Provided by: dpkg_1.20.5ubuntu2_amd64 bug

NAME

       dpkg - package manager for Debian

SYNOPSIS

       dpkg [option...] action

WARNING

       This manual is intended for users wishing to understand dpkg's command line options and
       package states in more detail than that provided by dpkg --help.

       It should not be used by package maintainers wishing to understand how dpkg will install
       their packages. The descriptions of what dpkg does when installing and removing packages
       are particularly inadequate.

DESCRIPTION

       dpkg is a tool to install, build, remove and manage Debian packages. The primary and more
       user-friendly front-end for dpkg is aptitude(8). dpkg itself is controlled entirely via
       command line parameters, which consist of exactly one action and zero or more options. The
       action-parameter tells dpkg what to do and options control the behavior of the action in
       some way.

       dpkg can also be used as a front-end to dpkg-deb(1) and dpkg-query(1). The list of
       supported actions can be found later on in the ACTIONS section. If any such action is
       encountered dpkg just runs dpkg-deb or dpkg-query with the parameters given to it, but no
       specific options are currently passed to them, to use any such option the back-ends need
       to be called directly.

INFORMATION ABOUT PACKAGES

       dpkg maintains some usable information about available packages. The information is
       divided in three classes: states, selection states and flags. These values are intended to
       be changed mainly with dselect.

   Package states
       not-installed
           The package is not installed on your system.

       config-files
           Only the configuration files of the package exist on the system.

       half-installed
           The installation of the package has been started, but not completed for some reason.

       unpacked
           The package is unpacked, but not configured.

       half-configured
           The package is unpacked and configuration has been started, but not yet completed for
           some reason.

       triggers-awaited
           The package awaits trigger processing by another package.

       triggers-pending
           The package has been triggered.

       installed
           The package is correctly unpacked and configured.

   Package selection states
       install
           The package is selected for installation.

       hold
           A package marked to be on hold is kept on the same version, that is, no automatic new
           installs, upgrades or removals will be performed on them, unless these actions are
           requested explicitly, or are permitted to be done automatically with the --force-hold
           option.

       deinstall
           The package is selected for deinstallation (i.e. we want to remove all files, except
           configuration files).

       purge
           The package is selected to be purged (i.e. we want to remove everything from system
           directories, even configuration files).

       unknown
           The package selection is unknown.  A package that is also in a not-installed state,
           and with an ok flag will be forgotten in the next database store.

   Package flags
       ok  A package marked ok is in a known state, but might need further processing.

       reinstreq
           A package marked reinstreq is broken and requires reinstallation. These packages
           cannot be removed, unless forced with option --force-remove-reinstreq.

ACTIONS

       -i, --install package-file...
           Install the package. If --recursive or -R option is specified, package-file must refer
           to a directory instead.

           Installation consists of the following steps:

           1. Extract the control files of the new package.

           2. If another version of the same package was installed before the new installation,
           execute prerm script of the old package.

           3. Run preinst script, if provided by the package.

           4. Unpack the new files, and at the same time back up the old files, so that if
           something goes wrong, they can be restored.

           5. If another version of the same package was installed before the new installation,
           execute the postrm script of the old package. Note that this script is executed after
           the preinst script of the new package, because new files are written at the same time
           old files are removed.

           6. Configure the package. See --configure for detailed information about how this is
           done.

       --unpack package-file...
           Unpack the package, but don't configure it. If --recursive or -R option is specified,
           package-file must refer to a directory instead.

       --configure package...|-a|--pending
           Configure a package which has been unpacked but not yet configured.  If -a or
           --pending is given instead of package, all unpacked but unconfigured packages are
           configured.

           To reconfigure a package which has already been configured, try the dpkg-
           reconfigure(8) command instead.

           Configuring consists of the following steps:

           1. Unpack the conffiles, and at the same time back up the old conffiles, so that they
           can be restored if something goes wrong.

           2. Run postinst script, if provided by the package.

       --triggers-only package...|-a|--pending
           Processes only triggers (since dpkg 1.14.17).  All pending triggers will be processed.
           If package names are supplied only those packages' triggers will be processed, exactly
           once each where necessary. Use of this option may leave packages in the improper
           triggers-awaited and triggers-pending states. This can be fixed later by running: dpkg
           --configure --pending.

