debhelper(7)              (2021-09-23)               debhelper(7)

     NAME
          debhelper - the debhelper tool suite

     SYNOPSIS
          dh_* [-v] [-a] [-i] [--no-act] [-ppackage] [-Npackage]
          [-Ptmpdir]

     DESCRIPTION
          Debhelper is used to help you build a Debian package. The
          philosophy behind debhelper is to provide a collection of
          small, simple, and easily understood tools that are used in
          debian/rules to automate various common aspects of building
          a package. This means less work for you, the packager.  It
          also, to some degree means that these tools can be changed
          if Debian policy changes, and packages that use them will
          require only a rebuild to comply with the new policy.

          A typical debian/rules file that uses debhelper will call
          several debhelper commands in sequence, or use dh(1) to
          automate this process. Examples of rules files that use
          debhelper are in /usr/share/doc/debhelper/examples/

          To create a new Debian package using debhelper, you can just
          copy one of the sample rules files and edit it by hand. Or
          you can try the dh-make package, which contains a dh_make
          command that partially automates the process. For a more
          gentle introduction, the maint-guide Debian package contains
          a tutorial about making your first package using debhelper.

          Except where the tool explicitly denotes otherwise, all of
          the debhelper tools assume that they run from the root
          directory of an unpacked source package.  This is so they
          can locate find files like debian/control when needed.

     DEBHELPER COMMANDS
          Here is the list of debhelper commands you can use. See
          their man pages for additional documentation.

          dh_assistant(1)
              tool for supporting debhelper tools and provide
              introspection

          dh_auto_build(1)
              automatically builds a package

          dh_auto_clean(1)
              automatically cleans up after a build

          dh_auto_configure(1)
              automatically configure a package prior to building

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          dh_auto_install(1)
              automatically runs make install or similar

          dh_auto_test(1)
              automatically runs a package's test suites

          dh_bugfiles(1)
              install bug reporting customization files into package
              build directories

          dh_builddeb(1)
              build Debian binary packages

          dh_clean(1)
              clean up package build directories

          dh_compress(1)
              compress files and fix symlinks in package build
              directories

          dh_dwz(1)
              optimize DWARF debug information in ELF binaries via dwz

          dh_fixperms(1)
              fix permissions of files in package build directories

          dh_gencontrol(1)
              generate and install control file

          dh_icons(1)
              Update caches of Freedesktop icons

          dh_install(1)
              install files into package build directories

          dh_installalternatives(1)
              install declarative alternative rules

          dh_installcatalogs(1)
              install and register SGML Catalogs

          dh_installchangelogs(1)
              install changelogs into package build directories

          dh_installcron(1)
              install cron scripts into etc/cron.*

          dh_installdeb(1)
              install files into the DEBIAN directory

          dh_installdebconf(1)
              install files used by debconf in package build

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              directories

          dh_installdirs(1)
              create subdirectories in package build directories

          dh_installdocs(1)
              install documentation into package build directories

          dh_installemacsen(1)
              register an Emacs add on package

          dh_installexamples(1)
              install example files into package build directories

          dh_installgsettings(1)
              install GSettings overrides and set dependencies

          dh_installifupdown(1)
              install if-up and if-down hooks

          dh_installinfo(1)
              install info files

          dh_installinit(1)
              install service init files into package build
              directories

          dh_installinitramfs(1)
              install initramfs hooks and setup maintscripts

          dh_installlogcheck(1)
              install logcheck rulefiles into etc/logcheck/

          dh_installlogrotate(1)
              install logrotate config files

          dh_installman(1)
              install man pages into package build directories

          dh_installmenu(1)
              install Debian menu files into package build directories

          dh_installmime(1)
              install mime files into package build directories

          dh_installmodules(1)
              register kernel modules

          dh_installpam(1)
              install pam support files

          dh_installppp(1)

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              install ppp ip-up and ip-down files

          dh_installsystemd(1)
              install systemd unit files

          dh_installsystemduser(1)
              install systemd unit files

          dh_installsysusers(1)
              install and integrates systemd sysusers files

          dh_installtmpfiles(1)
              install tmpfiles.d configuration files

          dh_installudev(1)
              install udev rules files

          dh_installwm(1)
              register a window manager

          dh_installxfonts(1)
              register X fonts

          dh_link(1)
              create symlinks in package build directories

          dh_lintian(1)
              install lintian override files into package build
              directories

          dh_listpackages(1)
              list binary packages debhelper will act on

          dh_makeshlibs(1)
              automatically create shlibs file and call dpkg-
              gensymbols

          dh_md5sums(1)
              generate DEBIAN/md5sums file

          dh_missing(1)
              check for missing files

          dh_movefiles(1)
              move files out of debian/tmp into subpackages

          dh_perl(1)
              calculates Perl dependencies and cleans up after
              MakeMaker

          dh_prep(1)
              perform cleanups in preparation for building a binary

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              package

          dh_shlibdeps(1)
              calculate shared library dependencies

          dh_strip(1)
              strip executables, shared libraries, and some static
              libraries

          dh_systemd_enable(1)
              enable/disable systemd unit files

          dh_systemd_start(1)
              start/stop/restart systemd unit files

          dh_testdir(1)
              test directory before building Debian package

          dh_testroot(1)
              ensure that a package is built with necessary level of
              root permissions

          dh_ucf(1)
              register configuration files with ucf

          dh_update_autotools_config(1)
              Update autotools config files

          dh_usrlocal(1)
              migrate usr/local directories to maintainer scripts

        Deprecated Commands
          A few debhelper commands are deprecated and should not be
          used.

          dh_installmanpages(1)
              old-style man page installer (deprecated)

        Other Commands
          If a program's name starts with dh_, and the program is not
          on the above lists, then it is not part of the debhelper
          package, but it should still work like the other programs
          described on this page.

     DEBHELPER CONFIG FILES
          Many debhelper commands make use of files in debian/ to
          control what they do. Besides the common debian/changelog
          and debian/control, which are in all packages, not just
          those using debhelper, some additional files can be used to
          configure the behavior of specific debhelper commands. These
          files are typically named debian/package.foo (where package
          of course, is replaced with the package that is being acted

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          on).

          For example, dh_installdocs uses files named
          debian/package.docs to list the documentation files it will
          install. See the man pages of individual commands for
          details about the names and formats of the files they use.
          Generally, these files will list files to act on, one file
          per line. Some programs in debhelper use pairs of files and
          destinations or slightly more complicated formats.

          Note for the first (or only) binary package listed in
          debian/control, debhelper will use debian/foo when there's
          no debian/package.foo file.  However, it is often a good
          idea to keep the package. prefix as it is more explicit.
          The primary exception to this are files that debhelper by
          default installs in every binary package when it does not
          have a package prefix (such as debian/copyright or
          debian/changelog).

