitude considers a recommendation to be “new” if the
       package declaring the recommendation is not currently installed, or if
       its installed version does not recommend a package of the same name.
       On the other hand, a recommendation is “previously satisfied” if the
       package declaring the recommendation is installed, the currently
       installed version recommends a package of the same name, and that
       recommendation is currently fulfilled.

       For example: suppose that version 1.0 of prog recommends version 4.0
       of libcool1, but version 2.0 of prog recommends version 5.0 of
       libcool1, and also recommends apache. If you choose to upgrade prog
       from version 1.0 to version 2.0, the recommendation of apache will be
       considered to be “new” because version 1.0 of prog did not recommend
       apache. On the other hand, the recommendation of libcool1 is not
       “new”, because version 1.0 of prog recommended libcool1, even though
       it recommended a different version. However, if libcool1 is installed,
       then that recommendation will be considered to be “previously
       satisfied”.

       If the configuration option APT::Install-Recommends is true, aptitude
       will always attempt to fulfill “new” and “previously satisfied”
       recommendations; all others will be ignored by immediate resolution.
       If that option is false, immediate dependency resolution will ignore
       all recommendations.

    2. If the dependency is on several packages combined with OR, examine
       each of the alternatives in the order that they are given. For
       instance, if a package depends on “exim | mail-transport-agent”,
       aptitude will first process exim, then mail-transport-agent.

    3. For each alternative, attempt to resolve it. If the dependency is a
       conflict, remove the current alternative if it is installed (and for
       an unversioned conflict, also remove any package providing the target
       of the conflict). Otherwise, install the candidate version of the
       current alternative if it satisfies the dependency. If not, or if
       there is no candidate version (for instance, because the current
       alternative is a virtual package), and if the dependency is
       unversioned, attempt to install the highest-priority package^[12]
       whose candidate version provides the target of the current
       alternative.

       For instance, say we are attempting to resolve “Depends: exim |
       mail-transport-agent”. aptitude will first attempt to install the
       package exim. If exim is not available, aptitude will then attempt to
       install the highest-priority package whose candidate version provides
       exim. If there is no such package, aptitude will install the
       highest-priority package whose candidate version provides the virtual
       package mail-transport-agent. On the other hand, suppose that the
       dependency is “Depends: exim (>= 2.0.0) | mail-transport-agent”, but
       only version 1.0 of exim is available. In this case, aptitude will not
       install exim (because the version does not match), nor will it attempt
       to install packages providing exim (because virtual packages cannot
       match a dependency with a version restriction). Thus, aptitude will
       fall back to installing the highest-priority package whose candidate
       version provides mail-transport-agent.

    4. If a package was installed by the previous step, resolve its
       dependencies using this algorithm, then stop.

   While this technique very often solves all the outstanding package
   dependencies, it can fail in a number of common circumstances.

     • Conflicts are resolved by removing the package that is the target of
       the conflict. But now other packages that depend on this package have
       unresolved dependencies; the immediate resolver makes no attempt to
       fix them.

     • A dependency might not be satisfiable due to version restrictions and
       due to the limitation that only candidate versions are considered. For
       instance, say that versions 1.0 and 2.0 of fileutils are available,
       that the candidate version is 1.0, and that the package octopus
       declares a dependency “Depends: fileutils (>= 2.0)”. Immediate
       resolution is unable to resolve this dependency: it will never
       consider version 2.0 of the package, since that is not the candidate
       version.

   The interactive dependency resolver can solve these situations and more.
   When there are broken dependencies left over, or when immediate dependency
   resolution is disabled, the interactive resolver will automatically start
   searching for a solution. The next section describes how to use the
   interactive dependency resolver.

  Resolving Dependencies Interactively

   If a dependency problem arises that cannot be handled using the immediate
   dependency resolver, aptitude can assist you in resolving it. As soon as a
   problem occurs, a red bar will appear at the bottom of the screen with a
   summary of aptitude's suggestion about how to fix it. For instance, in the
   following screenshot, aptitude is indicating that it can resolve the
   situation by keeping two packages at their current versions.

  Actions  Undo  Package  Resolver  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
 aptitude 0.3.3       #Broken: 1   Will free 48.6MB of disk space
 i A   nautilus                                             2.10.1-4   2.10.1-4
 i     nautilus-cd-burner                                   2.10.2-1.1 2.10.2-1.1
 i A   nautilus-data                                        2.10.1-4   2.10.1-4
 i     netspeed                                             0.12.1-1   0.12.1-1
 i A   oaf                                                  0.6.10-3   0.6.10-3
 i     pybliographer                                        1.2.6.2-1  1.2.6.2-1
 i     rhythmbox                                            0.8.8-13   0.8.8-13
 i     shermans-aquarium                                    3.0.1-1    3.0.1-1
 idA   sound-juicer                                 -1733kB 2.10.1-3   2.10.1-3
 GNOME 2 CD Ripper
 sound-juicer will be removed.


 The following packages depend on sound-juicer and will be broken by its
 removal:


   * gnome-desktop-environment depends on sound-juicer

 [1(1)/...] Suggest 2 keeps
 e: Examine  !: Apply  .: Next  ,: Previous

   As indicated at the bottom of the screen, you can view additional
   solutions by pressing . and ,, apply the current solution by pressing !,
   and examine the solution in more detail by pressing e. When you examine
   the current solution, a screen similar to the following will appear:

  Actions  Undo  Package  Resolver  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
                 Packages                          Resolve Dependencies
   --\ Keep the following packages at their current version:
     gstreamer0.8-cdparanoia                           [0.8.10-1 (unstable, now)]
     sound-juicer                                                [2.10.1-2 (now)]
















 [1(1)/...] Suggest 2 keeps
 e: Examine  !: Apply  .: Next  ,: Previous

   You can access information about the package affected by an action by
   simply pressing Enter while the package is highlighted. For a more
   detailed explanation of why aptitude made a particular decision, you can
   highlight the element in the list. When you do so, the lower half of the
   screen will display the dependency which was resolved by aptitude's
   choice, along with every way in which this dependency could have been
   resolved.

  Actions  Undo  Package  Resolver  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
                 Packages                          Resolve Dependencies
   --\ Keep the following packages at their current version:
     gstreamer0.8-cdparanoia                           [0.8.11-1 (unstable, now)]
     sound-juicer                                      [2.10.1-3 (unstable, now)]






 cdparanoia plugin for GStreamer
 sound-juicer depends upon gstreamer0.8-cdparanoia
 --\ The following actions will resolve this dependency:
   -> Downgrade sound-juicer [2.10.1-3 (unstable, now) -> 0.6.1-2 (testing)]
   -> Remove sound-juicer [2.10.1-3 (unstable, now)]
   -> Cancel the removal of gstreamer0.8-cdparanoia
   -> Downgrade gstreamer0.8-cdparanoia [0.8.11-1 (unstable, now) -> 0.8.8-3 (tes



 [1(1)/...] Suggest 2 keeps
 e: Examine  !: Apply  .: Next  ,: Previous

   You can guide the dependency resolver to a solution of which you approve
   by approving or rejecting the individual actions of a solution. If you
   approve an action, the resolver will choose it whenever possible, ignoring
   alternatives (when there are several approved alternatives, any one of
   them could be chosen). On the other hand, if you reject an action, the
   resolver will never choose that action.

   To reject an action, highlight it and press r; the rejection can be
   cancelled by pressing r again. Similarly, select an action and press a to
   approve it; press a again to restore its original state. You can undo
   either action by using Undo → Undo (Control+u) while the resolver screen
   is active. If you cancel a rejection or an approval, any solutions that
   were ignored will be available the next time that you generate a new
   solution.

   [Note] Note
          By default, the resolver rejects actions that change the state of
          held packages, or that install forbidden versions of packages. You
          can override these rejections, thus allowing the hold or forbidding
          to be automatically overridden, in the same way that you would
          override any other rejection. Setting the configuration option
          Aptitude::ProblemResolver::Allow-Break-Holds to true will disable
          this behavior, meaning that the resolver will always break holds
          (albeit at a penalty, see
          Aptitude::ProblemResolver::BreakHoldScore).

   Rejected actions are colored red and marked with an “R”, while approved
   actions are colored green and marked with an “A”. You can see this in the
   following screenshot, where the action “keep gstreamer0.8-cdparanoia at
   its current version” has been rejected, and the action “keep sound-juicer
   at its current version” has been approved.

  Actions  Undo  Package  Resolver  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
                 Packages                          Resolve Dependencies
   --\ Keep the following packages at their current version:
 R   gstreamer0.8-cdparanoia                           [0.8.11-1 (unstable, now)]
 A   sound-juicer                                      [2.10.1-3 (unstable, now)]
















 [1(1)/...] Suggest 2 keeps
 e: Examine  !: Apply  .: Next  ,: Previous

   Rejections and approvals only affect newly generated solutions. You can
   tell when a new solution will be generated by examining the indicator in
   the lower left hand corner of the screen: if there is a number in
   parentheses, it is the number of solutions that have been generated. Thus,
   when the number outside the parentheses and the number inside are
   identical (as above), pressing . will generate a new solution. If there is
   no number in parentheses (for instance, the indicator reads [1/5]), then
   there are no more solutions to generate. At any time, you can select the
   last generated solution by pressing >, and the first generated solution by
   pressing <.

   [Important] Important
               The state of the problem resolver is discarded when you modify
               the state of any package. If you mark a package for
               installation, for upgrade, for removal, etc, the resolver will
               forget all of your rejections and approvals, as well as all
               the solutions that have been generated so far.

   In addition to selecting actions in the list at the top of the screen, you
   can also select them using the list in the bottom half. To access this
   list, either click in it using the mouse or press Tab. Finally, to see the
   decisions that the problem resolver took arranged in order, press o. This
   will give a list of the dependencies that were resolved and the action
   taken to resolve them, as in the following screenshot.

  Actions  Undo  Package  Resolver  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
                 Packages                          Resolve Dependencies
   --\ gnome-desktop-environment depends upon sound-juicer
     -> Cancel the removal of sound-juicer
   --\ sound-juicer depends upon gstreamer0.8-cdparanoia
     -> Cancel the removal of gstreamer0.8-cdparanoia





 GNOME 2 CD Ripper
 gnome-desktop-environment depends upon sound-juicer
 --\ The following actions will resolve this dependency:
   -> Remove gnome-desktop-environment [1:2.10.2.3 (unstable, testing, now)]
   -> Cancel the removal of sound-juicer
   -> Downgrade sound-juicer [2.10.1-3 (unstable, now) -> 0.6.1-2 (testing)]




 [1(1)/...] Suggest 2 keeps
 e: Examine  !: Apply  .: Next  ,: Previous

   You can leave this display mode by pressing o again.

  Costs in the interactive dependency resolver

    Costs and cost components

   The cost of a solution produced by the interactive dependency resolver is
   a value that aptitude uses to determine how “bad” that solution is.
   Solutions that are “better” are always displayed before solutions that are
   “worse”. The cost of solutions is defined in the configuration option
   Aptitude::ProblemResolver::SolutionCost.

   Some typical costs are shown in Example 2.1, “Sample resolver costs”.

   Example 2.1. Sample resolver costs

   The default cost, sorting solutions by their safety cost, then by their
   apt pin priority:

 safety, priority

   Remove as few packages as possible, then cancel as few actions as
   possible:

 removals, canceled-actions

   Sort solutions by the number of packages they remove plus twice the number
   of actions they cancel.

 removals + 2 * canceled-actions

   As can be seen from the above examples, a cost is not necessarily a single
   number. In fact, a cost consists of one or more cost components, each of
   which is a number associated with the solution. When sorting solutions,
   the resolver examines cost components in order, proceeding to later
   components only if the earlier ones are equal. For instance, in the cost
   “removals, canceled-actions”, solutions with fewer removals always appear
   before solutions with more removals, regardless of how many canceled
   actions they have. However, solutions with the same number of removals are
   sorted so that solutions with fewer canceled actions appear first.

   Cost components come in two flavors: basic cost components and compound
   cost components.

   Basic components simply name some property of the solution, such as
   “upgrades” or “removals”. A list of built-in basic components provided by
   aptitude can be found in Table 2.1, “Basic cost components”. You can also
   create your own cost components using the add-to-cost-component and
   raise-cost-component hints; see the section called “Configuring resolver
   hints” for details.

   Each basic component is either a counter or a level. Counters count how
   many of a solution's actions meet some condition (such as removing
   packages or installing new packages), while levels associate a number with
   each action and compute the highest number associated with any action in
   the solution.

   Table 2.1. Basic cost components

┌────────────────────┬───────┬─────────────────────────────────────────────────────┐
│        Name        │ Type  │                     Description                     │
├────────────────────┼───────┼─────────────────────────────────────────────────────┤
│                    │       │Counts the number of holds that the solution breaks, │
│broken-holds        │Counter│if the resolver is allowed to break holds            │
│                    │       │(Aptitude::ProblemResolver::Allow-Break-Holds).      │
├────────────────────┼───────┼─────────────────────────────────────────────────────┤
│                    │       │Counts the number of pending actions that the        │
│canceled-actions    │Counter│solution cancels (keeping packages at their current  │
│                    │       │version).                                            │
├────────────────────┼───────┼─────────────────────────────────────────────────────┤
│installs            │Counter│Counts the number of packages that the solution      │
│                    │       │installs.                                            │
├────────────────────┼───────┼─────────────────────────────────────────────────────┤
│non-default-versions│Counter│Counts the number of versions that the solution      │
│                    │       │installs or upgrades from non-default sources.       │
├────────────────────┼───────┼─────────────────────────────────────────────────────┤
│                    │       │A value that increases as the apt pin priority of a  │
│priority            │Level  │version decreases. Specifically, this is computed by │
│                    │       │negating the pin priority (so, e.g., if the pin      │
│                    │       │priority is 500, this component will compute -500).  │
├────────────────────┼───────┼─────────────────────────────────────────────────────┤
│removals            │Counter│Counts the number of packages that the solution      │
│                    │       │removes.                                             │
├────────────────────┼───────┼─────────────────────────────────────────────────────┤
│removals-of-manual  │Counter│Counts the number of manually installed packages that│
│                    │       │the solution removes.                                │
├────────────────────┼───────┼─────────────────────────────────────────────────────┤
│                    │       │A broad heuristic that increases as actions become   │
│safety              │Level  │less “safe”; see the section called “Safety costs”   │
│                    │       │for details.                                         │
├────────────────────┼───────┼─────────────────────────────────────────────────────┤
│upgrades            │Counter│Counts the number of packages that the solution      │
│                    │       │upgrades.                                            │
└────────────────────┴───────┴─────────────────────────────────────────────────────┘

   Compound components are built by combining the values of basic components.
   For instance, removals + canceled-actions adds the components removal and
   canceled-actions, resulting in a component that counts the number of
   removals and canceled actions. Compound components combine counters by
   adding them together and levels by taking their maximum value, as shown in
   Figure 2.11, “Syntax of compound cost components”.

   [Note] Note
          It is an error to add two levels, or to take the maximum of two
          counters, or to combine levels and counters in any way. For
          instance, the costs removals + safety and max(upgrades, installs)
          will be treated as errors and ignored by the resolver.^[13]

   Figure 2.11. Syntax of compound cost components

   Add two or more basic costs:

                 [scale1]*cost1 + [scale2]*cost2 + ...


   Take the maximum value of two or more basic costs:

                 max([scale1]*cost1, [scale2]*cost2, ...)


   Note that each individual basic component can be multiplied by a scaling
   factor before it is combined with other components. This can be used to
   control the trade-offs that the resolver makes between costs. For
   instance, a cost of 2*removals + 3*upgrades says that three removals are
   exactly as “bad” as two upgrades. Solutions that contain four removals and
   one upgrade will be considered equivalent to solutions containing one
   removal and three upgrades, since both have a cost of eleven.

    Safety costs

   Figure 2.12. Safety cost levels

   Safety cost levels
   [Safety cost levels diagram]

   The safety cost component is a heuristic estimate of how “safe” or
   “unsafe” a solution is. Safety costs can be thought of as a way of
   dividing solutions into several numbered “levels”, where “less safe”
   levels are given higher numbers. Figure 2.12, “Safety cost levels” shows
   how this works with aptitude's default settings.

   [Tip] Tip
         Safety cost levels are just one way to control the order in which
         dependency solutions are returned. See the section called “Costs in
         the interactive dependency resolver” for a full description of how
         to change the order in which aptitude sorts solutions.

   By default, aptitude initializes the resolver with a “reasonable” set of
   safety cost levels. They are:

   Table 2.2. Default safety cost levels

┌──────┬──────────────────────────────────────────────┬─────────────────────────────────────────────────┐
│ Cost │                 Description                  │              Configuration option               │
│level │                                              │                                                 │
├──────┼──────────────────────────────────────────────┼─────────────────────────────────────────────────┤
│      │Solutions that include only “safe” actions    │                                                 │
│10,000│(installing the default target for a package  │Aptitude::ProblemResolver::Safe-Level,           │
│      │or keeping a package at its current version)  │Aptitude::ProblemResolver::Remove-Level          │
│      │and package removals.                         │                                                 │
├──────┼──────────────────────────────────────────────┼─────────────────────────────────────────────────┤
│      │The solution that cancels all the user's      │                                                 │
│      │actions. It used to be higher than            │                                                 │
│10,000│Aptitude::ProblemResolver::Remove-Level, but  │Aptitude::ProblemResolver::Keep-All-Level        │
│      │removing packages was ranked higher than      │                                                 │
│      │keeping the same packages, even if the package│                                                 │
│      │was to be upgraded.                           │                                                 │
├──────┼──────────────────────────────────────────────┼─────────────────────────────────────────────────┤
│40,000│Solutions that break holds set by the user or │Aptitude::ProblemResolver::Break-Hold-Level      │
│      │install forbidden versions.                   │                                                 │
├──────┼──────────────────────────────────────────────┼─────────────────────────────────────────────────┤
│      │Solutions that install packages from          │                                                 │
│50,000│non-default versions (such as “experimental”, │Aptitude::ProblemResolver::Non-Default-Level     │
│      │for instance).                                │                                                 │
├──────┼──────────────────────────────────────────────┼─────────────────────────────────────────────────┤
│60,000│Solutions that remove Essential packages.     │Aptitude::ProblemResolver::Remove-Essential-Level│
└──────┴──────────────────────────────────────────────┴─────────────────────────────────────────────────┘

   If a solution qualifies for several safety cost levels, it will be placed
   in the highest one, that is, the one that appears last. For example, a
   solution that upgrades one package to its default version and breaks a
   hold on a second package will be placed at level 40,000. You can adjust
   the levels of individual versions using resolver hints; see the section
   called “Configuring resolver hints” for details. The default levels are
   illustrated in Figure 2.12, “Safety cost levels”.

   Besides numbers you can also use the keywords “maximum” and “minimum” for
   cost levels. They refer to the maximal respective minimal integer value
   possible on the hardware architecture of your system.

  Configuring the interactive dependency resolver

    Configuring resolver hints

   To improve the quality of the dependency solutions that you receive, you
   can provide hints to the interactive dependency resolver. These hints can
   alter the priorities of the resolver, biasing it more strongly in favor of
   one version or package, or they can be used to “pre-load” the resolver
   with rejections and approvals, as if you had entered the resolver and
   manually rejected or approved various versions.

   Hints are stored in the apt configuration file, /etc/apt/apt.conf, in the
   configuration group “Aptitude::ProblemResolver::Hints” (see the section
   called “Configuration file reference” for details on the configuration
   file).

   Each resolver hint consists of an action, a target, and an optional
   version. A hint is written like this: "action target [version]". To apply
   a resolver hint, aptitude locates one or more packages using the value of
   target, chooses one or more versions of those packages using the value of
   version, and finally performs the given action.

   The action field of a resolver hint may be one of the following:

    1. “approve”: Approve the version, as if the command Resolver → Toggle
       Approved (a) had been invoked on it.

    2. “reject”: Reject the version, as if the command Resolver → Toggle
       Rejected (r) had been invoked on it.

    3. “discard”: Discard every solution containing the version. Differs from
       “reject” in that it is not visible to the user and cannot be modified
       interactively.

    4. “increase-safety-cost-to number”: increase the safety cost of any
       solution that contains the version to number; if its safety cost is
       already higher than number, this hint has no effect. The safety cost
       can be used (and is used by default) to control the order in which
       solutions appear; see the section called “Costs and cost components”
       and the section called “Safety costs” for details.

       Several special cost levels can be chosen by name:

         a. conflict, discard: instead of changing the safety cost, discard
            solutions containing the version as if the “discard” hint had
            been applied.

         b. maximum: the highest safety cost.

         c. minimum: the lowest safety cost. All searches start at this cost,
            so “increasing” a version to this cost has no effect. However,
            this value can also be used when adjusting the predefined cost
            levels: for instance, setting
            Aptitude::ProblemResolver::Remove-Level to “minimum” will cause
            removed packages to have no effect on the safety cost of a
            solution.

       [Note] Note
              The increase-safety-cost-to hint is applied in addition to any
              default safety cost that is due to the selected action. For
              instance, a hint that increases the safety cost of “install hal
              from experimental” to 15,000 will have no effect, because that
              action already has a safety cost of 50,000 (assuming that this
              version of hal is not the default candidate version).

    5. “number”: add the given number to the version's score, biasing the
       resolver in favor of it or (with a negative number) away from it. For
       instance, the hint 200 emacs adds 200 to the score of emacs, whereas
       the hint -10 emacs subtracts 10 from its score.

   If target field of a resolver hint contains a question mark (“?”) or tilde
   (“~”), it is considered to be a search pattern and all matching package
   versions are considered. Otherwise, it is considered to be the name of a
   package to select. So the target “g++” will select only the g++ package,
   but the target “?section(non-free)” will select any package in the
   non-free section. See the section called “Search patterns” for more
   information on search patterns.

   If the version field is not present, then all versions of the package are
   affected by the hint. Otherwise, it may have any of the following forms:

    1. “/archive”: the hint only affects versions that are available in the
       given archive.

    2. “<version”: the hint only affects versions whose version number is
       less than version.

    3. “<=version”: the hint only affects versions whose version number is
       less than or equal to version.

    4. “=version”: the hint only affects versions whose version number is
       version.

    5. “<>version”: the hint only affects versions whose version number is
       not version.

    6. “>=version”: the hint only affects versions whose version number is
       greater than or equal to version.

    7. “>version”: the hint only affects versions whose version number is
       greater than version.

    8. “:UNINST”: instead of affecting any of the versions of target, the
       hint affects the decision to remove target. For instance,
       “Aptitude::ProblemResolver::Hints { "reject aptitude :UNINST"; };”
       will prevent the resolver from attempting to remove aptitude.

    9. “version”: the hint only affects versions whose version number is
       version.

Search patterns

   When you search for a package or set a display limit in aptitude, the
   string you enter is known as a “search pattern”. While the most basic
   usage of search patterns is to match packages by name, aptitude allows you
   to create much more complex searches. In addition to the visual interface,
   some command-line operations can use search patterns; see Command-line
   reference for details.

   A search pattern consists of one or more conditions (sometimes known as
   “terms”); packages match the pattern if they match all of its terms. Terms
   generally start with a question mark (“?”), followed by the name of the
   match term, which describes the search that the term performs: for
   instance, the term ?name matches package names, while the term ?version
   matches package versions. Finally, any additional parameters to the search
   term are placed in parentheses (see the documentation of individual terms
   for details of what each term's parameters mean).

   [Note] Note
          Text with no leading “?” also forms a search pattern: aptitude will
          treat each word (or quoted string) as the argument to a ?name
          pattern, which searches for a package whose name matches the text
          when the text is interpreted as a regular expression.

   [Warning] Warning
             The behavior of aptitude when given a search pattern without a
             leading “?” (or “~”) is provided as a convenience for
             interactive use and will change in future releases; scripts that
             invoke aptitude should explicitly name the search strategy they
             want to use. That is, scripts should search for “?name(coq)”
             rather than “coq”).

  Searching for strings

   Many search terms take a string as a parameter and match it against one or
   more fields of a package. Strings can be entered either with or without
   double quotes (“"”), so “?name(scorch)” and “?name("scorch")” will perform
   the same search. If you enter a search string using double quotes, you can
   include a literal double-quote in the search string by placing a backslash
   (“\”) immediately before it: for instance, “?description("\"easy\"")” will
   match any package whose description contains the string “"easy"”.

