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 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

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_computeautosubstvars(1)
    compute substvars relevant to most packages

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 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)
    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_movetousr(1)
    canonicalize location according to merged-/usr

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

dh_prep(1)
    perform cleanups in preparation for building a binary 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 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 if there is only one binary package listed in debian/control, then debhelper will use debian/foo when there's no debian/package.foo 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/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:

•   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:

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 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:NAME
    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 token contains many substitution variables (50) or the total size of the expanded value exceed a certain size (4096 characters or 3x length of the original input - whichever is bigger).

Note the limit is per token. Every helper decides its own definition of a token. The common case of files like debian/package.install, each token is a file/path name.

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 out.

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 commands that modify the package build directory.

    Note that verbose mode may also output other "internal" commands that do not directly affect 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
    Use tmpdir for package build directory. The default is debian/package

--mainpackage=package
    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/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
    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).

-B[directory], --builddir[=directory], --builddirectory[=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 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 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 $@

        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 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 v14 mode, ensure debian/control has:

  Build-Depends: debhelper-compat (= 14)

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 14 in debian/compat, ensure debian/control has:

  Build-Depends: debhelper (>= 14~)

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 yourself). Setting a global DH_COMPAT environment variable is not recommended.

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 debhelper-compat-upgrade-checklist(7).

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.

-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.

When inserting the #DEBHELPER# token into a script, consider whether any of the hand written code has a compelling reason to appear before the #DEBHELPER# token. The #DEBHELPER# token will generally contain the code that start (postinst) or stop (prerm/preinst) any services the package is providing. Often (but not always), it is better to let the code from #DEBHELPER# run first. Common exceptions include things like set -e, initializing debconf (when needed) and special-cases like generation or hand-written management of configuration files. These things should generally occur before the #DEBHELPER# token.

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.

As of compat 14, debhelper will automatically inject the relevant dependencies for you, since the dependency is done via a "relationship substvar" (see <https://lists.debian.org/debian-devel/2024/02/msg00230.html> and <https://lists.debian.org/debian-devel/2024/03/msg00030.html> for details).

In earlier compat levels, you have to manually specify the relevant substvars in the relevant fields. Typically, ${misc:Depends} for the Depends field and ${misc:Pre-Depends} for the Pre-Depends fields.

The variables listed here are entirely independent of the standard ${shlibs:Depends} generated by dh_makeshlibs(1), and the ${perl:Depends} generated by dh_perl(1). For compat 13 and earlier you will also have to add these to the respective fields when relevant.

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

DH_QUIET
    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 passed.

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

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 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.

CFLAGS, CPPFLAGS, CXXFLAGS, OBJCFLAGS, OBJCXXFLAGS, GCJFLAGS, FFLAGS, FCFLAGS, LDFLAGS
    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.

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_BUILD_MAINT_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 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.

notrimdch
    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 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).

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. 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 non-empty.

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

debhelper-compat-upgrade-checklist(7)
    List of supported compat levels and an upgrade checklist for each of them.

/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>