          In some rare cases, you may want to have different versions
          of these files for different architectures or OSes. If files
          named debian/package.foo.ARCH or debian/package.foo.OS
          exist, where ARCH and OS are the same as the output of
          "dpkg-architecture -qDEB_HOST_ARCH" / "dpkg-architecture
          -qDEB_HOST_ARCH_OS", then they will be used in preference to
          other, more general files.

          Mostly, these config files are used to specify lists of
          various types of files. Documentation or example files to
          install, files to move, and so on.  When appropriate, in
          cases like these, you can use standard shell wildcard
          characters (? and * and [..] character classes) in the
          files.  You can also put comments in these files; lines
          beginning with # are ignored.

          The syntax of these files is intentionally kept very simple
          to make them easy to read, understand, and modify.

        Substitutions in debhelper config files
          In compatibility level 13 and later, it is possible to use
          simple substitutions in debhelper config files for the
          following tools:

          +o   dh_clean

          +o   dh_install

          +o   dh_installcatalogs

          +o   dh_installdeb

          +o   dh_installdirs

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          +o   dh_installdocs

          +o   dh_installexamples

          +o   dh_installinfo

          +o   dh_installman

          +o   dh_installwm

          +o   dh_link

          +o   dh_missing

          +o   dh_ucf

          All substitution variables are of the form ${foo} and the
          braces are mandatory.  Variable names are case-sensitive and
          consist of alphanumerics (a-zA-Z0-9), hyphens (-),
          underscores (_), and colons (:).  The first character must
          be an alphanumeric.

          If you need a literal dollar sign that cannot trigger a
          substitution, you can either use the ${Dollar} substitution
          or the sequence ${}.

          The following expansions are available:

          DEB_HOST_*, DEB_BUILD_*, DEB_TARGET_*
              Expands to the relevant dpkg-architecture(1) value
              (similar to dpkg-architecture -qVARIABLE_HERE).

              When in doubt, the DEB_HOST_* variant is the one that
              will work both for native and cross builds.

              For performance reasons, debhelper will attempt to
              resolve these names from the environment first before
              consulting dpkg-architecture(1).  This is mostly
              mentioned for completeness as it will not matter for
              most cases.

          Dollar
              Expands to a single literal $-symbol.  This symbol will
              never be considered part of a substitution variable.
              That is:

                 # Triggers an error
                 ${NO_SUCH_TOKEN}
                 # Expands to the literal value "${NO_SUCH_TOKEN}"
                 ${Dollar}{NO_SUCH_TOKEN}

              This variable equivalent to the sequence ${} and the two

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              can be used interchangeably.

          Newline, Space, Tab
              Expands to a single ASCII newline, space and tab
              respectively.

              This can be useful if you need to include a literal
              whitespace character (e.g. space) where it would
              otherwise be stripped or used as a separator.

          env:_NNNN_AAAA_MMMM_EEEE
              Expands to the environment variable NAME.  The
              environment variable must be set (but can be set to the
              empty string).

          Note that all variables must expand to a defined value.  As
          an example, if debhelper sees ${env:FOO}, then it will
          insist that the environment variable FOO is set (it can be
          set to the empty string).

          Substitution limits

          To avoid infinite loops and resource exhaustion, debhelper
          will stop with an error if the text contains many
          substitution variables (50) or they expand beyond a certain
          size (4096 characters or 3x length of the original input -
          whichever is bigger).

        Executable debhelper config files
          If you need additional flexibility, many of the debhelper
          tools (e.g. dh_install(1)) support executing a config file
          as a script.

          To use this feature, simply mark the config file as
          executable (e.g. chmod +x debian/_pppp_aaaa_cccc_kkkk_aaaa_gggg_eeee.install) and the
          tool will attempt to execute it and use the output of the
          script.  In many cases, you can use dh-exec(1) as
          interpreter of the config file to retain most of the
          original syntax while getting the additional flexibility you
          need.

          When using executable debhelper config files, please be
          aware of the following:

          +o   The executable config file must exit with success (i.e.
              its return code should indicate success).

          +o   In compatibility level 13+, the output will be subject
              to substitutions (see "Substitutions in debhelper config
              files") where the tool support these.  Remember to be
              careful if your generator also provides substitutions as
              this can cause unnecessary confusion.

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              Otherwise, the output will be used exactly as-is.
              Notably, debhelper will not expand wildcards or strip
              comments or strip whitespace in the output.

          If you need the package to build on a file system where you
          cannot disable the executable bit, then you can use
          dh-exec(1) and its strip-output script.

     SHARED DEBHELPER OPTIONS
          The following command line options are supported by all
          debhelper programs.

          -v, --verbose
              Verbose mode: show all commands that modify the package
              build directory.

          --no-act
              Do not really do anything. If used with -v, the result
              is that the command will output what it would have done.

          -a, --arch
              Act on architecture dependent packages that should be
              built for the DEB_HOST_ARCH architecture.

          -i, --indep
              Act on all architecture independent packages.

          -ppackage, --package=package
              Act on the package named package. This option may be
              specified multiple times to make debhelper operate on a
              given set of packages.

          -s, --same-arch
              Deprecated alias of -a.

              This option is removed in compat 12.

          -Npackage, --no-package=package
              Do not act on the specified package even if an -a, -i,
              or -p option lists the package as one that should be
              acted on.

          --remaining-packages
              Do not act on the packages which have already been acted
              on by this debhelper command earlier (i.e. if the
              command is present in the package debhelper log).  For
              example, if you need to call the command with special
              options only for a couple of binary packages, pass this
              option to the last call of the command to process the
              rest of packages with default settings.

          -Ptmpdir, --tmpdir=tmpdir

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              Use tmpdir for package build directory. The default is
              debian/package

          --mainpackage=package
              This little-used option changes the package which
              debhelper considers the "main package", that is, the
              first one listed in debian/control, and the one for
              which debian/foo files can be used instead of the usual
              debian/package.foo files.

          -O=option|bundle
              This is used by dh(1) when passing user-specified
              options to all the commands it runs. If the command
              supports the specified option or option bundle, it will
              take effect. If the command does not support the option
              (or any part of an option bundle), it will be ignored.

     COMMON DEBHELPER OPTIONS
          The following command line options are supported by some
          debhelper programs.  See the man page of each program for a
          complete explanation of what each option does.

          -n  Do not modify postinst, postrm, etc. scripts.

          -Xitem, --exclude=item
              Exclude an item from processing. This option may be used
              multiple times, to exclude more than one thing. The item
              is typically part of a filename, and any file containing
              the specified text will be excluded.

          -A, --all
              Makes files or other items that are specified on the
              command line take effect in ALL packages acted on, not
              just the first.

     BUILD SYSTEM OPTIONS
          The following command line options are supported by all of
          the dh_auto_* debhelper programs. These programs support a
          variety of build systems, and normally heuristically
          determine which to use, and how to use them.  You can use
          these command line options to override the default behavior.
          Typically these are passed to dh(1), which then passes them
          to all the dh_auto_* programs.