       -r, --remove package...|-a|--pending
           Remove an installed package.  This removes everything except conffiles and other data
           cleaned up by the postrm script, which may avoid having to reconfigure the package if
           it is reinstalled later (conffiles are configuration files that are listed in the
           DEBIAN/conffiles control file).  If there is no DEBIAN/conffiles control file nor
           DEBIAN/postrm script, this command is equivalent to calling --purge.  If -a or
           --pending is given instead of a package name, then all packages unpacked, but marked
           to be removed in file %ADMINDIR%/status, are removed.

           Removing of a package consists of the following steps:

           1. Run prerm script

           2. Remove the installed files

           3. Run postrm script

       -P, --purge package...|-a|--pending
           Purge an installed or already removed package. This removes everything, including
           conffiles, and anything else cleaned up from postrm.  If -a or --pending is given
           instead of a package name, then all packages unpacked or removed, but marked to be
           purged in file %ADMINDIR%/status, are purged.

           Note: Some configuration files might be unknown to dpkg because they are created and
           handled separately through the configuration scripts. In that case, dpkg won't remove
           them by itself, but the package's postrm script (which is called by dpkg), has to take
           care of their removal during purge. Of course, this only applies to files in system
           directories, not configuration files written to individual users' home directories.

           Purging of a package consists of the following steps:

           1. Remove the package, if not already removed. See --remove for detailed information
           about how this is done.

           2. Run postrm script.

       -V, --verify [package-name...]
           Verifies the integrity of package-name or all packages if omitted, by comparing
           information from the files installed by a package with the files metadata information
           stored in the dpkg database (since dpkg 1.17.2).  The origin of the files metadata
           information in the database is the binary packages themselves. That metadata gets
           collected at package unpack time during the installation process.

           Currently the only functional check performed is an md5sum verification of the file
           contents against the stored value in the files database.  It will only get checked if
           the database contains the file md5sum. To check for any missing metadata in the
           database, the --audit command can be used.

           The output format is selectable with the --verify-format option, which by default uses
           the rpm format, but that might change in the future, and as such, programs parsing
           this command output should be explicit about the format they expect.

       -C, --audit [package-name...]
           Performs database sanity and consistency checks for package-name or all packages if
           omitted (per package checks since dpkg 1.17.10).  For example, searches for packages
           that have been installed only partially on your system or that have missing, wrong or
           obsolete control data or files. dpkg will suggest what to do with them to get them
           fixed.

       --update-avail [Packages-file]
       --merge-avail [Packages-file]
           Update dpkg's and dselect's idea of which packages are available. With action
           --merge-avail, old information is combined with information from Packages-file. With
           action --update-avail, old information is replaced with the information in the
           Packages-file. The Packages-file distributed with Debian is simply named «Packages».
           If the Packages-file argument is missing or named «-» then it will be read from
           standard input (since dpkg 1.17.7). dpkg keeps its record of available packages in
           %ADMINDIR%/available.

           A simpler one-shot command to retrieve and update the available file is dselect
           update. Note that this file is mostly useless if you don't use dselect but an APT-
           based frontend: APT has its own system to keep track of available packages.

       -A, --record-avail package-file...
           Update dpkg and dselect's idea of which packages are available with information from
           the package package-file. If --recursive or -R option is specified, package-file must
           refer to a directory instead.

       --forget-old-unavail
           Now obsolete and a no-op as dpkg will automatically forget uninstalled unavailable
           packages (since dpkg 1.15.4), but only those that do not contain user information such
           as package selections.

       --clear-avail
           Erase the existing information about what packages are available.

       --get-selections [package-name-pattern...]
           Get list of package selections, and write it to stdout. Without a pattern, non-
           installed packages (i.e. those which have been previously purged) will not be shown.

       --set-selections
           Set package selections using file read from stdin. This file should be in the format
           “package state”, where state is one of install, hold, deinstall or purge. Blank lines
           and comment lines beginning with ‘#’ are also permitted.

           The available file needs to be up-to-date for this command to be useful, otherwise
           unknown packages will be ignored with a warning. See the --update-avail and
           --merge-avail commands for more information.

       --clear-selections
           Set the requested state of every non-essential package to deinstall (since dpkg
           1.13.18).  This is intended to be used immediately before --set-selections, to
           deinstall any packages not in list given to --set-selections.