   If you enter a “bare” string, one not surrounded by double quotes, then
   aptitude will consider the string to have “ended” when it encounters the
   closing parenthesis or the comma before a second argument to the search
   term. ^[14] To remove the special meaning of these characters, place a
   tilde (“~”) directly before them. For instance, “?description(etc))” is a
   syntax error, because the first “)” ends the ?description term, and the
   second “)” does not correspond to any “(”. In contrast,
   “?description(etc~))” matches any package whose description contains the
   text “etc)”. There are additional considerations if you are using the
   shorthand notation for a term; see the section called “Shorthand for
   search terms” for details.

   Most textual searches (for package names, descriptions, etc) are performed
   using case-insensitive regular expressions. A regular expression will
   match against a field if any portion of the field matches the expression;
   for instance, “ogg[0-9]” will match “libogg5”, “ogg123”, and “theogg4u”.
   Some characters have a special meaning within regular expressions ^[15] ,
   so if you want to match them in searches you need to backslash-escape
   them: for instance, to find “g++”, you should use the pattern “g\+\+”.

   The characters “!” and “|” have special meanings within search patterns.
   In order to include these characters in an unquoted string, you can place
   a tilde (“~”) directly before them. For instance, to match packages whose
   description contains either “grand” or “oblique”, use the pattern
   “?description(grand~|oblique)”. However, you will probably find it more
   convenient to simply use a quoted string in these cases:
   “?description("grand|oblique")”.

  Shorthand for search terms

   Some search terms can be written using “short” forms, which consist of a
   tilde (“~”) followed by a single character that identifies the term, and
   finally the arguments (if any) to the term. For instance, the short form
   of ?name(aptitude) is ~n aptitude.

   When writing a term using its short form, tilde characters and
   “whitespace” -- that is, space characters, tabs, and so on -- will break
   the term off and start a new term. For instance, “~mDaniel Burrows” will
   match any package whose maintainer field contains “Daniel” and whose name
   contains “Burrows”, while “~i~napt” matches installed packages whose name
   contains apt. To include whitespace characters in the search expression,
   you can either place a tilde in front of it (as in Daniel~ Burrows) or
   place quotation marks around it (as in "Debian Project" or even Debian"
   "Project). Inside a quoted string, the backslash character (“\”) can be
   used to cancel the special meaning of the quotation mark: for instance,
   ~d"\"email" will match any package whose description contains a quotation
   mark followed immediately by email. ^[16]

   [Note] Note
          Question marks (“?”) will not end the short form of a term, even if
          they are followed by the name of a search term. For instance,
          “~napt?priority(required)” will match all packages whose name
          matches the regular expression “apt?priority(required)”. To combine
          a short query term with a search term specified by name, add one or
          more spaces between the two terms, as in
          “~napt ?priority(required)”, or place quotation marks around the
          text (if any) following the short form of a term, as in
          “~n"apt"?priority(required)”.

   Table 2.3, “Quick guide to search terms” lists the short form of each
   search term.

  Searches and versions

   By default, a pattern matches a package if any version of the package
   matches the pattern. However, some patterns will restrict their
   sub-patterns to only match against some versions of a package. For
   instance, the search term ?depends(pattern) will select any package that
   depends on a package matching pattern. However, pattern will only be
   checked against the versions of the package that actually satisfy a
   dependency. This means that if foo depends on bar (>= 3.0) and versions
   2.0, 3.0, and 4.0 of bar are available, then in the search pattern
   ?depends(?version(2\.0)), only versions 3.0 and 4.0 will be tested against
   ?version(2\.0), and hence foo will not be found by this search.

   It matters which versions are checked because, as in the example above,
   some patterns will match one version but not another. For instance, the
   pattern ?installed will only match the version of the package (if any)
   that is currently installed. Similarly, the pattern
   ?maintainer(maintainer) will only match versions that have the given
   maintainer. Normally all versions of a package have the same maintainer,
   but this is not always the case; in fact, any search pattern that examines
   the fields of a package (other than its name, of course) will behave this
   way, because all the fields of a package can change between versions.

   To test a pattern against all the versions of a package, even if the
   pattern would normally be tested against only some of the versions, use
   the ?widen term. For instance, ?depends(?widen(?version(2\.0))) will match
   any package A that depends on a package B, where B has a version matching
   2.0, regardless of whether that version actually satisfies A's dependency.
   On the other hand, the ?narrow term restricts the versions that its
   sub-pattern is matched against: ?narrow(?installed,
   ?depends(?version(ubuntu))) will match any package whose installed version
   has a dependency that can be satisfied by a package whose version string
   contains “ubuntu”.

   [Note] Note
          There is a subtle, but important, distinction between matching a
          pattern against a package, and matching it against all the versions
          of that package. When a pattern is matched against a package, each
          of its terms is matched against the package, and so each term will
          match if any version of the package matches. In contrast, when a
          pattern is matched against each version of a package, it will
          successfully match if it matches when all its terms are matched
          against the same version of the package.

          For example: suppose that version 3.0-1 of the package aardvark is
          installed, but that version 4.0-1 is available. Then the search
          expression ?version(4\.0-1)?installed matches aardvark, because
          ?version(4\.0-1) matches against version 4.0-1 of aardvark, while
          ?installed matches against version 3.0-1. On the other hand, this
          expression does not match against all the versions of aardvark,
          because no single version is installed and also has a version
          number of 4.0-1.

  Explicit search targets

   Some particularly complex searches can be expressed in aptitude using
   explicit targets. In normal search expressions, there is no way to refer
   to the package or version that is currently being tested. For instance,
   suppose that you want to search for all packages P that depend on a second
   package Q such that Q recommends P. Clearly you need to start out with a
   ?depends(...) term. But the term filling in the ... needs to somehow
   select packages that are identical to the one being matched against
   ?depends. When describing the goal above, I dealt with this by giving the
   packages names, calling them P and Q; terms with explicit targets do
   exactly the same thing. ^[17]

   An explicit target is introduced by the ?for term:

   Figure 2.13. Syntax of the ?for term

 ?for variable: pattern

   This behaves exactly like pattern, but variable can be used within pattern
   to refer to the package or version that pattern is being matched against.
   You can use variable in two ways:

    1. The term ?= will match exactly the package or version indicated by the
       given variable. Specifically: if the corresponding ?for term is
       limited to a particular version, then ?= will match either that
       version (if ?= is limited) or the whole package; otherwise it will
       match any version of the package.

       See Example 2.2, “ Use of the ?= term. ” for an example of how to use
       ?=.

    2. The term ?bind(variable, pattern) will match any package or version if
       the value of variable matches against pattern.

       For ?-style terms, a shorthand form is available. The expression
       ?bind(variable, ?term[(args)]) can be replaced by
       ?variable:term(args).

       See Example 2.3, “Use of the ?bind term” for an example of how to use
       ?bind.

  Search term reference

   Table 2.3, “Quick guide to search terms” provides a brief summary of all
   the search terms provided by aptitude. A full description of each term can
   be found below.

   Table 2.3. Quick guide to search terms

┌────────────────────────────────┬────────────────────────────┬──────────────────┐
│           Long form            │         Short form         │   Description    │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select the package│
│                                │                            │bound to variable;│
│?=variable                      │                            │see the section   │
│                                │                            │called “Explicit  │
│                                │                            │search targets”.  │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select any package│
│?not(pattern)                   │!pattern                    │that does not     │
│                                │                            │match pattern.    │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│                                │                            │that have been    │
│?action(action)                 │~aaction                    │marked for the    │
│                                │                            │given action      │
│                                │                            │(e.g., “install”  │
│                                │                            │or “upgrade”).    │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│?all-versions(pattern)          │                            │whose versions all│
│                                │                            │match pattern.    │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select any package│
│?and(pattern1, pattern2)        │pattern1 pattern2           │that matches both │
│                                │                            │pattern1 and      │
│                                │                            │pattern2.         │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│?any-version(pattern)           │                            │for which at least│
│                                │                            │one version       │
│                                │                            │matches pattern.  │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│                                │                            │for the given     │
│                                │                            │architecture (such│
│?architecture(architecture)     │~rarchitecture              │as “amd64”, or    │
│                                │                            │“all”). Special   │
│                                │                            │values: native and│
│                                │                            │foreign.          │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│?archive(archive)               │~Aarchive                   │from the given    │
│                                │                            │archive (such as  │
│                                │                            │“unstable”).      │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│?automatic                      │~M                          │that were         │
│                                │                            │automatically     │
│                                │                            │installed.        │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Selects anything  │
│                                │                            │if variable       │
│?bind(variable, pattern)        │?variable:term-name[(args)] │matches pattern;  │
│                                │                            │see the section   │
│                                │                            │called “Explicit  │
│                                │                            │search targets”.  │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│?broken                         │~b                          │that have a broken│
│                                │                            │dependency.       │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select package    │
│?broken-depType                 │~BdepType                   │that have a broken│
│                                │                            │dependency of the │
│                                │                            │given depType.    │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│                                │                            │that have a broken│
│?broken-depType(pattern)        │~DB[depType:]pattern        │dependency of the │
│                                │                            │given depType     │
│                                │                            │matching pattern. │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│                                │                            │that a package    │
│?broken-reverse-depType(pattern)│~RBdepType:pattern          │matching pattern  │
│                                │                            │declares a broken │
│                                │                            │dependency of type│
│                                │                            │depType.          │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│?conflicts(pattern)             │~Cpattern                   │that conflict with│
│                                │                            │a package matching│
│                                │                            │pattern.          │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│?config-files                   │~c                          │that were removed │
│                                │                            │but not purged.   │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Match packages    │
│                                │                            │that declare a    │
│?depType(pattern)               │~D[depType:]pattern         │dependency of type│
│                                │                            │depType on a      │
│                                │                            │package matching  │
│                                │                            │pattern.          │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│?description(description)       │~ddescription               │whose description │
│                                │                            │matches           │
│                                │                            │description.      │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select essential  │
│                                │                            │packages, those   │
│?essential                      │~E                          │with Essential:   │
│                                │                            │yes in their      │
│                                │                            │control files.    │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│?exact-name(name)               │                            │Select packages   │
│                                │                            │named name.       │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│?false                          │~F                          │Select no         │
│                                │                            │packages.         │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│                                │                            │that match pattern│
│                                │                            │with variable     │
│                                │                            │bound to the      │
│?for variable: pattern          │                            │package being     │
│                                │                            │matched; see the  │
│                                │                            │section called    │
│                                │                            │“Explicit search  │
│                                │                            │targets”.         │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│                                │                            │that are not      │
│?garbage                        │~g                          │required by any   │
│                                │                            │manually installed│
│                                │                            │package.          │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│?installed                      │~i                          │Select installed  │
│                                │                            │packages.         │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│?maintainer(maintainer)         │~mmaintainer                │maintained by     │
│                                │                            │maintainer.       │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│                                │                            │with a multi-arch │
│                                │                            │capability of     │
│?multiarch(multiarch)           │                            │multiarch (that   │
│                                │                            │is, either        │
│                                │                            │“foreign”, “same”,│
│                                │                            │“allowed”, or     │
│                                │                            │“none”).          │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│                                │                            │for which a single│
│?narrow(filter, pattern)        │~S filter pattern           │version matches   │
│                                │                            │both filter and   │
│                                │                            │pattern.          │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│?name(name)                     │~nname, name                │with the given    │
│                                │                            │name.             │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│?new                            │~N                          │Select new        │
│                                │                            │packages.         │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Match installed   │
│?obsolete                       │~o                          │packages that     │
│                                │                            │cannot be         │
│                                │                            │downloaded.       │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│?or(pattern1, pattern2)         │pattern1 | pattern2         │that match        │
│                                │                            │pattern1,         │
│                                │                            │pattern2, or both.│
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│?origin(origin)                 │~Oorigin                    │with the given    │
│                                │                            │origin.           │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│?provides(pattern)              │~Ppattern                   │that provide a    │
│                                │                            │package matching  │
│                                │                            │pattern.          │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│?priority(priority)             │~ppriority                  │with the given    │
│                                │                            │priority.         │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│                                │                            │that are the      │
│                                │                            │targets of a      │
│?reverse-depType(pattern)       │~R[depType:]pattern         │dependency of type│
│                                │                            │depType declared  │
│                                │                            │by a package      │
│                                │                            │matching pattern. │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│                                │                            │that are the      │
│                                │                            │targets of a      │
│?reverse-broken-depType(pattern)│~RBdepType:pattern          │broken dependency │
│                                │                            │of type depType   │
│                                │                            │declared by a     │
│                                │                            │package matching  │
│                                │                            │pattern.          │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│?section(section)               │~ssection                   │Select packages in│
│                                │                            │the given section.│
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│                                │                            │whose source      │
│?source-package(name)           │~ename                      │package name      │
│                                │                            │matches the       │
│                                │                            │regular expression│
│                                │                            │name.             │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│                                │                            │whose source      │
│?source-version(version)        │                            │version matches   │
│                                │                            │the regular       │
│                                │                            │expression        │
│                                │                            │version.          │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│?tag(tag)                       │~Gtag                       │that have the     │
│                                │                            │given debtags tag.│
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Full-text search  │
│?term(keyword)                  │                            │for packages that │
│                                │                            │contain the given │
│                                │                            │keyword.          │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Full-text search  │
│                                │                            │for packages that │
│?term-prefix(keyword)           │                            │contain a keyword │
│                                │                            │that begins with  │
│                                │                            │the given keyword.│
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│?true                           │~T                          │Select all        │
│                                │                            │packages.         │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│?task(task)                     │~ttask                      │that are in the   │
│                                │                            │given task.       │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│?upgradable                     │~U                          │that are installed│
│                                │                            │and can be        │
│                                │                            │upgraded.         │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│                                │                            │that are marked   │
│?user-tag                       │                            │with a user-tag   │
│                                │                            │matching the      │
│                                │                            │regular expression│
│                                │                            │user-tag.         │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select packages   │
│                                │                            │whose version     │
│                                │                            │matches version   │
│?version(version)               │~Vversion                   │(special values:  │
│                                │                            │CURRENT,          │
│                                │                            │CANDIDATE, and    │
│                                │                            │TARGET).          │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│?virtual                        │~v                          │Select virtual    │
│                                │                            │packages.         │
├────────────────────────────────┼────────────────────────────┼──────────────────┤
│                                │                            │Select versions   │
│                                │                            │for which pattern │
│                                │                            │matches any       │
│                                │                            │version of the    │
│?widen(pattern)                 │~Wpattern                   │corresponding     │
│                                │                            │package,          │
│                                │                            │discarding local  │
│                                │                            │version           │
│                                │                            │restrictions.     │
└────────────────────────────────┴────────────────────────────┴──────────────────┘

   name

   Matches packages whose names match the regular expression name. This is
   the “default” search mode and is used for patterns that don't start with
   ~.

   [Note] Note
          To match packages whose names contain several different substrings,
          use the ?name term (described below); for instance,
          “?name(apti)?name(tude)” will match any package whose name contains
          both “apti” and “tude”.

   ?=variable

   Matches packages that correspond to the value of variable, which must be
   bound by an enclosing ?for. For instance, ?for x: ?depends( ?recommends(
   ?=x ) ) will match any package x that depends on a package which
   recommends x.

   For instance, the following search expression matches packages that
   conflict with themselves:

   Example 2.2.  Use of the ?= term.

   ?for x: ?conflicts(?=x)

   See the section called “Explicit search targets” for more information.

   ?not(pattern), !pattern

   Matches packages which do not match the pattern pattern. For instance,
   “?not(?broken)” selects packages that are not “broken”.

   [Note] Note
          To include a “!” in a search string, it must be “escaped” by
          placing a tilde (“~”) in front of it; otherwise, aptitude will
          consider it to be part of a ?not term. For instance, to select
          packages whose description contains “extra!”, use
          “?description(extra~!)”.

   ?and(pattern1, pattern2), pattern1 pattern2

   Matches packages that match both pattern1 and pattern2.

   ?or(pattern1, pattern2), pattern1 | pattern2

   Matches packages that match either pattern1 or pattern2.

   [Note] Note
          To use the character “|” in a regular expression, it must be
          “escaped” to prevent aptitude from creating an OR term from it:
          “~|”.

   (pattern)

   Matches pattern. For instance, “opengl (perl|python)” matches any package
   whose name contains opengl, and also contains either perl or python.

   ?action(action), ~aaction

   Matches packages upon which the given action is going to be performed.
   action can be “install”, “upgrade”, “downgrade”, “remove”, “purge”, “hold”
   (tests whether a package has been placed on hold), or “keep” (tests
   whether a package will be unchanged).

   [Note] Note
          Note that this only tests whether an action is actually queued up
          to be performed on a package, not whether it could be performed.
          Thus, for instance, ?action(upgrade) matches exactly those packages
          that you have already decided to upgrade, not packages which could
          be upgraded in the future (for that, use ?upgradable).

   ?all-versions(pattern)

   Matches any package whose versions all match the given expression. Each
   version of a package will be separately tested against pattern, and the
   package will match if all of its versions match. Packages without
   versions, such as virtual packages, will always be matched by this search
   term.

   This term may not be used in a context in which the versions to match
   against have already been narrowed, such as within ?depends or ?narrow.
   However, it may always be used within ?widen.

   ?any-version(pattern)

   Matches a package if any one of its versions matches the enclosed pattern.
   This is the dual to ?all-versions.

   This term may not be used in a context in which the versions to match
   against have already been narrowed, such as within ?depends or ?narrow.
   However, it may always be used within ?widen.

   [Note] Note
          This term is closely related to ?narrow. In fact,
          ?any-version(pattern1 pattern2) is exactly the same as
          ?narrow(pattern1, pattern2).

   [Note] Note
          To be precise, as with any other pattern, it is not packages but
          versions of the packages which are matched. For “aptitude search”
          and other uses it does not make much difference, but “aptitude
          versions” will only show the versions that match, not all versions
          of the package for which any version matches. For that, use an
          enclosing ?widen.

   ?architecture(architecture-spec), ~rarchitecture-spec

   Matches package versions for the given architecture-spec. For instance,
   “?architecture(amd64)” matches amd64 packages, while “?architecture(all)”
   matches arch-independent packages.

   It also accepts the special values native and foreign, and architecture
   wildcards (e.g. linux-any or any-amd64), as specified in Policy (“11.1
   Architecture specification strings”).

   ?archive(archive), ~Aarchive

   Matches package versions which are available from an archive that matches
   the regular expression archive. For instance, “?archive(testing)” matches
   any package available from the testing archive.

   ?automatic, ~M

   Matches packages which were automatically installed.

   ?bind(variable, pattern), ?variable:term-name[(args)]

   Matches any package or version if the given pattern matches the package or
   version bound to variable, which must be defined in an enclosing ?for.

   Example 2.3. Use of the ?bind term

   ?for x: ?depends(?depends(?for z: ?bind(x, ?depends(?=z))))

   ?for x: ?depends(?depends(?for z: ?x:depends(?=z)))

   The two search patterns in the above example both match any package x such
   that x depends on a package y which in turn depends on a package z such
   that x also depends directly on z. The first pattern uses ?bind directly,
   while the second one uses an equivalent shorthand syntax.

   See the section called “Explicit search targets” for more information.

   ?broken, ~b

   Matches packages that are “broken”: they have an unfulfilled dependency,
   predependency, breaks, or conflict.

   ?broken-depType, ~BdepType

   Matches packages which have an unfulfilled (“broken”) dependency of the
   given depType. depType can be “depends”, “predepends”, “recommends”,
   “suggests”, “breaks”, “conflicts”, or “replaces”.

   ?broken-depType(pattern), ~DB[depType:]pattern

   Matches packages with an unsatisfied dependency of type depType on a
   package matching pattern. depType may be any one of the dependency types
   listed in the documentation of ?broken-depType.

   ?conflicts(pattern), ~Cpattern

   Matches packages which conflict with a package matching the given pattern.
   For instance, “?conflicts(?maintainer(dburrows@debian.org))” matches any
   package which conflicts with a package I maintain.

   ?config-files, ~c

   Matches packages which have been removed, but whose configuration files
   remain on the system (ie, they were removed but not purged).

   ?depType(pattern), ~D[depType:]pattern

   depType may be any one of the dependency types given in the documentation
   of ?broken-depType, as well as provides: for instance, ?depends(libpng3)
   will match any package that depends on libpng3. If the short form (~D) is
   used and depType is not present, it defaults to depends.

   If depType is “provides”, matches packages that provide a package matching
   pattern (the equivalent of ?provides). Otherwise, matches packages which
   declare a dependency of type depType upon a package version which matches
   pattern.

   ?description(description), ~ddescription

   Matches packages whose description matches the regular expression
   description.

   ?essential, ~E

   Matches Essential packages.

   ?exact-name(name)

   Matches packages named name. This is similar to ?name, but the name must
   match exactly. For instance, the following pattern will match only the
   package apt; with ?name, it would also match aptitude, uvccapture, etc.

   Example 2.4. Use of the ?exact-name term

   ?exact-name(apt)

   ?false, ~F

   This term does not match any package. ^[18]

   ?for variable: pattern

   Matches pattern, but the given variable may be used inside pattern to
   refer to the package or package version this term to.

   You can use variable in two ways. To apply a ?-style term to the variable,
   write ?variable:term-name(args); for instance, ?x:depends(apt). In
   addition, the term ?=variable will select any package or version that
   matches the value of the given variable.

   For instance, the following term will match any package x that both
   depends and recommends a second package y.

   Example 2.5. Use of the ?for term

   ?for x: ?depends( ?for y: ?x:recommends( ?=y ) )

   See the section called “Explicit search targets” for more information.

   ?garbage, ~g

   Matches packages which are not installed, or which were automatically
   installed and are not depended upon by any installed package.

   ?installed, ~i

   Matches package versions which are currently installed.

   Since all versions are tested by default, this normally matches packages
   which are currently installed.

   ?maintainer(maintainer), ~mmaintainer

   Matches packages whose Maintainer field matches the regular expression
   maintainer. For instance, “?maintainer(joeyh)” will find all packages
   maintained by Joey Hess.

   ?multiarch(multiarch)

   Matches packages with the multi-arch capability specified by multiarch.
   For instance, “?multiarch(foreign)” will find all packages which can
   satisfy dependencies of packages for another architecture.
   “?multiarch(none)” will select packages with no multi-arch capability.

   ?narrow(filter, pattern), ~S filter pattern

   This term “narrows” the search to package versions matching filter. In
   particular, it matches any package version which matches both filter and
   pattern. The string value of the match is the string value of pattern.

   ?name(name), ~nname

   Matches packages whose name matches the regular expression name. For
   instance, most of the packages that match “?name(^lib)” are libraries of
   one sort or another.

   ?new, ~N

   Matches packages which are “new”: that is, they have been added to the
   archive since the last time the list of packages was cleared using Actions
   → Forget new packages (f) or the command-line action forget-new.

   ?obsolete, ~o

   This term matches any installed package which is not available in any
   version from any archive. These packages appear as “Obsolete or Locally
   Installed” in the visual interface.

   ?origin(origin), ~Oorigin

   Matches package versions whose origin matches the regular expression
   origin. For instance, “!?origin(debian)” will find any unofficial packages
   on your system (packages not from the Debian archive).

   ?provides(pattern), ~Ppattern

   Matches package versions which provide a package that matches the pattern.
   For instance, “?provides(mail-transport-agent)” will match all the
   packages that provide “mail-transport-agent”.

   ?priority(priority), ~ppriority

   Matches packages whose priority is priority; priority must be extra,
   important, optional, required, or standard. For instance,
   “?priority(required)” matches packages whose priority is “required”.

   ?reverse-depType(pattern), ~R[depType:]pattern

   depType may be either “provides” or one of the dependency types given in
   the documentation of ?broken-depType. If depType is not present, it
   defaults to depends.

   If depType is “provides”, matches packages whose name is provided by a
   package version matching pattern. Otherwise, matches packages which a
   package version matching pattern declares a dependency of type depType
   upon.

   ?reverse-broken-depType(pattern), ?broken-reverse-depType(pattern),
   ~RB[depType:]pattern

   depType may be either “provides” or one of the dependency types given in
   the documentation of ?broken-depType. If depType is not present, it
   defaults to depends.

   Matches packages which a package version matching pattern declares an
   unsatisfied dependency of type depType upon.

   ?section(section), ~ssection

   Matches packages whose section matches the regular expression section.

   ?source-package(name), ~ename

   Matches packages whose source package name matches the regular expression
   name.

   ?source-version(version)

   Matches packages whose source version matches the regular expression
   version.

   ?tag(tag), ~Gtag

   Matches packages whose Tag field matches the regular expression tag. For
   instance, the pattern ?tag(game::strategy) would match strategy games.