          -Sbuildsystem, --buildsystem=buildsystem
              Force use of the specified buildsystem, instead of
              trying to auto-select one which might be applicable for
              the package.

              Pass none as buildsystem to disable auto-selection.

          -Ddirectory, --sourcedir=directory, --sourcedirectory=directory

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              Assume that the original package source tree is at the
              specified directory rather than the top level directory
              of the Debian source package tree.

              Warning: The --sourcedir variant matches a similar named
              option in dh_install and dh_missing (etc.) for
              historical reasons.  While they have a similar name,
              they have very distinct purposes and in some cases it
              can cause errors when this variant is passed to dh (when
              then passes it on to all tools).

     --builddirectory[=directory]
          -B[directory], --builddir[=directory],
              Enable out of source building and use the specified
              directory as the build directory. If directory parameter
              is omitted, a default build directory will be chosen.

              If this option is not specified, building will be done
              in source by default unless the build system requires or
              prefers out of source tree building.  In such a case,
              the default build directory will be used even if
              --builddirectory is not specified.

              If the build system prefers out of source tree building
              but still allows in source building, the latter can be
              re-enabled by passing a build directory path that is the
              same as the source directory path.

          --parallel, --no-parallel
              Control whether parallel builds should be used if
              underlying build system supports them.  The number of
              parallel jobs is controlled by the DEB_BUILD_OPTIONS
              environment variable ("Debian Policy, section 4.9.1") at
              build time. It might also be subject to a build system
              specific limit.

              If neither option is specified, debhelper currently
              defaults to --parallel in compat 10 (or later) and
              --no-parallel otherwise.

              As an optimization, dh will try to avoid passing these
              options to subprocesses, if they are unnecessary and the
              only options passed.  Notably this happens when
              DEB_BUILD_OPTIONS does not have a parallel parameter (or
              its value is 1).

          --max-parallel=maximum
              This option implies --parallel and allows further
              limiting the number of jobs that can be used in a
              parallel build. If the package build is known to only
              work with certain levels of concurrency, you can set
              this to the maximum level that is known to work, or that

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              you wish to support.

              Notably, setting the maximum to 1 is effectively the
              same as using --no-parallel.

          --reload-all-buildenv-variables
              By default, dh(1) will compute several environment (e.g.
              by using dpkg-buildflags(1)) and cache them to avoid
              having all dh_auto_* tool recompute them.

              When passing this option, the concrete dh_auto_* tool
              will ignore the cache from dh(1) and retrigger a rebuild
              of these variables.  This is useful in the very rare
              case where the package need to do multiple builds but
              with different ...FLAGS options.  A concrete example
              would be needing to change the -O parameter in CFLAGS in
              the second build:

                  export DEB_CFLAGS_MAINT_APPEND=-O3

                  %:
                      dh $@

                  override_dh_auto_configure:
                      dh_auto_configure -Bbuild-deb ...
                      DEB_CFLAGS_MAINT_APPEND=-Os dh_auto_configure \
                         --reload-all-buildenv-variables -Bbuild-udeb ...

              Without --reload-all-buildenv-variables in the second
              call to dh_auto_configure(1), the change in
              DEB_CFLAGS_MAINT_APPEND would be ignored as
              dh_auto_configure(1) would use the cached value of
              CFLAGS set by dh(1).

              This option is only available with debhelper (>= 12.7~)
              when the package uses compatibility level 9 or later.

          --list, -l
              List all build systems supported by debhelper on this
              system. The list includes both default and third party
              build systems (marked as such). Also shows which build
              system would be automatically selected, or which one is
              manually specified with the --buildsystem option.

     COMPATIBILITY LEVELS
          From time to time, major non-backwards-compatible changes
          need to be made to debhelper, to keep it clean and well-
          designed as needs change and its author gains more
          experience. To prevent such major changes from breaking
          existing packages, the concept of debhelper compatibility
          levels was introduced. You must tell debhelper which
          compatibility level it should use, and it modifies its

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          behavior in various ways.

          In current debhelper, you can specify the compatibility
          level in debian/control by adding a Build-Depends on the
          debhelper-compat package.  For example, to use v13 mode,
          ensure debian/control has:

            Build-Depends: debhelper-compat (= 13)

          This also serves as an appropriate versioned build
          dependency on a sufficient version of the debhelper package,
          so you do not need to specify a separate versioned build
          dependency on the debhelper package unless you need a
          specific point release of debhelper (such as for the
          introduction of a new feature or bugfix within a
          compatibility level).

          Note that debhelper does not provide debhelper-compat for
          experimental or beta compatibility levels; packages
          experimenting with those compatibility levels should use
          debian/compat or DH_COMPAT.

          Prior versions of debhelper required specifying the
          compatibility level in the file debian/compat, and current
          debhelper still supports this for backward compatibility,
          though a package may not specify a compatibility level via
          multiple methods at once. To use this method, debian/compat
          should contain the compatibility level as a single number,
          and no other content. If you specify the compatibility level
          by this method, your package will also need a versioned
          build dependency on a version of the debhelper package equal
          to (or greater than) the compatibility level your package
          uses. So, if you specify compatibility level 13 in
          debian/compat, ensure debian/control has:

            Build-Depends: debhelper (>= 13~)

          Unless otherwise indicated, all debhelper documentation
          assumes that you are using the most recent compatibility
          level, and in most cases does not indicate if the behavior
          is different in an earlier compatibility level, so if you
          are not using the most recent compatibility level, you're
          advised to read below for notes about what is different in
          earlier compatibility levels.

        Supported compatibility levels
          These are the available compatibility levels:

          v5  This is the lowest supported compatibility level.

              If you are upgrading from an earlier compatibility
              level, please review debhelper-obsolete-compat(7).

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              This mode is deprecated.

          v6  Changes from v5 are:

              -       Commands that generate maintainer script
                      fragments will order the fragments in reverse
                      order for the prerm and postrm scripts.

              -       dh_installwm will install a slave manpage link
                      for x-window-manager.1.gz, if it sees the man
                      page in usr/share/man/man1 in the package build
                      directory.

              -       dh_builddeb did not previously delete everything
                      matching DH_ALWAYS_EXCLUDE, if it was set to a
                      list of things to exclude, such as
                      CVS:.svn:.git. Now it does.

              -       dh_installman allows overwriting existing man
                      pages in the package build directory. In
                      previous compatibility levels it silently
                      refuses to do this.

              This mode is deprecated.

          v7  Changes from v6 are:

              -       dh_install, will fall back to looking for files
                      in debian/tmp if it doesn't find them in the
                      current directory (or wherever you tell it look
                      using --sourcedir). This allows dh_install to
                      interoperate with dh_auto_install, which
                      installs to debian/tmp, without needing any
                      special parameters.

              -       dh_clean will read debian/clean and delete files
                      listed there.

              -       dh_clean will delete toplevel *-stamp files.

              -       dh_installchangelogs will guess at what file is
                      the upstream changelog if none is specified.