       --yet-to-unpack
           Searches for packages selected for installation, but which for some reason still
           haven't been installed.

           Note: This command makes use of both the available file and the package selections.

       --predep-package
           Print a single package which is the target of one or more relevant pre-dependencies
           and has itself no unsatisfied pre-dependencies.

           If such a package is present, output it as a Packages file entry, which can be
           massaged as appropriate.

           Note: This command makes use of both the available file and the package selections.

           Returns 0 when a package is printed, 1 when no suitable package is available and 2 on
           error.

       --add-architecture architecture
           Add architecture to the list of architectures for which packages can be installed
           without using --force-architecture (since dpkg 1.16.2).  The architecture dpkg is
           built for (i.e. the output of --print-architecture) is always part of that list.

       --remove-architecture architecture
           Remove architecture from the list of architectures for which packages can be installed
           without using --force-architecture (since dpkg 1.16.2). If the architecture is
           currently in use in the database then the operation will be refused, except if
           --force-architecture is specified. The architecture dpkg is built for (i.e. the output
           of --print-architecture) can never be removed from that list.

       --print-architecture
           Print architecture of packages dpkg installs (for example, “i386”).

       --print-foreign-architectures
           Print a newline-separated list of the extra architectures dpkg is configured to allow
           packages to be installed for (since dpkg 1.16.2).

       --assert-feature
           Asserts that dpkg supports the requested feature.  Returns 0 if the feature is fully
           supported, 1 if the feature is known but dpkg cannot provide support for it yet, and 2
           if the feature is unknown.  The current list of assertable features is:

           support-predepends
               Supports the Pre-Depends field (since dpkg 1.1.0).

           working-epoch
               Supports epochs in version strings (since dpkg 1.4.0.7).

           long-filenames
               Supports long filenames in deb(5) archives (since dpkg 1.4.1.17).

           multi-conrep
               Supports multiple Conflicts and Replaces (since dpkg 1.4.1.19).

           multi-arch
               Supports multi-arch fields and semantics (since dpkg 1.16.2).

           versioned-provides
               Supports versioned Provides (since dpkg 1.17.11).

           protected-field
               Supports the Protected field (since dpkg 1.20.1).

       --validate-thing string
           Validate that the thing string has a correct syntax (since dpkg 1.18.16).  Returns 0
           if the string is valid, 1 if the string is invalid but might be accepted in lax
           contexts, and 2 if the string is invalid.  The current list of validatable things is:

           pkgname
               Validates the given package name (since dpkg 1.18.16).

           trigname
               Validates the given trigger name (since dpkg 1.18.16).

           archname
               Validates the given architecture name (since dpkg 1.18.16).

           version
               Validates the given version (since dpkg 1.18.16).

       --compare-versions ver1 op ver2
           Compare version numbers, where op is a binary operator. dpkg returns true (0) if the
           specified condition is satisfied, and false (1) otherwise. There are two groups of
           operators, which differ in how they treat an empty ver1 or ver2. These treat an empty
           version as earlier than any version: lt le eq ne ge gt. These treat an empty version
           as later than any version: lt-nl le-nl ge-nl gt-nl. These are provided only for
           compatibility with control file syntax: < << <= = >= >> >. The < and > operators are
           obsolete and should not be used, due to confusing semantics. To illustrate: 0.1 < 0.1
           evaluates to true.

       -?, --help
           Display a brief help message.

       --force-help
           Give help about the --force-thing options.

       -Dh, --debug=help
           Give help about debugging options.

       --version
           Display dpkg version information.

           When used with --robot, the output will be the program version number in a dotted
           numerical format, with no newline.

       dpkg-deb actions
           See dpkg-deb(1) for more information about the following actions, and other actions
           and options not exposed by the dpkg front-end.

           -b, --build directory [archive|directory]
               Build a deb package.

           -c, --contents archive
               List contents of a deb package.

           -e, --control archive [directory]
               Extract control-information from a package.

           -x, --extract archive directory
               Extract the files contained by package.

           -X, --vextract archive directory
               Extract and display the filenames contained by a package.

           -f, --field  archive [control-field...]
               Display control field(s) of a package.

           --ctrl-tarfile archive
               Output the control tar-file contained in a Debian package.

           --fsys-tarfile archive
               Output the filesystem tar-file contained by a Debian package.