   For more information on tags and debtags, see
   http://debtags.alioth.debian.org.

   ?task(task), ~ttask

   Matches packages that appear in a task whose name matches the regular
   expression task.

   ?term(keyword)

   This term performs a full-text search for keyword in the apt package
   cache. When used with “aptitude search”, Search → Limit Display (l) in the
   curses front-end, or typed into a package search box in the GTK+
   front-end, this term will allow aptitude to accelerate the search using a
   Xapian index.

   ?term-prefix(keyword)

   This term performs a full-text search for any keyword beginning with
   keyword in the apt package cache. When used with “aptitude search”, Search
   → Limit Display (l) in the curses front-end, or typed into a package
   search box in the GTK+ front-end, this term will allow aptitude to
   accelerate the search using a Xapian index.

   This is similar to ?term, but matches extensions of the keyword. For
   instance, the following search pattern will match any package indexed
   under the keywords hour, hourglass, hourly, and so on:

   Example 2.6. Use of the ?term-prefix term

   ?term-prefix(hour)

   ?true, ~T

   This term matches any package. For instance, “?installed?provides(?true)”
   matches installed packages which provide any package.

   ?upgradable, ~U

   This term matches any installed package which can be upgraded.

   [Note] Note
          Note that this only tests whether there are upgrades available for
          a package, not whether an upgrade could be performed (with actions
          such as safe-upgrade or full-upgrade).

          For instance, there can be upgrades available for several packages,
          but maybe the upgraded versions of a subset conflict with each
          other, so they cannot be co-installed or not all of them upgraded
          at the same time.

   ?user-tag(tag)

   This term matches any package that is marked with a user-tag matching the
   regular expression tag.

   ?version(version), ~Vversion

   Matches any package version whose version number matches the regular
   expression version, with the exceptions noted below. For instance,
   “?version(debian)” matches packages whose version contains “debian”.

   The following values of version are treated specially. To search for
   version numbers containing these values, preface the value with a
   backslash; for instance, to find packages whose version number contains
   CURRENT, search for \CURRENT.

     • CURRENT matches the currently installed version of a package, if any.

     • CANDIDATE matches the version, if any, of the package that will be
       installed if you press + on the package or run aptitude install on it.

     • TARGET matches the version of a package that is currently targeted for
       installation, if any.

   ?virtual, ~v

   Matches any package which is purely virtual: that is, its name is provided
   by a package, but no package of that name exists. For instance,
   “?virtual?reverse-provides(?installed)” matches virtual packages which are
   provided by any installed package.

   ?widen(pattern), ~Wpattern

   “Widens” the match: if the versions to match against have been limited by
   an enclosing term (such as ?depends), these limits are dropped. Thus,
   ?widen(pattern) matches a package version if pattern matches any version
   of that package.

Customizing aptitude

  Customizing the package list

   The package list can be heavily customized: how packages are displayed,
   how the package hierarchy is formed, how packages are sorted, and even how
   the display is organized are all open to change.

    Customizing how packages are displayed

   This section describes how to configure the contents and format of the
   package list, status line, and header line, as well as the output of
   aptitude search.

   The format of each of these locations is defined by a “format string”. A
   format string is a string of text containing %-escapes such as %p, %S, and
   so on. The resulting output is created by taking the text and replacing
   the %-escapes according to their meanings (given below).

   A %-escape can either have a fixed size, in which case it is always
   replaced by the same amount of text (with extra space characters added to
   fill it out as necessary), or it can be “expandable”, meaning that it
   takes up the space that is not claimed by fixed-size columns. If there are
   several expandable columns, the extra space is divided evenly between
   them.

   All %-escapes come with a default size and/or expandability. The size of a
   %-escape can be changed by writing it between the % and the character
   identifying the escape; for instance, %20V generates the candidate version
   of the package, 20 characters wide. Placing a question mark (?) between
   the % and the character identifying the escape causes the column's “basic”
   width to vary depending on its content. Note that the resulting columns
   might not line up vertically!

   If you want a particular %-escape to be expandable, even though it
   normally has a fixed width, place a pound sign (ie, “#”) immediately after
   it. For instance, to display the candidate version of a package, no matter
   how long it is, use the format string %V#. You can also place # after
   something that is not a %-escape; aptitude will “expand” the text
   preceding the # by inserting extra spaces after it.

   In summary, the syntax of a %-escape is:

 %[width][?]code[#]

   The configuration variables Aptitude::UI::Package-Display-Format,
   Aptitude::UI::Package-Header-Format, and
   Aptitude::UI::Package-Status-Format define the default formats the package
   list, the header at the top of the package list, and the status line below
   the package list respectively. To change how the results of an aptitude
   search command are displayed, use the -F option.

   The following %-escapes are available in format strings:

   [Note] Note
          Some of the descriptions below refer to “the package”. In the GUI,
          this is either the package being displayed or the currently
          selected package; in the command-line search, this is the package
          being displayed.

    Escape       Name       Default size Expandable        Description
                                                    This is not really an
                                                    escape; it simply inserts
   %%       Literal %       1            No         a percent sign into the
                                                    output at the point at
                                                    which it occurs.
                                                    In some circumstances, a
                                                    display format string
                                                    will have “parameters”:
                                                    for instance, in the
                                                    command-line search, the
   %#number Parameter       Variable     No         groups matched by the
            Replacement                             search are used as
                                                    parameters when
                                                    displaying the result.
                                                    This format code will be
                                                    replaced by the parameter
                                                    indicated by number.
                                                    A single-character flag
                                                    summarizing any action to
   %a       Action Flag     1            No         be performed on the
                                                    package, as described in
                                                    Figure 2.10, “Values of
                                                    the “action” flag”.
                                                    A somewhat more verbose
   %A       Action          10           No         description of the action
                                                    to be performed on the
                                                    package.
                                                    If there are no broken
                                                    packages, produces
                                                    nothing. Otherwise,
   %B       Broken Count    12           No         produces a string such as
                                                    “Broken: 10” describing
                                                    the number of broken
                                                    packages.
                                                    A single-character flag
                                                    summarizing the current
   %c       Current State   1            No         state of the package, as
            Flag                                    described in Figure 2.9,
                                                    “Values of the “current
                                                    state” flag”.
                                                    A more verbose
   %C       Current State   11           No         description of the
                                                    current state of the
                                                    package.
   %d       Description     40           Yes        The package's short
                                                    description.
                                                    The size of the package
   %D       Package Size    8            No         file containing the
                                                    package.
                                                    Outputs the string of the
   %E       Architecture    10           No         architecture, for example
                                                    “amd64”.
                                                    Outputs the source
   %e       Source          30           No         package, for example
                                                    “aptitude” for
                                                    “aptitude-doc-en”.
                                                    The name of the computer
   %H       Hostname        15           No         on which aptitude is
                                                    running.
                                                    Displays the highest
                                                    priority assigned to a
                                                    package version; for
   %i       Pin priority    4            No         packages, displays the
                                                    priority of the version
                                                    which will be forced to
                                                    be installed (if any).
                                                    The (estimated) amount of
   %I       Installed Size  8            No         space the package takes
                                                    up on disk.
   %m       Maintainer      30           Yes        The maintainer of the
                                                    package.
                                                    If the package is
   %M       Automatic Flag  1            No         automatically installed,
                                                    outputs “A”; otherwise,
                                                    outputs nothing.
                            The length              Outputs the version of
   %n       Program Version of “0.8.12”. No         aptitude that is running,
                                                    currently “0.8.12”.
                            The length              Outputs the name of the
   %N       Program Name    of the name. No         program; usually
                                                    “aptitude”.
                                                    If no packages are going
                                                    to be installed, outputs
                                                    nothing. Otherwise,
                                                    outputs a string
                                                    describing the total size
   %o       Download Size   17           No         of all the package files
                                                    which will be installed
                                                    (an estimate of how much
                                                    needs to be downloaded);
                                                    for instance, “DL size:
                                                    1000B”.
                                                    Outputs a string of the
                                                    origin of the package,
   %O       Origin          30           No         for example
                                                    “Debian:unstable
                                                    [amd64]”.
                                                    Outputs the name of the
                                                    package. When a package
                                                    is displayed in a tree
   %p       Package Name    30           Yes        context, the name of the
                                                    package will be indented,
                                                    if possible, according to
                                                    its depth in the tree.
   %P       Priority        9            No         Outputs the priority of
                                                    the package.
                                                    Outputs the approximate
   %r       Reverse Depends 2            No         number of installed
            Count                                   packages which depend
                                                    upon the package.
                                                    Outputs an abbreviated
            Abbreviated                             description of the
   %R       Priority        3            No         package's priority: for
                                                    instance, “Important”
                                                    becomes “Imp”.
   %s       Section         10           No         Outputs the section of
                                                    the package.
                                                    If the package is
   %S       Trust Status    1            No         untrusted, displays the
                                                    letter "U".
   %t       Archive         10           Yes        The archive in which the
                                                    package is found.
                                                    Outputs “*” if the
                                                    package is tagged,
   %T       Tagged (and     30           No         nothing otherwise.^[19]
            user-tags)
                                                    This field also includes
                                                    user-tags.
                                                    If the scheduled actions
                                                    will alter the amount of
            Disk Usage                              space used on the disk,
   %u       Change          30           No         outputs a description of
                                                    the change in disk space;
                                                    for instance, “Will use
                                                    100MB of disk space.”
                                                    Outputs the currently
                                                    installed version of the
   %v       Current Version 14           No         package, or <none> if the
                                                    package is not currently
                                                    installed.
                                                    Outputs the version of
                                                    the package which would
            Candidate                               be installed if Package →
   %V       Version         14           No         Install (+) were issued
                                                    on the package, or <none>
                                                    if the package is not
                                                    currently available.
                                                    Outputs how much
                                                    additional space will be
   %Z       Size Change     9            No         used or how much space
                                                    will be freed by
                                                    installing, upgrading, or
                                                    removing a package.

    Customizing the package hierarchy

   The package hierarchy is generated by a grouping policy: rules describing
   how the hierarchy should be built. The grouping policy describes a
   “pipeline” of rules; each rule can discard packages, create
   sub-hierarchies in which packages reside, or otherwise manipulate the
   tree. The configuration items Aptitude::UI::Default-Grouping and
   Aptitude::UI::Default-Preview-Grouping set the grouping policies for newly
   created package lists and preview screens, respectively. You can set the
   grouping policy for the current package list by pressing G.

   The grouping policy is described by a comma-separated list of rules:
   rule1,rule2,.... Each rule consists of the name of the rule, possibly
   followed by arguments: for instance, versions or section(subdir). Whether
   arguments are required and how many arguments are required (or allowed)
   depends on the type of rule.

   Rules can be non-terminal or terminal. A non-terminal rule will process a
   package by generating some part of the hierarchy, then passing the package
   on to a later rule. A terminal rule, on the other hand, will also generate
   part of the tree (typically items corresponding to the package), but does
   not pass its package to a later rule. If no terminal rule is specified,
   aptitude will use the default rule, which is to create the standard
   “package items”.

 action

   Groups packages according to the action scheduled on them; packages that
   are not upgradable and will be unchanged are ignored. This is the grouping
   that is used in preview trees.

 architecture

   Groups packages according to their architecture.

 deps

   This is a terminal rule.

   Creates standard package items which can be expanded to reveal the
   dependencies of the package.

 filter(pattern)

   Include only packages for which at least one version matches pattern.

   If pattern is “missing”, no packages are discarded. This is a backwards
   compatibility feature and may be removed in the future.

 firstchar[(mode)]

   Groups packages based on the first character of their name.

   To be precise, it is not always the first letter -- for packages starting
   with lib* the name of the group is liba, libb, ... like in Debian FTPs.

   mode can be one of the following:

   binary

   Group based on the binary package name. This is the default if no mode is
   specified.

   Example 2.7. Grouping policy firstchar or firstchar(binary)

   With the source package dpkg as an example, the binary packages dselect,
   dpkg and dpkg-dev would be grouped under d, while libdpkg-dev and
   libdpkg-perl would be added to the libd group.

   source

   Group based on the source package name.

   This is useful for example when browsing packages coming from the same
   source package (source grouping policy) within large collections
   (examples: all installed packages, all upgradable packages, all packages
   from "main" section), to add an intermediate grouping step. In this way,
   one can for example emulate the hierarchy of FTPs (try grouping:
   "section(topdir),firstchar(source),source").

   Example 2.8. Grouping policy firstchar(source)

   Again, with the source package dpkg as an example, all the binary packages
   dselect, dpkg, dpkg-dev, libdpkg-dev and libdpkg-perl would be grouped
   under d.

 pattern(pattern [=> title] [{ policy }] [, ...])

   A customizable grouping policy. Each version of every package is matched
   against the given patterns. The first match found is used to assign a
   title to the package; packages are then grouped by their title. Strings of
   the form \N that occur in title will be replaced by the Nth result of the
   match. If title is not present, it is assumed to be \1. Note that packages
   which do not match any patterns will not appear in the tree at all.

   Example 2.9. Use of pattern to group packages by their maintainer

   pattern(?maintainer() => \1)

   The example above will group packages according to their Maintainer field.
   The policy pattern(?maintainer()) will do the same thing, as the absent
   title defaults to \1.

   Instead of => title, an entry may end with ||. This indicates that
   packages matching the corresponding pattern will be inserted into the tree
   at the same level as the pattern grouping, rather than being placed in
   subtrees.

   Example 2.10.  Use of pattern with some packages placed at the top level

   pattern(?action(remove) => Packages Being Removed, ?true ||)

   The example above will place packages that are being removed into a
   subtree, and place all the other packages at the current level, grouped
   according to the policies that follow pattern.

   By default, all the packages that match each pattern are grouped according
   to the rules that follow the pattern policy. To specify a different policy
   for some packages, write the policy in braces ({}) after the title of the
   group, after the ||, or after the pattern if neither is present. For
   instance:

   Example 2.11.  Use of the pattern grouping policy with sub-policies

   pattern(?action(remove) => Packages Being Removed {}, ?action(install) =>
   Packages Being Installed, ?true || {status})

   The policy in the above example has the following effects:

     • Packages that are being removed are placed into a subtree labeled
       “Packages Being Removed”; the grouping policy for this subtree is
       empty, so the packages are placed into a flat list.

     • Packages that are being installed are placed into a subtree labeled
       Packages Being Installed and grouped according to the policies that
       follow pattern.

     • All remaining packages are placed at the top level of the tree,
       grouped according to their status.

   See the section called “Search patterns” for more information on the
   format of pattern.

 priority

   Groups packages according to their priority.

 section[(mode[,passthrough])]

   Groups packages according to their Section field.

   mode can be one of the following:

   none

   Group based on the whole Section field, so categories like
   “non-free/games” will be created. This is the default if no mode is
   specified.

   topdir

   Group based on the part of the Section field before the first / character;
   if this part of the Section is not recognized, or if there is no /, the
   first entry in the list Aptitude::Sections::Top-Sections will be used
   instead.

   subdir

   Group based on the part of the Section field after the first / character,
   if it is contained in the list Aptitude::Sections::Top-Sections. If not,
   or if there is no /, group based on the entire Section field instead.

   subdirs

   Group based on the part of the Section field after the first / character,
   if the portion of the field preceding it is contained in the list
   Aptitude::Sections::Top-Sections; if not, or if there is no /, the entire
   field will be used. If there are multiple / characters in the portion of
   the field that is used, a hierarchy of groups will be formed. For
   instance, if “games” is not a member of Aptitude::Sections::Top-Sections,
   then a package with a section of “games/arcade” will be placed under the
   top-level heading “games”, in a sub-tree named “arcade”.

   If passthrough is present, packages which for some reason lack a true
   Section (for instance, virtual packages) will be passed directly to the
   next level of grouping without first being placed in sub-categories.

 status

   Groups packages into the following categories:

     • Security Updates

     • Upgradable

     • New

     • Installed

     • Not Installed

     • Obsolete and Locally Created

     • Virtual

 source

   Groups packages according to their source package name.

 tag[(facet)]

   Groups packages according to the Tag information stored in the Debian
   package files. If facet is provided, then only tags corresponding to that
   facet will be displayed, and packages lacking this facet will be hidden;
   otherwise, all packages will be displayed at least once (with tagless
   packages listed separately from packages that have tags).

   For more information on debtags, see http://debtags.alioth.debian.org.

 task

   Creates a tree called “Tasks” which contains the available tasks
   (information on tasks is read from debian-tasks.desc in the package
   tasksel). The rule following task will create its categories as siblings
   of Tasks.

 versions

   This is a terminal rule.

   Creates standard package items which can be expanded to reveal the
   versions of the package.

    Customizing how packages are sorted

   By default, packages in the package list or in the output of aptitude
   search are sorted by name. However, it is often useful to sort them
   according to different criteria (for instance, package size), and aptitude
   allows you to do just that by modifying the sorting policy.

   Like the grouping policy described in the previous section, the sorting
   policy is a comma-separated list. Each item in the list is the name of a
   sorting rule; if packages are “equal” according to the first rule, the
   second rule is used to sort them, and so on. Placing a tilde character (~)
   in front of a rule reverses the usual meaning of that rule. For instance,
   priority,~name will sort packages by priority, but packages with the same
   priority will be placed in reverse order according to name.

   To change the sorting policy for an active package list, press S. To
   change the default sorting for all package lists, set the configuration
   option Aptitude::UI::Default-Sorting. To change the sorting policy for
   aptitude search, use the --sort command-line option.

   The available rules are:

   installsize

   Sorts packages by the estimated amount of size they require when
   installed.

   installsizechange

   Sorts packages by the change in the installed size (estimated amount of
   size required when installed), comparing the current version (if
   installed) and the candidate version to be installed, upgraded or removed.

   debsize

   Sorts packages by the size of the package.

   name

   Sorts packages by name.

   priority

   Sorts packages by priority.

   version

   Sorts packages according to their version number.

  Customizing keybindings

   The keys used to activate commands in aptitude can be customized in the
   configuration file. Every command has an associated configuration variable
   under Aptitude::UI::Keybindings; to change the keystroke bound to a
   command, just set the corresponding variable to the keystroke. For
   instance, to make the key s perform a search, set
   Aptitude::UI::Keybindings::Search to “s”. You can require the Control key
   to be pressed by placing “C-” in front of the key: for instance, using
   “C-s” instead of “s” would bind Search to Control+s instead of s. Finally,
   you can bind a command to several keys at once using a comma-separated
   list: for instance, using “s,C-s” would cause both s and Control+s to
   perform a search.

   The following commands can be bound to keys by setting the variable
   Aptitude::UI::Keybindings::command, where command is the name of the
   command to be bound:

