The Debian Package Manager (Linux in a Nutshell, 3rd Edition)

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5.2. The Debian Package Manager

Debian GNU/Linux provides several package management tools, primarily intended to facilitate the building, installation, and management of binary packages. Debian package names generally end in .deb. The Debian package management tools include:

dpkg

5.2.1. Files

Some important files used by the Debian package management tools are:

control: Comes with each package; documents dependencies; contains the name and version of the package, a description, maintainer, installed size, and so on.
conffiles: Comes with each package and contains a list of the configuration files associated with the package.
preinst, postinst, prerm, postrm: Scripts that can be included in a package to be run before installation, after installation, before removal, or after removal of the package.
/var/lib/dpkg/available: Contains information about packages available on the system.
/var/lib/dpkg/status: Contains information about the status of packages available on the system.
/etc/apt/sources.list: A list for APT of package sources, used to locate packages. The sources are listed one per line, in order of preference.
/etc/apt/apt.conf: The main APT configuration file.

5.2.2. Package States and Selection States

The possible states that a package can be in are:

config-files: Only the configuration files for the package are present on the system.
half-configured: The package is unpacked and configuration was started but not completed.
half-installed: Installation was started but not completed.
installed: The package is unpacked and configured.
not-installed: The package is not installed.
unpacked: The package is unpacked but not configured.

The possible package selection states are:

deinstall: The package has been selected for deinstallation (i.e., for removal of everything but configuration files).
install: The package has been selected for installation.
purge: The package has been selected to be purged (i.e., for removal of everything including the configuration files).

5.2.3. Package Flags

There are two possible package flags that can be set for a package. They are:

hold: The package is not to be handled by dpkg, unless forced with the --force-hold option.
reinst-required: The package is broken and needs to be reinstalled. Such a package cannot be removed, unless forced with the --force-reinstreq option.

5.2.4. Scripts

In addition to the commands described in the next subsection, several shell and Perl scripts are included with the package manager for use in building packages:

dpkg-buildpackage: Help automate package building. Shell script.
dpkg-distaddfile: Add an entry for a file to debian/files. Perl script.
dpkg-genchanges: Generate an upload control file from the information in an unpacked, built, source tree and the files it has generated. Perl script.
dpkg-gencontrol: Read information from an unpacked source tree and display a binary package control file on standard output. Perl script.
dpkg-name: Rename Debian packages to their full package names. Shell script.
dpkg-parsechangelog: Read and parse the changelog from an unpacked source tree and write the information to standard output in machine-readable form. Perl script.
dpkg-scanpackages: Create a Packages file from a tree of binary packages. The Packages file is used by dselect to provide a list of packages available for installation. Perl script.
dpkg-shlibdeps: Calculate shared library dependencies for named executables. Perl script.
dpkg-source: Pack and unpack Debian source archives. Perl script.