           -I, --info archive [control-file...]
               Show information about a package.

       dpkg-query actions
           See dpkg-query(1) for more information about the following actions, and other actions
           and options not exposed by the dpkg front-end.

           -l, --list package-name-pattern...
               List packages matching given pattern.

           -s, --status package-name...
               Report status of specified package.

           -L, --listfiles package-name...
               List files installed to your system from package-name.

           -S, --search filename-search-pattern...
               Search for a filename from installed packages.

           -p, --print-avail package-name...
               Display details about package-name, as found in %ADMINDIR%/available. Users of
               APT-based frontends should use apt show package-name instead.

OPTIONS

       All options can be specified both on the command line and in the dpkg configuration file
       %PKGCONFDIR%/dpkg.cfg or fragment files (with names matching this shell pattern
       '[0-9a-zA-Z_-]*') on the configuration directory %PKGCONFDIR%/dpkg.cfg.d/. Each line in
       the configuration file is either an option (exactly the same as the command line option
       but without leading hyphens) or a comment (if it starts with a ‘#’).

       --abort-after=number
           Change after how many errors dpkg will abort. The default is 50.

       -B, --auto-deconfigure
           When a package is removed, there is a possibility that another installed package
           depended on the removed package. Specifying this option will cause automatic
           deconfiguration of the package which depended on the removed package.

       -Doctal, --debug=octal
           Switch debugging on. octal is formed by bitwise-oring desired values together from the
           list below (note that these values may change in future releases). -Dh or --debug=help
           display these debugging values.

               Number   Description
                    1   Generally helpful progress information
                    2   Invocation and status of maintainer scripts
                   10   Output for each file processed
                  100   Lots of output for each file processed
                   20   Output for each configuration file
                  200   Lots of output for each configuration file
                   40   Dependencies and conflicts
                  400   Lots of dependencies/conflicts output
                10000   Trigger activation and processing
                20000   Lots of output regarding triggers
                40000   Silly amounts of output regarding triggers
                 1000   Lots of drivel about e.g. the dpkg/info dir
                 2000   Insane amounts of drivel

       --force-things
       --no-force-things, --refuse-things
           Force or refuse (no-force and refuse mean the same thing) to do some things. things is
           a comma separated list of things specified below. --force-help displays a message
           describing them.  Things marked with (*) are forced by default.

           Warning: These options are mostly intended to be used by experts only. Using them
           without fully understanding their effects may break your whole system.

           all: Turns on (or off) all force options.

           downgrade(*): Install a package, even if newer version of it is already installed.

           Warning: At present dpkg does not do any dependency checking on downgrades and
           therefore will not warn you if the downgrade breaks the dependency of some other
           package. This can have serious side effects, downgrading essential system components
           can even make your whole system unusable. Use with care.

           configure-any: Configure also any unpacked but unconfigured packages on which the
           current package depends.

           hold: Allow automatic installs, upgrades or removals of packages even when marked to
           be on “hold”.  Note: This does not prevent these actions when requested explicitly.

           remove-reinstreq: Remove a package, even if it's broken and marked to require
           reinstallation. This may, for example, cause parts of the package to remain on the
           system, which will then be forgotten by dpkg.

           remove-protected: Remove, even if the package is considered protected (since dpkg
           1.20.1).  Protected packages contain mostly important system boot infrastructure.
           Removing them might cause the whole system to be unable to boot, so use with caution.

           remove-essential: Remove, even if the package is considered essential. Essential
           packages contain mostly very basic Unix commands. Removing them might cause the whole
           system to stop working, so use with caution.

           depends: Turn all dependency problems into warnings.  This affects the Pre-Depends and
           Depends fields.

           depends-version: Don't care about versions when checking dependencies.  This affects
           the Pre-Depends and Depends fields.

           breaks: Install, even if this would break another package (since dpkg 1.14.6).  This
           affects the Breaks field.

           conflicts: Install, even if it conflicts with another package. This is dangerous, for
           it will usually cause overwriting of some files.  This affects the Conflicts field.

           confmiss: Always install the missing conffile without prompting. This is dangerous,
           since it means not preserving a change (removing) made to the file.

           confnew: If a conffile has been modified and the version in the package did change,
           always install the new version without prompting, unless the --force-confdef is also
           specified, in which case the default action is preferred.