   ┌────────────────────────┬─────────────────────┬─────────────────────────┐
   │        Command         │       Default       │       Description       │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ If packages are broken  │
   │                        │                     │ and aptitude has        │
   │ ApplySolution          │ !                   │ suggested a solution to │
   │                        │                     │ the problem,            │
   │                        │                     │ immediately apply the   │
   │                        │                     │ solution.               │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Move to the beginning   │
   │                        │                     │ of the current display: │
   │ Begin                  │ home,C-a            │ to the top of a list,   │
   │                        │                     │ or to the left of a     │
   │                        │                     │ text entry field.       │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Cancels the current     │
   │                        │                     │ interaction: for        │
   │ Cancel                 │ C-g,escape,C-[      │ instance, discards a    │
   │                        │                     │ dialog box or           │
   │                        │                     │ deactivates the menu.   │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Displays the            │
   │                        │                     │ changelog.Debian of the │
   │ Changelog              │ C                   │ currently selected      │
   │                        │                     │ package or package      │
   │                        │                     │ version.                │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Changes the grouping    │
   │ ChangePkgTreeGrouping  │ G                   │ policy of the currently │
   │                        │                     │ active package list.    │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Changes the limit of    │
   │ ChangePkgTreeLimit     │ l                   │ the currently active    │
   │                        │                     │ package list.           │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Changes the sorting     │
   │ ChangePkgTreeSorting   │ S                   │ policy of the currently │
   │                        │                     │ active package list.    │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Marks the currently     │
   │ ClearAuto              │ m                   │ selected package as     │
   │                        │                     │ having been manually    │
   │                        │                     │ installed.              │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Collapses the selected  │
   │ CollapseAll            │ ]                   │ tree and all its        │
   │                        │                     │ children in a           │
   │                        │                     │ hierarchical list.      │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Collapses the selected  │
   │ CollapseTree           │ left                │ tree in a hierarchical  │
   │                        │                     │ list.                   │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ In dialog boxes, this   │
   │                        │                     │ is equivalent to        │
   │                        │                     │ pressing “Ok”; when     │
   │ Confirm                │ enter               │ interacting with a      │
   │                        │                     │ status-line multiple    │
   │                        │                     │ choice question, it     │
   │                        │                     │ chooses the default     │
   │                        │                     │ option.                 │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Switches the keyboard   │
   │ Cycle                  │ tab                 │ focus to the next       │
   │                        │                     │ “widget”.               │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │ CycleNext              │ f6                  │ Switches to the next    │
   │                        │                     │ active view.            │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Cycles through          │
   │ CycleOrder             │ o                   │ predefined arrangements │
   │                        │                     │ of the display.         │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │ CyclePrev              │ f7                  │ Switches to the         │
   │                        │                     │ previous active view.   │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Deletes all text        │
   │ DelBOL                 │ C-u                 │ between the cursor and  │
   │                        │                     │ the beginning of the    │
   │                        │                     │ line.                   │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Deletes the previous    │
   │ DelBack                │ backspace,C-h       │ character when entering │
   │                        │                     │ text.                   │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Deletes all text from   │
   │ DelEOL                 │ C-k                 │ the cursor to the end   │
   │                        │                     │ of the line.            │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Deletes the character   │
   │ DelForward             │ delete,C-d          │ under the cursor when   │
   │                        │                     │ entering text.          │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Displays the            │
   │ Dependencies           │ d                   │ dependencies of the     │
   │                        │                     │ currently selected      │
   │                        │                     │ package.                │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ When browsing the       │
   │                        │                     │ package list, cycles    │
   │ DescriptionCycle       │ i                   │ through the available   │
   │                        │                     │ views in the            │
   │                        │                     │ information area.       │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ When browsing the       │
   │ DescriptionDown        │ z                   │ package list, scrolls   │
   │                        │                     │ the information area    │
   │                        │                     │ down one line.          │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ When browsing the       │
   │ DescriptionUp          │ a                   │ package list, scrolls   │
   │                        │                     │ the information area up │
   │                        │                     │ one line.               │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ If not in a preview     │
   │                        │                     │ screen, display the     │
   │ DoInstallRun           │ g                   │ preview screen ^[a]; if │
   │                        │                     │ in a preview screen,    │
   │                        │                     │ perform an install run. │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Moves down: for         │
   │                        │                     │ instance, scrolls a     │
   │ Down                   │ down,j              │ text display down or    │
   │                        │                     │ selects the next item   │
   │                        │                     │ in a list.              │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ If packages are broken, │
   │                        │                     │ writes the current      │
   │ DumpResolver           │ *                   │ state of the            │
   │                        │                     │ problem-resolver to a   │
   │                        │                     │ file (for debugging     │
   │                        │                     │ purposes).              │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Move to the end of the  │
   │                        │                     │ current display: to the │
   │ End                    │ end,C-e             │ bottom of a list, or to │
   │                        │                     │ the right of a text     │
   │                        │                     │ entry field.            │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ If some packages are    │
   │                        │                     │ broken and aptitude has │
   │                        │                     │ suggested a solution,   │
   │ ExamineSolution        │ e                   │ display a dialog box    │
   │                        │                     │ with a detailed         │
   │                        │                     │ description of the      │
   │                        │                     │ proposed solution.      │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Expands the selected    │
   │ ExpandAll              │ [                   │ tree and all its        │
   │                        │                     │ children in a           │
   │                        │                     │ hierarchical list.      │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Expands the selected    │
   │ ExpandTree             │ right               │ tree in a hierarchical  │
   │                        │                     │ list.                   │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Select the first        │
   │ FirstSolution          │ <                   │ solution produced by    │
   │                        │                     │ the problem resolver.   │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Forbids a package from  │
   │                        │                     │ being upgraded to the   │
   │ ForbidUpgrade          │ F                   │ currently available     │
   │                        │                     │ version (or a           │
   │                        │                     │ particular version).    │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Discards all            │
   │                        │                     │ information about which │
   │ ForgetNewPackages      │ f                   │ packages are “new”      │
   │                        │                     │ (causes the list of     │
   │                        │                     │ “new” packages to       │
   │                        │                     │ become empty).          │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │ Help                   │ ?                   │ Displays the on-line    │
   │                        │                     │ help screen.            │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ In a line editor with   │
   │ HistoryNext            │ down,C-n            │ history, moves forwards │
   │                        │                     │ in the history.         │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ In a line editor with   │
   │ HistoryPrev            │ up,C-p              │ history, moves          │
   │                        │                     │ backwards in the        │
   │                        │                     │ history.                │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │ Hold                   │ =                   │ Places a package on     │
   │                        │                     │ hold.                   │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │ Install                │ +                   │ Flags a package for     │
   │                        │                     │ installation.           │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Marks a single package  │
   │                        │                     │ for installation; all   │
   │ InstallSingle          │ I                   │ other packages are kept │
   │                        │                     │ at their current        │
   │                        │                     │ version.                │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Cancels all             │
   │ Keep                   │ :                   │ installation or removal │
   │                        │                     │ requests and all holds  │
   │                        │                     │ for a package.          │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Select the last         │
   │ LastSolution           │ <                   │ solution produced by    │
   │                        │                     │ the problem resolver.   │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Moves left: for         │
   │                        │                     │ instance, moves one     │
   │ Left                   │ left,h              │ menu to the left in the │
   │                        │                     │ menu bar, or moves the  │
   │                        │                     │ cursor to the left when │
   │                        │                     │ editing text.           │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ In a hierarchical list, │
   │                        │                     │ selects the next        │
   │                        │                     │ sibling of the          │
   │ LevelDown              │ J                   │ currently selected item │
   │                        │                     │ (the next item at the   │
   │                        │                     │ same level with the     │
   │                        │                     │ same parent).           │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ In a hierarchical list, │
   │                        │                     │ selects the previous    │
   │                        │                     │ sibling of the          │
   │ LevelUp                │ K                   │ currently selected item │
   │                        │                     │ (the previous item at   │
   │                        │                     │ the same level with the │
   │                        │                     │ same parent).           │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Attempts to upgrade all │
   │                        │                     │ packages which are not  │
   │ MarkUpgradable         │ U                   │ held back or forbidden  │
   │                        │                     │ from upgrading. It also │
   │                        │                     │ installs new Essential  │
   │                        │                     │ or Required packages.   │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ In Minesweeper, places  │
   │ MineFlagSquare         │ f                   │ or removes a flag on a  │
   │                        │                     │ square.                 │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │ MineLoadGame           │ L                   │ Loads a Minesweeper     │
   │                        │                     │ game.                   │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │ MineSaveGame           │ S                   │ Saves a Minesweeper     │
   │                        │                     │ game.                   │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Sweeps around the       │
   │ MineSweepSquare        │ No binding          │ current square in       │
   │                        │                     │ Minesweeper.            │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │ MineUncoverSquare      │ No binding          │ Uncovers the current    │
   │                        │                     │ square in Minesweeper   │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Uncovers the current    │
   │                        │                     │ square in Minesweeper   │
   │ MineUncoverSweepSquare │ enter               │ if it is covered;       │
   │                        │                     │ otherwise, sweeps       │
   │                        │                     │ around it.              │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Moves the current       │
   │ NextPage               │ pagedown,C-f        │ display one page        │
   │                        │                     │ forward.                │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Advance the dependency  │
   │ NextSolution           │ .                   │ resolver to the next    │
   │                        │                     │ solution.               │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ This key will select    │
   │ No                     │ n^[b]               │ the “no” button in      │
   │                        │                     │ yes/no dialog boxes.    │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Selects the parent of   │
   │                        │                     │ the selected item in a  │
   │                        │ ^, left (in package │ hierarchical list. left │
   │ Parent                 │ items)              │ is used only in package │
   │                        │                     │ items (rows) when       │
   │                        │                     │ showing trees of        │
   │                        │                     │ packages.               │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Moves the current       │
   │ PrevPage               │ pageup,C-b          │ display one page        │
   │                        │                     │ backward.               │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Return the dependency   │
   │ PrevSolution           │ ,                   │ resolver to the         │
   │                        │                     │ previous solution.      │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Flags the currently     │
   │ Purge                  │ _                   │ selected package to be  │
   │                        │                     │ purged.                 │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Activates the currently │
   │ PushButton             │ space,enter         │ selected button, or     │
   │                        │                     │ toggles a checkbox.     │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │ Quit                   │ q                   │ Close the current view. │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │ QuitProgram            │ Q                   │ Quit the entire         │
   │                        │                     │ program.                │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Reject all resolver     │
   │                        │                     │ actions that would      │
   │ RejectBreakHolds       │                     │ break a hold;           │
   │                        │                     │ equivalent to Resolver  │
   │                        │                     │ → Reject Breaking       │
   │                        │                     │ Holds.                  │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │ Refresh                │ C-l                 │ Redraws the screen from │
   │                        │                     │ scratch.                │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │ Remove                 │ -                   │ Flags a package for     │
   │                        │                     │ removal.                │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Flags the currently     │
   │ ReInstall              │ L                   │ selected package to be  │
   │                        │                     │ reinstalled.            │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Repeats the last        │
   │ RepeatSearchBack       │ N                   │ search, but searches in │
   │                        │                     │ the opposite direction. │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │ ReSearch               │ n                   │ Repeats the last        │
   │                        │                     │ search.                 │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Displays packages which │
   │ ReverseDependencies    │ r                   │ depend upon the         │
   │                        │                     │ currently selected      │
   │                        │                     │ package.                │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Moves right: for        │
   │                        │                     │ instance, moves one     │
   │ Right                  │ right,l             │ menu to the right in    │
   │                        │                     │ the menu bar, or moves  │
   │                        │                     │ the cursor to the right │
   │                        │                     │ when editing text.      │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Activate the “search”   │
   │ Search                 │ /                   │ function of the         │
   │                        │                     │ currently active        │
   │                        │                     │ interface element.      │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Activate the “search    │
   │ SearchBack             │ \                   │ backwards” function of  │
   │                        │                     │ the currently active    │
   │                        │                     │ interface element.      │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ In a package tree,      │
   │ SearchBroken           │ b                   │ search for the next     │
   │                        │                     │ broken package.         │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Marks the current       │
   │ SetAuto                │ M                   │ package as having been  │
   │                        │                     │ automatically           │
   │                        │                     │ installed.              │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ In a package list,      │
   │ ShowHideDescription    │ D                   │ toggles whether the     │
   │                        │                     │ information area is     │
   │                        │                     │ visible.                │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ When viewing a          │
   │                        │                     │ solution, marks the     │
   │                        │                     │ currently selected      │
   │ SolutionActionApprove  │ a                   │ action as "approved"    │
   │                        │                     │ (it will be included in │
   │                        │                     │ future solutions        │
   │                        │                     │ whenever possible).     │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ When viewing a          │
   │                        │                     │ solution, marks the     │
   │ SolutionActionReject   │ r                   │ currently selected      │
   │                        │                     │ action as "rejected"    │
   │                        │                     │ (future solutions will  │
   │                        │                     │ not contain it).        │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Expands or collapses    │
   │ ToggleExpanded         │ enter               │ the currently selected  │
   │                        │                     │ tree in a hierarchical  │
   │                        │                     │ list.                   │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Activates or            │
   │ ToggleMenuActive       │ C-m,f10,C-space     │ deactivates the main    │
   │                        │                     │ menu.                   │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Cancels the last        │
   │                        │                     │ action, up to when      │
   │                        │                     │ aptitude was started OR │
   │ Undo                   │ C-_,C-u             │ the last time you       │
   │                        │                     │ update the package      │
   │                        │                     │ lists or installed      │
   │                        │                     │ packages.               │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Moves up: for instance, │
   │                        │                     │ scrolls a text display  │
   │ Up                     │ up,k                │ up or selects the       │
   │                        │                     │ previous item in a      │
   │                        │                     │ list.                   │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Updates the list of     │
   │ UpdatePackageList      │ u                   │ packages by fetching    │
   │                        │                     │ new lists from the      │
   │                        │                     │ Internet if necessary.  │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ Displays the available  │
   │ Versions               │ v                   │ versions of the         │
   │                        │                     │ currently selected      │
   │                        │                     │ package.                │
   ├────────────────────────┼─────────────────────┼─────────────────────────┤
   │                        │                     │ This key will select    │
   │ Yes                    │ y ^[b]              │ the “Yes” button in     │
   │                        │                     │ yes/no dialog boxes.    │
   ├────────────────────────┴─────────────────────┴─────────────────────────┤
   │ ^[a] unless Aptitude::Display-Planned-Action is false.                 │
   │                                                                        │
   │ ^[b] This default may be different in different locales.               │
   └────────────────────────────────────────────────────────────────────────┘

   In addition to letter keys, number keys, and punctuation, the following
   “special” keys can be bound:

   ┌──────────────────┬─────────────────────────────────────────────────────┐
   │     Key name     │                     Description                     │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ a1               │ The A1 key.                                         │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ a3               │ The A3 key.                                         │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ b2               │ The B2 key.                                         │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ backspace        │ The Backspace key.                                  │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ backtab          │ The back-tab key                                    │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ begin            │ The Begin key (not Home)                            │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ break            │ The “break” key.                                    │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ c1               │ The C1 key.                                         │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ c3               │ The C3 key.                                         │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ cancel           │ The Cancel key.                                     │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ create           │ The Create key.                                     │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ comma            │ Comma (,) -- note that because commas are used to   │
   │                  │ list keys, this is the only way to bind to a comma. │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ command          │ The Command key.                                    │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ copy             │ The Copy key.                                       │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ delete           │ The Delete key.                                     │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ delete_line      │ The “delete line” key.                              │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ down             │ The “down” arrow key.                               │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ end              │ The End key.                                        │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ entry            │ The Enter key.                                      │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ exit             │ The Exit key.                                       │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ f1, f2, ..., f10 │ The F1 through F10 keys.                            │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ find             │ The Find key.                                       │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ home             │ The Home key.                                       │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ insert           │ The Insert key.                                     │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ insert_exit      │ The “insert exit” key.                              │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ clear            │ The “clear” key.                                    │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ clear_eol        │ The “clear to end of line” key.                     │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ clear_eos        │ The “clear to end of screen” key.                   │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ insert_line      │ The “insert line” key.                              │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ left             │ The “left” arrow key.                               │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ mark             │ The Mark key.                                       │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ message          │ The Message key.                                    │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ move             │ The Move key.                                       │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ next             │ The Next key.                                       │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ open             │ The Open key.                                       │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ previous         │ The Previous key.                                   │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ print            │ The Print key.                                      │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ redo             │ The Redo key.                                       │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ reference        │ The Reference key.                                  │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ refresh          │ The Refresh key.                                    │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ replace          │ The Replace key.                                    │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ restart          │ The Restart key.                                    │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ resume           │ The Resume key.                                     │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ return           │ The Return key.                                     │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ right            │ The “right” arrow key.                              │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ save             │ The Save key.                                       │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ scrollf          │ The “scroll forward” key.                           │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ scrollr          │ The “scroll backwards” key.                         │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ select           │ The Select key.                                     │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ suspend          │ The Suspend key.                                    │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ pagedown         │ The “Page Down” key.                                │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ pageup           │ The “Page Up” key.                                  │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ space            │ The Space key                                       │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ tab              │ The Tab key                                         │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ undo             │ The Undo key.                                       │
   ├──────────────────┼─────────────────────────────────────────────────────┤
   │ up               │ The “up” arrow key.                                 │
   └──────────────────┴─────────────────────────────────────────────────────┘

   In addition to binding keys globally, it is possible to change key
   bindings for one particular part (or domain) of aptitude: for instance, to
   make Tab the equivalent of the right arrow key in menu bars, set
   Aptitude::UI::Keybindings::Menubar::Right to “tab,right”. The following
   domains are available:

   ┌───────────────┬────────────────────────────────────────────────────────┐
   │    Domain     │                      Description                       │
   ├───────────────┼────────────────────────────────────────────────────────┤
   │ EditLine      │ Used by line-editing widgets, such as the entry field  │
   │               │ in a “search” dialog.                                  │
   ├───────────────┼────────────────────────────────────────────────────────┤
   │ Menu          │ Used by drop-down menus.                               │
   ├───────────────┼────────────────────────────────────────────────────────┤
   │ Menubar       │ Used by the menu bar at the top of the screen.         │
   ├───────────────┼────────────────────────────────────────────────────────┤
   │ Minesweeper   │ Used by the Minesweeper mode.                          │
   ├───────────────┼────────────────────────────────────────────────────────┤
   │               │ Used by the multiple-choice prompts that appear if you │
   │ MinibufChoice │ have chosen to have some prompts appear in the status  │
   │               │ line.                                                  │
   ├───────────────┼────────────────────────────────────────────────────────┤
   │ Pager         │ Used when displaying a file on disk (for instance, the │
   │               │ help text).                                            │
   ├───────────────┼────────────────────────────────────────────────────────┤
   │               │ Used by packages, trees of packages, package versions, │
   │ PkgNode       │ and package dependencies when they appear in package   │
   │               │ lists.                                                 │
   ├───────────────┼────────────────────────────────────────────────────────┤
   │ PkgTree       │ Used by package lists.                                 │
   ├───────────────┼────────────────────────────────────────────────────────┤
   │ Table         │ Used by tables of widgets (for instance, dialog        │
   │               │ boxes).                                                │
   ├───────────────┼────────────────────────────────────────────────────────┤
   │ TextLayout    │ Used by formatted text displays, such as package       │
   │               │ descriptions.                                          │
   ├───────────────┼────────────────────────────────────────────────────────┤
   │ Tree          │ Used by all tree displays (including package lists,    │
   │               │ for which it can be overridden by PkgTree).            │
   └───────────────┴────────────────────────────────────────────────────────┘

  Customizing text colors and styles

   The colors and visual styles used by aptitude to display text can be
   extensively customized. Each visual element has an associated “style”,
   which describes the particular colors and visual attributes that will be
   used to display that element. Styles take the form of a list of color and
   attribute settings. This list is not necessarily exhaustive; if some
   colors or attributes are not explicitly specified, their values will be
   taken from the surrounding visual context. In fact, most visual elements
   have an “empty” style by default.

   You can change the contents of a style by creating a configuration group
   of the same name in the apt or aptitude configuration file. For instance,
   the “MenuBorder” style is used to draw the visual border around drop-down
   menus. By default, this border is drawn bold and white-on-blue. Placing
   the following text in the configuration file would change it to
   white-on-cyan:

 Aptitude::UI::Styles {
   MenuBorder {fg white; bg cyan; set bold;};
 };

   As you can see, a style's configuration group consists of a sequence of
   instructions. The general classes of instructions are:

   fg color

   Sets the text foreground to the given color. See below for a list of the
   colors known to aptitude.

   bg color

   Sets the text background to the given color. See below for a list of the
   colors known to aptitude.

   set attribute

   Enables the given text attribute. See below for a list of the text
   attributes known to aptitude.

   clear attribute

   Disables the given text attribute. See below for a list of the text
   attributes known to aptitude.

   flip attribute

   Toggles the given text attribute: if it is enabled in the surrounding
   element, it will be disabled, and vice versa. See below for a list of the
   text attributes known to aptitude.

   The colors that aptitude recognizes are black, blue, cyan, green, magenta,
   red, white, and yellow ^[20]. In addition, you may specify default in
   place of a background color to use the default terminal background (this
   could be the default color, an image file, or even “transparent”). The
   styles that aptitude recognizes are:

   blink

   Enables blinking text.

   bold

   Makes the foreground color of the text (or the background if reverse video
   is enabled) brighter.

   dim

   May cause text to be extra-dim on some terminals. No effect has been
   observed on common Linux terminals.

   reverse

   Swaps the foreground and background colors. Many visual elements flip this
   attribute to perform common highlighting tasks.

   standout

   This enables “the best highlighting mode of the terminal”. In xterms it is
   similar, but not idential to, reverse video; behavior on other terminals
   may vary.

   underline

   Enables underlined text.

   You can select several attributes at once by separating them with commas;
   for instance, set bold,standout;.

   [Note] Note
          As hinted at above, the interpretation of both styles and text
          attributes is highly terminal-dependent. You may need to experiment
          a bit to find out exactly what some settings do on your terminal.

   The following styles can be customized in aptitude:

   Figure 2.14. Customizable styles in aptitude

  ┌──────────────────────────┬───────────────┬─────────────────────────────────┐
  │          Style           │    Default    │           Description           │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │Bullet                    │fg yellow; set │The style of the bullets in      │
  │                          │bold;          │bulleted lists.                  │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │                          │               │The style of newer versions of   │
  │                          │               │the package in the changelog     │
  │                          │               │view. Note that aptitude will    │
  │ChangelogNewerVersion     │set bold;      │only highlight newer versions of │
  │                          │               │the package if you have the      │
  │                          │               │package                          │
  │                          │               │libparse-debianchangelog-perl    │
  │                          │               │installed.                       │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │Default                   │fg white; bg   │The basic style of the screen.   │
  │                          │black;         │                                 │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │DepBroken                 │fg black; bg   │The style of unfulfilled         │
  │                          │red;           │dependencies.                    │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │DisabledMenuEntry         │fg black; bg   │The style of menu entries that   │
  │                          │blue; set dim; │are disabled and cannot be used. │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │                          │               │The style used to indicate that a│
  │DownloadHit               │fg black; bg   │file was “hit”: i.e., it has not │
  │                          │green;         │changed since the last time it   │
  │                          │               │was downloaded.                  │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │DownloadProgress          │fg blue; bg    │The style of the progress        │
  │                          │yellow;        │indicator for a download.        │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │                          │fg white; bg   │The style of line editors (for   │
  │EditLine                  │black; clear   │instance, the entry in the       │
  │                          │reverse;       │“Search” dialog).                │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │Error                     │fg white; bg   │The style of error messages.     │
  │                          │red; set bold; │                                 │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │Header                    │fg white; bg   │The style of screen headers.     │
  │                          │blue; set bold;│                                 │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │                          │fg white; bg   │The style of the currently       │
  │HighlightedMenuBar        │blue; set      │selected menu name in the menu   │
  │                          │bold,reverse;  │bar.                             │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │                          │fg white; bg   │The style of the currently       │
  │HighlightedMenuEntry      │blue; set      │selected choice in a menu.       │
  │                          │bold,reverse;  │                                 │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │MediaChange               │fg yellow; bg  │The style of the dialog used to  │
  │                          │red; set bold; │ask the user to insert a new CD. │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │MenuBar                   │fg white; bg   │The style of the menu bar.       │
  │                          │blue; set bold;│                                 │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │MenuBorder                │fg white; bg   │The style of the borders that    │
  │                          │blue; set bold;│surround a drop-down menu.       │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │MenuEntry                 │fg white; bg   │The style of each entry in a     │
  │                          │blue;          │drop-down menu.                  │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │MineBomb                  │fg red; set    │The style of bombs in            │
  │                          │bold;          │Minesweeper.                     │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │MineBorder                │set bold;      │The style of the border drawn    │
  │                          │               │around a Minesweeper board.      │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │MineFlag                  │fg red; set    │The style of flags in            │
  │                          │bold;          │Minesweeper.                     │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │                          │               │The style of the number N in     │
  │MineNumberN               │Various        │Minesweeper; N may range from 0  │
  │                          │               │to 8.                            │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │                          │fg white; bg   │The color used to display “tabs” │
  │MultiplexTab              │blue;          │other than the currently selected│
  │                          │               │one.                             │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │MultiplexTabHighlighted   │fg blue; bg    │The color used to display the    │
  │                          │white;         │currently selected “tab”.        │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │                          │fg red; flip   │The style of packages in the     │
  │PkgBroken                 │reverse;       │package list which have          │
  │                          │               │unfulfilled dependencies.        │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │                          │               │The style of highlighted packages│
  │PkgBrokenHighlighted      │fg red;        │in the package list which have   │
  │                          │               │unfulfilled dependencies.        │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │                          │               │The style of packages which are  │
  │PkgNotInstalled           │               │not currently installed and will │
  │                          │               │not be installed.                │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │                          │               │The style of highlighted packages│
  │PkgNotInstalledHighlighted│               │which are not currently installed│
  │                          │               │and will not be installed.       │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │                          │               │The style of packages which are  │
  │PkgIsInstalled            │set bold;      │currently installed and for which│
  │                          │               │no actions are scheduled.        │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │                          │               │The style of highlighted packages│
  │PkgIsInstalledHighlighted │set bold; flip │which are currently installed and│
  │                          │reverse;       │for which no actions are         │
  │                          │               │scheduled.                       │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │                          │               │The style of packages in the     │
  │PkgToDowngrade            │set bold;      │package list which will be       │
  │                          │               │downgraded.                      │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │                          │set bold; flip │The style of highlighted packages│
  │PkgToDowngradeHighlighted │reverse        │in the package list which will be│
  │                          │               │downgraded.                      │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │PkgToHold                 │fg white; flip │The style of packages in the     │
  │                          │reverse;       │package list which are on hold.  │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │                          │               │The style of highlighted packages│
  │PkgToHoldHighlighted      │fg white;      │in the package list which are on │
  │                          │               │hold.                            │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │                          │               │The style of packages in the     │
  │PkgToInstall              │fg green; flip │package list which are being     │
  │                          │reverse;       │installed (not upgraded) or      │
  │                          │               │reinstalled.                     │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │                          │               │The style of highlighted packages│
  │PkgToInstallHighlighted   │fg green;      │in the package list which are    │
  │                          │               │being installed (not upgraded) or│
  │                          │               │reinstalled.                     │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │                          │fg magenta;    │The style of packages in the     │
  │PkgToRemove               │flip reverse;  │package list which will be       │
  │                          │               │removed or purged.               │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │                          │               │The style of highlighted packages│
  │PkgToRemoveHighlighted    │fg magenta;    │in the package list which will be│
  │                          │               │removed or purged.               │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │                          │fg cyan; flip  │The style of packages in the     │
  │PkgToUpgrade              │reverse;       │package list which will be       │
  │                          │               │upgraded.                        │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │                          │               │The style of highlighted packages│
  │PkgToUpgradeHighlighted   │fg cyan;       │in the package list which will be│
  │                          │               │upgraded.                        │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │                          │               │The style of progress indicators │
  │Progress                  │fg blue; bg    │such as the one that appears     │
  │                          │yellow;        │while the package cache is being │
  │                          │               │loaded.                          │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │SolutionActionApproved    │bg green;      │The style of approved actions in │
  │                          │               │a solution.                      │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │SolutionActionRejected    │bg red;        │The style of rejected actions in │
  │                          │               │a solution.                      │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │Status                    │fg white; bg   │The style of status lines at the │
  │                          │blue; set bold;│bottom of the screen.            │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │TreeBackground            │               │The basic color of all visual    │
  │                          │               │lists and trees.                 │
  ├──────────────────────────┼───────────────┼─────────────────────────────────┤
  │                          │fg red; bg     │The color used to display        │
  │TrustWarning              │black; set     │warnings about package trust.    │
  │                          │bold;          │                                 │
  └──────────────────────────┴───────────────┴─────────────────────────────────┘

  Customizing the display layout

   It is possible to rearrange the aptitude package list by making suitable
   modifications to the configuration file.

    Display elements

   The layout is stored in the configuration group
   Aptitude::UI::Default-Package-View, and consists of a list of display
   elements:

 Name Type {
   Row row;
   Column column;
   Width width;
   Height height;

   additional options...
 };

   This creates a display element named Name; the type of element created is
   determined by Type. The Row, Column, Width, and Height options must be
   present; they determine where the display element is placed. (see below
   for a detailed explanation of how display elements are arranged)

   For examples of how to change the display layout, see the theme
   definitions in the file /usr/share/aptitude/aptitude-defaults.

   The following types of display elements are available:

   Description

   This display element will contain the “information area” (typically a
   description of the currently selected package).

   The option PopUpDownKey gives the name of a keyboard command which will
   cause the display element to be shown or hidden. For instance, setting
   this to ShowHideDescription will give the current display element the same
   behavior as the default information area. The option PopUpDownLinked gives
   the name of another display element; the current element will be shown or
   hidden whenever the other element is.

   MainWidget

   This is a placeholder for the “main” display element: typically this is
   the list of packages. A display layout must contain exactly one MainWidget
   element: no more, no less.

   Static

   A region of the screen which displays some text, possibly containing
   formatting codes as described in the section called “Customizing how
   packages are displayed”. The text to display can be given in the Columns
   option, or it can be stored in another configuration variable specified by
   the ColumnsCfg option. The color of the text is determined by the color
   named by the Color option.

