dpkg(1)



dpkg(1)                           dpkg suite                           dpkg(1)

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(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.

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 not handled by dpkg, unless
              forced to do that with option --force-hold.

       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).

   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,  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 -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.   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.

       --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.

       --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.

              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).

       --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).

              pkgname
                     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.

       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
                  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.

              -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.

OPTIONS
       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 '#').

       --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: 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.

              depends-version:   Don't   care  about  versions  when  checking
              dependencies.

              breaks: Install, even if this would break another package (since
              dpkg 1.14.6).

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

              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.

              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  scrips 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).

       --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
              Change default administrative  directory,  which  contains  many
              files  that  give  information  about  status  of  installed  or
              uninstalled packages, etc.  (Defaults to <</var/lib/dpkg>>)

       --instdir=dir
              Change  default  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
              Changing  root  changes  instdir  to  <<dir>>  and  admindir  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.

       --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 /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 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.

       --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.

       PAGER  The program dpkg will execute when displaying the conffiles.

       SHELL  The program dpkg will execute when starting  a  new  interactive
              shell.

       COLUMNS
              Sets  the  number  of  columns  dpkg  should use when displaying
              formatted text.  Currently only used by --list.

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

   Internal environment
       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_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
       /etc/dpkg/dpkg.cfg.d/[0-9a-zA-Z_-]*
              Configuration fragment files (since dpkg 1.15.4).

       /etc/dpkg/dpkg.cfg
              Configuration file with default options.

       /var/log/dpkg.log
              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.

       /var/lib/dpkg/available
              List of available packages.

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

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

1.18.24                           2017-05-17                           dpkg(1)

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