doc tweak re target dependencies

[debhelper.git] / debhelper.pod

=head1 NAME

debhelper - the debhelper tool suite

=head1 SYNOPSIS

B<dh_>I<*> [B<-v>] [B<-a>] [B<-i>] [B<-s>] [B<--no-act>] [B<-p>I<package>] [B<-N>I<package>] [B<-P>I<tmpdir>]

=head1 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 F<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 F<debian/rules> file that uses debhelper will call several debhelper
commands in sequence, or use L<dh(1)> to automate this process. Examples of
rules files that use debhelper are in F</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 B<dh-make>
package, which contains a L<dh_make|dh_make(1)> command that partially
automates the process. For a more gentle introduction, the B<maint-guide> Debian 
package contains a tutorial about making your first package using debhelper.

=head1 DEBHELPER COMMANDS

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

=over 4

#LIST#

=back

=head2 Deprecated Commands

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

=over 4

#LIST_DEPRECATED#

=back

=head2 Other Commands

If a program's name starts with B<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.

=head1 DEBHELPER CONFIG FILES

Many debhelper commands make use of files in F<debian/> to control what they
do. Besides the common F<debian/changelog> and F<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/I<package>.foo (where I<package> of course,
is replaced with the package that is being acted on).

For example, B<dh_installdocs> uses files named F<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 that if a package is the first (or only) binary package listed in
F<debian/control>, debhelper will use F<debian/foo> if no F<debian/package.foo>
file can be found.

In some rare cases, you may want to have different versions of these files
for different architectures or OSes. If files named debian/I<package>.foo.I<ARCH>
or debian/I<package>.foo.I<OS> exist, where I<ARCH> and I<OS> are the same as the
output of "B<dpkg-architecture -qDEB_HOST_ARCH>" /
"B<dpkg-architecture -qDEB_HOST_ARCH_OS>",
then they will be used in preference to other, more general files.

In many cases, these config files are used to specify 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 (B<?> and B<*> and B<[>I<..>B<]> character classes) in the files.

You can also put comments in these files; lines beginning with B<#> are
ignored.

=head1 SHARED DEBHELPER OPTIONS

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

=over 4

=item B<-v>, B<--verbose>

Verbose mode: show all commands that modify the package build directory.

=item B<--no-act>

Do not really do anything. If used with -v, the result is that the command
will output what it would have done.

=item B<-a>, B<--arch>

Act on architecture dependent packages that should be built for the
build architecture.

=item B<-i>, B<--indep>

Act on all architecture independent packages.

=item B<-p>I<package>, B<--package=>I<package>

Act on the package named I<package>. This option may be specified multiple
times to make debhelper operate on a given set of packages.

=item B<-s>, B<--same-arch>

This used to be a smarter version of the B<-a> flag, but the B<-a> flag is now
equally smart.

=item B<-N>I<package>, B<--no-package=>I<package>

Do not act on the specified package even if an B<-a>, B<-i>, or B<-p> option lists
the package as one that should be acted on.

=item B<--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. 

=item B<--ignore=>I<file>

Ignore the specified file. This can be used if F<debian/> contains a debhelper
config file that a debhelper command should not act on. Note that
F<debian/compat>, F<debian/control>, and F<debian/changelog> can't be ignored, but
then, there should never be a reason to ignore those files.

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

=item B<-P>I<tmpdir>, B<--tmpdir=>I<tmpdir>

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

=item B<--mainpackage=>I<package>

This little-used option changes the package which debhelper considers the
"main package", that is, the first one listed in F<debian/control>, and the
one for which F<debian/foo> files can be used instead of the usual
F<debian/package.foo> files.

=item B<-O=>I<option>|I<bundle>

This is used by L<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.

=back

=head1 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.

=over 4

=item B<-n>

Do not modify F<postinst>, F<postrm>, etc. scripts.

=item B<-X>I<item>, B<--exclude=>I<item>

Exclude an item from processing. This option may be used multiple times,
to exclude more than one thing.

=item B<-A>, B<--all>

Makes files or other items that are specified on the command line take effect
in ALL packages acted on, not just the first.

=back

=head1 BUILD SYSTEM OPTIONS

All of the B<dh_auto_>I<*> debhelper programs set environment variables
listed by B<dpkg-buildflags>, unless they are already set. They
support DEB_BUILD_OPTIONS=noopt too.

The following command line options are supported by all of the B<dh_auto_>I<*>
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.

=over 4

=item B<-S>I<buildsystem>, B<--buildsystem=>I<buildsystem>

Force use of the specified I<buildsystem>, instead of trying to auto-select
one which might be applicable for the package.

=item B<-D>I<directory>, B<--sourcedirectory=>I<directory>

Assume that the original package source tree is at the specified
I<directory> rather than the top level directory of the Debian
source package tree.

=item B<-B>[I<directory>], B<--builddirectory=>[I<directory>]

Enable out of source building and use the specified I<directory> as the build
directory. If I<directory> parameter is omitted, a default build directory
will 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
B<--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.

=item B<--parallel>

Enable parallel builds if underlying build system supports them.
The number of parallel jobs is controlled by the
B<DEB_BUILD_OPTIONS> environment variable (L<Debian Policy, section 4.9.1>) at
build time. It might also be subject to a build system specific limit.