   Static items can be displayed and hidden in the same way as Description
   items, using the PopUpDownKey and PopUpDownLinked options.

    Placement of display elements

   The display elements are arranged in a “table”. The upper-left corner of
   an element is in the cell given by its Row and Column options (typically
   starting from row 0 and column 0, but this is not required). The width of
   an element in cells is given by its Width option, and its height is given
   by its Height option.

   Once the display elements are arranged and have been given an initial
   amount of space on the screen, there is likely to be space left over. If
   there is extra vertical space, each row containing a display element whose
   RowExpand option is true will be allocated a share of the extra space;
   similarly, if there is extra horizontal space, each column containing a
   display element whose ColExpand option is true will be allocated a share
   of the extra space.

   In the event that there is not enough space, every row and column whose
   widgets all have their RowShrink or ColShrink options set to true will be
   shrunk. If this is not enough, all rows and columns are shrunk to fit into
   the available space.

   If a display element is not expanded, but its row or column is, its
   alignment is determined by the RowAlign and ColAlign options. Setting them
   to Left, Right, Top, Bottom, or Center will tell aptitude where to place
   the element within the row or column.

   For instance, the following configuration group creates a static element
   named “Header”, which is three cells wide and will expand horizontally but
   not vertically. It has the same color as other header lines and uses the
   standard display format for header lines:

 Header Static {
   Row 0;
   Column 0;
   Width 3;
   Height 1;

   ColExpand true;
   ColAlign Center;

   RowAlign Center;

   Color ScreenHeaderColor;
   ColumnsCfg HEADER;
 };

    Display layout option reference

   The following options are available for display elements:

   ColAlign alignment;

   alignment must be either Left, Right, or Center. If the row containing the
   current display element is wider than the element itself and ColExpand is
   false, the element will be placed within the row according to the value of
   alignment.

   If this option is not present, it defaults to Left.

   ColExpand true|false;

   If this option is set to true, the column containing this display element
   will be allocated a share of any extra horizontal space that is available.

   If this option is not present, it defaults to false.

   Color colorname;

   This option applies to Static elements. colorname is the name of a color
   (for instance, ScreenStatusColor) which should be used as the “default”
   color for this display element.

   If this option is not present, it defaults to DefaultWidgetBackground.

   ColShrink true|false;

   If this option is set to true on each element in a column and there is not
   enough horizontal space, the column will be shrunk as necessary to fit the
   available space. Note that a column may be shrunk even if ColShrink is
   false; it simply indicates that aptitude should try shrinking a particular
   column before shrinking other columns.

   If this option is not present, it defaults to false.

   Column column;

   Specifies the leftmost column containing this display element.

   Columns format;

   This option applies to Static display elements for which the ColumnsCfg
   option is not set. It sets the displayed contents of the status item; it
   is a format string as described in the section called “Customizing how
   packages are displayed”.

   ColumnsCfg HEADER|STATUS|name;

   This option applies to Static display elements. It sets the display format
   of the current element to the value of another configuration variable: if
   it is HEADER or STATUS, the options Aptitude::UI::Package-Header-Format
   and Aptitude::UI::Package-Status-Format, repectively, are used; otherwise,
   the option name is used.

   If this option is not present, the value of the Columns option is used to
   control the contents of the static item.

   Height height;

   Specifies the height of the current display element.

   PopUpDownKey command;

   This option applies to Description and Static display elements.

   command is the name of a keyboard command (for instance,
   ShowHideDescription). When this key is pressed, the display element will
   be hidden if it is visible, and displayed if it is hidden.

   PopUpDownLinked element;

   This option applies to Description and Static display elements.

   element is the name of a display element. When element is displayed, the
   current element will also be displayed; when element is hidden, the
   current element will also be hidden.

   Row row;

   Specifies the uppermost row containing this display element.

   RowAlign alignment;

   alignment must be either Top, Bottom, or Center. If the row containing the
   current display element is taller than the element itself and RowExpand is
   false, the element will be placed within the row according to the value of
   alignment.

   If this option is not present, it defaults to Top.

   RowExpand true|false;

   If this option is set to true, the row containing this display element
   will be allocated a share of any extra vertical space that is available.

   If this option is not present, it defaults to false.

   RowShrink true|false;

   If this option is set to true on each element in a row and there is not
   enough vertical space, the row will be shrunk as necessary to fit the
   available space. Note that a row may be shrunk even if RowShrink is false;
   it simply indicates that aptitude should try shrinking a particular row
   before shrinking other rows.

   If this option is not present, it defaults to false.

   Visible true|false;

   If set to false, this display element will initially be hidden. Presumably
   only useful in conjunction with PopUpDownKey and/or PopUpDownLinked.

   If this option is not present, it defaults to true.

   Width width;

   Specifies the width of the current display element.

  Configuration file reference

    Configuration file format

   In its basic form, aptitude's configuration file is a list of options and
   their values. Each line of the file should have the form “Option Value;”:
   for instance, the following line in the configuration file sets the option
   Aptitude::Theme to “Dselect”.

 Aptitude::Theme "Dselect";

   An option can “contain” other options if they are written in curly braces
   between the option and the semicolon following it, like this:

 Aptitude::UI {
   Package-Status-Format "";
   Package-Display-Format "";
 };

   An option that contains other options is sometimes called a group. In
   fact, the double colons that appear in option names are actually a
   shorthand way of indicating containment: the option
   Aptitude::UI::Default-Grouping is contained in the group Aptitude::UI,
   which itself is contained in the group Aptitude. Thus, if you wanted to,
   you could set this option to "" as follows:

 Aptitude {
   UI {
     Default-Grouping "";
   };
 };

   For more information on the format of the configuration file, see the
   manual page apt.conf(5).

    Locations of configuration files

   aptitude's configuration is read from the following sources, in order:

    1. Configuration file options specified on the command-line.

    2. The user's configuration file, ~/.aptitude/config. This file is
       overwritten when the user modifies settings in the Options menu.

    3. The system configuration file, /etc/apt/apt.conf.

    4. The system configuration fragment files, /etc/apt/apt.conf.d/*.

    5. The file specified by the APT_CONFIG environment variable (if any).

    6. Default values stored in /usr/share/aptitude/aptitude-defaults.

    7. Default values built into aptitude.

   When an option is being checked, these sources are searched in order, and
   the first one that provides a value for the option is used. For instance,
   setting an option in /etc/apt/apt.conf will override aptitude's defaults
   for that option, but will not override user settings in
   ~/.aptitude/config.

    Available configuration options

   The following configuration options are used by aptitude. Note that these
   are not the only available configuration options; options used by the
   underlying apt system are not listed here. See the manual pages apt(8) and
   apt.conf(5) for information on apt options.

   Option: APT::AutoRemove::RecommendsImportant
   Default: true
   Description: If this option is true, then aptitude will not consider
   packages to be unused (and thus will not automatically remove them) as
   long as any installed package recommends them, even if
   APT::Install-Recommends is false. For more information, see the section
   called “Managing automatically installed packages”.
   Option: APT::AutoRemove::SuggestsImportant
   Default: true
   Description: If this option is true, then aptitude will not consider
   packages to be unused (and thus will not automatically remove them) as
   long as any installed package suggests them. For more information, see the
   section called “Managing automatically installed packages”.
   Option: APT::Get::List-Cleanup
   Default: true
   Description: A synonym for APT::List-Cleanup. If either of these options
   is set to false, aptitude will not delete old package list files after
   downloading a new set of package lists.
   Option: APT::List-Cleanup
   Default: true
   Description: A synonym for APT::Get::List-Cleanup. If either of these
   options is set to false, aptitude will not delete old package list files
   after downloading a new set of package lists.
   Option: APT::Install-Recommends
   Default: true
   Description: If this option is true and Aptitude::Auto-Install is true,
   then whenever you mark a package for installation, aptitude will also mark
   the packages it recommends for installation. Furthermore, if this option
   is true, aptitude will not consider packages to be unused (and thus will
   not automatically remove them) as long as any installed package reommends
   them. For more information, see the section called “Managing automatically
   installed packages” and the section called “Immediate dependency
   resolution”.
   Option: Aptitude::Allow-Null-Upgrade
   Default: false
   Description: Normally, if you try to start an install run when no actions
   will be performed, aptitude will print a warning and return to the package
   list. If this option is true, aptitude will continue to the preview screen
   whenever there are upgradable packages, rather than displaying a reminder
   about the Actions → Mark Upgradable (U) command.
   Option: Aptitude::Always-Use-Safe-Resolver
   Default: false
   Description: If this option is true, aptitude's command-line actions will
   always use a “safe” dependency resolver, as if --safe-resolver had been
   passed on the command line.
   Option: Aptitude::Autoclean-After-Update
   Default: false
   Description: If this option is true, aptitude will clean up obsolete files
   (see Actions → Clean obsolete files) every time you update the package
   list. This option is similar to Aptitude::Clean-After-Install.
   Option: Aptitude::Auto-Fix-Broken
   Default: true
   Description: If this option is false, aptitude will ask for permission
   before attempting to fix any broken packages.
   Option: Aptitude::Auto-Install
   Default: true
   Description: If this option is true, aptitude will automatically attempt
   to fulfill the dependencies of a package when you mark a package to be
   installed or upgraded.
   Option: Aptitude::Auto-Install-Remove-Ok
   Default: false
   Description: If this option is true, aptitude will automatically remove
   conflicting packages when you mark a package to be installed or upgraded.
   Normally these conflicts are flagged and you must handle them manually.
   Option: Aptitude::Auto-Upgrade
   Default: false
   Description: If this option is true, aptitude will automatically flag all
   upgradable packages for upgrade when the program starts, as if you had
   issued the command Actions → Mark Upgradable (U).
   Option: Aptitude::Clean-After-Install
   Default: false
   Description: If this option is true, aptitude will clean up all files in
   the package cache directory (see Actions → Clean package cache) after
   successful installation of packages (or similar operations). This option
   is similar to Aptitude::Autoclean-After-Update.
   Option: Aptitude::CmdLine::Always-Prompt
   Default: false
   Description: In command-line mode, if this is set, aptitude will always
   prompt before starting to install or remove packages, even if the prompt
   would normally be skipped. This is equivalent to the -P command-line
   option.
   Option: Aptitude::CmdLine::Assume-Yes
   Default: false
   Description: In command-line mode, if this option is true, aptitude will
   act as if the user had answered “yes” to every prompt, causing most
   prompts to be skipped. This is equivalent to the -y command-line option.
   Option: Aptitude::CmdLine::Disable-Columns
   Default: false
   Description: If this option is enabled, the results of command-line
   searches (performed via aptitude search) will not be formatted into
   fixed-width columns or truncated to the screen width. This is equivalent
   to the --disable-columns command-line option.
   Option: Aptitude::CmdLine::Download-Only
   Default: false
   Description: In command-line mode, if this option is true, aptitude will
   download package files but not install them. This is equivalent to the -d
   command-line option.
   Option: Aptitude::CmdLine::Fix-Broken
   Default: false
   Description: In command-line mode, if this option is true, aptitude will
   be more aggressive when attempting to fix the dependencies of broken
   packages. This is equivalent to the -f command-line option.
   Option: Aptitude::CmdLine::Versions-Group-By
   Default: Set to auto, none, package, or source-package to control whether
   and how the output of aptitude versions is grouped. Equivalent to the
   command-line option --group-by (see its documentation for more description
   of what the values mean).
   Option: Aptitude::CmdLine::Ignore-Trust-Violations
   Default: false
   Description: In command-line mode, causes aptitude to ignore the
   installation of untrusted packages. This is a synonym for
   APT::Get::AllowUnauthenticated.
   Option: Aptitude::CmdLine::Package-Display-Format
   Default: %c%a%M %p# - %d#
   Description: This is a format string, as described in the section called
   “Customizing how packages are displayed”, which is used to display the
   results of a command-line search. This is equivalent to the -F
   command-line option.
   Option: Aptitude::CmdLine::Package-Display-Width
   Default:
   Description: This option gives the width in characters for which
   command-line search results should be formatted. If it is empty (the
   default; ie, ""), search results will be formatted for the current
   terminal size, or for an 80-column display if the terminal size cannot be
   determined.
   Option: Aptitude::CmdLine::Progress::Percent-On-Right
   Default: false
   Description: This option controls whether command-line progress indicators
   display the percentage on the left-hand side of the screen, in the same
   style as apt-get, or on the right-hand side (the default). This option
   does not affect download progress indicators.
   Option: Aptitude::CmdLine::Progress::Retain-Completed
   Default: false
   Description: If this value is false, then command-line progress indicators
   will be deleted and overwritten once the task they represent is completed.
   If it is true, then they will be left on the terminal. This option does
   not affect download progress indicators.
   Option: Aptitude::CmdLine::Request-Strictness
   Default: 10000
   Description: When run in command-line mode, if dependency problems are
   encountered, aptitude will add this value to the problem resolver score of
   each action that you explicitly request.
   Option: Aptitude::CmdLine::Resolver-Debug
   Default: false
   Description: In command-line mode, if this option is true, aptitude will
   print extremely verbose information while attempting to resolve broken
   dependencies. As the name suggests, this option is primarily meant to aid
   in debugging the problem resolver.
   Option: Aptitude::CmdLine::Resolver-Dump
   Default:
   Description: In command-line mode, if it is necessary to resolve broken
   dependencies and this option is set to the name of a writable file, the
   resolver state will be dumped to this file before any calculations are
   undertaken.
   Option: Aptitude::CmdLine::Resolver-Show-Steps
   Default: false
   Description: If this option is true, then a dependency solution will be
   displayed as a sequence of resolutions of individual dependencies; for
   instance, “wesnoth depends upon wesnoth-data (= 1.2.4-1) -> installing
   wesnoth-data 1.2.4-1 (unstable)”. To toggle between the two display modes,
   press o at the prompt “Accept this solution?”.
   Option: Aptitude::CmdLine::Show-Deps
   Default: false
   Description: In command-line mode, if this option is true, aptitude will
   display a brief summary of the dependencies (if any) relating to a
   package's state. This is equivalent to the -D command-line option.
   Option: Aptitude::CmdLine::Show-Size-Changes
   Default: false
   Description: In command-line mode, if this option is true, aptitude will
   display the expected change in the amount of space used by each package.
   This is equivalent to the -Z command-line option.
   Option: Aptitude::CmdLine::Show-Summary
   Default: no-summary
   Description: This option sets the default value of the command-line
   argument --show-summary. See the documentation of --show-summary for a
   list of the allowed values of this option and their meanings.
   Option: Aptitude::CmdLine::Show-Versions
   Default: false
   Description: In command-line mode, if this option is true, aptitude will
   display the version of a package that is being installed or removed. This
   is equivalent to the -V command-line option.
   Option: Aptitude::CmdLine::Show-Why
   Default: false
   Description: In command-line mode, if this option is true, aptitude will
   display the manually installed packages that require each automatically
   installed package, or the manually installed packages that cause a
   conflict with each automatically removed package. This is equivalent to
   the -W command-line option and displays the same information you can
   access via aptitude why or by pressing i in a package list.
   Option: Aptitude::CmdLine::Version-Display-Format
   Default: %c%a%M %p# %t %i
   Description: This is a format string, as described in the section called
   “Customizing how packages are displayed”, which is used to display the
   output of aptitude versions. This is equivalent to the -F command-line
   option.
   Option: Aptitude::CmdLine::Versions-Show-Package-Names
   Default: Set to always, auto, or never to control when package names are
   displayed in the output of aptitude versions. Equivalent to the
   command-line option --show-package-names (see its documentation for more
   description of what the values mean).
   Option: Aptitude::Safe-Resolver::Show-Resolver-Actions
   Default: false
   Description: If this option is enabled, then when the “safe” dependency
   resolver has been activated via --safe-resolver or because the
   command-line action is safe-upgrade, it will display a summary of the
   actions taken by the resolver before showing the installation preview.
   Equivalent to the command-line option --show-resolver-actions.
   Option: Aptitude::Screenshot::IncrementalLoadLimit
   Default: 16384
   Description: The minimum size in bytes at which aptitude will begin to
   display screenshots incrementally. Below this size, screenshots will not
   appear until they are fully downloaded.
   Option: Aptitude::Screenshot::Cache-Max
   Default: 4194304
   Description: The maximum number of bytes of screenshot data that aptitude
   will store in memory for screenshots that are not currently being
   displayed. The default is four megabytes.
   Option: Aptitude::CmdLine::Simulate
   Default: false
   Description: This option is deprecated; use Aptitude::Simulate instead. In
   command-line mode, causes aptitude to just display the actions that would
   be performed (rather than actually performing them); in the visual
   interface, causes aptitude to start in read-only mode regardless of
   whether you are root or not. This is equivalent to the -s command-line
   option.
   Option: Aptitude::CmdLine::Verbose
   Default: 0
   Description: This controls how verbose the command-line mode of aptitude
   is. Every occurrence of the -v command-line option adds 1 to this value.
   Option: Aptitude::CmdLine::Visual-Preview
   Default: false
   Description: If this option is true, aptitude will enter its visual
   interface to display the preview of an installation run and to download
   packages.
   Option: Aptitude::Delete-Unused
   Default: true
   Description: If this option is true, automatically installed packages
   which are no longer required will be automatically removed. For more
   information, see the section called “Managing automatically installed
   packages”.
   Option: Aptitude::Delete-Unused-Pattern
   Default:
   Description: Deprecated alias for Aptitude::Keep-Unused-Pattern. If
   Aptitude::Keep-Unused-Pattern is unset or set to an empty string, the
   value of this configuration option will override it. Otherwise,
   Aptitude::Delete-Unused-Pattern is ignored.
   Option: Aptitude::Display-Planned-Action
   Default: true
   Description: If this option is true, aptitude will display a preview
   screen before actually carrying out the actions you have requested.
   Option: Aptitude::Forget-New-On-Install
   Default: false
   Description: If this option is true, aptitude will clear the list of new
   packages whenever you install, upgrade, or remove packages, as if you had
   issued the command Actions → Forget new packages (f).
   Option: Aptitude::Forget-New-On-Update
   Default: false
   Description: If this option is true, aptitude will clear the list of new
   packages whenever the package list is updated, as if you had issued the
   command Actions → Forget new packages (f).
   Option: Aptitude::Get-Root-Command
   Default: su:/bin/su
   Description: This option sets the external command that aptitude will use
   to switch to the root user (see the section called “Becoming root”). It
   has the form protocol:command. protocol must be either su or sudo; it
   determines how aptitude invokes the program when it wants to gain root
   privileges. If protocol is su, then “command -c arguments” is used to
   become root; otherwise, aptitude uses “command arguments”. The first word
   in command is the name of the program that should be invoked; remaining
   words are treated as arguments to that program.
   Option: Aptitude::Ignore-Old-Tmp
   Default: false
   Description: Old versions of aptitude created a directory ~/.aptitude/.tmp
   which is no longer necessary. If the directory exists and
   Aptitude::Ignore-Old-Tmp is true, aptitude will ask you whether to remove
   this directory. This option is automatically set to true after you reply.
   On the other hand, if the directory does not exist, this option is set to
   false so that you will be notified if it reappears.
   Option: Aptitude::Ignore-Recommends-Important
   Default: false
   Description: In previous versions of aptitude, the setting
   Aptitude::Recommends-Important caused recommendations to be installed
   automatically, the same way that APT::Install-Recommends does today. If
   this option is set to false and Aptitude::Recommends-Important is also set
   to false, aptitude will set APT::Install-Recommends to false and set
   Aptitude::Ignore-Recommends-Important to true on startup.
   Option: Aptitude::Keep-Recommends
   Default: false
   Description: This is an obsolete option; use
   APT::AutoRemove::RecommendsImportant instead. Setting this option to true
   has the same effect as setting APT::AutoRemove::RecommendsImportant to
   true.
   Option: Aptitude::Keep-Suggests
   Default: false
   Description: This is an obsolete option; use
   APT::AutoRemove::SuggestsImportant instead. Setting this option to true
   has the same effect as setting APT::AutoRemove::SuggestsImportant to true.
   Option: Aptitude::Keep-Unused-Pattern
   Default:
   Description: If Aptitude::Delete-Unused is true, only unused packages
   which do not match this pattern (see the section called “Search patterns”)
   will be removed. If this option is set to an empty string (the default),
   all unused packages will be removed.
   Option: Aptitude::LockFile
   Default: /var/lock/aptitude
   Description: A file that will be fcntl-locked to ensure that at most one
   aptitude process can modify the cache at once. In normal circumstances,
   you should never need to modify this; it may be useful for debugging.
   Note: if aptitude complains that it cannot acquire a lock, this is not
   because the lock file needs to be deleted. fcntl locks are managed by the
   kernel and will be destroyed when the program holding them terminates;
   failure to acquire the lock means that another running program is using
   it!
   Option: Aptitude::Localize-Log
   Default: false
   Description: If this option is enabled, aptitude will use the user's
   locale for messages and dates in the log file; otherwise it is written in
   the "classic" locale, to avoid having the log file written in different
   languages (depending on the locales of the users running the program).
   Option: Aptitude::Log
   Default: /var/log/aptitude
   Description: If this is set to a nonempty string, aptitude will log the
   package installations, removals, and upgrades that it performs. If the
   value of Aptitude::Log begins with a pipe character (ie, “|”), the
   remainder of its value is used as the name of a command into which the log
   will be piped: for instance, |mail -s 'Aptitude install run' root will
   cause the log to be emailed to root. To log to multiple files or commands,
   you may set this option to a list of log targets.
   Option: Aptitude::Logging::File
   Default:
   Description: If this is set to a nonempty string, aptitude will write
   logging messages to it; setting it to “-” causes logging messages to be
   printed to standard output. This differs from the setting Aptitude::Log:
   that file is used to log installations and removals, whereas this file is
   used to log program events, errors, and debugging messages (if enabled).
   This option is equivalent to the command-line argument --log-file. See
   also Aptitude::Logging::Levels.
   Option: Aptitude::Logging::Levels
   Default: (empty)
   Description: This option is a group whose members control which log
   messages are written. Each entry is either “level”, to set the global log
   level (the log level of the root logger) to the given level, or
   “category:level”, where category is the category of messages to modify
   (such as aptitude.resolver.hints.match) and level is the lowest log level
   of messages in that category that should be displayed. Valid log levels
   are “fatal”, “error”, “warn”, “info”, “debug”, and “trace”. The
   command-line option --log-level can be used to set or override any log
   level.
   Option: Aptitude::Parse-Description-Bullets
   Default: true
   Description: If this option is enabled, aptitude will attempt to
   automatically detect bulleted lists in package descriptions. This will
   generally improve how descriptions are displayed, but it is not entirely
   backwards-compatible; some descriptions might be formatted less
   attractively when this option is true than when it is false.
   Option: Aptitude::Pkg-Display-Limit
   Default:
   Description: The default filter applied to the package list; see the
   section called “Search patterns” for details about its format.
   Option: Aptitude::ProblemResolver::Allow-Break-Holds
   Default: false
   Description: If this option is set to true, the problem resolver will
   consider breaking package holds or installing forbidden versions in order
   to resolve a dependency. If it is set to false, these actions will be
   rejected by default, although you can always enable them manually (see the
   section called “Resolving Dependencies Interactively”).
   Option: Aptitude::ProblemResolver::BreakHoldScore
   Default: -300
   Description: How much to reward or penalize solutions that change the
   state of a held package or install a forbidden version. Note that unless
   Aptitude::ProblemResolver::Allow-Break-Holds is set to true, the resolver
   will never break a hold or install a forbidden version unless it has
   explicit permission from the user.
   Option: Aptitude::ProblemResolver::Break-Hold-Level
   Default: 50000
   Description: The safety cost assigned to actions that break a hold set by
   the user (by upgrading a held package or by installing a forbidden version
   of a package). See the section called “Safety costs” for a description of
   safety costs.
   Option: Aptitude::ProblemResolver::BrokenScore
   Default: -100
   Description: How much to reward or penalize prospective solutions based on
   the number of dependencies they break. For each dependency broken by a
   possible solution, this many points are added to its score; typically this
   should be a negative value.
   Option: Aptitude::ProblemResolver::CancelRemovalScore
   Default: -300
   Description: How much weight the problem resolver should give to not
   remove or purge a package requested to be removed or purged.
   Option: Aptitude::ProblemResolver::DefaultResolutionScore
   Default: 400
   Description: How much to reward or penalize prospective solutions based on
   how many “default” resolutions for currently unsatisfied dependencies they
   install. The default resolution is the resolution that “apt-get install”
   or the “immediate dependency resolver” would pick. The score is only
   applied for dependencies and recommendations whose targets are not
   currently installed.
   Option: Aptitude::ProblemResolver::Discard-Null-Solution
   Default: true
   Description: If this option is true, aptitude will never suggest
   cancelling all of your proposed actions in order to resolve a dependency
   problem.
   Option: Aptitude::ProblemResolver::EssentialRemoveScore
   Default: -100000
   Description: How much to reward or penalize solutions that remove an
   Essential package.
   Option: Aptitude::ProblemResolver::Remove-Essential-Level
   Default: 60000
   Description: The safety cost assigned to actions that remove an Essential
   package. See the section called “Safety costs” for a description of safety
   costs.
   Option: Aptitude::ProblemResolver::ExtraScore
   Default: 0
   Description: Any version of a package whose Priority is “extra” will have
   this many points added to its score.
   Option: Aptitude::ProblemResolver::FullReplacementScore
   Default: 500
   Description: Removing a package and installing another package that fully
   replaces it (i.e., conflicts with it, replaces it, and provides it) is
   assigned this score.
   Option: Aptitude::ProblemResolver::FutureHorizon
   Default: 50
   Description: How many “steps” the resolver should run after finding the
   first solution. Although aptitude attempts to generate better solutions
   before worse solutions, sometimes it is unable to do so; this setting
   causes the resolver to briefly continue searching for a better solution
   before displaying its results, rather than stopping immediately after it
   finds the first solution.
   Option: Aptitude::ProblemResolver::Hints
   Default: (empty)
   Description: This option is a group whose members are used to configure
   the problem resolver. Each item in the group is a string describing an
   action that should be applied to one or more packages. The syntax for each
   hint, and the effect that hints have, may be found in the section called
   “Configuring resolver hints”.
   Option: Aptitude::ProblemResolver::ImportantScore
   Default: 4
   Description: Any version of a package whose Priority is “important” will
   have this many points added to its score.
   Option: Aptitude::ProblemResolver::Infinity
   Default: 1000000
   Description: A “maximum” score for potential solutions. If a set of
   actions has a score worse than -Infinity, it will be discarded
   immediately.
   Option: Aptitude::ProblemResolver::InstallScore
   Default: -20
   Description: How much weight the problem resolver should give to
   installing a package, if the package is not already going to be installed.
   Option: Aptitude::ProblemResolver::Keep-All-Level
   Default: 10000
   Description: The safety cost assigned to the single solution that cancels
   all of the actions selected by the user. See the section called “Safety
   costs” for a description of safety costs.
   Option: Aptitude::ProblemResolver::KeepScore
   Default: 0
   Description: How much weight the problem resolver should give to keeping a
   package in its current state, if that package is not already going to be
   kept in its current state.
   Option: Aptitude::ProblemResolver::NonDefaultScore
   Default: -40
   Description: How much weight the problem resolver should give to
   installing a non-default version of the package (one that is not the
   current version and not the “candidate version”).
   Option: Aptitude::ProblemResolver::Non-Default-Level
   Default: 50000
   Description: The safety cost assigned to actions that install non-default
   versions of a package. For instance, if version 5 of a package is
   installed, versions 6, 7, and 8 are available, and version 7 is the
   default version, then versions 6 and 8 will be given a safety cost that is
   at least this high. See the section called “Safety costs” for a
   description of safety costs.
   Option: Aptitude::ProblemResolver::OptionalScore
   Default: 1
   Description: Any version of a package whose Priority is “optional” will
   have this many points added to its score.
   Option: Aptitude::ProblemResolver::PreserveAutoScore
   Default: 0
   Description: How much weight the problem resolver should give to
   preserving automatic installations or removals.
   Option: Aptitude::ProblemResolver::PreserveManualScore
   Default: 20
   Description: How much weight the problem resolver should give to
   preserving explicit user selections.
   Option: Aptitude::ProblemResolver::RemoveObsoleteScore
   Default: 310
   Description: How much weight the problem resolver should give to removing
   an obsolete package (if it is not already marked for removal). It should
   at least counter RemoveScore, because it will still be applied.
   Option: Aptitude::ProblemResolver::RemoveScore
   Default: -300
   Description: How much weight the problem resolver should give to removing
   a package (if it is not already marked for removal).
   Option: Aptitude::ProblemResolver::Remove-Level
   Default: 10000
   Description: The safety cost assigned to actions that remove a package.
   See the section called “Safety costs” for a description of safety costs.
   Option: Aptitude::ProblemResolver::RequiredScore
   Default: 8
   Description: Any version of a package whose Priority is “required” will
   have this many points added to its score.
   Option: Aptitude::ProblemResolver::ResolutionScore
   Default: 50
   Description: In addition to all other scoring factors, proposed solutions
   that actually resolve all unsatisfied dependencies are awarded this many
   extra points.
   Option: Aptitude::ProblemResolver::Safe-Level
   Default: 10000
   Description: The safety cost assigned to actions that install the default
   version of a package, upgrade a package to its default version, or cancel
   installing or upgrading a package. Solutions assigned this cost could be
   generated by aptitude safe-upgrade. See the section called “Safety costs”
   for a description of safety costs.
   Option: Aptitude::ProblemResolver::SolutionCost
   Default: safety,priority
   Description: Describes how to determine the cost of a solution. See the
   section called “Costs in the interactive dependency resolver” for a
   description of what solution costs are, what they do, and the syntax used
   to specify them. If the cost cannot be parsed, an error is issued and the
   default cost is used instead.
   Option: Aptitude::ProblemResolver::StandardScore
   Default: 2
   Description: Any version of a package whose Priority is “standard” will
   have this many points added to its score.
   Option: Aptitude::ProblemResolver::StepLimit
   Default: 5000
   Description: The maximum number of “steps” which should be performed by
   the problem resolver on each attempt to find a solution to a dependency
   problem. Decreasing this number will make aptitude “give up” sooner;
   increasing it will permit the search for a solution to consume much more
   time and memory before it is aborted. Setting StepLimit to 0 will disable
   the problem resolver entirely. The default value is large enough to
   accomodate commonly encountered situations, while preventing aptitude from
   “blowing up” if an overly complicated problem is encountered. (note: this
   applies only to command-line searches; in the visual interface, the
   resolver will continue working until it reaches a solution)
   Option: Aptitude::ProblemResolver::StepScore
   Default: -10
   Description: How much to reward or penalize prospective solutions based on
   their length. For each action performed by a solution, these many points
   are added to its score. The larger this value is, the more the resolver
   tends to stick with its first choice rather than considering alternatives;
   this will cause it to produce a solution more quickly, but the solution
   might be of slightly lower quality than it would otherwise be.
   Option: Aptitude::ProblemResolver::Trace-Directory
   Default:
   Description: If this value is set, then each time the problem resolver
   produces a solution, a stripped-down version of the package state
   sufficient to reproduce that solution is written to the given file. If
   Aptitude::ProblemResolver::Trace-File is also set, the same information
   will also be written to the trace file. Trace directories are more
   transparent than trace files, and are more suitable for, e.g., including
   in source trees as test cases.
   Option: Aptitude::ProblemResolver::Trace-File
   Default:
   Description: If this value is set, then each time the problem resolver
   produces a solution, a stripped-down version of the package state
   sufficient to reproduce that solution is written to the given file. If
   Aptitude::ProblemResolver::Trace-Directory is also set, the same
   information will also be written to the trace directory. A trace file is
   simply a compressed archive of a trace directory; it will take less space
   than the trace directory and is suitable for transmission over a network.
   Option: Aptitude::ProblemResolver::UndoFullReplacementScore
   Default: -500
   Description: Installing a package and removing another package that fully
   replaces it (i.e., conflicts with it, replaces it, and provides it) is
   assigned this score.
   Option: Aptitude::ProblemResolver::UnfixedSoftScore
   Default: -200
   Description: How much to reward or penalize leaving a Recommends
   relationship unresolved. This should typically be less than RemoveScore,
   or aptitude will tend to remove packages rather than leaving their
   Recommendations unfixed. See the section called “Resolving Dependencies
   Interactively” for details.
   Option: Aptitude::ProblemResolver::UpgradeScore
   Default: 30
   Description: How much weight the problem resolver should give to upgrading
   (or downgrading) a package to its candidate version, if the package was
   not already going to be upgraded.
   Option: Aptitude::Purge-Unused
   Default: false
   Description: If this option is true and Aptitude::Delete-Unused is also
   true, then packages which are unused will be purged from the system,
   removing their configuration files and perhaps other important data. For
   more information about which packages are considered to be “unused”, see
   the section called “Managing automatically installed packages”. THIS
   OPTION CAN CAUSE DATA LOSS! DO NOT ENABLE IT UNLESS YOU KNOW WHAT YOU ARE
   DOING!
   Option: Aptitude::Recommends-Important
   Default: true
   Description: This is an obsolete configuration option that has been
   superseded by APT::Install-Recommends. On startup, aptitude will copy
   Aptitude::Recommends-Important (if it exists) to APT::Install-Recommends
   and then clear Aptitude::Recommends-Important in your user configuration
   file.
   Option: Aptitude::Safe-Resolver::No-New-Installs
   Default: false
   Description: If this option is true, then when the “safe” dependency
   resolver has been activated via --safe-resolver or by using the
   safe-upgrade command-line action, the resolver will not be allowed to
   install packages that are not currently installed.
   Option: Aptitude::Safe-Resolver::No-New-Upgrades
   Default: false
   Description: If this option is enabled, then when the “safe” dependency
   resolver has been activated via --safe-resolver or by using the
   safe-upgrade command-line action, the resolver will not be allowed to
   resolve dependencies by upgrading packages.
   Option: Aptitude::Sections::Descriptions
   Default: See $prefix/share/aptitude/section-descriptions
   Description: This option is a group whose members define the descriptions
   displayed for each section when using the “section” package hierarchy
   grouping policy. Descriptions are assigned to section trees based on the
   last component of the name: for instance, a member of this group named
   “games” will be used to describe the Sections “games”, “non-free/games”,
   and “non-free/desktop/games”. Within the text of section descriptions, the
   string “\n” will be replaced by a line-break, and the string “''” will be
   replaced by a double-quote character.
   Option: Aptitude::Sections::Top-Sections
   Default: "main"; "contrib"; "non-free"; "non-US";
   Description: A configuration group whose elements are the names of the
   top-level archive sections. The “topdir”, “subdir”, and “subdirs” grouping
   policies use this list to interpret Section fields: if the first path
   element of a package's Section is not contained in this list, or if its
   Section has only one element, then the package will be grouped using the
   first member of this list as its first path element. For example, if the
   first member of Top-Sections is “main”, then a package whose Section is
   “games/arcade” will be treated as if its Section field were
   “main/games/arcade”.
   Option: Aptitude::Simulate
   Default: false
   Description: In command-line mode, causes aptitude to just display the
   actions that would be performed (rather than actually performing them); in
   the visual interface, causes aptitude to start in read-only mode
   regardless of whether you are root or not. This is equivalent to the -s
   command-line option.
   Option: Aptitude::Spin-Interval
   Default: 500
   Description: The number of milliseconds to delay in between updating the
   “spinner” that appears while the problem resolver is running.
   Option: Aptitude::Suggests-Important
   Default: false
   Description: This is an obsolete option; use
   APT::AutoRemove::SuggestsImportant instead. Setting this option to true
   has the same effect as setting APT::AutoRemove::SuggestsImportant to true.
   Option: Aptitude::Suppress-Read-Only-Warning
   Default: false
   Description: If this option is false, aptitude will display a warning the
   first time that you attempt to modify package states while aptitude is in
   read-only mode.
   Option: Aptitude::Theme
   Default:
   Description: The theme that aptitude should use; see the section called
   “Themes” for more information.
   Option: Aptitude::Track-Dselect-State
   Default: true
   Description: If this option is set to true, aptitude will attempt to
   detect when a change to a package's state has been made using dselect or
   dpkg: for instance, if you remove a package using dpkg, aptitude will not
   try to reinstall it. Note that this may be somewhat buggy.
   Option: Aptitude::UI::Advance-On-Action
   Default: false
   Description: If this option is set to true, changing a package's state
   (for instance, marking it for installation) will cause aptitude to advance
   the highlight to the next package in the current group.
   Option: Aptitude::UI::Auto-Show-Reasons
   Default: true
   Description: If this option is set to true, selecting a package which is
   broken or which appears to be causing other packages to be broken will
   cause the information area to automatically display some reasons why the
   breakage might be occuring.
   Option: Aptitude::UI::Default-Grouping
   Default:
   filter(missing),status,section(subdirs,passthrough),section(topdir)
   Description: Sets the default grouping policy used for package lists. See
   the section called “Customizing the package hierarchy” for additional
   information on grouping policies.
   Option: Aptitude::UI::Default-Package-View
   Default:
   Description: This option is a group whose members define the default
   layout of aptitude's display. See the section called “Customizing the
   display layout” for more information.
   Option: Aptitude::UI::Default-Preview-Grouping
   Default: action
   Description: Sets the default grouping policy used for preview screens.
   See the section called “Customizing the package hierarchy” for additional
   information on grouping policies.
   Option: Aptitude::UI::Default-Sorting
   Default: name
   Description: The default sorting policy of package views. See the section
   called “Customizing how packages are sorted” for more information.
   Option: Aptitude::UI::Description-Visible-By-Default
   Default: true
   Description: When a package list is first displayed, the information area
   (which typically contains the long description of the current package)
   will be visible if this option is true and hidden if it is false.
   Option: Aptitude::UI::Exit-On-Last-Close
   Default: true
   Description: If this option is true, closing all the active views will
   quit aptitude; otherwise, aptitude will not exit until you issue the
   command Actions → Quit (Q). See the section called “Working with multiple
   views” for more information.
   Option: Aptitude::UI::Fill-Text
   Default: false
   Description: If this option is true, aptitude will format descriptions so
   that each line is exactly the width of the screen.
   Option: Aptitude::UI::Flat-View-As-First-View
   Default: false
   Description: If this option is true, aptitude will display a flat view on
   startup instead of the default view.
   Option: Aptitude::UI::HelpBar
   Default: true
   Description: If this option is true, a line of information about important
   keystrokes will be displayed at the top of the screen.
   Option: Aptitude::UI::Incremental-Search
   Default: true
   Description: If this option is true, aptitude will perform “incremental”
   searches: as you type the search pattern, it will search for the next
   package matching what you have typed so far.
   Option: Aptitude::UI::InfoAreaTabs
   Default: false
   Description: If this option is true, aptitude will display tabs at the top
   of the information area (the pane at the bottom of the screen) describing
   the different modes the area can be set to.
   Option: Aptitude::UI::Keybindings
   Default:
   Description: This is a group whose members define the connections between
   keystrokes and commands in aptitude. For more information, see the section
   called “Customizing keybindings”.
   Option: Aptitude::UI::Menubar-Autohide
   Default: false
   Description: If this option is set to true, the menu bar will be hidden
   while it is not in use.
   Option: Aptitude::UI::Minibuf-Download-Bar
   Default: false
   Description: If this option is set to true, aptitude will use a less
   obtrusive mechanism to display the progress of downloads: a bar at the
   bottom of the screen will appear which displays the current download
   status. While the download is active, pressing q will abort it.
   Option: Aptitude::UI::Minibuf-Prompts
   Default: false
   Description: If this option is true, some prompts (such as yes/no and
   multiple-choice prompts) will be displayed at the bottom of the screen
   instead of in dialog boxes.
   Option: Aptitude::UI::New-Package-Commands
   Default: true
   Description: If this option is set to false, commands such as Package →
   Install (+) will have the same deprecated behavior that they did in
   antique versions of aptitude.
   Option: Aptitude::UI::Package-Display-Format
   Default: %c%a%M %p %Z %v %V
   Description: This option controls the format string used to display
   packages in package lists. For more information on format strings, see the
   section called “Customizing how packages are displayed”.
   Option: Aptitude::UI::Package-Header-Format
   Default: %N %n @ %H #%B %u %o
   Description: This option controls the format string used to display the
   header line of package lists (ie, the line that appears between the
   package list and the menu bar). For more information on format strings,
   see the section called “Customizing how packages are displayed”.
   Option: Aptitude::UI::Package-Status-Format
   Default: %d
   Description: This option controls the format string used to display the
   status line of package lists (ie, the line that appears between the
   package list and the information area). For more information on format
   strings, see the section called “Customizing how packages are displayed”.
   Option: Aptitude::UI::Pause-After-Download
   Default: OnlyIfError
   Description: If this option is true, aptitude will display a message after
   it finishes downloading packages, asking you if you want to continue with
   the installation. If it is OnlyIfError, a message will only be displayed
   if a download failed. Otherwise, if the option is set to false, aptitude
   will immediately proceed to the next screen after completing a download.
   Option: Aptitude::UI::Preview-Limit
   Default:
   Description: The default filter applied to the preview screen; see the
   section called “Search patterns” for details about its format.
   Option: Aptitude::UI::Prompt-On-Exit
   Default: true
   Description: If this option is true, aptitude will display a confirmation
   prompt before shutting down.
   Option: Aptitude::UI::Styles
   Default:
   Description: This is a configuration group whose contents define what
   textual styles aptitude uses to display information. For more information,
   see the section called “Customizing text colors and styles”.
   Option: Aptitude::UI::ViewTabs
   Default: true
   Description: If this option is set to false, aptitude will not display
   “tabs” describing the currently active views at the top of the screen.
   Option: Aptitude::Warn-Not-Root
   Default: true
   Description: If this option is true, aptitude will detect when you need
   root privileges to do something, and ask you whether you want to switch to
   the root account if you aren't root already. See the section called
   “Becoming root” for more information.
   Option: DebTags::Vocabulary
   Default: /usr/share/debtags/vocabulary
   Description: The location of the debtags vocabulary file; used to load in
   the package tag metadata.
   Option: Dir::Aptitude::state
   Default: /var/lib/aptitude
   Description: The directory in which aptitude's persistent state
   information is stored.
   Option: Quiet
   Default: 0
   Description: This controls the quietness of the command-line mode. Setting
   it to a higher value will disable more progress indicators.