              This mode is deprecated.

          v8  Changes from v7 are:

              -       Commands will fail rather than warning when they
                      are passed unknown options.

              -       dh_makeshlibs will run dpkg-gensymbols on all
                      shared libraries that it generates shlibs files

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                      for. So -X can be used to exclude libraries.
                      Also, libraries in unusual locations that dpkg-
                      gensymbols would not have processed before will
                      be passed to it, a behavior change that can
                      cause some packages to fail to build.

              -       dh requires the sequence to run be specified as
                      the first parameter, and any switches come after
                      it. Ie, use "dh $@ --foo", not "dh --foo $@".

              -       dh_auto_* prefer to use Perl's Module::Build in
                      preference to Makefile.PL.

              This mode is deprecated.

          v9  Changes from v8 are:

              -       Multiarch support. In particular,
                      dh_auto_configure passes multiarch directories
                      to autoconf in --libdir and --libexecdir.

              -       dh is aware of the usual dependencies between
                      targets in debian/rules.  So, "dh binary" will
                      run any build, build-arch, build-indep, install,
                      etc targets that exist in the rules file.
                      There's no need to define an explicit binary
                      target with explicit dependencies on the other
                      targets.

              -       dh_strip compresses debugging symbol files to
                      reduce the installed size of -dbg packages.

              -       dh_auto_configure does not include the source
                      package name in --libexecdir when using
                      autoconf.

              -       dh does not default to enabling
                      --with=python-support

                      (Obsolete: As the dh_pysupport tool was removed
                      from Debian stretch.  Since debhelper/10.3, dh
                      no longer enables this sequence add-on
                      regardless of compat level)

              -       All of the dh_auto_* debhelper programs and dh
                      set environment variables listed by dpkg-
                      buildflags, unless they are already set.

              -       dh_auto_configure passes dpkg-buildflags CFLAGS,
                      CPPFLAGS, and LDFLAGS to perl Makefile.PL and
                      Build.PL

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              -       dh_strip puts separated debug symbols in a
                      location based on their build-id.

              -       Executable debhelper config files are run and
                      their output used as the configuration.

              This mode is deprecated.

          v10 Changes from v9 are:

              -       dh_installinit will no longer install a file
                      named debian/package as an init script.

              -       dh_installdocs will error out if it detects
                      links created with --link-doc between packages
                      of architecture "all" and non-"all" as it breaks
                      binNMUs.

              -       dh_installdeb no longer installs a maintainer-
                      provided debian/package.shlibs file.  This is
                      now done by dh_makeshlibs instead.

              -       dh_installwm refuses to create a broken package
                      if no man page can be found (required to
                      register for the x-window-manager alternative).

              -       Debhelper will default to --parallel for all
                      buildsystems that support parallel building.
                      This can be disabled by using either
                      --no-parallel or passing --max-parallel with a
                      value of 1.

              -       The dh command will not accept any of the
                      deprecated "manual sequence control" parameters
                      (--before, --after, etc.).  Please use override
                      targets instead.

                      Retroactively applied to earlier compat levels:
                      dh no longer accepts any of these since
                      debhelper/12.4.

              -       The dh command will no longer use log files to
                      track which commands have been run.  The dh
                      command still keeps track of whether it already
                      ran the "build" sequence and skip it if it did.

                      The main effects of this are:

                      -   With this, it is now easier to debug the
                          install or/and binary sequences because they
                          can now trivially be re-run (without having
                          to do a full "clean and rebuild" cycle)

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                      -   The main caveat is that dh_* now only keeps
                          track of what happened in a single override
                          target.  When all the calls to a given
                          dh_cmd command happens in the same override
                          target everything will work as before.

                          Example of where it can go wrong:

                            override_dh_foo:
                              dh_foo -pmy-pkg

                            override_dh_bar:
                              dh_bar
                              dh_foo --remaining

                          In this case, the call to dh_foo --remaining
                          will also include my-pkg, since dh_foo
                          -pmy-pkg was run in a separate override
                          target.  This issue is not limited to
                          --remaining, but also includes -a, -i, etc.

              -       The dh_installdeb command now shell-escapes the
                      lines in the maintscript config file.  This was
                      the original intent but it did not work properly
                      and packages have begun to rely on the
                      incomplete shell escaping (e.g. quoting file
                      names).

              -       The dh_installinit command now defaults to
                      --restart-after-upgrade.  For packages needing
                      the previous behaviour, please use
                      --no-restart-after-upgrade.

              -       The autoreconf sequence is now enabled by
                      default.  Please pass --without autoreconf to dh
                      if this is not desirable for a given package

              -       The systemd sequence is now enabled by default.
                      Please pass --without systemd to dh if this is
                      not desirable for a given package.

              -       Retroactively removed: dh no longer creates the
                      package build directory when skipping running
                      debhelper commands. This will not affect
                      packages that only build with debhelper
                      commands, but it may expose bugs in commands not
                      included in debhelper.

                      This compatibility feature had a bug since its
                      inception in debhelper/9.20130516 that made it
                      fail to apply in compat 9 and earlier.  As there
                      has been no reports of issues caused by this bug

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                      in those ~5 years, this item have been removed
                      rather than fixed.

          v11 This mode is discouraged.

              The compat 11 is discouraged for new packages as it
              suffers from feature interaction between dh_installinit
              and dh_installsystemd causing services to not run
              correctly in some cases.  Please consider using
              compatibility mode 10 or 12 instead.  More details about
              the issue are available in Debian#887904 and
              <https://lists.debian.org/debian-release/2019/04/msg01442.html>.

              Changes from v10 are:

              -       dh_installinit no longer installs service or
                      tmpfile files, nor generates maintainer scripts
                      for those files.  Please use the new
                      dh_installsystemd helper.

              -       The dh_systemd_enable and dh_systemd_start
                      helpers have been replaced by the new
                      dh_installsystemd helper.  For the same reason,
                      the systemd sequence for dh has also been
                      removed.  If you need to disable the
                      dh_installsystemd helper tool, please use an
                      empty override target.

                      Please note that the dh_installsystemd tool has
                      a slightly different behaviour in some cases
                      (e.g. when using the --name parameter).

              -       dh_installdirs no longer creates debian/package
                      directories unless explicitly requested (or it
                      has to create a subdirectory in it).

                      The vast majority of all packages will be
                      unaffected by this change.

              -       The makefile buildsystem now passes
                      INSTALL="install --strip-program=true" to
                      make(1).  Derivative buildsystems (e.g.
                      configure or cmake) are unaffected by this
                      change.

              -       The autoconf buildsystem now passes
                      --runstatedir=/run to ./configure.

              -       The cmake buildsystem now passes
                      -DCMAKE_INSTALL_RUNSTATEDIR=/run to cmake(1).

              -       dh_installman will now prefer detecting the

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                      language from the path name rather than the
                      extension.