5.2.5. Debian Package Manager Command Summary

apt-cdrom	apt-cdrom [options] command Add a new CD-ROM to APT's list of available sources. Currently, the only command is add, which is required (except with the --help option). The database of CD-ROM IDs that APT maintains is /var/state/apt/cdroms.list. Options Options can be specified on the command line or they may be set in the configuration file. Boolean options set in the configuration file can be overridden on the command line in a number of different ways, a couple of which are --no-opt and -opt=no, where opt is the single-character or full name of the option. -a, --thorough Do a thorough package scan. May be needed with some old Debian CD-ROMs. -c, --config-file Specify a configuration file to be read after the default configuration file. -d, --cdrom Specify the CD-ROM mount point, which must be listed in /etc/fstab. The configuration option is Acquire::cdrom::mount. -f, --fast Do a fast copy, assuming the files are valid and don't all need checking. Specify this only if this disk has been run before without error. The configuration option is APT::CDROM::Fast. -h, --help Print help message and exit. -m, --no-mount Don't mount or unmount the mount point. The configuration option is APT::CDROM::NoMount. -n, --just-print, --recon, --no-act Check everything, but don't actually make any changes. The configuration option is APT::CDROM::NoAct. -o, --option Set a configuration option. Syntax is -o group::tool=option (e.g., APT::CDROM=Fast). -r, --rename Prompt for a new label and rename the disk to the new value. The configuration option is APT::CDROM::Rename. -v, --version Print the version information and exit.
apt-get	apt-get [options] command [package...] A command-line tool for handling packages. Will eventually be a backend to APT. Commands autoclean Like clean, but remove only package files that can no longer be downloaded. clean Clear the local repository of retrieved package files. check Update the package cache and check for broken packages. dist-upgrade Like upgrade but also handle dependencies intelligently. dselect-upgrade Used together with dselect. Track the changes made by dselect to the Status field of available packages and take actions necessary to realize that status. install package... Install one or more packages. Specify the package name, not the full filename. Other required packages also are retrieved and installed. With a hyphen appended to the package name, the package is removed if it is already installed. remove package... Remove one or more packages. Specify the package name, not the full filename. With a plus sign appended to the name, the package is installed. source package... Find source packages and download them into the current directory. If specified with --compile, the source packages are compiled into binary packages. With --download-only, the source packages are not unpacked. update Resynchronize the package overview files from their sources. Must be done before an upgrade or dist-upgrade. upgrade Install the latest versions of all packages currently installed. Run update first. Options Options can be specified on the command line or they may be set in the configuration file. Boolean options set in the configuration file can be overridden on the command line in one of several ways, a couple of which are --no-opt and -opt=no, where opt is the single-character or full name of the option. -b, --compile, --build Compile source packages after download. -c, --config-file Specify a configuration file to read after the default. -d, --download-only Retrieve package files, but don't unpack or install them. The configuration option is APT::Get::Download-only. -f, --fix-broken Try to fix a system with broken dependencies. Can be used alone or with a command. The configuration option is APT::Get::Fix-Broken. --force-yes Force yes. Causes APT to continue without prompting if it is doing something that could damage your system. Use with great caution and only if absolutely necessary. The configuration option is APT::Get::force-yes. -h, --help Display a help message and exit. --ignore-hold Ignore a hold placed on a package. Use with dist-upgrade to override many undesired holds. The configuration option is APT::Get::Ignore-Hold. -m, --ignore-missing, --fix-missing Ignore missing or corrupted packages or packages that cannot be retrieved. Can cause problems when used with -f. --no-download Disable package downloading; use with --ignore-missing to force APT to use only the packages that have already been downloaded. --no-upgrade Do not upgrade packages. Use with install to prevent upgrade of packages that are already installed. The configuration option is APT::Get::no-upgrade. -o, --option Set a configuration option. Syntax is -o group::tool=option (e.g., APT::Get=force-yes). --print-uris Print URIs of files instead of fetching them. Print path, destination filename, size, and expected MD5 hash. The configuration option is APT::Get::Print-URIs. -q, --quiet Quiet. Omit progress indicators, produce only logging output. Add a q to make even quieter. -s, --simulate, --just-print, --dry-run, --recon, --no-act Go through the motions, but don't actually make any changes to the system. The configuration option is APT::Get::Simulate. -u, --show-upgraded Print a list of all packages to be upgraded. The configuration option is APT::Get::Show-Upgraded. -v, --version Display the version and exit. -y, --yes, --assume-yes Automatically reply "yes" to prompts and run noninteractively. Abort if there is an error. The configuration option is APT::Get::Assume-Yes.
dpkg	dpkg [options] action A tool for installing, managing, and building packages. Serves as a frontend to dpkg-deb. dpkg actions These actions are carried out by dpkg itself: -i pkgfile, --install pkgfile Install the package specified as pkgfile. With -R or --recursive, pkgfile must be a directory. **--unpack pkgfile Unpack the package, but don't configure it. With -R or --recursive*, pkgfile* must be a directory. --configure [packages\|-a\|--pending] Reconfigure one or more unpacked packages. If -a or --pending is given instead of packages, configure all packages that are unpacked but not configured. -r, --remove** [packages\|-a\|--pending] --purge** [packages\|-a\|--pending] Remove or purge one or more installed packages. Removal gets rid of everything except the configuration files listed in debian/conffiles; purging also removes the configuration files. If -a or --pending is given instead of packages, dpkg removes or purges all packages that are unpacked and marked (in /var/lib/dpkg/status) for removing or purging. **--print-avail package** Print the details about package from /var/lib/dpkg/available. **--update-avail pkgs-file --merge-avail pkgs-file** Update the record of available files kept in /var/lib/dpkg/available. This information is used by dpkg and dselect to determine what packages are available. Update will replace the information with the contents of the pkgs-file, distributed as Packages. Merge combines the information from Packages with the existing information. -A pkgfile, --record-avail pkgfile Update the record of available files kept in /var/lib/dpkg/available with information from pkgfile. This information is used by dpkg and dselect to determine what packages are available. With -R or --recursive, pkgfile must be a directory. --forget-old-unavail Forget about uninstalled unavailable packages. --clear-avail Remove existing information about what packages are available. -l, --list** [pkg-name-pattern]** List all packages whose names match the specified pattern. With no pattern, list all packages in /var/lib/dpkg/available. The pattern can include standard shell wildcard characters and may have to be quoted to prevent the shell from doing filename expansion. -s packages, --status packages Report the status of one or more packages by displaying the entry in the status database /var/lib/dpkg/status. -C, --audit Search for partially installed packages and suggest how to get them working. --get-selections [pattern] Get list of package selections and write to standard output. With pattern specified, write selections that match the pattern. --set-selections Set package selections based on input file read from standard input. --yet-to-unpack Search for uninstalled packages that have been selected for installation. -L packages, --listfiles packages List installed files that came from the specified package or packages. -S filename-pattern, --search filename-pattern Search installed packages for a filename. The pattern can include standard shell wildcard characters and may have to be quoted to prevent the shell from doing filename expansion. --print-architecture Print target architecture. --print-gnu-build-architecture Print the GNU version of the target architecture. --print-installation-architecture Print host architecture for installation. **--compare-versions ver1 op ver2 Perform a binary comparison of two version numbers. The operators `lt le eq ne ge gt` treat a missing version as earlier. The operators `lt-nl le-nl ge-nl gt-nl` treat a missing version as later (where `nl` is "not later"). There is a third set of operators (`< << <= = >= >> >`) that is provided for compatibility with control-file syntax. dpkg returns zero for success (i.e., the condition is satisfied) and nonzero otherwise. --help Print help message and exit. --force-help Print help message about the --force-**list options and exit. -Dh, --debug=help Print debugging help message and exit. --license Print dpkg license information and exit. Accepts the spelling --licence in addition to --license. --version Print dpkg version information and exit. dpkg-deb actions The following actions can be specified for dpkg and are passed to dpkg-deb for execution. Also see dpkg-deb. *-b dir* [archive], --build dir [archive]** Build a package. -c archive, --contents archive List the contents of a package. -e, --control archive dir Extract control information from a package. *-f archive* [control-fields], --field archive [control-fields] Display the control field or fields of a package. -I archive [control-files], --info archive [control-files] Show information about a package. --fsys-tarfile archive** Display the filesystem tar- file contained by a package. -x archive dir, --extract archive dir Extract the files from a package. -X archive dir, --vextract archive dir Extract and display the filenames from a package. Options **--abort-after=num** Abort processing after num errors. Default is 50. -B, --auto-deconfigure When a package is removed, automatically deconfigure any other package that depended on it. -Doctal, --debug=octal Turn on debugging, with the octal value specifying the desired level of debugging information. Use -Dh or --debug=help to display the possible values. You can OR the values to get the desired output. -E, --skip-same-version Don't install the package if this version is already installed. **--force-list, --no-force-list, --refuse-list** Force or refuse to force an operation. list is specified as a comma-separated item of options. With --force, a warning is printed, but processing continues. --refuse and --no-force cause processing to stop with an error. The force/refuse options are: architecture Process even if intended for a different architecture. auto-select Select or deselect packages to install or remove them. Forced by default. bad-path Some programs are missing from the path. configure-any Configure any unconfigured package that the package depends on. conflicts Permit installation of conflicting packages. Can result in problems from files being overwritten. depends Turn dependency problems into warnings. depends-version Warn of version problems when checking dependencies, but otherwise ignore. downgrade Install even if a newer version is already installed. Forced by default. hold Process packages even if they are marked to be held. not-root Try to install or remove even when not logged on as root. overwrite Overwrite a file from one package with the same file from another package. Forced by default. overwrite-dir Overwrite one package's directory with a file from another package. overwrite-diverted Overwrite a diverted file with an undiverted version. remove-essential Remove an essential package. Note that this can cause your system to stop working. remove-reinstreq Remove packages that are broken and are marked to require reinstallation. -G Don't install a package if a newer version is already installed. The same as --refuse-downgrade. **--ignore-depends=pkglist** Dependency problems result only in a warning for the packages in pkglist. --largemem Specify that dpkg can use as much memory as it needs. --new New binary package format. This is a dpkg-deb option. --no-act Go through the motions, but don't actually write any changes. Used for testing. Be sure to specify before the action; otherwise changes might be written. --nocheck Ignore the contents of the control file when building a package. This is a dpkg-deb option. -O, --selected-only Process only packages that are marked as selected for installation. --old Old binary package format. This is a dpkg-deb option. -R, --recursive Recursively handle .deb files found in the directories specified with -A, --install, --unpack, and --avail and their subdirectories. -R, --root=dir, --admindir=dir, --instdir=dir Change default directories. admindir contains administrative files with status and other information about packages; it defaults to /var/lib/dpkg. instdir is the directory in which packages are installed and defaults to /. Changing the root directory to dir automatically changes instdir to dir and admindir to /dir/var/lib/dpkg. --smallmem Specify that dpkg should try to preserve memory.