           confold: If a conffile has been modified and the version in the package did change,
           always keep the old version without prompting, unless the --force-confdef is also
           specified, in which case the default action is preferred.

           confdef: If a conffile has been modified and the version in the package did change,
           always choose the default action without prompting. If there is no default action it
           will stop to ask the user unless --force-confnew or --force-confold is also been
           given, in which case it will use that to decide the final action.

           confask: If a conffile has been modified always offer to replace it with the version
           in the package, even if the version in the package did not change (since dpkg 1.15.8).
           If any of --force-confnew, --force-confold, or --force-confdef is also given, it will
           be used to decide the final action.

           overwrite: Overwrite one package's file with another's file.

           overwrite-dir: Overwrite one package's directory with another's file.

           overwrite-diverted: Overwrite a diverted file with an undiverted version.

           statoverride-add: Overwrite an existing stat override when adding it (since dpkg
           1.19.5).

           statoverride-remove: Ignore a missing stat override when removing it (since dpkg
           1.19.5).

           security-mac(*): Use platform-specific Mandatory Access Controls (MAC) based security
           when installing files into the filesystem (since dpkg 1.19.5).  On Linux systems the
           implementation uses SELinux.

           unsafe-io: Do not perform safe I/O operations when unpacking (since dpkg 1.15.8.6).
           Currently this implies not performing file system syncs before file renames, which is
           known to cause substantial performance degradation on some file systems, unfortunately
           the ones that require the safe I/O on the first place due to their unreliable
           behaviour causing zero-length files on abrupt system crashes.

           Note: For ext4, the main offender, consider using instead the mount option nodelalloc,
           which will fix both the performance degradation and the data safety issues, the latter
           by making the file system not produce zero-length files on abrupt system crashes with
           any software not doing syncs before atomic renames.

           Warning: Using this option might improve performance at the cost of losing data, use
           with care.

           script-chrootless: Run maintainer scripts without chroot(2)ing into instdir even if
           the package does not support this mode of operation (since dpkg 1.18.5).

           Warning: This can destroy your host system, use with extreme care.

           architecture: Process even packages with wrong or no architecture.

           bad-version: Process even packages with wrong versions (since dpkg 1.16.1).

           bad-path: PATH is missing important programs, so problems are likely.

           not-root: Try to (de)install things even when not root.

           bad-verify: Install a package even if it fails authenticity check.

       --ignore-depends=package,...
           Ignore dependency-checking for specified packages (actually, checking is performed,
           but only warnings about conflicts are given, nothing else).  This affects the Pre-
           Depends, Depends and Breaks fields.

       --no-act, --dry-run, --simulate
           Do everything which is supposed to be done, but don't write any changes. This is used
           to see what would happen with the specified action, without actually modifying
           anything.

           Be sure to give --no-act before the action-parameter, or you might end up with
           undesirable results. (e.g. dpkg --purge foo --no-act will first purge package “foo”
           and then try to purge package ”--no-act”, even though you probably expected it to
           actually do nothing).

       -R, --recursive
           Recursively handle all regular files matching pattern *.deb found at specified
           directories and all of its subdirectories. This can be used with -i, -A, --install,
           --unpack and --record-avail actions.

       -G  Don't install a package if a newer version of the same package is already installed.
           This is an alias of --refuse-downgrade.

       --admindir=dir
           Set the administrative directory to directory.  This directory contains many files
           that give information about status of installed or uninstalled packages, etc.
           Defaults to «%ADMINDIR%».

       --instdir=dir
           Set the installation directory, which refers to the directory where packages are to be
           installed. instdir is also the directory passed to chroot(2) before running package's
           installation scripts, which means that the scripts see instdir as a root directory.
           Defaults to «/».

       --root=dir
           Set the root directory to directory, which sets the installation directory to «dir»
           and the administrative directory to «dir%ADMINDIR%».

       -O, --selected-only
           Only process the packages that are selected for installation. The actual marking is
           done with dselect or by dpkg, when it handles packages. For example, when a package is
           removed, it will be marked selected for deinstallation.

       -E, --skip-same-version
           Don't install the package if the same version of the package is already installed.

