# &aptitude; user's manual

## Introduction

> John Fouhy

> 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.

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 chapGettingStarted.

### 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 .

   - The `cwidget` library, available in the package `libcwidget-dev` or from .

   - 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 . (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-&VERSION;.tar.gz` to unpack the source code. Once the source code is unpacked, type `cd aptitude-&VERSION; && ./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 ) and execute the command `git clone git://anonscm.debian.org/aptitude/aptitude.git` to retrieve the most recent source code.

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!

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

##### Mailing list

The primary mailing list for &aptitude; development is aptitude-devel@lists.alioth.debian.org. Archives of the list are located at . To subscribe, visit the Web page .

##### 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 or RSS feed available at .

##### 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`.

## Getting started

> Lao Tsu

> A journey of a thousand miles must begin with a single step.

&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 chapRefGuide 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 secUsingCmdline.

#### &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:

[main screen, package view]

     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 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:

[main screen, package view]

     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.

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:

[package view, expand one group]

     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:

[package view, expand Installed Packages group, then expand admin group]

     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!

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.

[package view, expand Installed Packages group, then expand admin group, then expand main group]

     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.

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:

[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 secSearchPatterns, it is possible to find packages based on many complex criteria.

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:

[package tree limit 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
    --- 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:

[package view, limited by string '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.

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

You can also change packages using the Package menu; see secPackageMenu for details.

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.

[package view, kaffeine-mozilla package to be installed]

     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.

At any time, you can use &undo-undo; 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`:

[package view, packages broken after attempting 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 &Sbroken;.

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:

[dependency resolver #1]

     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:

[dependency resolver #2]

     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.

[dependency resolver #3]

     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.

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`.

[dependency resolver #4]

     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

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.

. Approved actions will turn green and will be marked with A, as in the following screenshot: [dependency resolver #5]

     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

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:

[preview actions, installing kaffeine-mozilla]

     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

A switch is a letter preceded by a hyphen: for instance, -a, -v, etc.

.

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.

  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

  Purging a package removes the package, as well as all its configuration files.

  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 `pattern`s, 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 secSearchPatterns.

  In fact, the same is true of the commands that take packages as arguments, such as `install` or `show`.

  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 secReference.

## &aptitude; reference guide

> Lewis Carrol , Alice in Wonderland

> 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.'

&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.

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.

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 chapGettingStarted.

&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 secConfig.

### 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: `key` `Menu` `Item`. 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

###### Commands available in the Actions menu

Command | Description
&actions-install; | If an installation preview is not visible, display one; otherwise, perform an install run as described in secInstallRun.
&actions-update; | Bring the package list up-to-date.
&actions-upgrade; | Flag all upgradable packages, except those which are held or forbidden from upgrading, for upgrade.
&actions-forget; | Discard all information about what packages are new (empty the New Packages tree).
&actions-cancel; | Cancel all pending actions from this session (including installations, removals, upgrades, holds, marking as automatically installed...). This is roughly equivalent to restart the program.
&actions-clean; | Delete all the compressed packages that were downloaded by &aptitude; Or any other &apt; utility. .
&actions-clean-obs; | Delete any compressed packages that were downloaded by &aptitude; and are no longer available. These are presumed to be packages which are obsolete, and can be deleted to save disk space without requiring an otherwise unnecessary download.
&actions-mine; | Play a game of Minesweeper, as described in secMinesweeper.
&actions-su; | Continue working as the &root; user; see secBecomingRoot.
&actions-quit; | Quit &aptitude;, saving any changes to package states.

##### The Undo menu

###### Commands available in the Undo menu

Command | Description
&undo-undo; | Cancel the effect of the last change to a 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

###### 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 reinstallation.
&package-remove; | Flag the currently selected package for removal.
&package-purge; | Flag the currently selected package to be purged.
&package-keep; | Cancel any pending installation, upgrade, or removal of the currently selected package, and remove any hold that was set on the package.
&package-hold; | Hold the currently selected package back.
&package-markauto; | Mark the currently selected package as an automatically installed package. For more information on manually and automatically installed packages, see secAutoInstall.
&package-markmanual; | Mark the currently selected package as a manually installed package. For more information on manually and automatically installed packages, see secAutoInstall.
&package-forbid; | If a package that can be upgraded is selected, forbid it from being upgraded to the currently available version. If a version of a package is selected, forbid the package from being upgraded to that version.
&package-information; | Display a screen containing information about the currently selected package, such as the packages it depends upon, the packages which depend upon it, and its available versions.
&package-cycle-information; | When browsing the package list, cycles through the information that can be displayed in the information area (the lower half of the display). The information area can display the 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.
&package-changelog; | Display the currently selected package's Debian changelog. To see the changelog of a particular version, select that version and execute this command.

##### The Resolver menu

###### Commands available in the Resolver menu

Command | Description
&resolver-examine; | Display a detailed description of the problem resolver's current suggestion (see secResolver).
&resolver-apply; | Carry out the actions that the problem resolver is currently suggesting.
&resolver-next; | Select the problem resolver's next suggestion.
&resolver-previous; | Select the problem resolver's previous suggestion.
&resolver-first; | Select the problem resolver's first suggestion.
&resolver-last; | Select the problem resolver's most recently generated solution (see secResolver).
&resolver-reject; | When examining a solution, toggle whether the currently selected action is rejected and move to the next action (see secResolver). If the action is currently approved, its approval will be cancelled.
&resolver-approve; | When examining a solution, toggle whether the currently selected action is approved and move to the next action (see secResolver). If the action is currently rejected, its rejection will be cancelled.
&resolver-view-target; | When examining a solution, view detailed information about the package which is affected by the currently selected action (see secResolver).
&resolver-reject-break-holds; | Reject (as if with &resolver-reject;) all actions that would break a hold on a package or install a forbidden version. These actions are rejected by default unless `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

###### Commands available in the Search menu

Command | Description
&search-find; | Find the next package in the package list that matches a search pattern (see secSearchPatterns).
&search-find-back; | Find the previous package in the package list that matches a search pattern (see secSearchPatterns).
&search-refind; | Repeat the last Find command.
&search-repeat-find-back; | Repeat the last Find command, but in the opposite direction. If the last Find command was Find Backwards, this will perform a forwards search, and vice versa.
&search-limit; | Filter the current package list by removing any packages which do not match a search pattern (see secSearchPatterns).
&search-unlimit; | Un-filter the current package list (all packages will be shown).
&search-find-broken; | Find the next broken package. This is equivalent to searching for &Sbroken;.