  Themes

   A theme in aptitude is simply a collection of settings that “go together”.
   Themes work by overriding the default values of options: if an option is
   not set in the system configuration file or in your personal configuration
   file, aptitude will use the setting from the current theme, if one is
   available, before using the standard default value.

   A theme is simply a named group under Aptitude::Themes; each configuration
   option contained in the group will override the corresponding option in
   the global configuration. For instance, if the Dselect theme is selected,
   the option Aptitude::Themes::Dselect::Aptitude::UI::Package-Display-Format
   will override the default value of the option
   Aptitude::UI::Package-Display-Format.

   To select a theme, set the configuration option Aptitude::Theme to the
   name of the theme; for instance,

 Aptitude::Theme Vertical-Split;

   The following themes are shipped with aptitude in
   /usr/share/aptitude/aptitude-defaults:

   Dselect

   This theme makes aptitude look and behave more like the legacy dselect
   package manager:

  Actions  Undo  Package  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
 --\ Installed Packages
   --\ Priority required
     --\ base - The Debian base system
 c   base  base-file 3.0.16      3.0.16      Debian base system miscellaneous fil
 c   base  base-pass 3.5.7       3.5.7       Debian base system master password a
 c   base  bash      2.05b-15    2.05b-15    The GNU Bourne Again SHell
 c   base  bsdutils  1:2.12-7    1:2.12-7    Basic utilities from 4.4BSD-Lite
 c   base  coreutils 5.0.91-2    5.0.91-2    The GNU core utilities
 c   base  debianuti 2.8.3       2.8.3       Miscellaneous utilities specific to
 c   base  diff      2.8.1-6     2.8.1-6     File comparison utilities
 base-files                      installed ; none                       required
 This package contains the basic filesystem hierarchy of a Debian system, and
 several important miscellaneous files, such as /etc/debian_version,
 /etc/host.conf, /etc/issue, /etc/motd, /etc/profile, /etc/nsswitch.conf, and
 others, and the text of several common licenses in use on Debian systems.







   Vertical-Split

   This theme rearranges the display: instead of the current package's
   description appearing underneath the package list, it is displayed to the
   right of the package list. This theme is useful with very wide terminals,
   and perhaps also when editing the built-in hierarchy of packages.

  Actions  Undo  Package  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
 aptitude 0.2.14.1
 --\ Installed Packages                  Modern computers support the Advanced  #
   --\ admin - Administrative utilities  Configuration and Power Interface
     --\ main - The main Debian archive  (ACPI) to allow intelligent power
 i   acpid         1.0.3-19   1.0.3-19   management on your system and to query
 i   alien         8.44       8.44       battery and configuration status.
 i   anacron       2.3-9      2.3-9
 i   apt-show-vers 0.07       0.07       ACPID is a completely flexible, totally
 i A apt-utils     0.5.25     0.5.25     extensible daemon for delivering ACPI
 i   apt-watch     0.3.2-2    0.3.2-2    events. It listens on a file
 i   aptitude      0.2.14.1-2 0.2.14.1-2 (/proc/acpi/event) and when an event
 i   at            3.1.8-11   3.1.8-11   occurs, executes programs to handle the
 i   auto-apt      0.3.20     0.3.20     event. The programs it executes are
 i   cron          3.0pl1-83  3.0pl1-83  configured through a set of
 i   debconf       1.4.29     1.4.29     configuration files, which can be
 i   debconf-i18n  1.4.29     1.4.29     dropped into place by packages or by
 i A debootstrap   0.2.39     0.2.39     the admin.
 i A deborphan     1.7.3      1.7.3
 i   debtags       0.16       0.16       In order to use this package you need a
 i A defoma        0.11.8     0.11.8     recent Kernel (=>2.4.7). This can be
 i   discover      2.0.4-5    2.0.4-5    one including the patches on
 Utilities for using ACPI power management

Playing Minesweeper

   In case you get tired of installing and removing packages, aptitude
   includes a version of the classic game “Minesweeper”. To start it, select
   Actions → Play Minesweeper; the initial Minesweeper board will appear:

  Actions  Undo  Package  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
 Minesweeper                                              10/10 mines  13 seconds





                                    +--------+
                                    |        |
                                    |        |
                                    |        |
                                    |        |
                                    |        |
                                    |        |
                                    |        |
                                    |        |
                                    +--------+






   Within the rectangle that appears on the screen are hidden ten mines. Your
   goal is to determine, through intuition, logic, and luck, where those
   mines are, without setting any of them off! To do this, you must uncover
   all the squares that do not contain mines; in doing so, you will learn
   important information regarding which squares do contain mines. Beware,
   however: uncovering a square that contains a mine will set it off, ending
   your game immediately!

   To uncover a square (and find out whether a mine is hidden there), select
   the square with the arrow keys and press Enter:

  Actions  Undo  Package  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
 Minesweeper                                             10/10 mines  387 seconds





                                    +--------+
                                    | 2......|
                                    | 2111...|
                                    |    1...|
                                    | 1111...|
                                    |11...111|
                                    |...113  |
                                    |1122    |
                                    |        |
                                    +--------+






   As you can see, some of the hidden (blank) parts of the board have been
   revealed in this screenshot. The squares containing a . are squares which
   are not next to any mines; the numbers in the remaining squares indicate
   how many mines they are next to.

   If you think you know where a mine is, you can place a “flag” on it. To do
   this, select the suspected square and press f. For instance, in the
   screenshot below, I decided that the square on the left-hand side of the
   board looked suspicious...

  Actions  Undo  Package  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
 Minesweeper                                              9/10 mines  961 seconds





                                    +--------+
                                    | 2......|
                                    | 2111...|
                                    |    1...|
                                    |F1111...|
                                    |11...111|
                                    |...113  |
                                    |1122    |
                                    |        |
                                    +--------+






   As you can see, an F appeared in the selected square. It is no longer
   possible to uncover this square, even accidentally, until the flag is
   removed (by pressing f again). Once you have placed flags on all the mines
   that are next to a square (for instance, the squares labelled 1 next to
   the flag above), you can “sweep” around the square. This is just a
   convenient shortcut to uncover all the squares next to it (except those
   containing a flag, of course). For instance, sweeping around the 1 above:

  Actions  Undo  Package  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
 Minesweeper                                              9/10 mines  2290 seconds





                                    +--------+
                                    | 2......|
                                    | 2111...|
                                    |221 1...|
                                    |F1111...|
                                    |11...111|
                                    |...113  |
                                    |1122    |
                                    |        |
                                    +--------+






   Luckily (or was it luck?), my guess about the location of that mine was
   correct. If I had been wrong, I would have lost immediately:

  Actions  Undo  Package  Search  Options  Views  Help
 f10: Menu  ?: Help  q: Quit  u: Update  g: Download/Install/Remove Pkgs
 Minesweeper                                   Minesweeper    Lost in 2388 seconds





                                    +--------+
                                    |^2......|
                                    |^2111...|
                                    |221^1...|
                                    |^1111...|
                                    |11...111|
                                    |...113^ |
                                    |1122* ^ |
                                    | ^ ^   ^|
                                    +--------+






   When you lose, the locations of all the mines are revealed: unexploded
   mines are indicated by a caret symbol (^), and the one you “stepped on” is
   indicated by an asterisk (*).

