+ dh $@ --with python-central
+
+If your package uses autotools and you want to freshen F<config.sub> and
+F<config.guess> with newer versions from the B<autotools-dev> package
+at build time, you can use some commands provided in B<autotools-dev>
+that automate it, like this.
+
+ #!/usr/bin/make -f
+ %:
+ dh $@ --with autotools_dev
+
+Here is how to force use of Perl's B<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
+
+To patch your package using quilt, you can tell B<dh> to use quilt's B<dh>
+sequence addons like this:
+
+ #!/usr/bin/make -f
+ %:
+ dh $@ --with quilt
+
+Here is an example of overriding where the B<dh_auto_>I<*> 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 B<dh_auto_>I<*> commands to build
+in a subdirectory, which will be removed on B<clean>.
+
+ #!/usr/bin/make -f
+ %:
+ dh $@ --builddirectory=build
+
+If your package can be built in parallel, you can support parallel building
+as follows. Then B<dpkg-buildpackage -j> will work.
+
+ #!/usr/bin/make -f
+ %:
+ dh $@ --parallel
+
+Here is a way to prevent B<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:
+
+Sometimes, you may need to make an override target only run commands when a
+particular package is being built. This can be accomplished using
+L<dh_listpackages(1)> to test what is being built. For example:
+
+ #!/usr/bin/make -f
+ %:
+ dh $@
+
+ override_dh_fixperms:
+ dh_fixperms
+ ifneq (,$(filter foo, $(shell dh_listpackages)))
+ chmod 4755 debian/foo/usr/bin/foo
+ endif
+
+Finally, remember that you are not limited to using override targets in the
+rules file when using B<dh>. You can also explicitly define the regular
+rules file targets when it makes sense to do so. A common reason to do this
+is if your package needs different B<build-arch> and B<build-indep> targets.
+For example, a package with a long document build process can put it in
+B<build-indep>.
+
+ #!/usr/bin/make -f
+ %:
+ dh $@
+
+ binary: binary-arch binary-indep ;
+ binary-arch:: build-arch
+ binary-indep:: build-indep
+ build: build-arch build-indep ;
+ build-indep:
+ $(MAKE) docs
+ build-arch:
+ $(MAKE) bins
+
+=head1 INTERNALS
+
+If you're curious about B<dh>'s internals, here's how it works under the hood.
+
+Each debhelper command will record when it's successfully run in
+F<debian/package.debhelper.log>. (Which B<dh_clean> deletes.) So B<dh> can tell
+which commands have already been run, for which packages, and skip running
+those commands again.
+
+Each time B<dh> is run, 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. The B<--until>, B<--before>, B<--after>, and B<--remaining>
+options can override this behavior.
+
+A sequence can also run dependent targets in debian/rules. For
+example, the "binary" sequence runs the "install" target. This will
+show up in the dh output as "debian/rules install", but internally
+will be called "rules:install" in the sequence. The "install"
+sequence likewise runs "debian/rules build", internally named
+"rules:build".
+
+B<dh> uses the B<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.