              -       dh_auto_install will now only create the
                      destination directory it needs.  Previously, it
                      would create the package build directory for all
                      packages.  This will not affect packages that
                      only build with debhelper commands, but it may
                      expose bugs in commands not included in
                      debhelper.

              -       The helpers dh_installdocs, dh_installexamples,
                      dh_installinfo, and dh_installman now error out
                      if their config has a pattern that does not
                      match anything or reference a path that does not
                      exist.

                      Known exceptions include building with the nodoc
                      profile, where the above tools will silently
                      permit failed matches where the patterns are
                      used to specify documentation.

              -       The helpers dh_installdocs, dh_installexamples,
                      dh_installinfo, and dh_installman now accept the
                      parameter --sourcedir with same meaning as
                      dh_install. Furthermore, they now also fall back
                      to debian/tmp like dh_install.

                      Migration note: A bug in debhelper 11 up to
                      11.1.5 made dh_installinfo incorrectly ignore
                      --sourcedir.

              -       The perl-makemaker and perl-build build systems
                      no longer pass -I. to perl.  Packages that still
                      need this behaviour can emulate it by using the
                      PERL5LIB environment variable.  E.g. by adding
                      export PERL5LIB=. in their debian/rules file (or
                      similar).

              -       The PERL_USE_UNSAFE_INC environment variable is
                      no longer set by dh or any of the dh_auto_*
                      tools.  It was added as a temporary work around
                      to avoid a lot of packages failing to build at
                      the same time.

                      Note this item will eventually become obsolete
                      as upstream intends to drop support for the
                      PERL_USE_UNSAFE_INC environment variable.  When
                      perl drops support for it, then this variable
                      will be removed retroactively from existing
                      compat levels as well.

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              -       The dh_makeshlibs helper will now exit with an
                      error if objdump returns a non-zero exit from
                      analysing a given file.

              -       The dh_installdocs and dh_installexamples tools
                      may now install most of the documentation in a
                      different path to comply with the recommendation
                      from Debian policy ยง12.3 (since version 3.9.7).

                      Note that if a given source package only
                      contains a single binary package in
                      debian/control or none of the packages are -doc
                      packages, then this change is not relevant for
                      that source package and you can skip to the next
                      change.

                      By default, these tools will now attempt to
                      determine a "main package for the documentation"
                      (called a doc-main-package from here on) for
                      every -doc package.  If they find such a doc-
                      main-package, they will now install the
                      documentation into the path /usr/share/doc/doc-
                      main-package in the given doc package.  I.e. the
                      path can change but the documentation is still
                      shipped in the -doc package.

                      The --doc-main-package option can be used when
                      the auto-detection is insufficient or to reset
                      the path to its previous value if there is a
                      reason to diverge from Debian policy
                      recommendation.

                      Some documentation will not be affected by this
                      change.  These exceptions include the copyright
                      file, changelog files, README.Debian, etc.
                      These files will still be installed in the path
                      /usr/share/doc/package.

              -       The dh_strip and dh_shlibdeps tools no longer
                      uses filename patterns to determine which files
                      to process.  Instead, they open the file and
                      look for an ELF header to determine if a given
                      file is an shared object or an ELF executable.

                      This change may cause the tools to process more
                      files than previously.

          v12 Changes from v11 are:

              -       The dh_makeshlibs tool now generates shlibs
                      files with versioned dependency by default.
                      This means that -VUpstream-Version (a.k.a. -V)

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                      is now the default.

                      If an unversioned dependency in the shlibs file
                      is wanted, this can be obtained by passing
                      -VNone instead.  However, please see
                      dh_makeshlibs(1) for the caveat of unversioned
                      dependencies.

              -       The -s (--same-arch) option is removed.  Please
                      use -a (--arch) instead.

              -       Invoking dh_clean -k now causes an error instead
                      of a deprecation warning.

              -       The --no-restart-on-upgrade option in
                      dh_installinit has been removed.  Please use the
                      new name --no-stop-on-upgrade

              -       There was a bug in the doit (and similar)
                      functions from Debian::Debhelper::Dh_Lib that
                      made them spawn a shell in one particular
                      circumstance.  This bug is now removed and will
                      cause helpers that rely on the bug to fail with
                      a "command not found"-error.

              -       The --list-missing and --fail-missing in
                      dh_install has been removed.  Please use
                      dh_missing and its corresponding options, which
                      can also see the files installed by other
                      helpers.

              -       The dh_installinit helper no longer installs
                      configuration for the upstart init system.
                      Instead, it will abort the build if it finds an
                      old upstart configuration file.  The error is
                      there to remind the package maintainer to ensure
                      the proper removal of the conffiles shipped in
                      previous versions of the package (if any).

              -       The dh_installdeb tool will do basic validation
                      of some dpkg-maintscript-helper(1) commands and
                      will error out if the commands appear to be
                      invalid.

              -       The dh_missing tool will now default to
                      --list-missing.

              -       The dh_makeshlibs tool will now only pass
                      libraries to dpkg-gensymbols(1) if the ELF
                      binary has a SONAME (containing ".so").

              -       The dh_compress tool no longer compresses

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                      examples (i.e. anything installed in
                      </usr/share/doc/package/examples>.)

              -       The standard sequence in dh now includes dh_dwz
                      and dh_installinitramfs by default.  This makes
                      the dwz and installinitramfs sequences obsolete
                      and they will now fail with an error.  If you
                      want to skip these commands, then please insert
                      an empty override target for them in
                      debian/rules (e.g. override_dh_dwz:)

              -       The build systems meson and autoconf no longer
                      explicitly set the --libexecdir variable and
                      thus relies on the build system default - which
                      should be /usr/libexec (per FHS 3.0, adopted in
                      Debian Policy 4.1.5).

                      If a particular upstream package does not use
                      the correct default, the parameter can often be
                      passed manually via dh_auto_configure(1).  E.g.
                      via the following example:

                          override_dh_auto_configure:
                              dh_auto_configure -- --libexecdir=/usr/libexec

                      Note the -- before the --libexecdir parameter.

              -       Retroactively removed in debhelper/13.5:

                      The dh_installdeb tool would no longer installs
                      the maintainer provided conffiles file as it was
                      deemed unnecessary.  However, the remove-on-
                      upgrade from dpkg/1.20 made the file relevant
                      again and dh_installdeb now installs it again in
                      compat levels 12+.

              -       The dh_installsystemd tool no longer relies on
                      dh_installinit for handling systemd services
                      that have a sysvinit alternative.  Both tools
                      must now be used in such a case to ensure the
                      service is properly started under both sysvinit
                      and systemd.

                      If you have an override for dh_installinit (e.g.
                      to call it with --no-start) then you will
                      probably need one for dh_installsystemd as well
                      now.

                      This change makes dh_installinit inject a
                      misc:Pre-Depends for init-system-helpers (>=
                      1.54~).  Please ensure that the package lists
                      ${misc:Pre-Depends} in its Pre-Depends field

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                      before upgrading to compat 12.