   ══════════════════════════════════════════════════════════════════════════

   ^[7] I am pleased to say that the number of requests of this sort fell off
   precipitously following the initial publication of this Guide. It would be
   a happy occurrence if there was a connection between the two events.

   ^[8] This is sometimes referred to as an “install run”, even though you
   might be upgrading or removing packages in addition to installing them.

   ^[9] As noted above, it does not indicate that the packages in the archive
   are secure, or even non-malicious; it merely shows that they are genuine.

   ^[10] More precisely: they will be removed when there is no path via
   Depends, PreDepends, or Recommends to them from a manually installed
   package. If APT::AutoRemove::SuggestsImportant is true, a Suggests
   relationship is also enough to keep a package installed.

   ^[11] Or when immediate resolution is disabled.

   ^[12] The package with the highest dpkg priority, not the package with the
   highest apt pin priority.

   ^[13] This limit was imposed because more complex cost structures could
   make it difficult to optimize the resolver. Future versions of the program
   might remove some of the restrictions if they turn out to be unnecessary.

   ^[14] aptitude will only treat the comma as special if there is a second
   argument, so (for instance) “?name(apt,itude)” searches for the string
   “apt,itude” in the Name field of packages.

   While this behavior is well-defined, it may be surprising; I recommend
   using quoted strings for any pattern that contains characters that could
   have a special meaning.

   ^[15] Characters with a special meaning include: “+”, “-”, “.”, “(”, “)”,
   “|”, “[”, “]”, “^”, “$”, and “?”. Note that some of these are also
   aptitude metacharacters, so if you want to type (for instance) a literal
   “|”, it must be double-escaped: “?description(\~|)” will match packages
   whose description contains a vertical bar character (“|”).

   ^[16] The backslash escapes \\, \n, and \t are also available.

   ^[17] Astute readers will note that this is essentially a way to
   explicitly name the variable in the λ-terms corresponding to the term. A
   typical term would have the form “λ x . name-equals(x, pattern)”; giving
   this an explicit target makes x visible in the search language.

   ^[18] This is provided largely for symmetry with ?true.

   ^[19] Currently tagging is not supported; this escape is for future use.

   ^[20] On some terminals, a “yellow” background will actually come out
   brown.

                 Chapter 3. aptitude frequently asked questions

           “What ... is your name?”                                     

           “I am Arthur, King of the Britons.”

           “What ... is your quest?”

           “I seek the Holy Grail!”

           “What ... is the airspeed velocity of an unladen swallow?”

           “What do you mean? An African or a European swallow?”

           “Huh? I ... I don't kn---AAAAAUUUGGGHH!”
                                           -- Monty Python and the Holy Grail

   3.1. How can I find exactly one package by name?

   3.2. How can I find broken packages?

   3.3. I want to select text, why doesn't aptitude let me disable the mouse?

   3.1. How can I find exactly one package by name?
        As mentioned in the section called “Search patterns”, when you search
        for a package by name, the text you enter is actually a regular
        expression. Thus, the search pattern “^name$” will match only a
        package named name.

        For instance, you can find apt (but not aptitude or synaptic) by
        entering ^apt$; you can find g++ (but not g++-2.95 or g++-3.0) by
        entering ^g\+\+$.
   3.2. How can I find broken packages?
        Use the command Search → Find Broken (b).
   3.3. I want to select text, why doesn't aptitude let me disable the mouse?
        Normally, you cannot select text in an xterm while a program running
        in that terminal (such as aptitude) is using the mouse. However, you
        can override this behavior and perform a selection by holding the
        Shift key down while you click on the terminal.

                               Chapter 4. Credits

           No-one remembers the singer. The song remains.              
                                            -- Terry Pratchett, The Last Hero

   This section commemorates some of the people who have contributed to
   aptitude over its lifetime.

   [Note] Note
          This section is presently rather incomplete and will likely be
          updated and expanded as time goes on (in particular, there are many
          missing translation credits due to the huge number of sources of
          translations ^[21]). If you think you should be on this list,
          please email <dburrows@debian.org> with an explanation of why you
          think so.

   Translations and internationalization

   Brazilian translation

   Andre Luis Lopes, Gustavo Silva

   Chinese translation

   Carlos Z.F. Liu

   Czech translation

   Miroslav Kure

   Danish translation

   Morten Brix Pedersen, Morten Bo Johansen

   Dutch translation

   Luk Claes

   Finnish translation

   Jaakko Kangasharju

   French translation

   Martin Quinson, Jean-Luc Coulon

   German translation

   Sebastian Schaffert, Erich Schubert, Sebastian Kapfer, Jens Seidel

   Italian translation

   Danilo Piazzalunga

   Japanese translation

   Yasuo Eto, Noritada Kobayashi

   Lithuanian translation

   Darius ?itkevicius

   Polish translation

   Michal Politowski

   Portuguese translation

   Nuno Sénica, Miguel Figueiredo

   Norwegian translation

   Håvard Korsvoll

   Spanish translation

   Jordi Malloch, Ruben Porras

   Swedish translation

   Daniel Nylander

   Initial i18n patch

   Masato Taruishi

   i18n triaging and maintainence

   Christian Perrier

   Documentation

   User's Manual

   Daniel Burrows

   Programming

   Program design and implementation

   Daniel Burrows

   Support for the dpkg Breaks field

   Ian Jackson, Michael Vogt

   ══════════════════════════════════════════════════════════════════════════

   ^[21] It should be possible to compile a fairly complete list of i18n
   contributors based on the ChangeLog, its references to the Debian bug
   tracking system, and the revision history of aptitude, but doing so will
   require a large investment of time that is not currently available.

                             Command-line reference

   ══════════════════════════════════════════════════════════════════════════

   Table of Contents

   aptitude — high-level interface to the package manager

   aptitude-create-state-bundle — bundle the current aptitude state

   aptitude-run-state-bundle — unpack an aptitude state bundle and invoke
   aptitude on it

Name

   aptitude — high-level interface to the package manager

Synopsis

   aptitude [options...] { autoclean | clean | forget-new | keep-all | update
   }

   aptitude [options...] { full-upgrade | safe-upgrade } [packages...]

   aptitude [options...] { build-dep | build-depends | changelog | download |
   forbid-version | hold | install | markauto | purge | reinstall | remove |
   show | showsrc | source | unhold | unmarkauto | versions } packages...

   aptitude extract-cache-subset output-directory packages...

   aptitude [options...] search patterns...

   aptitude [options...] { add-user-tag | remove-user-tag } tag packages...

   aptitude [options...] { why | why-not } [patterns...] package

   aptitude [-S fname] [ --autoclean-on-startup | --clean-on-startup | -i |
   -u ]

   aptitude help

Description

   aptitude is a text-based interface to the Debian GNU/Linux package system.

   It allows the user to view the list of packages and to perform package
   management tasks such as installing, upgrading, and removing packages.
   Actions may be performed from a visual interface or from the command-line.

Command-line actions

   The first argument which does not begin with a hyphen (“-”) is considered
   to be an action that the program should perform. If an action is not
   specified on the command-line, aptitude will start up in visual mode.

   The following actions are available:

   install

   Install one or more packages. The packages should be listed after the
   “install” command; if a package name contains a tilde character (“~”) or a
   question mark (“?”), it will be treated as a search pattern and every
   package matching the pattern will be installed (see the section “Search
   Patterns” in the aptitude reference manual).

   To select a particular version of the package, append “=version” to the
   package name: for instance, “aptitude install apt=0.3.1”. Similarly, to
   select a package from a particular archive, append “/archive” to the
   package name: for instance, “aptitude install apt/experimental”. You
   cannot specify both an archive and a version for a package.

   Not every package listed on the command line has to be installed; you can
   tell aptitude to do something different with a package by appending an
   “override specifier” to the name of the package. For example, aptitude
   remove wesnoth+ will install wesnoth, not remove it. The following
   override specifiers are available:

   package+

   Install package.

   If the package was not installed, it is marked as manually installed, and
   the dependencies newly installed are marked with the automatic flag. If
   the package or the dependencies were already installed, the automatic flag
   is preserved. See the section about automatic installations in the
   documentation for more information.

   package+M

   Install package and immediately mark it as automatically installed (note
   that if nothing depends on package, this will cause it to be immediately
   removed).

   package-

   Remove package.

   package_

   Purge package: remove it and all its associated configuration and data
   files.

   package=

   Place package on hold: cancel any active installation, upgrade, or
   removal, and prevent this package from being automatically upgraded in the
   future.

   package:

   Keep package at its current version: cancel any installation, removal, or
   upgrade. Unlike “hold” (above) this does not prevent automatic upgrades in
   the future.

   package&M

   Mark package as having been automatically installed.

   package&m

   Mark package as having been manually installed.

   package&BD

   Install the build-dependencies of a package.

   As a special case, “install” with no arguments will act on any
   stored/pending actions.

   [Note] Note
          Once you enter Y at the final confirmation prompt, the “install”
          command will modify aptitude's stored information about what
          actions to perform. Therefore, if you issue (e.g.) the command
          “aptitude install foo bar” on packages previously uninstalled, and
          then the installation fails once aptitude has started downloading
          and installing packages, you will need to run “aptitude remove foo
          bar” to go back to the previous state (and possibly undo
          installations or upgrades to other packages that were affected by
          the “install” action).

   remove, purge, reinstall

   These commands are the same as “install”, but apply the named action to
   all packages given on the command line for which it is not overridden.

   For instance, “aptitude remove '~ndeity'” will remove all packages whose
   name contains “deity”.

   build-depends, build-dep

   Satisfy the build-dependencies of a package. Each package name may be a
   source package, in which case the build dependencies of that source
   package are installed; otherwise, binary packages are found in the same
   way as for the “install” command, and the build-dependencies of the source
   packages that build those binary packages are satisfied.

   If the command-line parameter --arch-only is present, only
   architecture-dependent build dependencies (i.e., not Build-Depends-Indep
   or Build-Conflicts-Indep) will be obeyed.

   markauto, unmarkauto

   Mark packages as automatically installed or manually installed,
   respectively. Packages are specified in exactly the same way as for the
   “install” command. For instance, “aptitude markauto '~slibs'” will mark
   all packages in the “libs” section as having been automatically installed.

   For more information on automatically installed packages, see the section
   “Managing Automatically Installed Packages” in the aptitude reference
   manual.

   hold, unhold, keep

   Mark packages to be on hold, remove this property, or set to keep in the
   current state. Packages are specified in exactly the same way as for the
   “install” command. For instance, “aptitude hold '~e^dpkg$'” will mark all
   packages coming from the source package “dpkg” to be on hold.

   The difference between hold and keep is that hold will cause a package to
   be ignored by future safe-upgrade or full-upgrade commands, while keep
   merely cancels any scheduled actions on the package. unhold will allow a
   package to be upgraded by future safe-upgrade or full-upgrade commands,
   without otherwise altering its state.

   keep-all

   Cancels all scheduled actions on all packages; any packages whose sticky
   state indicates an installation, removal, or upgrade will have this sticky
   state cleared.

   forget-new

   Forgets all internal information about what packages are “new” (equivalent
   to pressing “f” when in visual mode).

   This command accepts package names or patterns as arguments. If the string
   contains a tilde character (“~”) or a question mark (“?”), it will be
   treated as a search pattern and every package matching the pattern will be
   considered (see the section “Search Patterns” in the aptitude reference
   manual).

   forbid-version

   Forbid a package from being upgraded to a particular version, while
   allowing automatic upgrades to future versions. This is useful for example
   to avoid a known broken version of a package, without having to set and
   clear manual holds.

   By default, aptitude will select the forbidden version to be the one which
   the package would normally be upgraded (the candidate version). This may
   be overridden by appending “=version” to the package name: for instance,
   “aptitude forbid-version vim=1.2.3.broken-4”.

   To revert the action, “aptitude install package” will remove the ban. To
   remove the forbidden version without installing the candidate version, the
   current version should be appended: “install package=version”.

   update

   Updates the list of available packages from the apt sources (this is
   equivalent to “apt-get update”)

   safe-upgrade

   Upgrades installed packages to their most recent version. Installed
   packages will not be removed unless they are unused (see the section
   “Managing Automatically Installed Packages” in the aptitude reference
   manual). Packages which are not currently installed may be installed to
   resolve dependencies unless the --no-new-installs command-line option is
   supplied.

   If no packages are listed on the command line, aptitude will attempt to
   upgrade every package that can be upgraded. Otherwise, aptitude will
   attempt to upgrade only the packages which it is instructed to upgrade.
   The packages can be extended with suffixes in the same manner as arguments
   to aptitude install, so you can also give additional instructions to
   aptitude here; for instance, aptitude safe-upgrade bash dash- will attempt
   to upgrade the bash package and remove the dash package.

   It is sometimes necessary to remove one package in order to upgrade
   another; this command is not able to upgrade packages in such situations.
   Use the full-upgrade command to upgrade as many packages as possible.

   full-upgrade

   Upgrades installed packages to their most recent version, removing or
   installing packages as necessary. It also installs new Essential or
   Required packages. This command is less conservative than safe-upgrade and
   thus more likely to perform unwanted actions. However, it is capable of
   upgrading packages that safe-upgrade cannot upgrade.

   If no packages are listed on the command line, aptitude will attempt to
   upgrade every package that can be upgraded. Otherwise, aptitude will
   attempt to upgrade only the packages which it is instructed to upgrade.
   The packages can be extended with suffixes in the same manner as arguments
   to aptitude install, so you can also give additional instructions to
   aptitude here; for instance, aptitude full-upgrade bash dash- will attempt
   to upgrade the bash package and remove the dash package.

   [Note] Note
          This command was originally named dist-upgrade for historical
          reasons, and aptitude still recognizes dist-upgrade as a synonym
          for full-upgrade.

   search

   Searches for packages matching one of the patterns supplied on the command
   line. All packages which match any of the given patterns will be
   displayed; for instance, “aptitude search '~N' edit” will list all “new”
   packages and all packages whose name contains “edit”. For more information
   on search patterns, see the section “Search Patterns” in the aptitude
   reference manual.

   [Note] Note
          In the example above, “aptitude search '~N' edit” has two arguments
          after search and thus is searching for two patterns: “~N” and
          “edit”. As described in the search pattern reference, a single
          pattern composed of two sub-patterns separated by a space (such as
          “~N edit”) matches only if both patterns match. Thus, the command
          “aptitude search '~N edit'” will only show “new” packages whose
          name contains “edit”.

   Unless you pass the -F option, the output of aptitude search will look
   something like this:

 i   apt                             - Advanced front-end for dpkg
 pi  apt-build                       - frontend to apt to build, optimize and in
 cp  apt-file                        - APT package searching utility -- command-
 ihA raptor-utils                    - Raptor RDF Parser utilities

   Each search result is listed on a separate line. The first character of
   each line indicates the current state of the package: the most common
   states are p, meaning that no trace of the package exists on the system,
   c, meaning that the package was deleted but its configuration files remain
   on the system, i, meaning that the package is installed, and v, meaning
   that the package is virtual. The second character indicates the stored
   action (if any; otherwise a blank space is displayed) to be performed on
   the package, with the most common actions being i, meaning that the
   package will be installed, d, meaning that the package will be deleted,
   and p, meaning that the package and its configuration files will be
   removed. If the third character is A, the package was automatically
   installed.

   For a complete list of the possible state and action flags, see the
   section “Accessing Package Information” in the aptitude reference guide.
   To customize the output of search, see the command-line options -F and
   --sort.

   show

   Displays detailed information about one or more packages. If a package
   name contains a tilde character (“~”) or a question mark (“?”), it will be
   treated as a search pattern and all matching packages will be displayed
   (see the section “Search Patterns” in the aptitude reference manual).

   If the verbosity level is 1 or greater (i.e., at least one -v is present
   on the command-line), information about all versions of the package is
   displayed. Otherwise, information about the “candidate version” (the
   version that “aptitude install” would download) is displayed.

   You can display information about a different version of the package by
   appending =version to the package name; you can display the version from a
   particular archive or release by appending /archive or /release to the
   package name: for instance, /unstable or /sid. If either of these is
   present, then only the version you request will be displayed, regardless
   of the verbosity level.

   If the verbosity level is 1 or greater, the package's architecture,
   compressed size, filename, and md5sum fields will be displayed. If the
   verbosity level is 2 or greater, the select version or versions will be
   displayed once for each archive in which they are found.

   showsrc

   Displays detailed information about one or more source packages.

   This is a thin wrapper over apt(8).

   source

   Downloads one or more source packages.

   This is a thin wrapper over apt(8).

   versions

   Displays the versions of the packages listed on the command-line.

 $ aptitude versions wesnoth
 p   1:1.4.5-1                                                             100
 p   1:1.6.5-1                                    unstable                 500
 p   1:1.7.14-1                                   experimental             1

   Each version is listed on a separate line. The leftmost three characters
   indicate the current state, planned state (if any), and whether the
   package was automatically installed; for more information on their
   meanings, see the documentation of aptitude search. To the right of the
   version number you can find the releases from which the version is
   available, and the pin priority of the version.

   If a package name contains a tilde character (“~”) or a question mark
   (“?”), it will be treated as a search pattern and all matching versions
   will be displayed (see the section “Search Patterns” in the aptitude
   reference manual). This means that, for instance, aptitude versions '~i'
   will display all the versions that are currently installed on the system
   and nothing else, not even other versions of the same packages.

 $ aptitude versions '~nexim4-daemon-light'
 Package exim4-daemon-light:
 i   4.71-3                                                                100
 p   4.71-4                                       unstable                 500

 Package exim4-daemon-light-dbg:
 p   4.71-4                                       unstable                 500

   If the input is a search pattern, or if more than one package's versions
   are to be displayed, aptitude will automatically group the output by
   package, as shown above. You can disable this via --group-by=none, in
   which case aptitude will display a single list of all the versions that
   were found and automatically include the package name in each output line:

 $ aptitude versions --group-by=none '~nexim4-daemon-light'
 i   exim4-daemon-light 4.71-3                                             100
 p   exim4-daemon-light 4.71-4                    unstable                 500
 p   exim4-daemon-light-dbg 4.71-4                unstable                 500

   To disable the package name, pass --show-package-names=never:

 $ aptitude versions --show-package-names=never --group-by=none '~nexim4-daemon-light'
 i   4.71-3                                                                100
 p   4.71-4                                       unstable                 500
 p   4.71-4                                       unstable                 500

   In addition to the above options, the information printed for each version
   can be controlled by the command-line option -F. The order in which
   versions are displayed can be controlled by the command-line option
   --sort. To prevent aptitude from formatting the output into columns, use
   --disable-columns.

   add-user-tag, remove-user-tag

   Adds a user tag to or removes a user tag from the selected group of
   packages. If a package name contains a tilde (“~”) or question mark (“?”),
   it is treated as a search pattern and the tag is added to or removed from
   all the packages that match the pattern (see the section “Search Patterns”
   in the aptitude reference manual).

   User tags are arbitrary strings associated with a package. They can be
   used with the ?user-tag(tag) search term, which will select all the
   packages that have a user tag matching tag.

   why, why-not

   Explains the reason that a particular package should or cannot be
   installed on the system.

   This command searches for packages that require or conflict with the given
   package. It displays a sequence of dependencies leading to the target
   package, along with a note indicating the installed state of each package
   in the dependency chain:

 $ aptitude why kdepim
 i   nautilus-data Recommends nautilus
 i A nautilus      Recommends desktop-base (>= 0.2)
 i A desktop-base  Suggests   gnome | kde | xfce4 | wmaker
 p   kde           Depends    kdepim (>= 4:3.4.3)

   The command why finds a dependency chain that installs the package named
   on the command line, as above. Note that the dependency that aptitude
   produced in this case is only a suggestion. This is because no package
   currently installed on this computer depends on or recommends the kdepim
   package; if a stronger dependency were available, aptitude would have
   displayed it.

   In contrast, why-not finds a dependency chain leading to a conflict with
   the target package:

 $ aptitude why-not textopo
 i   ocaml-core          Depends   ocamlweb
 i A ocamlweb            Depends   tetex-extra | texlive-latex-extra
 i A texlive-latex-extra Conflicts textopo

   If one or more patterns are present (in addition to the mandatory last
   argument, which should be a valid package name), then aptitude will begin
   its search at these patterns. That is, the first package in the chain it
   prints to explain why package is or is not installed, will be a package
   matching the pattern in question. The patterns are considered to be
   package names unless they contain a tilde character (“~”) or a question
   mark (“?”), in which case they are treated as search patterns (see the
   section “Search Patterns” in the aptitude reference manual).

   If no patterns are present, then aptitude will search for dependency
   chains beginning at manually installed packages. This effectively shows
   the packages that have caused or would cause a given package to be
   installed.

   [Note] Note
          aptitude why does not perform full dependency resolution; it only
          displays direct relationships between packages. For instance, if A
          requires B, C requires D, and B and C conflict, “aptitude why-not
          D” will not produce the answer “A depends on B, B conflicts with C,
          and D depends on C”.

   By default aptitude outputs only the “most installed, strongest, tightest,
   shortest” dependency chain. That is, it looks for a chain that only
   contains packages which are installed or will be installed; it looks for
   the strongest possible dependencies under that restriction; it looks for
   chains that avoid ORed dependencies and Provides; and it looks for the
   shortest dependency chain meeting those criteria. These rules are
   progressively weakened until a match is found.

   If the verbosity level is 1 or more, then all the explanations aptitude
   can find will be displayed, in inverse order of relevance. If the
   verbosity level is 2 or more, a truly excessive amount of debugging
   information will be printed to standard output.

   This command returns 0 if successful, 1 if no explanation could be
   constructed, and -1 if an error occurred.

   clean

   Removes all previously downloaded .deb files from the package cache
   directory (usually /var/cache/apt/archives).

   autoclean

   Removes any cached packages which can no longer be downloaded. This allows
   you to prevent a cache from growing out of control over time without
   completely emptying it.

   changelog

   Downloads and displays the Debian changelog for each of the given source
   or binary packages.

   By default, the changelog for the version which would be installed with
   “aptitude install” is downloaded. You can select a particular version of a
   package by appending =version to the package name; you can select the
   version from a particular archive or release by appending /archive or
   /release to the package name (for instance, /unstable or /sid).

   download

   Downloads the .deb file for the given package to the current directory.

   This is a thin wrapper over apt(8).

   extract-cache-subset

   Copy the apt configuration directory (/etc/apt) and a subset of the
   package database to the specified directory. If no packages are listed,
   the entire package database is copied; otherwise only the entries
   corresponding to the named packages are copied. Each package name may be a
   search pattern, and all the packages matching that pattern will be
   selected (see the section “Search Patterns” in the aptitude reference
   manual). Any existing package database files in the output directory will
   be overwritten.

   Dependencies in binary package stanzas will be rewritten to remove
   references to packages not in the selected set.

   help

   Displays a brief summary of the available commands and options.

Options

   The following options may be used to modify the behavior of the actions
   described above. Note that while all options will be accepted for all
   commands, some options don't apply to particular commands and will be
   ignored by those commands.

   --add-user-tag tag

   For full-upgrade, safe-upgrade, forbid-version, hold, install, keep-all,
   markauto, unmarkauto, purge, reinstall, remove, unhold, and unmarkauto:
   add the user tag tag to all packages that are installed, removed, or
   upgraded by this command as if with the add-user-tag command.

   --add-user-tag-to tag,pattern

   For full-upgrade, safe-upgrade, forbid-version, hold, install, keep-all,
   markauto, unmarkauto, purge, reinstall, remove, unhold, and unmarkauto:
   add the user tag tag to all packages that match pattern as if with the
   add-user-tag command. The pattern is a search pattern as described in the
   section “Search Patterns” in the aptitude reference manual.

   For instance, aptitude safe-upgrade --add-user-tag-to
   "new-installs,?action(install)" will add the tag new-installs to all the
   packages installed by the safe-upgrade command.