##### The Options menu

###### Commands available in the Options menu

Command | Description
&options-preferences; | Open a new top-level view in which you can modify &aptitude;'s settings. Configuration options are displayed in a tree similar to the 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.

##### The Views menu

For an overview of how views work, see secViews.

###### Commands available in the Views menu

Command | Description
&views-next; | Change to the next active view.
&views-prev; | Change to the previous active view.
&views-close; | Close the current view.
&views-new; | Create a new view of the package list.
&views-audit; | Create a view that displays packages which are not installed, and which a package installed on your system Recommends.
&views-flat; | Create a new view of the package list in which packages are not categorized.
&views-debtags; | Create a new view of the package list in which packages are categorized according to their debtags entries.
Additional items | A number of additional menu items appear; these correspond to the currently active views. To switch directly to a view, select it from the menu.

##### The Help menu

###### Commands available in the Help menu

Command | Description
&help-about; | Display some copyright information.
&help-help; | Display the on-line help page.
&help-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:

[view tab bar, tabs: Packages, apt info, libc6 info]

     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;. To switch to the next or previous view, use &views-next; and &views-prev;, 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;.

#### 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;:

[become root 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
    --- 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-su;. 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; 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.

You can customize how package synopses are displayed; see secDisplayFormat 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 secAutoInstall), and the fourth character indicates whether the package is trusted (see secTrust).

The possible values of the current state flag are given in figureCurrentFlag and the possible values of the action flag are given in figureActionFlag.

###### 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.

###### 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.
`h` | - | the package will be held back: it will be kept at its current version, 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.
`B` | - | the package is broken: some of its dependencies will not be 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:

[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 +.

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;.

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
Install: &package-install; | Flag the current package for installation. If the package is not installed, it will be 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.
Remove: &package-remove; | Flag the currently selected package for removal. If the package is installed, it will be removed.
Purge: &package-purge; | Flag the current package to be purged. 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.
Keep: &package-keep; | Flag the current package to be kept at its current version. 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.
Hold: &package-hold; | Set a persistent hold on the package. As with Keep, any action that was to be performed on the package is cancelled. In addition, the package will not be automatically upgraded That is, it will be unaffected by &actions-upgrade; or the `full-upgrade` or `safe-upgrade` command-line actions. until the hold is removed. You may cancel a hold by issuing the Install command.
&package-forbid; | The package will not be automatically upgraded 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 version of a package, the package will not be 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.
Reinstall: &package-reinstall; | Flag the current package for reinstallation. Note that the reinstallation will not be saved when you quit &aptitude; or perform an 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).
&package-markauto;, &package-markmanual; | Sets whether the package is treated as having been automatically installed; automatically installed packages will be removed when no other package requires them. For more information, see secAutoInstall.

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; clears the new status of all packages in the package list, and &actions-upgrade; flags every package which can be upgraded for upgrade, except for packages that are held back or would be upgraded to a forbidden version.

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.

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

To commit your changes, use the &actions-install; 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; to cancel the installation, or use &actions-install; 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;; to delete only files which cannot be downloaded again (ie, obsolete packages), use &actions-clean-obs;.

#### 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.

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.

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.

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:

[untrusted packages/versions warning]

     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`.

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

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.

. 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

Or when immediate resolution is disabled.

. 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

   The package with the highest `dpkg` priority, not the package with the highest &apt; pin priority.

   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.

[package view, packages broken after attempting 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 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:

[dependency resolver #1]

     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.

[explanation about dependency resolver decisions]

     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; 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.

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.

[rejections and approvals in dependency resolution]

     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 <.

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.

[explanations of dependency resolver solutions]

     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 exampleResolverCosts.

###### 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 tableBasicCostComponents. You can also create your own cost components using the `add-to-cost-component` and `raise-cost-component` hints; see secDependencyResolutionHints 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.

##### Basic cost components

Name | Type | Description
`broken-holds` | Counter | Counts the number of holds that the solution breaks, if the resolver is allowed to break holds (`Aptitude::ProblemResolver::Allow-Break-Holds`).
`canceled-actions` | Counter | Counts the number of pending actions that the 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.
`priority` | Level | A value that increases as the apt pin priority of a 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.
`safety` | Level | A broad heuristic that increases as actions become less safe; see secDependencyResolutionCostsSafetyCosts 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 figureCompoundCostComponents.

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.

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.

###### 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

###### 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. figureSafetyCostLevels shows how this works with &aptitude;'s default settings.

