Default sequence of debhelper

Question

I am trying to get a better understanding of debhelper's dh tool. As I understand it, dh is a frontend for various dh_* helper tools. These helper tools can both be called standalone or automatically from the dh tool. Usually a debian/rules file is created which somehow invokes dh and possibly overrides certain dh_* invocations. dh then seems to know which of the dh_* tools it needs to invoke and in which sequence.

The example under /usr/share/doc/debhelper/examples/rules.tiny contains the following as an example for a debian/rules file:

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

What is the sequence of dh_* helper tools that gets executed by dh as result of this rules file? And more importantly, how does dh determine this sequence and where is this documented.

Answer 1

The sequence of helper tools that will get executed depends on a few things:

1. what build target is being passed. these include: build-arch, build-indep, build, clean, install-indep, install-arch, install, binary-arch, binary-indep, and binary. The meanings of (most of) these are discussed in Debian Policy §4.9.
2. the Debhelper compat level (as found in the debian/compat file)
3. your version of Debhelper (although an effort is made to make different versions work the same given the same compat level)
4. what helper commands have already been run since the last clean (in debhelper compat levels 9 and lower)
5. what addons are being used (the --with and --without options)
6. what override targets exist in the makefile (e.g. override_dh_auto_test)

As you can see, it could be confusing to document which commands are run, in which order, for all the possible build targets and configuration arrangements (or even just for the most common ones). The way to know, therefore, is to use the --no-act argument to dh, with your build directory set up the way you want it.

Here is an example run with the binary target in a dummy build directory I've just made using dh_make, put into compat level 10. The exact commands or the exact ordering you will see will likely be slightly different:

~/dh-demo$ dh binary --no-act
    dh_testdir
    dh_update_autotools_config
    dh_autoreconf
    dh_auto_configure
    dh_auto_build
    dh_auto_test
    dh_testroot
    dh_prep
    dh_installdirs
    dh_auto_install
    dh_install
    dh_installdocs
    dh_installchangelogs
    dh_installexamples
    dh_installman
    dh_installcatalogs
    dh_installcron
    dh_installdebconf
    dh_installemacsen
    dh_installifupdown
    dh_installinfo
    dh_systemd_enable
    dh_installinit
    dh_systemd_start
    dh_installmenu
    dh_installmime
    dh_installmodules
    dh_installlogcheck
    dh_installlogrotate
    dh_installpam
    dh_installppp
    dh_installudev
    dh_installgsettings
    dh_bugfiles
    dh_ucf
    dh_lintian
    dh_gconf
    dh_icons
    dh_perl
    dh_usrlocal
    dh_link
    dh_installwm
    dh_installxfonts
    dh_strip_nondeterminism
    dh_compress
    dh_fixperms
    dh_strip
    dh_makeshlibs
    dh_shlibdeps
    dh_installdeb
    dh_gencontrol
    dh_md5sums
    dh_builddeb