   --allow-new-upgrades

   When the safe resolver is being used (i.e., --safe-resolver was passed,
   the action is safe-upgrade, or Aptitude::Always-Use-Safe-Resolver is set
   to true), allow the dependency resolver to install upgrades for packages
   regardless of the value of Aptitude::Safe-Resolver::No-New-Upgrades.

   --allow-new-installs

   Allow the safe-upgrade command to install new packages; when the safe
   resolver is being used (i.e., --safe-resolver was passed, the action is
   safe-upgrade, or Aptitude::Always-Use-Safe-Resolver is set to true), allow
   the dependency resolver to install new packages. This option takes effect
   regardless of the value of Aptitude::Safe-Resolver::No-New-Installs.

   --allow-untrusted

   Install packages from untrusted sources without prompting. You should only
   use this if you know what you are doing, as it could easily compromise
   your system's security.

   --disable-columns

   This option causes aptitude search and aptitude versions to output their
   results without any special formatting. In particular: normally aptitude
   will add whitespace or truncate search results in an attempt to fit its
   results into vertical “columns”. With this flag, each line will be formed
   by replacing any format escapes in the format string with the
   corresponding text; column widths will be ignored.

   For instance, the first few lines of output from “aptitude search -F '%p
   %V' --disable-columns libedataserver” might be:

 disksearch 1.2.1-3
 hp-search-mac 0.1.3
 libbsearch-ruby 1.5-5
 libbsearch-ruby1.8 1.5-5
 libclass-dbi-abstractsearch-perl 0.07-2
 libdbix-fulltextsearch-perl 0.73-10

   As in the above example, --disable-columns is often useful in combination
   with a custom display format set using the command-line option -F.

   This corresponds to the configuration option
   Aptitude::CmdLine::Disable-Columns.

   -D, --show-deps

   For commands that will install or remove packages (install, full-upgrade,
   etc), show brief explanations of automatic installations and removals.

   This corresponds to the configuration option Aptitude::CmdLine::Show-Deps.

   -d, --download-only

   Download packages to the package cache as necessary, but do not install or
   remove anything. By default, the package cache is stored in
   /var/cache/apt/archives.

   This corresponds to the configuration option
   Aptitude::CmdLine::Download-Only.

   -F format, --display-format format

   Specify the format which should be used to display output from the search
   and versions commands. For instance, passing “%p %v %V” for format will
   display a package's name, followed by its currently installed version and
   its candidate version (see the section “Customizing how packages are
   displayed” in the aptitude reference manual for more information).

   The command-line option --disable-columns is often useful in combination
   with -F.

   For search, this corresponds to the configuration option
   Aptitude::CmdLine::Package-Display-Format; for versions, this corresponds
   to the configuration option Aptitude::CmdLine::Version-Display-Format.

   -f

   Try hard to fix the dependencies of broken packages, even if it means
   ignoring the actions requested on the command line.

   This corresponds to the configuration item Aptitude::CmdLine::Fix-Broken.

   --full-resolver

   When package dependency problems are encountered, use the default “full”
   resolver to solve them. Unlike the “safe” resolver activated by
   --safe-resolver, the full resolver will happily remove packages to fulfill
   dependencies. It can resolve more situations than the safe algorithm, but
   its solutions are more likely to be undesirable.

   This option can be used to force the use of the full resolver even when
   Aptitude::Always-Use-Safe-Resolver is true.

   --group-by grouping-mode

   Control how the versions command groups its output. The following values
   are recognized:

     • archive to group packages by the archive they occur in (“stable”,
       “unstable”, etc). If a package occurs in several archives, it will be
       displayed in each of them.

     • auto to group versions by their package unless there is exactly one
       argument and it is not a search pattern.

     • none to display all the versions in a single list without any
       grouping.

     • package to group versions by their package.

     • source-package to group versions by their source package.

     • source-version to group versions by their source package and source
       version.

   This corresponds to the configuration option
   Aptitude::CmdLine::Versions-Group-By.

   -h, --help

   Display a brief help message. Identical to the help action.

   --log-file=file

   If file is a nonempty string, log messages will be written to it, except
   that if file is “-”, the messages will be written to standard output
   instead. If this option appears multiple times, the last occurrence is the
   one that will take effect.

   This does not affect the log of installations that aptitude has performed
   (/var/log/aptitude); the log messages written using this configuration
   include internal program events, errors, and debugging messages. See the
   command-line option --log-level to get more control over what gets logged.

   This corresponds to the configuration option Aptitude::Logging::File.

   --log-level=level, --log-level=category:level

   --log-level=level causes aptitude to only log messages whose level is
   level or higher. For instance, setting the log level to error will cause
   only messages at the log levels error and fatal to be displayed; all
   others will be hidden. Valid log levels (in descending order) are off,
   fatal, error, warn, info, debug, and trace. The default log level is warn.

   --log-level=category:level causes messages in category to only be logged
   if their level is level or higher.

   --log-level may appear multiple times on the command line; the most
   specific setting is the one that takes effect, so if you pass
   --log-level=aptitude.resolver:fatal and
   --log-level=aptitude.resolver.hints.match:trace, then messages in
   aptitude.resolver.hints.parse will only be printed if their level is
   fatal, but all messages in aptitude.resolver.hints.match will be printed.
   If you set the level of the same category two or more times, the last
   setting is the one that will take effect.

   This does not affect the log of installations that aptitude has performed
   (/var/log/aptitude); the log messages written using this configuration
   include internal program events, errors, and debugging messages. See the
   command-line option --log-file to change where log messages go.

   This corresponds to the configuration group Aptitude::Logging::Levels.

   --log-resolver

   Set some standard log levels related to the resolver, to produce logging
   output suitable for processing with automated tools. This is equivalent to
   the command-line options --log-level=aptitude.resolver.search:trace
   --log-level=aptitude.resolver.search.tiers:info.

   --no-new-installs

   Prevent safe-upgrade from installing any new packages; when the safe
   resolver is being used (i.e., --safe-resolver was passed or
   Aptitude::Always-Use-Safe-Resolver is set to true), forbid the dependency
   resolver from installing new packages. This option takes effect regardless
   of the value of Aptitude::Safe-Resolver::No-New-Installs.

   This mimics the historical behavior of apt-get upgrade.

   --no-new-upgrades

   When the safe resolver is being used (i.e., --safe-resolver was passed or
   Aptitude::Always-Use-Safe-Resolver is set to true), forbid the dependency
   resolver from installing upgrades for packages regardless of the value of
   Aptitude::Safe-Resolver::No-New-Upgrades.

   --no-show-resolver-actions

   Do not display the actions performed by the “safe” resolver, overriding
   any configuration option or earlier --show-resolver-actions.

   -O order, --sort order

   Specify the order in which output from the search and versions commands
   should be displayed. For instance, passing “installsize” for order will
   list packages in order according to their size when installed (see the
   section “Customizing how packages are sorted” in the aptitude reference
   manual for more information).

   Prepending the order keyword with a tilde character (~) reverses the order
   from ascending to descending.

   The default sort order is name,version.

   -o key=value

   Set a configuration file option directly; for instance, use -o
   Aptitude::Log=/tmp/my-log to log aptitude's actions to /tmp/my-log. For
   more information on configuration file options, see the section
   “Configuration file reference” in the aptitude reference manual.

   -P, --prompt

   Always display a prompt before downloading, installing or removing
   packages, even when no actions other than those explicitly requested will
   be performed.

   This corresponds to the configuration option
   Aptitude::CmdLine::Always-Prompt.

   --purge-unused

   If Aptitude::Delete-Unused is set to “true” (its default), then in
   addition to removing each package that is no longer required by any
   installed package, aptitude will also purge them, removing their
   configuration files and perhaps other important data. For more information
   about which packages are considered to be “unused”, see the section
   “Managing Automatically Installed Packages” in the aptitude reference
   manual. THIS OPTION CAN CAUSE DATA LOSS! DO NOT USE IT UNLESS YOU KNOW
   WHAT YOU ARE DOING!

   This corresponds to the configuration option Aptitude::Purge-Unused.

   -q[=n], --quiet[=n]

   Suppress all incremental progress indicators, thus making the output
   loggable. This may be supplied multiple times to make the program quieter,
   but unlike apt-get, aptitude does not enable -y when -q is supplied more
   than once.

   The optional =n may be used to directly set the amount of quietness (for
   instance, to override a setting in /etc/apt/apt.conf); it causes the
   program to behave as if -q had been passed exactly n times.

   -R, --without-recommends

   Do not treat recommendations as dependencies when installing new packages
   (this overrides settings in /etc/apt/apt.conf and ~/.aptitude/config).
   Packages previously installed due to recommendations will not be removed.

   This corresponds to the pair of configuration options
   APT::Install-Recommends and APT::AutoRemove::RecommendsImportant.

   -r, --with-recommends

   Treat recommendations as dependencies when installing new packages (this
   overrides settings in /etc/apt/apt.conf and ~/.aptitude/config).

   This corresponds to the configuration option APT::Install-Recommends

   --remove-user-tag tag

   For full-upgrade, safe-upgrade forbid-version, hold, install, keep-all,
   markauto, unmarkauto, purge, reinstall, remove, unhold, and unmarkauto:
   remove the user tag tag from all packages that are installed, removed, or
   upgraded by this command as if with the add-user-tag command.

   --remove-user-tag-from tag,pattern

   For full-upgrade, safe-upgrade forbid-version, hold, install, keep-all,
   markauto, unmarkauto, purge, reinstall, remove, unhold, and unmarkauto:
   remove the user tag tag from all packages that match pattern as if with
   the remove-user-tag command. The pattern is a search pattern as described
   in the section “Search Patterns” in the aptitude reference manual.

   For instance, aptitude safe-upgrade --remove-user-tag-from
   "not-upgraded,?action(upgrade)" will remove the not-upgraded tag from all
   packages that the safe-upgrade command is able to upgrade.

   -s, --simulate

   In command-line mode, print the actions that would normally be performed,
   but don't actually perform them. This does not require root privileges. In
   the visual interface, always open the cache in read-only mode regardless
   of whether you are root.

   This corresponds to the configuration option Aptitude::Simulate.

   --safe-resolver

   When package dependency problems are encountered, use a “safe” algorithm
   to solve them. This resolver attempts to preserve as many of your choices
   as possible; it will never remove a package or install a version of a
   package other than the package's default candidate version. It is the same
   algorithm used in safe-upgrade; indeed, aptitude --safe-resolver
   full-upgrade is equivalent to aptitude safe-upgrade. Because safe-upgrade
   always uses the safe resolver, it does not accept the --safe-resolver
   flag.

   This option is equivalent to setting the configuration variable
   Aptitude::Always-Use-Safe-Resolver to true.

   --schedule-only

   For commands that modify package states, schedule operations to be
   performed in the future, but don't perform them. You can execute scheduled
   actions by running aptitude install with no arguments. This is equivalent
   to making the corresponding selections in visual mode, then exiting the
   program normally.

   For instance, aptitude --schedule-only install evolution will schedule the
   evolution package for later installation.

   --show-package-names when

   Controls when the versions command shows package names. The following
   settings are allowed:

     • always: display package names every time that aptitude versions runs.

     • auto: display package names when aptitude versions runs if the output
       is not grouped by package, and either there is a pattern-matching
       argument or there is more than one argument.

     • never: never display package names in the output of aptitude versions.

   This option corresponds to the configuration item
   Aptitude::CmdLine::Versions-Show-Package-Names.

   --show-resolver-actions

   Display the actions performed by the “safe” resolver and by safe-upgrade.

   When executing the command safe-upgrade or when the option --safe-resolver
   is present, aptitude will display a summary of the actions performed by
   the resolver before printing the installation preview. This is equivalent
   to the configuration option
   Aptitude::Safe-Resolver::Show-Resolver-Actions.

   --show-summary[=MODE]

   Changes the behavior of “aptitude why” to summarize each dependency chain
   that it outputs, rather than displaying it in long form. If this option is
   present and MODE is not “no-summary”, chains that contain Suggests
   dependencies will not be displayed: combine --show-summary with -v to see
   a summary of all the reasons for the target package to be installed.

   MODE can be any one of the following:

    1. no-summary: don't show a summary (the default behavior if
       --show-summary is not present).

    2. first-package: display the first package in each chain. This is the
       default value of MODE if it is not present.

    3. first-package-and-type: display the first package in each chain, along
       with the strength of the weakest dependency in the chain.

    4. all-packages: briefly display each chain of dependencies leading to
       the target package.

    5. all-packages-with-dep-versions: briefly display each chain of
       dependencies leading to the target package, including the target
       version of each dependency.

   This option corresponds to the configuration item
   Aptitude::CmdLine::Show-Summary; if --show-summary is present on the
   command-line, it will override Aptitude::CmdLine::Show-Summary.

   Example 12. Usage of --show-summary

   --show-summary used with -v to display all the reasons a package is
   installed:

 $ aptitude -v --show-summary why foomatic-db
 Packages requiring foomatic-db:
   cupsys-driver-gutenprint
   foomatic-db-engine
   foomatic-db-gutenprint
   foomatic-db-hpijs
   foomatic-filters-ppds
   foomatic-gui
   kde
   printconf
   wine

 $ aptitude -v --show-summary=first-package-and-type why foomatic-db
 Packages requiring foomatic-db:
   [Depends] cupsys-driver-gutenprint
   [Depends] foomatic-db-engine
   [Depends] foomatic-db-gutenprint
   [Depends] foomatic-db-hpijs
   [Depends] foomatic-filters-ppds
   [Depends] foomatic-gui
   [Depends] kde
   [Depends] printconf
   [Depends] wine

 $ aptitude -v --show-summary=all-packages why foomatic-db
 Packages requiring foomatic-db:
   cupsys-driver-gutenprint D: cups-driver-gutenprint D: cups R: foomatic-filters R: foomatic-db-engine D: foomatic-db
   foomatic-filters-ppds D: foomatic-filters R: foomatic-db-engine D: foomatic-db
   kde D: kdeadmin R: system-config-printer-kde D: system-config-printer R: hal-cups-utils D: cups R: foomatic-filters R: foomatic-db-engine D: foomatic-db
   wine D: libwine-print D: cups-bsd R: cups R: foomatic-filters R: foomatic-db-engine D: foomatic-db
   foomatic-db-engine D: foomatic-db
   foomatic-db-gutenprint D: foomatic-db
   foomatic-db-hpijs D: foomatic-db
   foomatic-gui D: python-foomatic D: foomatic-db-engine D: foomatic-db
   printconf D: foomatic-db

 $ aptitude -v --show-summary=all-packages-with-dep-versions why foomatic-db
 Packages requiring foomatic-db:
   cupsys-driver-gutenprint D: cups-driver-gutenprint (>= 5.0.2-4) D: cups (>= 1.3.0) R: foomatic-filters (>= 4.0) R: foomatic-db-engine (>= 4.0) D: foomatic-db (>= 20090301)
   foomatic-filters-ppds D: foomatic-filters R: foomatic-db-engine (>= 4.0) D: foomatic-db (>= 20090301)
   kde D: kdeadmin (>= 4:3.5.5) R: system-config-printer-kde (>= 4:4.2.2-1) D: system-config-printer (>= 1.0.0) R: hal-cups-utils D: cups R: foomatic-filters (>= 4.0) R: foomatic-db-engine (>= 4.0) D: foomatic-db (>= 20090301)
   wine D: libwine-print (= 1.1.15-1) D: cups-bsd R: cups R: foomatic-filters (>= 4.0) R: foomatic-db-engine (>= 4.0) D: foomatic-db (>= 20090301)
   foomatic-db-engine D: foomatic-db
   foomatic-db-gutenprint D: foomatic-db
   foomatic-db-hpijs D: foomatic-db
   foomatic-gui D: python-foomatic (>= 0.7.9.2) D: foomatic-db-engine D: foomatic-db (>= 20090301)
   printconf D: foomatic-db


   --show-summary used to list a chain on one line:

 $ aptitude --show-summary=all-packages why aptitude-gtk libglib2.0-data
 Packages requiring libglib2.0-data:
   aptitude-gtk D: libglib2.0-0 R: libglib2.0-data

   -t release, --target-release release

   Set the release from which packages should be installed. For instance,
   “aptitude -t experimental ...” will install packages from the experimental
   distribution unless you specify otherwise.

   This will affect the default candidate version of packages according to
   the rules described in apt_preferences(5).

   This corresponds to the configuration item APT::Default-Release.

   -V, --show-versions

   Show which versions of packages will be installed.

   This corresponds to the configuration option
   Aptitude::CmdLine::Show-Versions.

   -v, --verbose

   Causes some commands (for instance, show) to display extra information.
   This may be supplied multiple times to get more and more information.

   This corresponds to the configuration option Aptitude::CmdLine::Verbose.

   --version

   Display the version of aptitude and some information about how it was
   compiled.

   --visual-preview

   When installing or removing packages from the command line, instead of
   displaying the usual prompt, start up the visual interface and display its
   preview screen.

   -W, --show-why

   In the preview displayed before packages are installed or removed, show
   which manually installed package requires each automatically installed
   package. For instance:

 $ aptitude --show-why install mediawiki
 ...
 The following NEW packages will be installed:
   libapache2-mod-php5{a} (for mediawiki)  mediawiki  php5{a} (for mediawiki)
   php5-cli{a} (for mediawiki)  php5-common{a} (for mediawiki)
   php5-mysql{a} (for mediawiki)

   When combined with -v or a non-zero value for Aptitude::CmdLine::Verbose,
   this displays the entire chain of dependencies that lead each package to
   be installed. For instance:

 $ aptitude -v --show-why install libdb4.2-dev
 The following NEW packages will be installed:
   libdb4.2{a} (libdb4.2-dev D: libdb4.2)  libdb4.2-dev
 The following packages will be REMOVED:
   libdb4.4-dev{a} (libdb4.2-dev C: libdb-dev P<- libdb-dev)

   This option will also describe why packages are being removed, as shown
   above. In this example, libdb4.2-dev conflicts with libdb-dev, which is
   provided by libdb-dev.

   This argument corresponds to the configuration option
   Aptitude::CmdLine::Show-Why and displays the same information that is
   computed by aptitude why and aptitude why-not.

   -w width, --width width

   Specify the display width which should be used for output from the search
   and versions commands (in the command line).

   By default and when the output is seen directly in a terminal, the
   terminal width is used. When the output is redirected or piped, a very
   large "unlimited" line width is used, and this option is ignored.

   This corresponds to the configuration option
   Aptitude::CmdLine::Package-Display-Width

   -y, --assume-yes

   When a yes/no prompt would be presented, assume that the user entered
   “yes”. In particular, suppresses the prompt that appears when installing,
   upgrading, or removing packages. Prompts for “dangerous” actions, such as
   removing essential packages, will still be displayed. This option
   overrides -P.

   This corresponds to the configuration option
   Aptitude::CmdLine::Assume-Yes.

   -Z

   Show how much disk space will be used or freed by the individual packages
   being installed, upgraded, or removed.

   This corresponds to the configuration option
   Aptitude::CmdLine::Show-Size-Changes.

   The following options apply to the visual mode of the program, but are
   primarily for internal use; you generally won't need to use them yourself.

   --autoclean-on-startup

   Deletes old downloaded files when the program starts (equivalent to
   starting the program and immediately selecting Actions → Clean obsolete
   files). You cannot use this option and “--clean-on-startup”, “-i”, or “-u”
   at the same time.

   --clean-on-startup

   Cleans the package cache when the program starts (equivalent to starting
   the program and immediately selecting Actions → Clean package cache). You
   cannot use this option and “--autoclean-on-startup”, “-i”, or “-u” at the
   same time.

   -i

   Displays a download preview when the program starts (equivalent to
   starting the program and immediately pressing “g”). You cannot use this
   option and “--autoclean-on-startup”, “--clean-on-startup”, or “-u” at the
   same time.

   -S fname

   Loads the extended state information from fname instead of the standard
   state file.

   -u

   Begins updating the package lists as soon as the program starts. You
   cannot use this option and “--autoclean-on-startup”, “--clean-on-startup”,
   or “-i” at the same time.

Environment

   HOME

   If $HOME/.aptitude exists, aptitude will store its configuration file in
   $HOME/.aptitude/config. Otherwise, it will look up the current user's home
   directory using getpwuid(2) and place its configuration file there.

   PAGER

   If this environment variable is set, aptitude will use it to display
   changelogs when “aptitude changelog” is invoked. If not set, it defaults
   to more.

   TMP

   If TMPDIR is unset, aptitude will store its temporary files in TMP if that
   variable is set. Otherwise, it will store them in /tmp.

   TMPDIR

   aptitude will store its temporary files in the directory indicated by this
   environment variable. If TMPDIR is not set, then TMP will be used; if TMP
   is also unset, then aptitude will use /tmp.

Files

   /var/lib/aptitude/pkgstates

   The file in which stored package states and some package flags are stored.

   /etc/apt/apt.conf, /etc/apt/apt.conf.d/*, ~/.aptitude/config

   The configuration files for aptitude. ~/.aptitude/config overrides
   /etc/apt/apt.conf. See apt.conf(5) for documentation of the format and
   contents of these files.

See also

   apt-get(8), apt(8), /usr/share/doc/aptitude/html/lang/index.html from the
   package aptitude-doc-lang

   ══════════════════════════════════════════════════════════════════════════

Name

   aptitude-create-state-bundle — bundle the current aptitude state

Synopsis

   aptitude-create-state-bundle [options...] output-file

Description

   [Note] Note
          This command is mostly for internal use and bug reporting in
          exceptional cases, it is not intended for end-users under normal
          circumstances.

   aptitude-create-state-bundle produces a compressed archive storing the
   files that are required to replicate the current package archive state.
   The following files and directories are included in the bundle:

     • $HOME/.aptitude

     • /var/lib/aptitude

     • /var/lib/apt

     • /var/cache/apt/*.bin

     • /etc/apt

     • /var/lib/dpkg/status

   The output of this program can be used as an argument to
   aptitude-run-state-bundle(1).

Options

   --force-bzip2

   Override the autodetection of which compression algorithm to use. By
   default, aptitude-create-state-bundle uses bzip2(1) if it is available,
   and gzip(1) otherwise. Passing this option forces the use of bzip2 even if
   it doesn't appear to be available.

   --force-gzip

   Override the autodetection of which compression algorithm to use. By
   default, aptitude-create-state-bundle uses bzip2(1) if it is available,
   and gzip(1) otherwise. Passing this option forces the use of gzip even if
   bzip2 is available.

   --help

   Print a brief usage message, then exit.

   --print-inputs

   Instead of creating a bundle, display a list of the files and directories
   that the program would include if it generated a bundle.

File format

   The bundle file is simply a tar(1) file compressed with bzip2(1) or
   gzip(1), with each of the input directory trees rooted at “.”.

See also

   aptitude-run-state-bundle(1), aptitude(8), apt(8)

   ══════════════════════════════════════════════════════════════════════════

Name

   aptitude-run-state-bundle — unpack an aptitude state bundle and invoke
   aptitude on it

Synopsis

   aptitude-run-state-bundle [options...] input-file [ program
   [arguments...]]

Description

   [Note] Note
          This command is mostly for internal use and bug reporting in
          exceptional cases, it is not intended for end-users under normal
          circumstances.

   aptitude-run-state-bundle unpacks the given aptitude state bundle created
   by aptitude-create-state-bundle(1) to a temporary directory, invokes
   program on it with the supplied arguments, and removes the temporary
   directory afterwards. If program is not supplied, it defaults to
   aptitude(8).

Options

   The following options may occur on the command-line before the input file.
   Options following the input file are presumed to be arguments to aptitude.

   --append-args

   Place the options that give the location of the state bundle at the end of
   the command line when invoking program, rather than at the beginning (the
   default is to place options at the beginning).

   --help

   Display a brief usage summary.

   --prepend-args

   Place the options that give the location of the state bundle at the
   beginning of the command line when invoking program, overriding any
   previous --append-args (the default is to place options at the beginning).

   --no-clean

   Do not remove the unpacked state directory after running aptitude. You
   might want to use this if, for instance, you are debugging a problem that
   appears when aptitude's state file is modified. When aptitude finishes
   running, the name of the state directory will be printed so that you can
   access it in the future.

   This option is enabled automatically by --statedir.

   --really-clean

   Delete the state directory after running aptitude, even if --no-clean or
   --statedir was supplied.

   --statedir

   Instead of treating the input file as a state bundle, treat it as an
   unpacked state bundle. For instance, you can use this to access the state
   directory that was created by a prior run with --no-clean.

   --unpack

   Unpack the input file to a temporary directory, but don't actually run
   aptitude.

See also

   aptitude-create-state-bundle(1), aptitude(8), apt(8)