dpkg-deb	dpkg-deb action [options] Backend command for building and managing Debian package archives. Also see dpkg; you'll often want to use dpkg to pass commands through to dpkg-deb, rather than call dpkg-deb directly. Actions *-b dir* [archive], --build dir [archive]** Create an archive from the filesystem tree starting with directory dir. The directory must have a DEBIAN subdirectory containing the control file and any other control information. If archive is specified and is a filename, the package is written to that file; if no archive is specified, the package is written to dir.deb. If the archive already exists, it is replaced. If archive is the name of a directory, the dpkg-deb looks in the control file for the information it needs to generate the package name. (Note that for this reason, you cannot use --no-check with a directory name.) -c archive, --contents archive List the filesystem-tree portion of archive. -e, --control archive dir Extract control information from archive into the directory dir, which is created if it doesn't exist. *-f archive* [control-fields], --field archive [control-fields]** Extract information about one or more fields in the control file for archive. If no fields are provided, print the entire control file. -h, --help Print help information and exit. *-I archive* [control-files], --info archive [control-files]** Provide information about binary package archive. If no control files are provided, print a summary of the package contents; otherwise, print the control files in the order they were specified. An error message is printed to standard error for any missing components. **--fsys-tarfile archive** Extract the filesystem tree from archive, and send it to standard output in tar format. Can be used with tar to extract individual files from an archive. --license Print the license information and exit. Accepts the spelling --licence in addition to --license. --version Print the version number and exit. -x archive dir, --extract archive dir -X archive dir, --vextract archive dir Extract the filesystem tree from archive into the specified directory, creating dir if it doesn't already exist. -x (--extract) works silently, while -X (--vextract) lists the files as it extracts them. Do not use this option to install packages; use dpkg instead. Options -D Turn on debugging. --new Build a new-style archive format (this is the default). --no-check Don't check the control file before building an archive. This lets you build a broken archive. --old Build an old-style archive format.
dpkg-split	dpkg-split [action] [options] Split a binary package into smaller pieces and reassemble the pieces, manually or in automatic mode. The automatic mode maintains a queue of parts for reassembling. Useful for transferring to and from floppy disks. Actions **-a -o output part, --auto -o output part** Add part to the queue for automatic reassembly and if all the parts are available, reassemble the package as output. *-d [packages], --discard* [packages]** Discard parts from the automatic-assembly queue. If any packages are specified, discard only parts from those packages. Otherwise, empty the queue. -I parts, --info parts Print information about the part file or files specified. -j parts, --join parts Join the parts of a package file together from the parts specified. The default output file is package-version.deb. -l, --listq List the contents of the queue of parts waiting for reassembly, giving the package name, the parts that are on the queue, and the number of bytes. *-s full-package* [prefix], --full-package [prefix]** Split the package full-package into parts, named prefixNofM.deb. The prefix defaults to the full-package name without the .deb extension. -h, --help Print help message and exit. --license Print the license information and exit. Accepts the spelling --licence in addition to --license. --version Print the version information and exit. Options --depotdir Specify an alternate directory depotdir for the queue of parts waiting for reassembly. Default is /var/lib/dpkg. --msdos Force --split output filenames to be MS-DOS-compatible. -Q, --npquiet Do not print an error message for a part that doesn't belong to a binary package when doing automatic queuing or reassembly. -o output, --output output Use output as the filename for a reassembled package. -S num, --partsize num When splitting, specify the maximum part size (num) in kilobytes. Default is 450 KB.
dselect	dselect [options] [action] A screen-oriented user frontend to dpkg. The primary user interface for installing and managing packages. See dpkg and dpkg-deb for information on building packages. Actions If dselect is run with no action specified on the command line, it displays the following menu: * 0. [A]ccess Choose the access method to use. 1. [U]pdate Update list of available packages, if possible. 2. [S]elect Request which packages you want on your system. 3. [I]nstall Install and upgrade wanted packages. 4. [C]onfig Configure any packages that are unconfigured. 5. [R]emove Remove unwanted software. 6. [Q]uit Quit dselect. The asterisk (on the first line here) shows the currently selected option. Any of the menu items can be specified directly on the command line as an action (access, update, select, install, config, remove, quit) to go directly to the desired activity. For example: % `dselect access` If you enter quit on the command line, dselect exits immediately without doing anything. An additional command-line action is menu, which displays the menu and is equivalent to omitting the action. Options **--admindir dir** Change the directory that holds internal data files to dir. Default is /var/lib/dpkg. *-D [file], --debug* [file]** Turn on debugging. Send output to file if specified. --help Print help message and exit. --license Print the license information and exit. Accepts the spelling --licence in addition to --license. --version Print version information and exit.

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