dh

DH(1)                              Debhelper                             DH(1)

NAME
       dh - debhelper command sequencer

SYNOPSIS
       dh sequence [--with addon[,addon ...]] [--list] [debhelperoptions]

DESCRIPTION
       dh runs a sequence of debhelper commands. The supported sequences
       correspond to the targets of a debian/rules file: build-arch, build-
       indep, build, clean, install-indep, install-arch, install, binary-arch,
       binary-indep, and binary.

OVERRIDE AND HOOK TARGETS
       A debian/rules file using dh can override the command that is run at
       any step in a sequence, by defining an override target.  It is also
       possible to inject a commands before or after any step without
       affecting the step itself.

   Injecting commands before or after a step
       Note: This feature requires debhelper 12.8 or later plus the package
       must use compatibility mode 10 or later.

       To inject commands before dh_command, add a target named
       execute_before_dh_command to the rules files.  Similarly, if you want
       to inject commands after dh_command, add the target
       execute_after_dh_command.  Both targets can be used for the same
       dh_command and also even if the command is overridden (as described in
       "Overriding a command" below).

       When these targets are defined, dh will call the targets respectively
       before or after it would invoke dh_command (or its override target).

   Overriding a command
       To override dh_command, add a target named override_dh_command to the
       rules file. When it would normally run dh_command, dh will instead call
       that target. The override target can then run the command with
       additional options, or run entirely different commands instead. See
       examples below.

   Architecture dependent/independent override and hook targets
       The override and hook targets can also be defined to run only when
       building architecture dependent or architecture independent packages.
       Use targets with names like override_dh_command-arch and
       execute_afterdh_command-indep.

       This feature is available since debhelper 8.9.7 (for override targets)
       and 12.8 (for hook targets).

   Completely empty targets
       As a special optimization, dh will skip a target if it is completely
       empty.  This is mostly useful for override targets, where the command
       will simply be skipped without the overhead of invoking a dummy target.

       Note that the target has to be completely empty for this to work:

            # Skip dh_bar - the good and optimized way
            # Some rationale for skipping dh_bar goes here
            override_dh_bar:

            # Skip dh_foo - the slow way
            override_dh_foo:
               # Some rationale for skipping dh_foo goes here
               # (these comments causes a dummy target to be run)

   Verifying targets are picked up by dh
       If you want to confirm that dh has seen an override or a hook target,
       you can use the following command as an example:

           $ dh binary --no-act | grep dh_install | head -n5
                dh_installdirs
                dh_install
                debian/rules execute_after_dh_install
                dh_installdocs
                dh_installchangelogs

       The debian/rules execute_after_dh_install in the output, which signals
       that dh registered a execute_after_dh_install target and would run it
       directly after dh_install(1).

       Note that "Completely empty targets" will be omitted in the listing
       above.  This makes it a bit harder to spot as you are looking for the
       omission of a command name.  But otherwise, the principle remains the
       same.

OPTIONS
       --with addon[,addon ...]
           Add the debhelper commands specified by the given addon to
           appropriate places in the sequence of commands that is run. This
           option can be repeated more than once, or multiple addons can be
           listed, separated by commas.  This is used when there is a third-
           party package that provides debhelper commands. See the PROGRAMMING
           file for documentation about the sequence addon interface.

           A Build-Depends relation on the package dh-sequence-addon implies a
           --with addon. This avoids the need for an explicit --with in
           debian/rules that only duplicates what is already declared via the
           build dependencies in debian/control.  The relation can (since
           12.5) be made optional via e.g.  build-profiles.  This enables you
           to easily disable an addon that is only useful with certain
           profiles (e.g. to facilitate bootstrapping).

           Since debhelper 12.5, addons can also be activated in indep-only
           mode (via Build-Depends-Indep) or arch-only mode (via Build-
           Depends-Arch). Such addons are only active in the particular
           sequence (e.g. binary-indep) which simplifies dependency management
           for cross-builds.

           Please note that addons activated via Build-Depends-Indep or Build-
           Depends-Arch are subject to additional limitations to ensure the
           result is deterministic even when the addon is unavailable (e.g.
           during clean).  This implies that some addons are incompatible with
           these restrictions and can only be used via Build-Depends (or
           manually via debian/rules).  Currently, such addons can only add
           commands to sequences.

       --without addon
           The inverse of --with, disables using the given addon. This option
           can be repeated more than once, or multiple addons to disable can
           be listed, separated by commas.

       --list, -l
           List all available addons.

           When called only with this option, dh can be called from any
           directory (i.e. it does not need access to files from a source
           package).

       --no-act
           Prints commands that would run for a given sequence, but does not
           run them.

           Note that dh normally skips running commands that it knows will do
           nothing.  With --no-act, the full list of commands in a sequence is
           printed.

       Other options passed to dh are passed on to each command it runs. This
       can be used to set an option like -v or -X or -N, as well as for more
       specialised options.

EXAMPLES
       To see what commands are included in a sequence, without actually doing
       anything:

               dh binary-arch --no-act

       This is a very simple rules file, for packages where the default
       sequences of commands work with no additional options.

               #!/usr/bin/make -f
               %:
                       dh $@

       Often you'll want to pass an option to a specific debhelper command.
       The easy way to do with is by adding an override target for that
       command.

