debhelper(7) — Linux manual page


debhelper(7)                    Debhelper                   debhelper(7)

NAME         top

       debhelper - the debhelper tool suite

SYNOPSIS         top

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

DESCRIPTION         top

       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

       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.


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

           tool for supporting debhelper tools and provide introspection

           automatically builds a package

           automatically cleans up after a build

           automatically configure a package prior to building

           automatically runs make install or similar

           automatically runs a package's test suites

           install bug reporting customization files into package build

           build Debian binary packages

           clean up package build directories

           compress files and fix symlinks in package build directories

           optimize DWARF debug information in ELF binaries via dwz

           fix permissions of files in package build directories

           generate and install control file

           Update caches of Freedesktop icons

           install files into package build directories

           install declarative alternative rules

           install and register SGML Catalogs

           install changelogs into package build directories

           install cron scripts into etc/cron.*

           install files into the DEBIAN directory

           install files used by debconf in package build directories

           create subdirectories in package build directories

           install documentation into package build directories

           register an Emacs add on package

           install example files into package build directories

           install GSettings overrides and set dependencies

           install if-up and if-down hooks

           install info files

           install service init files into package build directories

           install initramfs hooks and setup maintscripts

           install logcheck rulefiles into etc/logcheck/

           install logrotate config files

           install man pages into package build directories

           install Debian menu files into package build directories

           install mime files into package build directories

           register kernel modules

           install pam support files

           install ppp ip-up and ip-down files

           install systemd unit files

           install systemd unit files

           install and integrates systemd sysusers files

           install tmpfiles.d configuration files

           install udev rules files

           register a window manager

           register X fonts

           create symlinks in package build directories

           install lintian override files into package build directories

           list binary packages debhelper will act on

           automatically create shlibs file and call dpkg-gensymbols

           generate DEBIAN/md5sums file

           check for missing files

           move files out of debian/tmp into subpackages

           canonicalize location according to merged-/usr

           calculates Perl dependencies and cleans up after MakeMaker

           perform cleanups in preparation for building a binary package

           calculate shared library dependencies

           strip executables, shared libraries, and some static

           enable/disable systemd unit files

           start/stop/restart systemd unit files

           test directory before building Debian package

           ensure that a package is built with necessary level of root

           register configuration files with ucf

           Update autotools config files

           migrate usr/local directories to maintainer scripts

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

           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.


       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/ (where package of course, is
       replaced with the package that is being acted on).

       For example, dh_installdocs uses files named debian/
       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

       Note if there is only one binary package listed in
       debian/control, then debhelper will use debian/foo when there's
       no debian/ file.  In compat levels before compat 15,
       this fallback also occurs for the first binary package listed in
       debian/control when there are multiple binary packages. However,
       it is often a good idea to keep the package. prefix as it is more
       explicit and also required when upgrading to compat 15.

       Additionally, there are some special cases where debhelper will
       always fallback to a prefix-less version.  These are cases such
       as debian/copyright and debian/changelog, where the files are
       generally used and needed for all binary packages.

       In some rare cases, you may want to have different versions of
       these files for different architectures or OSes. If files named
       debian/ or debian/ 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:

       •   dh_clean

       •   dh_install

       •   dh_installcatalogs

       •   dh_installdeb

       •   dh_installdirs

       •   dh_installdocs

       •   dh_installexamples

       •   dh_installinfo

       •   dh_installman

       •   dh_installwm

       •   dh_link

       •   dh_missing

       •   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:

           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.

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

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

           This variable equivalent to the sequence ${} and the two can
           be used interchangeably.

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

           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.

           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

       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

       Substitution limitations: filtering

       The built-in substitution cannot be used to "filter" out content.
       Attempts to create "comments" or "empty lines" via substitution
       will result in those variables being considered a token in its
       own right with the content given.