       --pre-invoke=command
       --post-invoke=command
           Set an invoke hook command to be run via “sh -c” before or after the dpkg run for the
           unpack, configure, install, triggers-only, remove, purge, add-architecture and remove-
           architecture dpkg actions (since dpkg 1.15.4; add-architecture and remove-architecture
           actions since dpkg 1.17.19). This option can be specified multiple times. The order
           the options are specified is preserved, with the ones from the configuration files
           taking precedence.  The environment variable DPKG_HOOK_ACTION is set for the hooks to
           the current dpkg action.

           Note: Front-ends might call dpkg several times per invocation, which might run the
           hooks more times than expected.

       --path-exclude=glob-pattern
       --path-include=glob-pattern
           Set glob-pattern as a path filter, either by excluding or re-including previously
           excluded paths matching the specified patterns during install (since dpkg 1.15.8).

           Warning: Take into account that depending on the excluded paths you might completely
           break your system, use with caution.

           The glob patterns use the same wildcards used in the shell, were ‘*’ matches any
           sequence of characters, including the empty string and also ‘/’.  For example,
           «/usr/*/READ*» matches «/usr/share/doc/package/README».  As usual, ‘?’ matches any
           single character (again, including ‘/’).  And ‘[’ starts a character class, which can
           contain a list of characters, ranges and complementations. See glob(7) for detailed
           information about globbing.  Note: The current implementation might re-include more
           directories and symlinks than needed, to be on the safe side and avoid possible unpack
           failures; future work might fix this.

           This can be used to remove all paths except some particular ones; a typical case is:

            --path-exclude=/usr/share/doc/*
            --path-include=/usr/share/doc/*/copyright

           to remove all documentation files except the copyright files.

           These two options can be specified multiple times, and interleaved with each other.
           Both are processed in the given order, with the last rule that matches a file name
           making the decision.

           The filters are applied when unpacking the binary packages, and as such only have
           knowledge of the type of object currently being filtered (e.g. a normal file or a
           directory) and have not visibility of what objects will come next.  Because these
           filters have side effects (in contrast to find(1) filters), excluding an exact
           pathname that happens to be a directory object like /usr/share/doc will not have the
           desired result, and only that pathname will be excluded (which could be automatically
           reincluded if the code sees the need).  Any subsequent files contained within that
           directory will fail to unpack.

           Hint: make sure the globs are not expanded by your shell.

       --verify-format format-name
           Sets the output format for the --verify command (since dpkg 1.17.2).

           The only currently supported output format is rpm, which consists of a line for every
           path that failed any check.  The lines start with 9 characters to report each specific
           check result, a ‘?’ implies the check could not be done (lack of support, file
           permissions, etc), ‘.’ implies the check passed, and an alphanumeric character implies
           a specific check failed; the md5sum verification failure (the file contents have
           changed) is denoted with a ‘5’ on the third character.  The line is followed by a
           space and an attribute character (currently ‘c’ for conffiles), another space and the
           pathname.

       --status-fd n
           Send machine-readable package status and progress information to file descriptor n.
           This option can be specified multiple times. The information is generally one record
           per line, in one of the following forms:

           status: package: status
               Package status changed; status is as in the status file.

           status: package : error : extended-error-message
               An error occurred. Any possible newlines in extended-error-message will be
               converted to spaces before output.

           status: file : conffile-prompt : 'real-old' 'real-new' useredited distedited
               User is being asked a conffile question.

           processing: stage: package
               Sent just before a processing stage starts. stage is one of upgrade, install (both
               sent before unpacking), configure, trigproc, disappear, remove, purge.

       --status-logger=command
           Send machine-readable package status and progress information to the shell command's
           standard input, to be run via “sh -c” (since dpkg 1.16.0).  This option can be
           specified multiple times.  The output format used is the same as in --status-fd.

       --log=filename
           Log status change updates and actions to filename, instead of the default
           %LOGDIR%/dpkg.log. If this option is given multiple times, the last filename is used.
           Log messages are of the form:

           YYYY-MM-DD HH:MM:SS startup type command
               For each dpkg invocation where type is archives (with a command of unpack or
               install) or packages (with a command of configure, triggers-only, remove or
               purge).

           YYYY-MM-DD HH:MM:SS status state pkg installed-version
               For status change updates.

           YYYY-MM-DD HH:MM:SS action pkg installed-version available-version
               For actions where action is one of install, upgrade, configure, trigproc,
               disappear, remove or purge.

           YYYY-MM-DD HH:MM:SS conffile filename decision
               For conffile changes where decision is either install or keep.