              -       The third-party dh_golang tool (from dh-golang
                      package) now defaults on honoring
                      DH_GOLANG_EXCLUDES variable for source
                      installation in -dev packages and not only
                      during the building process. Please set
                      DH_GOLANG_EXCLUDES_ALL to false to revert to the
                      previous behaviour. See
                      Debian::Debhelper::Buildsystem::golang(3pm) for
                      details and examples.

              -       dh_installsystemduser is now included in the dh
                      standard sequence by default.

              -       The python-distutils buildsystem is now removed.
                      Please use the third-party build system pybuild
                      instead.

          v13 This is the recommended mode of operation.

              Changes from v12 are:

              -       The meson+ninja build system now uses meson test
                      instead of ninja test when running the test
                      suite.  Any override of dh_auto_test that passes
                      extra parameters to upstream test runner should
                      be reviewed as meson test is not command line
                      compatible with ninja test.

              -       All debhelper like tools based on the official
                      debhelper library (including dh and the official
                      dh_* tools) no longer accepts abbreviated
                      command parameters.  At the same time, dh now
                      optimizes out calls to redundant dh_* helpers
                      even when passed long command line options.

              -       The ELF related debhelper tools (dh_dwz,
                      dh_strip, dh_makeshlibs, dh_shlibdeps) are now
                      only run for arch dependent packages by default
                      (i.e. they are excluded from *-indep targets and
                      are passed -a by default). If you need them for
                      *-indep targets, you can add an explicit Build-
                      Depends on dh-sequence-elf-tools.

              -       The third-party gradle build system (from
                      gradle-debian-helper package) now runs the
                      upstream-provided test suite automatically.  To
                      suppress such behavior, override dh_auto_test.

              -       The dh_installman tool now aborts if it sees
                      conflicting definitions of a manpage.  This

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                      typically happens if the upstream build system
                      is installing a compressed version and the
                      package lists an uncompressed version of the
                      manpage in debian/package.manpages.  Often the
                      easiest fix is to remove the manpage from
                      debian/package.manpages (assuming both versions
                      are identical).

              -       The dh_auto_* helpers now reset the environment
                      variables HOME and common XDG_* variable.
                      Please see description of the environment
                      variables in "ENVIRONMENT" for how this is
                      handled.

                      This feature changed between debhelper 13 and
                      debhelper 13.2.

              -       The dh command will now error if an override or
                      hook target for an obsolete command are present
                      in debian/rules (e.g.
                      override_dh_systemd_enable:).

              -       The dh_missing command will now default to
                      --fail-missing.  This can be reverted to a non-
                      fatal warning by explicitly passing
                      --list-missing like it was in compat 12.

                      If you do not want the warning either, please
                      omit the call to dh_missing.  If you use the dh
                      command sequencer, then you can do this by
                      inserting an empty override target in the
                      debian/rules file of the relevant package.  As
                      an example:

                          # Disable dh_missing
                          override_dh_missing:

              -       The dh command sequencer now runs
                      dh_installtmpfiles in the default sequence.  The
                      dh_installtmpfiles takes over handling of
                      tmpfiles.d configuration files.  Related
                      functionality in dh_installsystemd is now
                      disabled.

                      Note that dh_installtmpfiles responds to
                      debian/package.tmpfiles where dh_installsystemd
                      used a name without the trailing "s".

              -       Many dh_* tools now support limited variable
                      expansion via the ${foo} syntax.  In many cases,
                      this can be used to reference paths that contain
                      either spaces or dpkg-architecture(1) values.

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                      While this can reduce the need for dh-exec(1) in
                      some cases, it is not a replacement dh-exec(1)
                      in general.  If you need filtering, renaming,
                      etc., the package will still need dh-exec(1).

                      Please see "Substitutions in debhelper config
                      files" for syntax and available substitution
                      variables.  To dh_* tool writers, substitution
                      expansion occurs as a part of the filearray and
                      filedoublearray functions.

              -       The dh command sequencer will now skip all hook
                      and override targets for dh_auto_test, dh_dwz
                      and dh_strip when DEB_BUILD_OPTIONS lists the
                      relevant nocheck / nostrip options.

                      Any package relying on these targets to always
                      be run should instead move relevant logic out of
                      those targets.  E.g. non-test related packaging
                      code from override_dh_auto_test would have to be
                      moved to execute_after_dh_auto_build or
                      execute_before_dh_auto_install.

              -       The cmake buildsystem now passes
                      -DCMAKE_SKIP_INSTALL_ALL_DEPENDENCY=ON to
                      cmake(1) to speed up automatic installation
                      process. If for some reason you need previous
                      behavior, override the flag:

                          dh_auto_configure -- -DCMAKE_SKIP_INSTALL_ALL_DEPENDENCY=OFF ...

          v14 This compatibility level is still open for development;
              use with caution.

              Changes from v13 are:

              -       The cmake buildsystem now passes
                      -DCMAKE_SKIP_RPATH=ON and
                      -DCMAKE_BUILD_RPATH_USE_ORIGIN=ON to cmake(1) to
                      avoid some reproducibility issues.

                      This can cause issues with running binaries
                      directly from the build directories as they
                      might now require a manually set
                      LD_LIBRARY_PATH.  If you need to override this
                      change, we recommend that you try to pass the
                      -DCMAKE_SKIP_RPATH=OFF option first to see if
                      that fixes the problem (leaving
                      CMAKE_BUILD_RPATH_USE_ORIGIN at its new
                      default).  This should undo the need for
                      LD_LIBRARY_PATH and avoid the reproducibility
                      issues on Linux, where $ORIGIN is supported by

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                      the runtime linkers.

              -       The tool dh_installsysusers is now included in
                      the default sequence.

              -       Use of the dh_gconf command in override and hook
                      targets now causes an error.  The dh_gconf
                      command has been a no-op for years and was
                      removed in debhelper 13.4.

              -       The dh sequencer will warn if the single-binary
                      addon is implicitly activated to warn
                      maintainers of the pending compat 15 change in
                      dh_auto_install.

                      Maintainers are urged to either explicitly
                      activate the single-binary addon to preserve the
                      existing behaviour (e.g., by adding dh-
                      sequence-single-binary to Build-Depends), or
                      explicitly passing --destdir to dh_auto_install
                      if used and then passing --without single-binary
                      to dh (the latter to silence the warning).

                      The rationale for this change to avoid
                      "surprises" when adding a second binary package
                      later.  Previously, debhelper would silently
                      change behaviour often resulting in empty binary
                      packages being uploaded to the archive by
                      mistake. With the new behaviour, the single-
                      binary addon will detect the mismatch and warn
                      the maintainer of what is about to happen.

          v15 This compatibility level is still open for development;
              use with caution.