               #!/usr/bin/make -f
               %:
                       dh $@

               override_dh_strip:
                       dh_strip -Xfoo

               override_dh_auto_configure:
                       dh_auto_configure -- --with-foo --disable-bar

       Sometimes the automated dh_auto_configure(1) and dh_auto_build(1) can't
       guess what to do for a strange package. Here's how to avoid running
       either and instead run your own commands.

               #!/usr/bin/make -f
               %:
                       dh $@

               override_dh_auto_configure:
                       ./mondoconfig

               override_dh_auto_build:
                       make universe-explode-in-delight

       Another common case is wanting to do something manually before or after
       a particular debhelper command is run.

               #!/usr/bin/make -f
               %:
                       dh $@

               # Example assumes debhelper/12.8 and compat 10+
               execute_after_dh_fixperms:
                       chmod 4755 debian/foo/usr/bin/foo

       If you are on an older debhelper or compatibility level, the above
       example would have to be written as.

               #!/usr/bin/make -f
               %:
                       dh $@

               # Older debhelper versions or using compat 9 or lower.
               override_dh_fixperms:
                       dh_fixperms
                       chmod 4755 debian/foo/usr/bin/foo

       Python tools are not run by dh by default, due to the continual change
       in that area. Here is how to use dh_python2.

               #!/usr/bin/make -f
               %:
                       dh $@ --with python2

       Here is how to force use of Perl's Module::Build build system, which
       can be necessary if debhelper wrongly detects that the package uses
       MakeMaker.

               #!/usr/bin/make -f
               %:
                       dh $@ --buildsystem=perl_build

       Here is an example of overriding where the dh_auto_* commands find the
       package's source, for a package where the source is located in a
       subdirectory.

               #!/usr/bin/make -f
               %:
                       dh $@ --sourcedirectory=src

       And here is an example of how to tell the dh_auto_* commands to build
       in a subdirectory, which will be removed on clean.

               #!/usr/bin/make -f
               %:
                       dh $@ --builddirectory=build

       If your package can be built in parallel, please either use compat 10
       or pass --parallel to dh. Then dpkg-buildpackage -j will work.

               #!/usr/bin/make -f
               %:
                       dh $@ --parallel

       If your package cannot be built reliably while using multiple threads,
       please pass --no-parallel to dh (or the relevant dh_auto_* command):

               #!/usr/bin/make -f
               %:
                       dh $@ --no-parallel

       Here is a way to prevent dh from running several commands that you
       don't want it to run, by defining empty override targets for each
       command.

               #!/usr/bin/make -f
               %:
                       dh $@

               # Commands not to run:
               override_dh_auto_test override_dh_compress override_dh_fixperms:

       A long build process for a separate documentation package can be
       separated out using architecture independent overrides.  These will be
       skipped when running build-arch and binary-arch sequences.

               #!/usr/bin/make -f
               %:
                       dh $@

               override_dh_auto_build-indep:
                       $(MAKE) -C docs

               # No tests needed for docs
               override_dh_auto_test-indep:

               override_dh_auto_install-indep:
                       $(MAKE) -C docs install

       Adding to the example above, suppose you need to chmod a file, but only
       when building the architecture dependent package, as it's not present
       when building only documentation.

               # Example assumes debhelper/12.8 and compat 10+
               execute_after_dh_fixperms-arch:
                       chmod 4755 debian/foo/usr/bin/foo

INTERNALS
       If you're curious about dh's internals, here's how it works under the
       hood.

       In compat 10 (or later), dh creates a stamp file
       debian/debhelper-build-stamp after the build step(s) are complete to
       avoid re-running them.  It is possible to avoid the stamp file by
       passing --without=build-stamp to dh.  This makes "no clean" builds
       behave more like what some people expect at the expense of possibly
       running the build and test twice (the second time as root or under
       fakeroot(1)).

       Inside an override target, dh_* commands will create a log file
       debian/package.debhelper.log to keep track of which packages the
       command(s) have been run for.  These log files are then removed once
       the override target is complete.

       In compat 9 or earlier, each debhelper command will record when it's
       successfully run in debian/package.debhelper.log. (Which dh_clean
       deletes.) So dh can tell which commands have already been run, for
       which packages, and skip running those commands again.

       Each time dh is run (in compat 9 or earlier), it examines the log, and
       finds the last logged command that is in the specified sequence. It
       then continues with the next command in the sequence.

       A sequence can also run dependent targets in debian/rules.  For
       example, the "binary" sequence runs the "install" target.

       dh uses the DH_INTERNAL_OPTIONS environment variable to pass
       information through to debhelper commands that are run inside override
       targets. The contents (and indeed, existence) of this environment
       variable, as the name might suggest, is subject to change at any time.

       Commands in the build-indep, install-indep and binary-indep sequences
       are passed the -i option to ensure they only work on architecture
       independent packages, and commands in the build-arch, install-arch and
       binary-arch sequences are passed the -a option to ensure they only work
       on architecture dependent packages.

SEE ALSO
       debhelper(7)

       This program is a part of debhelper.

AUTHOR
       Joey Hess <joeyh@debian.org>

12.10ubuntu1                      2020-03-27                             DH(1)