       --robot
           Use a machine-readable output format. This provides an interface for programs that
           need to parse the output of some of the commands that do not otherwise emit a machine-
           readable output format. No localization will be used, and the output will be modified
           to make it easier to parse.

           The only currently supported command is --version.

       --no-pager
           Disables the use of any pager when showing information (since dpkg 1.19.2).

       --no-debsig
           Do not try to verify package signatures.

       --no-triggers
           Do not run any triggers in this run (since dpkg 1.14.17), but activations will still
           be recorded.  If used with --configure package or --triggers-only package then the
           named package postinst will still be run even if only a triggers run is needed. Use of
           this option may leave packages in the improper triggers-awaited and triggers-pending
           states. This can be fixed later by running: dpkg --configure --pending.

       --triggers
           Cancels a previous --no-triggers (since dpkg 1.14.17).

EXIT STATUS

       0   The requested action was successfully performed.  Or a check or assertion command
           returned true.

       1   A check or assertion command returned false.

       2   Fatal or unrecoverable error due to invalid command-line usage, or interactions with
           the system, such as accesses to the database, memory allocations, etc.

ENVIRONMENT

   External environment
       PATH
           This variable is expected to be defined in the environment and point to the system
           paths where several required programs are to be found. If it's not set or the programs
           are not found, dpkg will abort.

       HOME
           If set, dpkg will use it as the directory from which to read the user specific
           configuration file.

       TMPDIR
           If set, dpkg will use it as the directory in which to create temporary files and
           directories.

       SHELL
           The program dpkg will execute when starting a new interactive shell, or when spawning
           a command via a shell.

       PAGER
       DPKG_PAGER
           The program dpkg will execute when running a pager, which will be executed with
           «$SHELL -c», for example when displaying the conffile differences.  If SHELL is not
           set, «sh» will be used instead.  The DPKG_PAGER overrides the PAGER environment
           variable (since dpkg 1.19.2).

       DPKG_COLORS
           Sets the color mode (since dpkg 1.18.5).  The currently accepted values are: auto
           (default), always and never.

       DPKG_FORCE
           Sets the force flags (since dpkg 1.19.5).  When this variable is present, no built-in
           force defaults will be applied.  If the variable is present but empty, all force flags
           will be disabled.

       DPKG_ADMINDIR
           If set and the --admindir or --root options have not been specified, it will be used
           as the dpkg administrative directory (since dpkg 1.20.0).

       DPKG_FRONTEND_LOCKED
           Set by a package manager frontend to notify dpkg that it should not acquire the
           frontend lock (since dpkg 1.19.1).

   Internal environment
       LESS
           Defined by dpkg to “-FRSXMQ”, if not already set, when spawning a pager (since dpkg
           1.19.2).  To change the default behavior, this variable can be preset to some other
           value including an empty string, or the PAGER or DPKG_PAGER variables can be set to
           disable specific options with «-+», for example DPKG_PAGER="less -+F".

       DPKG_ROOT
           Defined by dpkg on the maintainer script environment to indicate which installation to
           act on (since dpkg 1.18.5).  The value is intended to be prepended to any path
           maintainer scripts operate on.  During normal operation, this variable is empty.  When
           installing packages into a different instdir, dpkg normally invokes maintainer scripts
           using chroot(2) and leaves this variable empty, but if --force-script-chrootless is
           specified then the chroot(2) call is skipped and instdir is non-empty.

       DPKG_ADMINDIR
           Defined by dpkg on the maintainer script environment to indicate the dpkg
           administrative directory to use (since dpkg 1.16.0).  This variable is always set to
           the current --admindir value.

       DPKG_FORCE
           Defined by dpkg on the subprocesses environment to all the currently enabled force
           option names separated by commas (since dpkg 1.19.5).

       DPKG_SHELL_REASON
           Defined by dpkg on the shell spawned on the conffile prompt to examine the situation
           (since dpkg 1.15.6).  Current valid value: conffile-prompt.

       DPKG_CONFFILE_OLD
           Defined by dpkg on the shell spawned on the conffile prompt to examine the situation
           (since dpkg 1.15.6).  Contains the path to the old conffile.

       DPKG_CONFFILE_NEW
           Defined by dpkg on the shell spawned on the conffile prompt to examine the situation
           (since dpkg 1.15.6).  Contains the path to the new conffile.