              Changes from v14 are:

              -       The dh_auto_install tool no longer defaults to
                      --destdir=debian/_pppp_aaaa_cccc_kkkk_aaaa_gggg_eeee for source packages
                      only producing a single binary.  If this
                      behaviour is wanted, the package should
                      explicitly activate the single-binary dh addon
                      (e.g., by adding dh-sequence-single-binary to
                      Build-Depends) or pass --destdir to
                      dh_auto_install.

                      The rationale for this change to avoid
                      "surprises" when adding a second binary package
                      later.  Previously, debhelper would silently
                      change behaviour often resulting in empty binary
                      packages being uploaded to the archive by
                      mistake. With the new behaviour, the single-

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                      binary addon will detect the mismatch and warn
                      the maintainer of what is about to happen.

     NOTES
        Multiple binary package support
          If your source package generates more than one binary
          package, debhelper programs will default to acting on all
          binary packages when run. If your source package happens to
          generate one architecture dependent package, and another
          architecture independent package, this is not the correct
          behavior, because you need to generate the architecture
          dependent packages in the binary-arch debian/rules target,
          and the architecture independent packages in the binary-
          indep debian/rules target.

          To facilitate this, as well as give you more control over
          which packages are acted on by debhelper programs, all
          debhelper programs accept the -a, -i, -p, and -s parameters.
          These parameters are cumulative. If none are given,
          debhelper programs default to acting on all packages listed
          in the control file, with the exceptions below.

          First, any package whose Architecture field in
          debian/control does not match the DEB_HOST_ARCH architecture
          will be excluded ("Debian Policy, section 5.6.8").

          Also, some additional packages may be excluded based on the
          contents of the DEB_BUILD_PROFILES environment variable and
          Build-Profiles fields in binary package stanzas in
          debian/control, according to the draft policy at
          <https://wiki.debian.org/BuildProfileSpec>.

          Interaction between package selections and Build-Profiles

          Build-Profiles affect which packages are included in the
          package selections mechanisms in debhelper.  Generally, the
          package selections are described from the assumption that
          all packages are enabled.  This section describes how the
          selections react when a package is disabled due to the
          active Build-Profiles (or lack of active Build-Profiles).

          -a/--arch, -i/--indep OR no selection options (a raw "dh_X" call)
              The package disabled by Build-Profiles is silently
              excluded from the selection.

              Note you will receive a warning if all packages related
              to these selections are disabled.  In that case, it
              generally does not make sense to do the build in the
              first place.

          -N package / --no-package package
              The option is accepted and effectively does nothing.

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          -p package / --package package
              The option is accepted, but debhelper will not act on
              the package.

          Note that it does not matter whether a package is enabled or
          disabled by default.

        Automatic generation of Debian install scripts
          Some debhelper commands will automatically generate parts of
          Debian maintainer scripts. If you want these automatically
          generated things included in your existing Debian maintainer
          scripts, then you need to add #DEBHELPER# to your scripts,
          in the place the code should be added.  #DEBHELPER# will be
          replaced by any auto-generated code when you run
          dh_installdeb.

          If a script does not exist at all and debhelper needs to add
          something to it, then debhelper will create the complete
          script.

          All debhelper commands that automatically generate code in
          this way let it be disabled by the -n parameter (see above).

          Note that the inserted code will be shell code, so you
          cannot directly use it in a Perl script. If you would like
          to embed it into a Perl script, here is one way to do that
          (note that I made sure that $1, $2, etc are set with the set
          command):

            my $temp="set -e\nset -- @ARGV\n" . << 'EOF';
            #DEBHELPER#
            EOF
            if (system($temp)) {
               my $exit_code = ($? >> 8) & 0xff;
               my $signal = $? & 0x7f;
               if ($exit_code) {
                   die("The debhelper script failed with error code: ${exit_code}");
               } else {
                   die("The debhelper script was killed by signal: ${signal}");
               }
            }

        Automatic generation of miscellaneous dependencies.
          Some debhelper commands may make the generated package need
          to depend on some other packages. For example, if you use
          dh_installdebconf(1), your package will generally need to
          depend on debconf. Or if you use dh_installxfonts(1), your
          package will generally need to depend on a particular
          version of xutils. Keeping track of these miscellaneous
          dependencies can be annoying since they are dependent on how
          debhelper does things, so debhelper offers a way to automate
          it.

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          All commands of this type, besides documenting what
          dependencies may be needed on their man pages, will
          automatically generate a substvar called ${misc:Depends}. If
          you put that token into your debian/control file, it will be
          expanded to the dependencies debhelper figures you need.

          This is entirely independent of the standard
          ${shlibs:Depends} generated by dh_makeshlibs(1), and the
          ${perl:Depends} generated by dh_perl(1).  You can choose not
          to use any of these, if debhelper's guesses don't match
          reality.

        Package build directories
          By default, all debhelper programs assume that the temporary
          directory used for assembling the tree of files in a package
          is debian/package.

          Sometimes, you might want to use some other temporary
          directory. This is supported by the -P flag. For example,
          "dh_installdocs -Pdebian/tmp", will use debian/tmp as the
          temporary directory. Note that if you use -P, the debhelper
          programs can only be acting on a single package at a time.
          So if you have a package that builds many binary packages,
          you will need to also use the -p flag to specify which
          binary package the debhelper program will act on.

        udebs
          Debhelper includes support for udebs. To create a udeb with
          debhelper, add "Package-Type: udeb" to the package's stanza
          in debian/control.  Debhelper will try to create udebs that
          comply with debian-installer policy, by making the generated
          package files end in .udeb, not installing any documentation
          into a udeb, skipping over preinst, postrm, prerm, and
          config scripts, etc.

     ENVIRONMENT
          This section describes some of the environment variables
          that influences the behaviour of debhelper or which
          debhelper interacts with.

          It is important to note that these must be actual
          environment variables in order to affect the behaviour of
          debhelper (not simply Makefile variables).  To specify them
          properly in debian/rules, be sure to "export" them. For
          example, "export DH_VERBOSE".

          DH_VERBOSE
              Set to 1 to enable verbose mode. Debhelper will output
              every command it runs. Also enables verbose build logs
              for some build systems like autoconf.

          DH_QUIET

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              Set to 1 to enable quiet mode. Debhelper will not output
              commands calling the upstream build system nor will dh
              print which subcommands are called and depending on the
              upstream build system might make that more quiet, too.
              This makes it easier to spot important messages but
              makes the output quite useless as buildd log.  Ignored
              if DH_VERBOSE is also set.

          DH_COMPAT
              Temporarily specifies what compatibility level debhelper
              should run at, overriding any value specified via
              Build-Depends on debhelper-compat or via the
              debian/compat file.

          DH_NO_ACT
              Set to 1 to enable no-act mode.

          DH_OPTIONS
              All debhelper tools will parse command line arguments
              listed in this variable before any command option (as if
              they had been prepended to the command line arguments).
              Unfortunately, some third-party provided tools may not
              support this variable and will ignore these command line
              arguments.

              When using dh(1), it can be passed options that will be
              passed on to each debhelper command, which is generally
              better than using DH_OPTIONS.