Safety cost levels are just one way to control the order in which dependency solutions are returned. See secDependencyResolutionCosts 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:

##### Default safety cost levels

Cost level | Description | Configuration option
10,000 | Solutions that include only safe actions (installing the default target for a package or keeping a package at its current version) and package removals. | `Aptitude::ProblemResolver::Safe-Level`, `Aptitude::ProblemResolver::Remove-Level`
10,000 | The solution that cancels all the user's actions. It used to be higher than `Aptitude::ProblemResolver::Remove-Level`, but removing packages was ranked higher than keeping the same packages, even if the package was to be upgraded. | `Aptitude::ProblemResolver::Keep-All-Level`
40,000 | Solutions that break holds set by the user or install forbidden versions. | `Aptitude::ProblemResolver::Break-Hold-Level`
50,000 | Solutions that install packages from non-default versions (such as `experimental`, for instance). | `Aptitude::ProblemResolver::Non-Default-Level`
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 secDependencyResolutionHints for details. The default levels are illustrated in figureSafetyCostLevels.

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 secConfigFile 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-approve; had been invoked on it.

2. `reject`: Reject the version, as if the command &resolver-reject; 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 secDependencyResolutionCostsAndCostComponents and secDependencyResolutionCostsSafetyCosts for details.

   Several special cost levels can be chosen by name:

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

   2. `maximum`: the highest safety cost.

   3. `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.

   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 secSearchPatterns 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 secReference 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 &Sname; matches package names, while the term &Sversion; 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).

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

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 `&Sname;(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 `&Sname;(scorch)` and `&Sname;("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, `&Sdescription;("\"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.

&aptitude; will only treat the comma as special if there is a second argument, so (for instance) `&Sname;(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.

To remove the special meaning of these characters, place a tilde (`~`) directly before them. For instance, `&Sdescription;(etc))` is a syntax error, because the first `)` ends the &Sdescription; term, and the second `)` does not correspond to any `(`. In contrast, `&Sdescription;(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 secSearchShorthand 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

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: `&Sdescription;(\~|)` will match packages whose description contains a vertical bar character (`|`).

, 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 `&Sdescription;(grand~|oblique)`. However, you will probably find it more convenient to simply use a quoted string in these cases: `&Sdescription;("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 `&Sname;(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`.

The backslash escapes `\\`, `\n`, and `\t` are also available.

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)`.

tableSearchTermQuickGuide 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 `&Sdepends;(`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 `&Sdepends;(&Sversion;(2\.0))`, only versions `3.0` and `4.0` will be tested against `&Sversion;(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 &Sinstalled; will only match the version of the package (if any) that is currently installed. Similarly, the pattern `&Smaintainer;(`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 &Swiden; term. For instance, `&Sdepends;(&Swiden;(&Sversion;(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 &Snarrow; term restricts the versions that its sub-pattern is matched against: `&Snarrow;(&Sinstalled;, &Sdepends;(&Sversion;(ubuntu)))` will match any package whose installed version has a dependency that can be satisfied by a package whose version string contains `ubuntu`.

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 `&Sversion;(4\.0-1)&Sinstalled;` matches `aardvark`, because `&Sversion;(4\.0-1)` matches against version `4.0-1` of `aardvark`, while &Sinstalled; 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 `&Sdepends;(...)` term. But the term filling in the `...` needs to somehow select packages that are identical to the one being matched against `&Sdepends;`. 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.

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.

An explicit target is introduced by the &Sfor; term:

##### Syntax of the &Sfor; 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 &Sequal; will match exactly the package or version indicated by the given variable. Specifically: if the corresponding &Sfor; term is limited to a particular version, then &Sequal; will match either that version (if &Sequal; is limited) or the whole package; otherwise it will match any version of the package.

   See exampleSearchEqual for an example of how to use &Sequal;.

2. The term `&Sbind;(`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 `&Sbind;(`variable`, ?`term`(`args`))` can be replaced by `?`variable`:`term`(`args`)`.

   See exampleSearchBind for an example of how to use `?bind`.

#### Search term reference

tableSearchTermQuickGuide provides a brief summary of all the search terms provided by &aptitude;. A full description of each term can be found below.