       If you want filtering, consider using an executable debhelper
       config file with dh-exec as interpreter. The dh-exec tool
       supports several features out of the box. Though keep in mind
       that dh-exec has its own substitution logic that can feature
       interact with the one from debhelper.

   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/package.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:

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

       •   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. Notably, the commonly used dh-exec
           tool has its own substitution support.

           Otherwise, the output will be used exactly as-is.  Notably,
           debhelper will not expand wildcards or strip comments or
           strip whitespace in the output it reads. The dh-exec tool has
           an output filter on by default that will prune these things

       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.


       The following command line options are supported by all debhelper

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

           Note that verbose mode may also output other "internal"
           commands that do not directly affect the package build

           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.

           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

       -Ptmpdir, --tmpdir=tmpdir
           Use tmpdir for package build directory. The default is

           Deprecated: This option has no practical use in compat 15 or
           later as the behaviour it affects is removed in compat 15.

           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/ files.

           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.


       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


       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
           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

       -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

           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

           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).

           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 you wish to support.

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

           By default, dh(1) will compute several environment variables
           (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 $@

                   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.


       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 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

         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 put the compat level in
       the X-DH-Compat field of the source stanza of the debian/control
       file (or, if only for selected commands, the DH_COMPAT
       environment variable).

       Historically, debhelper required specifying the compatibility
       level in the file debian/compat, and debhelper up to version 14
       supports this for backward compatibility. To use this method, the
       debian/compat file 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~)

       Note that you must use exactly one method for specifying the
       default debhelper compat level of the package. Whenever possible,
       the debhelper-compat build-dependency is recommended.

       If needed be, the DH_COMPAT environment variable can be used to
       override the compat level for a given command.  The feature is
       mostly useful for either temporarily upgrading a few commands to
       a new compat level or keeping a few commands on a lower compat
       level.  The feature is best used sparingly as it effectively
       introduces special-cases into the debian/rules file that may be
       surprising to maintainers or reviewers (or, in the long term, to

       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
       The list of supported compatibility levels and the related
       upgrade check list has moved to

NOTES         top

   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

       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.

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

       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 $temp="set -e\nset -- @ARGV\n" . << 'EOF';
         if (system($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.

       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

       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.

       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         top

       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

           Set to a non-empty value to enable verbose mode.  Please see
           the -v / --verbose option for details.

           Set to a non-empty value 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 or -v / --verbose is

           Temporarily specifies what compatibility level debhelper
           should run at, overriding the default compat level of the
           source package.

           Set to 1 to enable no-act mode.

           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

           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.

           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

           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 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.

           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.

           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 <>.
           In this project, the environment variables (such as
           DH_COLORS) are considered an explicit request for color.

           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.

           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.

           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).

           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

           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

           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

           This value will cause the official debhelper tools will skip
           actions and helpers that either remove, detach or deduplicate
           debugging symbols in ELF binaries.

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

           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).

           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

           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.

           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

           This value will cause dh_installchangelogs(1) to act as if it
           had been passed the --no-trim option, forcing it to forgo
           removing older entries from changelogs.

       noautodbgsym, noddebs
           The official name is noautodbgsym.  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).

           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.

           This value will cause the official debhelper build systems to
           configure upstream builds to be terse (i.e. 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 directly. For
           commands provided by the debhelper package, it also causes
           the tools to act like the DH_QUIET environment variable was

       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         top

           List of supported compat levels and an upgrade checklist for
           each of them.

           A set of example debian/rules files that use debhelper.

           Debhelper web site.

AUTHOR         top

       Joey Hess <>

COLOPHON         top

       This page is part of the debhelper (helper programs for
       debian/rules) project.  Information about the project can be
       found at [unknown -- if you know, please contact man-] If you have a bug report for this manual page,
       send it to  This page was obtained from
       the project's upstream Git repository
       ⟨⟩ on 2024-06-14.
       (At that time, the date of the most recent commit that was found
       in the repository was 2024-06-09.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to

13.15.3                        2024-06-07                   debhelper(7)

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