Provided by: dpkg_1.19.7ubuntu3.2_amd64 bug


       dpkg - package manager for Debian


       dpkg [option...] action


       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.


       dpkg is a tool to install, build, remove and manage Debian packages. The primary and  more
       user-friendly  front-end  for  dpkg is aptitude(1). 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.


       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
              The package is not installed on your system.

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

              The installation of the package has  been  started,  but  not  completed  for  some

              The package is unpacked, but not configured.

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

              The package awaits trigger processing by another package.

              The package has been triggered.

              The package is correctly unpacked and configured.

   Package selection states
              The package is selected for installation.

       hold   A package marked to be on hold is not handled by dpkg, unless  forced  to  do  that
              with option --force-hold.

              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).

              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.

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


       -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

              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 /var/lib/dpkg/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 /var/lib/dpkg/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 /var/lib/dpkg/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.

              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.

              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

              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.

              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.

              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.

              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

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

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

              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:

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

                     Supports epochs in version strings (since dpkg

                     Supports long filenames in deb(5) archives (since dpkg

                     Supports multiple Conflicts and Replaces (since dpkg

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

                     Supports versioned Provides (since dpkg 1.17.11).

       --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

                     Validates the given package name (since dpkg 1.18.16).

                     Validates the given trigger name (since dpkg 1.18.16).

                     Validates the given architecture name (since dpkg 1.18.16).

                     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.

              Give help about the --force-thing options.

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

              Display dpkg version information.

       dpkg-deb actions
              See dpkg-deb(1) for more information about the following actions.

              -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
              -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.

              -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
                  /var/lib/dpkg/available. Users of APT-based frontends
                  should use apt-cache show package-name instead.


       All  options  can be specified both on the command line and in the dpkg configuration file
       /etc/dpkg/dpkg.cfg or fragment files (with names matching this  shell  pattern  '[0-9a-zA-
       Z_-]*')   on   the   configuration  directory  /etc/dpkg/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 ‘#’).

              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

       --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: Process packages even when marked “hold”.

              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-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

              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

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

              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
              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 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

              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.

              Set  the administrative directory to directory.  This directory contains many files
              that give information about status  of  installed  or  uninstalled  packages,  etc.
              Defaults to «/var/lib/dpkg».

              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 «/».

              Set the root directory to directory, which sets the installation directory to «dir»
              and the administrative directory to «dir/var/lib/dpkg».

       -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.

              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.

              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


              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.

              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

              Log status  change  updates  and  actions  to  filename,  instead  of  the  default
              /var/log/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

              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.

              Disables the use of any pager when showing information (since dpkg 1.19.2).

              Do not try to verify package signatures.

              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

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


       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.


   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

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

              The program dpkg will execute when running a pager, 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).

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

              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.

              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".

              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.

              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.

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

              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.

              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.

              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.

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

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

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

              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).

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

              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).

              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).


              Configuration fragment files (since dpkg 1.15.4).

              Configuration file with default options.

              Default log file (see /etc/dpkg/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.

              List of available packages.

              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).


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


       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 /var/lib/dpkg/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 for more details), for example:
            apt-cache dumpavail | dpkg --merge-avail
       or with dpkg 1.17.6 and earlier:
            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  can be gained by installing any of the following packages: apt,
       aptitude and debsums.


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


       See /usr/share/doc/dpkg/THANKS for the list of people who have contributed to dpkg.