#### Quick guide to search terms

Long form | Short form | Description
`&Sequal;`variable`` |  | Select the package bound to `variable`; see secExplicitMatchers.
`&Snot;(`pattern`)` | `!`pattern`` | Select any package that does not match `pattern`.
`&Saction;(`action`)` | ~a`action` | Select packages that have been marked for the given `action` (e.g., `install` or `upgrade`).
`&Sall-versions;(`pattern`)` |  | Select packages whose versions all match `pattern`.
`&Sand;(`pattern1`, `pattern2`)` | `pattern1` `pattern2` | Select any package that matches both `pattern1` and `pattern2`.
`&Sany-version;(`pattern`)` |  | Select packages for which at least one version matches `pattern`.
`&Sarchitecture;(`architecture`)` | ~r`architecture` | Select packages for the given architecture (such as `amd64`, or `all`). Special values: `native` and `foreign`.
`&Sarchive;(`archive`)` | `~A`archive`` | Select packages from the given archive (such as `unstable`).
`&Sautomatic;` | `~M` | Select packages that were automatically installed.
`&Sbind;(`variable`, `pattern`)` | `?`variable`:`term-name`(`args`)` | Selects anything if `variable` matches `pattern`; see secExplicitMatchers.
`&Sbroken;` | `~b` | Select packages that have a broken dependency.
`&Sbroken-type;` | `~B`depType`` | Select package that have a broken dependency of the given `depType`.
`&Sbroken-type-term;(`pattern`)` | `~DB`depType`:`pattern`` | Select packages that have a broken dependency of the given `depType` matching `pattern`.
`&Sbroken-reverse-dep;(`pattern`)` | `~RB``depType`:``pattern`` | Select packages that a package matching `pattern` declares a broken dependency of type `depType`.
`&Sconflicts;(`pattern`)` | `~C`pattern`` | Select packages that conflict with a package matching `pattern`.
`&Sconfig-files;` | `~c` | Select packages that were removed but not purged.
`&Sdep;(`pattern`)` | `~D`depType`:`pattern`` | Match packages that declare a dependency of type `depType` on a package matching `pattern`.
`&Sdescription;(`description`)` | `~d`description`` | Select packages whose description matches `description`.
`&Sessential;` | `~E` | Select essential packages, those with `Essential: yes` in their control files.
`&Sexact-name;(`name`)` |  | Select packages named `name`.
`&Sfalse;` | `~F` | Select no packages.
`&Sfor; `variable`: `pattern`` |  | Select packages that match `pattern` with `variable` bound to the package being matched; see secExplicitMatchers.
`&Sgarbage;` | `~g` | Select packages that are not required by any manually installed package.
`&Sinstalled;` | `~i` | Select installed packages.
`&Smaintainer;(`maintainer`)` | `~m`maintainer`` | Select packages maintained by `maintainer`.
`&Smultiarch;(`multiarch`)` |  | Select packages with a multi-arch capability of `multiarch` (that is, either `foreign`, `same`, `allowed`, or `none`).
`&Snarrow;(`filter`, `pattern`)` | `~S `filter` `pattern`` | Select packages for which a single version matches both `filter` and `pattern`.
`&Sname;(`name`)` | `~n`name``, ``name`` | Select packages with the given `name`.
`&Snew;` | `~N` | Select new packages.
`&Sobsolete;` | `~o` | Match installed packages that cannot be downloaded.
`&Sor;(`pattern1`, `pattern2`)` | ``pattern1` | `pattern2`` | Select packages that match `pattern1`, `pattern2`, or both.
`&Sorigin;(`origin`)` | `~O`origin`` | Select packages with the given `origin`.
`&Sprovides;(`pattern`)` | `~P`pattern`` | Select packages that provide a package matching `pattern`.
`&Spriority;(`priority`)` | `~p`priority`` | Select packages with the given `priority`.
`&Sreverse-dep;(`pattern`)` | `~R`depType`:`pattern`` | Select packages that are the targets of a dependency of type `depType` declared by a package matching `pattern`.
`&Sreverse-broken-dep;(`pattern`)` | `~RB``depType`:``pattern`` | Select packages that are the targets of a broken dependency of type `depType` declared by a package matching `pattern`.
`&Ssection;(`section`)` | `~s`section`` | Select packages in the given `section`.
`&Ssource-package;(`name`)` | `~e`name`` | Select packages whose source package name matches the regular expression `name`.
`&Ssource-version;(`version`)` |  | Select packages whose source version matches the regular expression `version`.
`&Stag;(`tag`)` | `~G`tag`` | Select packages that have the given debtags `tag`.
`&Sterm;(`keyword`)` |  | Full-text search for packages that contain the given `keyword`.
`&Sterm-prefix;(`keyword`)` |  | Full-text search for packages that contain a keyword that begins with the given `keyword`.
`&Strue;` | `~T` | Select all packages.
`&Stask;(`task`)` | `~t`task`` | Select packages that are in the given `task`.
`&Supgradable;` | `~U` | Select packages that are installed and can be upgraded.
`&Suser-tag;` |  | Select packages that are marked with a user-tag matching the regular expression `user-tag`.
`&Sversion;(`version`)` | `~V`version`` | Select packages whose version matches `version` (special values: `CURRENT`, `CANDIDATE`, and `TARGET`).
`&Svirtual;` | `~v` | Select virtual packages.
`&Swiden;(`pattern`)` | `~W`pattern`` | Select versions for which `pattern` matches any version of the 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 `~`.

  To match packages whose names contain several different substrings, use the &Sname; term (described below); for instance, `&Sname;(apti)&Sname;(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 &Sfor;. For instance, `&Sfor; x: &Sdepends;( &Srecommends;( ?=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:

  ##### Use of the `?=` term.

  `&Sfor; x: &Sconflicts;(?=x)`

  See secExplicitMatchers for more information.

`?not(`pattern`)`, `!`pattern``

- Matches packages which do not match the pattern `pattern`. For instance, `?not(&Sbroken;)` selects packages that are not broken.

  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 `&Sdescription;(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`.

  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`)`, `~a`action``

- 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 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, `&Saction;(upgrade)` matches exactly those packages that you have already decided to upgrade, not packages which could be upgraded in the future (for that, use `&Supgradable;`).

`?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 &Sdepends; or &Snarrow;. However, it may always be used within &Swiden;.

`?any-version(`pattern`)`

- Matches a package if any one of its versions matches the enclosed pattern. This is the dual to &Sall-versions;.

  This term may not be used in a context in which the versions to match against have already been narrowed, such as within &Sdepends; or &Snarrow;. However, it may always be used within &Swiden;.

  This term is closely related to &Snarrow;. In fact, `?any-version(`pattern1` `pattern2`)` is exactly the same as `&Snarrow;(`pattern1`, `pattern2`)`.

  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 &Swiden;.

`?architecture(`architecture-spec`)`, `~r`architecture-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`)`, `~A`archive``

- 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 &Sfor;.

  ##### Use of the `?bind` term

  `&Sfor; x: &Sdepends;(&Sdepends;(&Sfor; z: ?bind(x, &Sdepends;(&Sequal;z))))`

  `&Sfor; x: &Sdepends;(&Sdepends;(&Sfor; z: ?x:depends(&Sequal;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 secExplicitMatchers for more information.

`?broken`, `~b`

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

`?broken-`depType``, `~B`depType``

- 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`)`, `~C`pattern``

- Matches packages which conflict with a package matching the given `pattern`. For instance, `?conflicts(&Smaintainer;(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, `&Sdepends;(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 &Sprovides;). Otherwise, matches packages which declare a dependency of type `depType` upon a package version which matches `pattern`.

