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debhelper

the debhelper tool suite

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

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.

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

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 directories
build Debian binary packages
clean up package build directories
compress files and fix symlinks in package build directories
fix permissions of files in package build directories
install GConf defaults files and register schemas
generate and install control file
Update caches of Freedesktop icons
install files into package build directories
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 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 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
move files out of debian/tmp into subpackages
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 libraries
test directory before building Debian package
ensure that a package is built as root
register configuration files with ucf
Update autotools config files
migrate usr/local directories to maintainer scripts

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

deprecated no-op
old-style man page installer (deprecated)
deprecated no-op
suid registration program (deprecated)
undocumented.7 symlink program (deprecated no-op)

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/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 for the first (or only) binary package listed in debian/control, debhelper will use debian/foo when there's no debian/package.foo file.

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. If you prefer power and complexity, you can make the file executable, and write a program that outputs whatever content is appropriate for a given situation. When you do so, the output is not further processed to expand wildcards or strip comments.

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

Verbose mode: show all commands that modify the package build directory.
Do not really do anything. If used with -v, the result is that the command will output what it would have done.
Act on architecture dependent packages that should be built for the build architecture.
Act on all architecture independent packages.
Act on the package named package. This option may be specified multiple times to make debhelper operate on a given set of packages.
This used to be a smarter version of the -a flag, but the -a flag is now equally smart.
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 settings.
Ignore the specified file. This can be used if debian/ contains a debhelper config file that a debhelper command should not act on. Note that debian/compat, debian/control, and debian/changelog can't be ignored, but then, there should never be a reason to ignore those files.

For example, if upstream ships a debian/init that you don't want dh_installinit to install, use --ignore=debian/init

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

Do not modify postinst, postrm, etc. scripts.
Exclude an item from processing. This option may be used multiple times, to exclude more than one thing. The \fIitem\fR is typically part of a filename, and any file containing the specified text will be excluded.
Makes files or other items that are specified on the command line take effect in ALL packages acted on, not just the first.

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.

Force use of the specified buildsystem, instead of trying to auto-select one which might be applicable for the package.
Assume that the original package source tree is at the specified directory rather than the top level directory of the Debian source package tree.
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.

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 unncessary 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.

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 tell debhelper which compatibility level it should use, and it modifies its behavior in various ways.

Tell debhelper what compatibility level to use by writing a number to debian/compat. For example, to turn on v9 mode:

  % echo 9 > debian/compat

Your package will also need a versioned build dependency on a version of debhelper equal to (or greater than) the compatibility level your package uses. So for compatibility level 9, ensure debian/control has:

  Build-Depends: debhelper (>= 9)

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.

These are the available compatibility levels:

This is the lowest supported compatibility level.

This mode is deprecated.

Changes from v3 are:
  • dh_makeshlibs -V will not include the Debian part of the version number in the generated dependency line in the shlibs file.
  • You are encouraged to put the new ${misc:Depends} into debian/control to supplement the ${shlibs:Depends} field.
  • dh_fixperms will make all files in bin/ directories and in etc/init.d executable.
  • dh_link will correct existing links to conform with policy.

This mode is deprecated.

Changes from v4 are:
  • Comments are ignored in debhelper config files.
  • dh_strip --dbg-package now specifies the name of a package to put debugging symbols in, not the packages to take the symbols from.
  • dh_installdocs skips installing empty files.
  • dh_install errors out if wildcards expand to nothing.
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.
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.
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 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 is the recommended mode of operation.

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

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 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.
  • 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 migrate to use override targets instead.
  • 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 affects 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)
  • 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 every thing 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.

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 build 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>.

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}");
     }
  }

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.

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.

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.

The following environment variables can influence the behavior of debhelper. It is important to note that these must be actual environment variables in order to function properly (not simply Makefile variables). To specify them properly in debian/rules, be sure to "export" them. For example, "export 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.
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.
Temporarily specifies what compatibility level debhelper should run at, overriding any value in debian/compat.
Set to 1 to enable no-act mode.
Anything in this variable will be prepended to the command line arguments of all debhelper commands.

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

/usr/share/doc/debhelper/examples/
A set of example debian/rules files that use debhelper.
<http://joeyh.name/code/debhelper/>
Debhelper web site.

Joey Hess <joeyh@debian.org>