       DPKG_HOOK_ACTION
           Defined by dpkg on the shell spawned when executing a hook action (since dpkg 1.15.4).
           Contains the current dpkg action.

       DPKG_RUNNING_VERSION
           Defined by dpkg on the maintainer script environment to the version of the currently
           running dpkg instance (since dpkg 1.14.17).

       DPKG_MAINTSCRIPT_PACKAGE
           Defined by dpkg on the maintainer script environment to the (non-arch-qualified)
           package name being handled (since dpkg 1.14.17).

       DPKG_MAINTSCRIPT_PACKAGE_REFCOUNT
           Defined by dpkg on the maintainer script environment to the package reference count,
           i.e. the number of package instances with a state greater than not-installed (since
           dpkg 1.17.2).

       DPKG_MAINTSCRIPT_ARCH
           Defined by dpkg on the maintainer script environment to the architecture the package
           got built for (since dpkg 1.15.4).

       DPKG_MAINTSCRIPT_NAME
           Defined by dpkg on the maintainer script environment to the name of the script
           running, one of preinst, postinst, prerm or postrm (since dpkg 1.15.7).

       DPKG_MAINTSCRIPT_DEBUG
           Defined by dpkg on the maintainer script environment to a value (‘0’ or ‘1’) noting
           whether debugging has been requested (with the --debug option) for the maintainer
           scripts (since dpkg 1.18.4).

FILES

       %PKGCONFDIR%/dpkg.cfg.d/[0-9a-zA-Z_-]*
           Configuration fragment files (since dpkg 1.15.4).

       %PKGCONFDIR%/dpkg.cfg
           Configuration file with default options.

       %LOGDIR%/dpkg.log
           Default log file (see %PKGCONFDIR%/dpkg.cfg and option --log).

       The other files listed below are in their default directories, see option --admindir to
       see how to change locations of these files.

       %ADMINDIR%/available
           List of available packages.

       %ADMINDIR%/status
           Statuses of available packages. This file contains information about whether a package
           is marked for removing or not, whether it is installed or not, etc. See section
           INFORMATION ABOUT PACKAGES for more info.

           The status file is backed up daily in /var/backups. It can be useful if it's lost or
           corrupted due to filesystems troubles.

       The format and contents of a binary package are described in deb(5).

BUGS

       --no-act usually gives less information than might be helpful.

EXAMPLES

       To list installed packages related to the editor vi(1) (note that dpkg-query does not load
       the available file anymore by default, and the dpkg-query --load-avail option should be
       used instead for that):

        dpkg -l '*vi*'

       To see the entries in %ADMINDIR%/available of two packages:

        dpkg --print-avail elvis vim | less

       To search the listing of packages yourself:

        less /var/lib/dpkg/available

       To remove an installed elvis package:

        dpkg -r elvis

       To install a package, you first need to find it in an archive or CDROM. The available file
       shows that the vim package is in section editors:

        cd /media/cdrom/pool/main/v/vim
        dpkg -i vim_4.5-3.deb

       To make a local copy of the package selection states:

        dpkg --get-selections> myselections

       You might transfer this file to another computer, and after having updated the available
       file there with your package manager frontend of choice (see
       https://wiki.debian.org/Teams/Dpkg/FAQ for more details), for example:

        apt-cache dumpavail | dpkg --merge-avail

       or with dpkg 1.17.6 and earlier:

        avail=$(mktemp)
        apt-cache dumpavail> "$avail"
        dpkg --merge-avail "$avail"
        rm "$avail"

       you can install it with:

        dpkg --clear-selections
        dpkg --set-selections <myselections

       Note that this will not actually install or remove anything, but just set the selection
       state on the requested packages. You will need some other application to actually download
       and install the requested packages. For example, run apt-get dselect-upgrade.

       Ordinarily, you will find that dselect(1) provides a more convenient way to modify the
       package selection states.

ADDITIONAL FUNCTIONALITY

       Additional functionality can be gained by installing any of the following packages: apt,
       aptitude and debsums.

SEE ALSO

       aptitude(8), apt(8), dselect(1), dpkg-deb(1), dpkg-query(1), deb(5), deb-control(5),
       dpkg.cfg(5), and dpkg-reconfigure(8).

AUTHORS

       See %PKGDOCDIR%/THANKS for the list of people who have contributed to dpkg.