`?description(`description`)`, `~d`description``

- 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 &Sname;, but the name must match exactly. For instance, the following pattern will match only the package `apt`; with &Sname;, it would also match `aptitude`, `uvccapture`, etc.

  ##### Use of the `?exact-name` term

  `?exact-name(apt)`

`?false`, `~F`

- This term does not match any package.

  This is provided largely for symmetry with &Strue;.

`?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 `&Sequal;`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`.

  ##### Use of the `?for` term

  `?for x: &Sdepends;( ?for y: ?x:recommends( &Sequal;y ) )`

  See secExplicitMatchers 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`)`, `~m`maintainer``

- Matches packages whose Maintainer field matches the regular expression `maintainer`. For instance, `&Smaintainer;(joeyh)` will find all packages maintained by Joey Hess.

`?multiarch(`multiarch`)`

- Matches packages with the multi-arch capability specified by `multiarch`. For instance, `&Smultiarch;(foreign)` will find all packages which can satisfy dependencies of packages for another architecture. `&Smultiarch;(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`)`, `~n`name``

- Matches packages whose name matches the regular expression `name`. For instance, most of the packages that match `&Sname;(^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; 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`)`, `~O`origin``

- 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`)`, `~P`pattern``

- 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`)`, `~p`priority``

- 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`)`, `~s`section``

- Matches packages whose section matches the regular expression `section`.

`?source-package(`name`)`, `~e`name``

- 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`)`, `~G`tag``

- 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 .

`?task(`task`)`, `~t`task``

- 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; 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; 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 &Sterm;, 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:

  ##### Use of the `?term-prefix` term

  `?term-prefix(hour)`

`?true`, `~T`

- This term matches any package. For instance, `&Sinstalled;&Sprovides;(&Strue;)` matches installed packages which provide any package.

`?upgradable`, `~U`

- This term matches any installed package which can be upgraded.

  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`)`, `~V`version``

- 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&Sreverse-provides;(&Sinstalled;)` matches virtual packages which are provided by any installed package.

`?widen(`pattern`)`, `~W`pattern``

- Widens the match: if the versions to match against have been limited by an enclosing term (such as &Sdepends;), these limits are dropped. Thus, `&Swiden;(`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:

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
- `%%` Literal `%` 1 No This is not really an escape; it simply inserts a percent sign into the output at the point at which it occurs.
- `%#`number`` Parameter Replacement Variable No In some circumstances, a display format string will have parameters: for instance, in the command-line `search`, the groups matched by the search are used as parameters when displaying the result. This format code will be replaced by the parameter indicated by `number`.
- `%a` Action Flag 1 No A single-character flag summarizing any action to be performed on the package, as described in figureActionFlag.
- `%A` Action 10 No A somewhat more verbose description of the action to be performed on the package.
- `%B` Broken Count 12 No If there are no broken packages, produces nothing. Otherwise, produces a string such as `Broken: 10` describing the number of broken packages.
- `%c` Current State Flag 1 No A single-character flag summarizing the current state of the package, as described in figureCurrentFlag.
- `%C` Current State 11 No A more verbose description of the current state of the package.
- `%d` Description 40 Yes The package's short description.
- `%D` Package Size 8 No The size of the package file containing the package.
- `%E` Architecture 10 No Outputs the string of the architecture, for example `amd64`.
- `%e` Source 30 No Outputs the source package, for example `aptitude` for `aptitude-doc-en`.
- `%H` Hostname 15 No The name of the computer on which &aptitude; is running.
- `%i` Pin priority 4 No Displays the highest priority assigned to a package version; for packages, displays the priority of the version which will be forced to be installed (if any).
- `%I` Installed Size 8 No The (estimated) amount of space the package takes up on disk.
- `%m` Maintainer 30 Yes The maintainer of the package.
- `%M` Automatic Flag 1 No If the package is automatically installed, outputs `A`; otherwise, outputs nothing.
- `%n` Program Version The length of &VERSION;. No Outputs the version of &aptitude; that is running, currently `&VERSION;`.
- `%N` Program Name The length of the name. No Outputs the name of the program; usually `aptitude`.
- `%o` Download Size 17 No If no packages are going to be installed, outputs nothing. Otherwise, outputs a string describing the total size of all the package files which will be installed (an estimate of how much needs to be downloaded); for instance, `DL size: 1000B`.
- `%O` Origin 30 No Outputs a string of the origin of the package, for example `Debian:unstable [amd64]`.
- `%p` Package Name 30 Yes Outputs the name of the package. When a package is displayed in a tree 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.
- `%r` Reverse Depends Count 2 No Outputs the approximate number of installed packages which depend upon the package.
- `%R` Abbreviated Priority 3 No Outputs an abbreviated description of the package's priority: for instance, `Important` becomes `Imp`.
- `%s` Section 10 No Outputs the section of the package.
- `%S` Trust Status 1 No If the package is untrusted, displays the letter "U".
- `%t` Archive 10 Yes The archive in which the package is found.
- `%T` Tagged (and user-tags) 30 No

  Outputs `*` if the package is tagged, nothing otherwise.

  Currently tagging is not supported; this escape is for future use.

  This field also includes user-tags.

- `%u` Disk Usage Change 30 No If the scheduled actions will alter the amount of space used on the disk, outputs a description of the change in disk space; for instance, `Will use 100MB of disk space.`
- `%v` Current Version 14 No Outputs the currently installed version of the package, or `<none>` if the package is not currently installed.
- `%V` Candidate Version 14 No Outputs the version of the package which would be installed if &package-install; were issued on the package, or `<none>` if the package is not currently available.
- `%Z` Size Change 9 No Outputs how much additional space will be 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.