          DH_ALWAYS_EXCLUDE
              If set, this adds the value the variable is set to to
              the -X options of all commands that support the -X
              option. Moreover, dh_builddeb will rm -rf anything that
              matches the value in your package build tree.

              This can be useful if you are doing a build from a CVS
              source tree, in which case setting DH_ALWAYS_EXCLUDE=CVS
              will prevent any CVS directories from sneaking into the
              package you build. Or, if a package has a source tarball
              that (unwisely) includes CVS directories, you might want
              to export DH_ALWAYS_EXCLUDE=CVS in debian/rules, to make
              it take effect wherever your package is built.

              Multiple things to exclude can be separated with colons,
              as in DH_ALWAYS_EXCLUDE=CVS:.svn

          DH_EXTRA_ADDONS
              If set, this adds the specified dh addons to be run in
              the appropriate places in the sequence of commands. This
              is equivalent to specifying the addon to run with the
              --with flag in the debian/rules file. Any --without
              calls specifying an addon in this environment variable

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              will not be run.

              This is intended to be used by downstreams or specific
              local configurations that require a debhelper addon to
              be run during multiple builds without having to patch a
              large number of rules file. If at all possible, this
              should be avoided in favor of a --with flag in the rules
              file.

          DH_COLORS, DPKG_COLORS
              These variables can be used to control whether debhelper
              commands should use colors in their textual output.  Can
              be set to "always", "auto" (the default), or "never".

              Note that DPKG_COLOR also affects a number of dpkg
              related tools and debhelper uses it on the assumption
              that you want the same color setting for dpkg and
              debhelper.  In the off-hand chance you want different
              color setting for debhelper, you can use DH_COLORS
              instead or in addition to DPKG_COLORS.

          NO_COLOR
              If no explicit request for color has been given (e.g.
              DH_COLORS and DPKG_COLORS are both unset), the presence
              of this environment variable cause the default color
              setting to be "never".

              The variable is defined according to
              <https://no-color.org/>.  In this project, the
              environment variables (such as DH_COLORS) are considered
              an explicit request for color.

     FFLAGS, FCFLAGS, LDFLAGS
          CFLAGS, CPPFLAGS, CXXFLAGS, OBJCFLAGS, OBJCXXFLAGS, GCJFLAGS,
              By default (in any non-deprecated compat level),
              debhelper will automatically set these flags by using
              dpkg-buildflags(1), when they are unset.  If you need to
              change the default flags, please use the features from
              dpkg-buildflags(1) to do this (e.g.
              DEB_BUILD_MAINT_OPTIONS=hardening=all or
              DEB_CPPFLAGS_MAINT_APPEND=-DCUSTOM_MACRO=true) rather
              than setting the concrete variable directly.

          HOME, XDG_*
              In compat 13 and later, these environment variables are
              reset before invoking the upstream build system via the
              dh_auto_* helpers.  The variables HOME (all dh_auto_*
              helpers) and XDG_RUNTIME_DIR (dh_auto_test only) will be
              set to a writable directory. All remaining variables and
              XDG_RUNTIME_DIR (except for during dh_auto_test) will be
              cleared.

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              The HOME directory will be created as an empty directory
              but it will be reused between calls to dh_auto_*.  Any
              content will persist until explicitly deleted or
              dh_clean.

          DEB_BUILD_OPTIONS
              Please see "Supported flags in DEB_BUILD_OPTIONS" for
              this environment variable.

              Please note that this variable should not be altered by
              package maintainers inside debian/rules to change the
              behaviour of debhelper.  Instead, where the package
              maintainer need these features, they should look
              disabling the relevant feature directly (e.g. by
              overriding the concrete tools).

          DEB_MAINT_BUILD_OPTIONS
              This is a dpkg specific environment variable (see e.g.
              dpkg-buildflags(1)).  The debhelper tool suite silently
              ignores it.

              It is documented here because it has a similar name to
              DEB_BUILD_OPTIONS, which make some people mistakenly
              assume that debhelper will also react to this variable.

        Supported flags in DEB_BUILD_OPTIONS
          The debhelper tool suite reacts to the following flags in
          DEB_BUILD_OPTIONS.

          dherroron=obsolete-compat-levels
              This is a debhelper specific value.

              When dherroron is present and set to obsolete-compat-
              levels, then debhelper tools will promote deprecation
              warnings for usage of old soon to be removed compat
              levels into errors.

              This is useful for automated checking for code relying
              on deprecated compat levels that is scheduled for
              removal.

              This option is intended for testing purposes; not
              production builds.

          nostrip
              This value will change the content of the debs being
              built.  The .deb packages built when this is set is
              therefore not bit-for-bit reproducible with a regular
              build in the general case.

              This value will cause the official debhelper tools will
              skip actions and helpers that either remove, detach or

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              deduplicate debugging symbols in ELF binaries.

              This value affects dh_dwz(1) and dh_strip(1).

          nocheck
              This value will cause the official debhelper build
              systems to skip runs of upstream test suites.

              Package maintainers looking to avoid running the
              upstream tests should not rely on this.  Instead, they
              can add an empty override target to skip dh_auto_test.

              This value affects dh_auto_test(1).

          nodoc
              This value will change the content of the debs being
              built.  The .deb packages built when this is set is
              therefore not bit-for-bit reproducible with a regular
              build in the general case.

              This value will cause several debhelper tools to skip
              installation of documentation such as manpages or
              upstream provided documentation.  Additionally, the
              tools will also ignore if declared documentation is
              "missing" on the assumption that the documentation has
              not been built.

              This value effects tools like dh_installdocs(1), which
              knows it is working with documentation.

          noautodbgsym, noddebs
              The official name is autodbgsym.  The noddebs variant is
              accepted for historical reasons.

              This value causes debhelper to skip the generation of
              automatically generated debug symbol packages.

              This value affects dh_strip(1).

          parallel=N
              This value enables debhelper to use up to N threads or
              processes (subject to parameters like --no-parallel and
              --max-parallel=M).  Not all debhelper tools work with
              parallel tasks and may silently ignore the request.

              This value affects many debhelper tools.  Most notably
              dh_auto_*, which will attempt to run the underlying
              upstream build system with that number of threads.

          terse
              This value will cause the official debhelper build
              systems to configure upstream builds to be terse (i.e.

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              reduce verbosity in their output).  This is subject to
              the upstream and the debhelper build system supporting
              such features.

              This value affects most dh_auto_* tools.

          Unknown flags are silently ignored.

          Note third-party debhelper-like tools or third-party
          provided build systems may or may not react to the above
          flags.  This tends to depend on implementation details of
          the tool.

     SEE ALSO
          /usr/share/doc/debhelper/examples/
              A set of example debian/rules files that use debhelper.

          <http://joeyh.name/code/debhelper/>
              Debhelper web site.

     AUTHOR
          Joey Hess <joeyh@debian.org>

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