  ###### 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"`).

  ###### 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 `pattern`s. 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 `pattern`s will not appear in the tree at all.

  ###### Use of `pattern` to group packages by their maintainer

  `pattern(&Smaintainer;() => \1)`

  The example above will group packages according to their Maintainer field. The policy `pattern(&Smaintainer;())` 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.

  ###### Use of `pattern` with some packages placed at the top level

  `pattern(&Saction;(remove) => Packages Being Removed, &Strue; ||)`

  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:

  ###### Use of the `pattern` grouping policy with sub-policies

  `pattern(&Saction;(remove) => Packages Being Removed {}, &Saction;(install) => Packages Being Installed, &Strue; || {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 secSearchPatterns 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 .

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

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.
`MinibufChoice` | Used by the multiple-choice prompts that appear if you have chosen to have some prompts appear in the status line.
`Pager` | Used when displaying a file on disk (for instance, the help text).
`PkgNode` | Used by packages, trees of packages, package versions, 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`

On some terminals, a yellow background will actually come out brown.

. 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;`.

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;:

##### Customizable styles in &aptitude;

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

#### 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 secDisplayFormat. 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 secDisplayFormat.

`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 Default Description
- `APT::AutoRemove::RecommendsImportant` `true` 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 secAutoInstall.
- `APT::AutoRemove::SuggestsImportant` `true` 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 secAutoInstall.
- `APT::Get::List-Cleanup` `true` 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.
- `APT::List-Cleanup` `true` 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.
- `APT::Install-Recommends` `true` 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 secAutoInstall and secImmediateResolution.
- `Aptitude::Allow-Null-Upgrade` `false` 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-upgrade; command.
- `Aptitude::Always-Use-Safe-Resolver` `false` 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.
- `Aptitude::Autoclean-After-Update` `false` If this option is `true`, &aptitude; will clean up obsolete files (see &actions-clean-obs;) every time you update the package list. This option is similar to `Aptitude::Clean-After-Install`.
- `Aptitude::Auto-Fix-Broken` `true` If this option is `false`, &aptitude; will ask for permission before attempting to fix any broken packages.
- `Aptitude::Auto-Install` `true` 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.
- `Aptitude::Auto-Install-Remove-Ok` `false` 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.
- `Aptitude::Auto-Upgrade` `false` 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-upgrade;.
- `Aptitude::Clean-After-Install` `false` If this option is `true`, &aptitude; will clean up all files in the package cache directory (see &actions-clean;) after successful installation of packages (or similar operations). This option is similar to `Aptitude::Autoclean-After-Update`.
- `Aptitude::CmdLine::Always-Prompt` `false` 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.
- `Aptitude::CmdLine::Assume-Yes` `false` 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.
- `Aptitude::CmdLine::Disable-Columns` `false` 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.
- `Aptitude::CmdLine::Download-Only` `false` 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.
- `Aptitude::CmdLine::Fix-Broken` `false` 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.
- `Aptitude::CmdLine::Versions-Group-By` 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).
- `Aptitude::CmdLine::Ignore-Trust-Violations` `false` In command-line mode, causes &aptitude; to ignore the installation of untrusted packages. This is a synonym for `APT::Get::AllowUnauthenticated`.
- `Aptitude::CmdLine::Package-Display-Format` `%c%a%M %p# - %d#` This is a format string, as described in secDisplayFormat, which is used to display the results of a command-line search. This is equivalent to the `-F` command-line option.
- `Aptitude::CmdLine::Package-Display-Width` 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.
- `Aptitude::CmdLine::Progress::Percent-On-Right` `false` 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.
- `Aptitude::CmdLine::Progress::Retain-Completed` `false` 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.
- `Aptitude::CmdLine::Request-Strictness` `10000` 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.
- `Aptitude::CmdLine::Resolver-Debug` `false` 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.
- `Aptitude::CmdLine::Resolver-Dump` 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.
- `Aptitude::CmdLine::Resolver-Show-Steps` `false` 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?`.
- `Aptitude::CmdLine::Show-Deps` `false` 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.
- `Aptitude::CmdLine::Show-Size-Changes` `false` 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.
- `Aptitude::CmdLine::Show-Summary` `no-summary` 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.
- `Aptitude::CmdLine::Show-Versions` `false` 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.
- `Aptitude::CmdLine::Show-Why` `false` 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.
- `Aptitude::CmdLine::Version-Display-Format` `%c%a%M %p# %t %i` This is a format string, as described in secDisplayFormat, which is used to display the output of `aptitude versions`. This is equivalent to the `-F` command-line option.
- `Aptitude::CmdLine::Versions-Show-Package-Names` 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).
- `Aptitude::Safe-Resolver::Show-Resolver-Actions` `false` 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`.
- `Aptitude::Screenshot::IncrementalLoadLimit` `16384` 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.
- `Aptitude::Screenshot::Cache-Max` `4194304` 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.
- `Aptitude::CmdLine::Simulate` `false` 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.
- `Aptitude::CmdLine::Verbose` `0` This controls how verbose the command-line mode of &aptitude; is. Every occurrence of the `-v` command-line option adds 1 to this value.
- `Aptitude::CmdLine::Visual-Preview` `false` If this option is `true`, &aptitude; will enter its visual interface to display the preview of an installation run and to download packages.
- `Aptitude::Delete-Unused` `true` If this option is `true`, automatically installed packages which are no longer required will be automatically removed. For more information, see secAutoInstall.
- `Aptitude::Delete-Unused-Pattern` 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.
- `Aptitude::Display-Planned-Action` `true` If this option is `true`, &aptitude; will display a preview screen before actually carrying out the actions you have requested.
- `Aptitude::Forget-New-On-Install` `false` 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;.
- `Aptitude::Forget-New-On-Update` `false` 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;.
- `Aptitude::Get-Root-Command` `su:/bin/su` This option sets the external command that &aptitude; will use to switch to the &root; user (see secBecomingRoot). 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.
- `Aptitude::Ignore-Old-Tmp` `false` 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.
- `Aptitude::Ignore-Recommends-Important` `false` 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.
- `Aptitude::Keep-Recommends` `false` 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`.
- `Aptitude::Keep-Suggests` `false` 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`.
- `Aptitude::Keep-Unused-Pattern` If `Aptitude::Delete-Unused` is `true`, only unused packages which do not match this pattern (see secSearchPatterns) will be removed. If this option is set to an empty string (the default), all unused packages will be removed.
- `Aptitude::LockFile` `/var/lock/aptitude` 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!
- `Aptitude::Localize-Log` `false` 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).
- `Aptitude::Log` `/var/log/aptitude` 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.
- `Aptitude::Logging::File` `` 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`.
- `Aptitude::Logging::Levels` (empty) 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.
- `Aptitude::Parse-Description-Bullets` `true` 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`.
- `Aptitude::Pkg-Display-Limit` The default filter applied to the package list; see secSearchPatterns for details about its format.
- `Aptitude::ProblemResolver::Allow-Break-Holds` `false` 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 secResolver).
- `Aptitude::ProblemResolver::BreakHoldScore` `-300` 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.
- `Aptitude::ProblemResolver::Break-Hold-Level` `50000` 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 secDependencyResolutionCostsSafetyCosts for a description of safety costs.
- `Aptitude::ProblemResolver::BrokenScore` `-100` 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.
- `Aptitude::ProblemResolver::CancelRemovalScore` `-300` How much weight the problem resolver should give to not remove or purge a package requested to be removed or purged.
- `Aptitude::ProblemResolver::DefaultResolutionScore` `400` 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.
- `Aptitude::ProblemResolver::Discard-Null-Solution` `true` If this option is `true`, &aptitude; will never suggest cancelling all of your proposed actions in order to resolve a dependency problem.
- `Aptitude::ProblemResolver::EssentialRemoveScore` `-100000` How much to reward or penalize solutions that remove an Essential package.
- `Aptitude::ProblemResolver::Remove-Essential-Level` `60000` The safety cost assigned to actions that remove an Essential package. See secDependencyResolutionCostsSafetyCosts for a description of safety costs.
- `Aptitude::ProblemResolver::ExtraScore` `0` Any version of a package whose Priority is extra will have this many points added to its score.
- `Aptitude::ProblemResolver::FullReplacementScore` `500` 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.
- `Aptitude::ProblemResolver::FutureHorizon` `50` 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.
- `Aptitude::ProblemResolver::Hints` (empty) 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 secDependencyResolutionHints.
- `Aptitude::ProblemResolver::ImportantScore` `4` Any version of a package whose Priority is important will have this many points added to its score.
- `Aptitude::ProblemResolver::Infinity` `1000000` A maximum score for potential solutions. If a set of actions has a score worse than `-Infinity`, it will be discarded immediately.
- `Aptitude::ProblemResolver::InstallScore` `-20` How much weight the problem resolver should give to installing a package, if the package is not already going to be installed.
- `Aptitude::ProblemResolver::Keep-All-Level` `10000` The safety cost assigned to the single solution that cancels all of the actions selected by the user. See secDependencyResolutionCostsSafetyCosts for a description of safety costs.
- `Aptitude::ProblemResolver::KeepScore` `0` 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.
- `Aptitude::ProblemResolver::NonDefaultScore` `-40` 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).
- `Aptitude::ProblemResolver::Non-Default-Level` `50000` 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 secDependencyResolutionCostsSafetyCosts for a description of safety costs.
- `Aptitude::ProblemResolver::OptionalScore` `1` Any version of a package whose Priority is optional will have this many points added to its score.
- `Aptitude::ProblemResolver::PreserveAutoScore` `0` How much weight the problem resolver should give to preserving automatic installations or removals.
- `Aptitude::ProblemResolver::PreserveManualScore` `20` How much weight the problem resolver should give to preserving explicit user selections.
- `Aptitude::ProblemResolver::RemoveObsoleteScore` `310` 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.
- `Aptitude::ProblemResolver::RemoveScore` `-300` How much weight the problem resolver should give to removing a package (if it is not already marked for removal).
- `Aptitude::ProblemResolver::Remove-Level` `10000` The safety cost assigned to actions that remove a package. See secDependencyResolutionCostsSafetyCosts for a description of safety costs.
- `Aptitude::ProblemResolver::RequiredScore` `8` Any version of a package whose Priority is required will have this many points added to its score.
- `Aptitude::ProblemResolver::ResolutionScore` `50` In addition to all other scoring factors, proposed solutions that actually resolve all unsatisfied dependencies are awarded this many extra points.
- `Aptitude::ProblemResolver::Safe-Level` `10000` 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 secDependencyResolutionCostsSafetyCosts for a description of safety costs.
- `Aptitude::ProblemResolver::SolutionCost` `safety,priority` Describes how to determine the cost of a solution. See secDependencyResolutionCosts 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.
- `Aptitude::ProblemResolver::StandardScore` `2` Any version of a package whose Priority is standard will have this many points added to its score.
- `Aptitude::ProblemResolver::StepLimit` `5000` 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)
- `Aptitude::ProblemResolver::StepScore` `-10` 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.
- `Aptitude::ProblemResolver::Trace-Directory` 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.
- `Aptitude::ProblemResolver::Trace-File` 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.
- `Aptitude::ProblemResolver::UndoFullReplacementScore` `-500` 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.
- `Aptitude::ProblemResolver::UnfixedSoftScore` `-200` 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 secResolver for details.
- `Aptitude::ProblemResolver::UpgradeScore` `30` 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.
- `Aptitude::Purge-Unused` `false` 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 secAutoInstall. THIS OPTION CAN CAUSE DATA LOSS! DO NOT ENABLE IT UNLESS YOU KNOW WHAT YOU ARE DOING!
- `Aptitude::Recommends-Important` `true` 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.
- `Aptitude::Safe-Resolver::No-New-Installs` `false` 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.
- `Aptitude::Safe-Resolver::No-New-Upgrades` `false` 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.
- `Aptitude::Sections::Descriptions` See `$prefix/share/aptitude/section-descriptions` 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.
- `Aptitude::Sections::Top-Sections` `"main"; "contrib"; "non-free"; "non-US";` 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`.
- `Aptitude::Simulate` `false` 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.
- `Aptitude::Spin-Interval` `500` The number of milliseconds to delay in between updating the spinner that appears while the problem resolver is running.
- `Aptitude::Suggests-Important` `false` 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`.
- `Aptitude::Suppress-Read-Only-Warning` `false` 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.
- `Aptitude::Theme` The theme that &aptitude; should use; see secThemes for more information.
- `Aptitude::Track-Dselect-State` `true` 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.
- `Aptitude::UI::Advance-On-Action` `false` 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.
- `Aptitude::UI::Auto-Show-Reasons` `true` 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.
- `Aptitude::UI::Default-Grouping` `filter(missing),status,section(subdirs,passthrough),section(topdir)` Sets the default grouping policy used for package lists. See secGroupingPolicy for additional information on grouping policies.
- `Aptitude::UI::Default-Package-View` This option is a group whose members define the default layout of &aptitude;'s display. See secDisplayLayout for more information.
- `Aptitude::UI::Default-Preview-Grouping` `action` Sets the default grouping policy used for preview screens. See secGroupingPolicy for additional information on grouping policies.
- `Aptitude::UI::Default-Sorting` `name` The default sorting policy of package views. See secSortingPolicy for more information.
- `Aptitude::UI::Description-Visible-By-Default` `true` 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`.
- `Aptitude::UI::Exit-On-Last-Close` `true` 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;. See secViews for more information.
- `Aptitude::UI::Fill-Text` `false` If this option is `true`, &aptitude; will format descriptions so that each line is exactly the width of the screen.
- `Aptitude::UI::Flat-View-As-First-View` `false` If this option is `true`, &aptitude; will display a flat view on startup instead of the default view.
- `Aptitude::UI::HelpBar` `true` If this option is `true`, a line of information about important keystrokes will be displayed at the top of the screen.
- `Aptitude::UI::Incremental-Search` `true` 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.
- `Aptitude::UI::InfoAreaTabs` `false` 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.
- `Aptitude::UI::Keybindings` This is a group whose members define the connections between keystrokes and commands in &aptitude;. For more information, see secKeybindings.
- `Aptitude::UI::Menubar-Autohide` `false` If this option is set to `true`, the menu bar will be hidden while it is not in use.
- `Aptitude::UI::Minibuf-Download-Bar` `false` 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.
- `Aptitude::UI::Minibuf-Prompts` `false` 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.
- `Aptitude::UI::New-Package-Commands` `true` 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;.
- `Aptitude::UI::Package-Display-Format` `%c%a%M %p %Z %v %V` This option controls the format string used to display packages in package lists. For more information on format strings, see secDisplayFormat.
- `Aptitude::UI::Package-Header-Format` `%N %n @ %H #%B %u %o` 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 secDisplayFormat.
- `Aptitude::UI::Package-Status-Format` `%d` 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 secDisplayFormat.
- `Aptitude::UI::Pause-After-Download` `OnlyIfError` 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.
- `Aptitude::UI::Preview-Limit` The default filter applied to the preview screen; see secSearchPatterns for details about its format.
- `Aptitude::UI::Prompt-On-Exit` `true` If this option is `true`, &aptitude; will display a confirmation prompt before shutting down.
- `Aptitude::UI::Styles` This is a configuration group whose contents define what textual styles &aptitude; uses to display information. For more information, see secStyle.
- `Aptitude::UI::ViewTabs` `true` If this option is set to `false`, &aptitude; will not display tabs describing the currently active views at the top of the screen.
- `Aptitude::Warn-Not-Root` `true` 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 secBecomingRoot for more information.
- `DebTags::Vocabulary` `/usr/share/debtags/vocabulary` The location of the `debtags` vocabulary file; used to load in the package tag metadata.
- `Dir::Aptitude::state` `/var/lib/aptitude` The directory in which &aptitude;'s persistent state information is stored.
- `Quiet` `0` 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:

  [dselect theme]

       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.

  [vertical split theme]

       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-mine;; the initial Minesweeper board will appear:

[Minesweeper screen #1]

     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:

[Minesweeper screen #2]

     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...

[Minesweeper screen #3]

     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:

[Minesweeper screen #4]

     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:

[Minesweeper screen #5]

     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 (`*`).

## aptitude frequently asked questions

> Monty Python and the Holy Grail

> 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!

How can I find exactly one package by name?

As mentioned in secSearchPatterns, 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$`; you can find `g++` (but not `g++-2.95` or `g++-3.0`) by entering `^g\+\+$`.

How can I find broken packages?

Use the command &search-find-broken;.

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.

## Credits

> Terry Pratchett , The Last Hero

> No-one remembers the singer. The song remains.

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

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

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.

). 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

## Command-line reference

&manpage;