If this option is not specified, debhelper currently defaults to not
allowing parallel package builds.

=item B<--max-parallel=>I<maximum>

This option implies B<--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.

=item B<--list>, B<-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 B<--buildsystem> option.

=back

=head1 COMPATABILITY 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 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
F<debian/compat>. For example, to turn on v8 mode:

  % echo 8 > debian/compat

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:

=over 4

=item v1

This is the original debhelper compatibility level, and so it is the default
one. In this mode, debhelper will use F<debian/tmp> as the package tree
directory for the first binary package listed in the control file, while using
debian/I<package> for all other packages listed in the F<control> file.

This mode is deprecated.

=item v2

In this mode, debhelper will consistently use debian/I<package>
as the package tree directory for every package that is built.

This mode is deprecated.

=item v3

This mode works like v2, with the following additions:

=over 8

=item -

Debhelper config files support globbing via B<*> and B<?>, when appropriate. To
turn this off and use those characters raw, just prefix with a backslash.

=item -

B<dh_makeshlibs> makes the F<postinst> and F<postrm> scripts call B<ldconfig>.

=item -

Every file in F<etc/> is automatically flagged as a conffile by B<dh_installdeb>.

=back

This mode is deprecated.

=item v4

Changes from v3 are:

=over 8

=item -

B<dh_makeshlibs -V> will not include the Debian part of the version number in
the generated dependency line in the shlibs file.

=item -

You are encouraged to put the new B<${misc:Depends}> into F<debian/control> to
supplement the B<${shlibs:Depends}> field.

=item -

B<dh_fixperms> will make all files in F<bin/> directories and in F<etc/init.d>
executable.

=item -

B<dh_link> will correct existing links to conform with policy.

=back

This mode is deprecated.

=item v5

Changes from v4 are:

=over 8

=item -

Comments are ignored in debhelper config files.

=item -

B<dh_strip --dbg-package> now specifies the name of a package to put debugging
symbols in, not the packages to take the symbols from.

=item -

B<dh_installdocs> skips installing empty files.

=item -

B<dh_install> errors out if wildcards expand to nothing.

=back

=item v6

Changes from v5 are:

=over 8

=item -

Commands that generate maintainer script fragments will order the
fragments in reverse order for the F<prerm> and F<postrm> scripts.

=item -

B<dh_installwm> will install a slave manpage link for F<x-window-manager.1.gz>,
if it sees the man page in F<usr/share/man/man1> in the package build
directory.

=item -

B<dh_builddeb> did not previously delete everything matching
B<DH_ALWAYS_EXCLUDE>, if it was set to a list of things to exclude, such as
B<CVS:.svn:.git>. Now it does.

=item -

B<dh_installman> allows overwriting existing man pages in the package build
directory. In previous compatibility levels it silently refuses to do this.

=back

=item v7

Changes from v6 are:

=over 8

=item -

B<dh_install>, will fall back to looking for files in F<debian/tmp> if it doesn't
find them in the current directory (or wherever you tell it look using
B<--sourcedir>). This allows B<dh_install> to interoperate with B<dh_auto_install>,
which installs to F<debian/tmp>, without needing any special parameters.

=item -

B<dh_clean> will read F<debian/clean> and delete files listed there.

=item -

B<dh_clean> will delete toplevel F<*-stamp> files.

=item -

B<dh_installchangelogs> will guess at what file is the upstream changelog if
none is specified.

=back

=item v8

This is the recommended mode of operation.

Changes from v7 are:

=over 8

=item -

Commands will fail rather than warning when they are passed unknown options.

=item -

B<dh_makeshlibs> will run B<dpkg-gensymbols> on all shared libraries that it
generates shlibs files for. So B<-X> can be used to exclude libraries.
Also, libraries in unusual locations that B<dpkg-gensymbols> would not
have processed before will be passed to it, a behavior change that 
can cause some packages to fail to build.

=item -

B<dh> requires the sequence to run be specified as the first parameter, and
any switches come after it. Ie, use "B<dh $@ --foo>", not "B<dh --foo $@>".

=item -

B<dh_auto_>I<*> prefer to use Perl's B<Module::Build> in preference to F<Makefile.PL>.

=back

=item v9

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

Changes from v8 are:

=over 8

=item - 

Multiarch support. In particular, B<dh_auto_configure> passes
multiarch directories to autoconf in --libdir and --libexecdir.

=item -

dh allows defining custom build, build-arch, and build-indep targets
in debian/rules, without needing to manually define the other targets
that depend on them.

=item -

B<dh_auto_configure> does not include the source package name
in --libexecdir when using autoconf.

=item -

B<dh> does not default to enabling --with=python-support

=back

=back

=head1 NOTES

=head2 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 F<debian/rules> target, and the architecture independent packages
in the binary-indep F<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
B<-a>, B<-i>, B<-p>, and B<-s> parameters. These parameters are cumulative. 
If none are given, debhelper programs default to acting on all packages listed
in the control file.

=head2 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
B<#DEBHELPER#> to your scripts, in the place the code should be added.
B<#DEBHELPER#> will be replaced by any auto-generated code when you run
B<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 $temp="set -e\nset -- @ARGV\n" . << 'EOF';
  #DEBHELPER#
  EOF
  system ($temp) / 256 == 0
        or die "Problem with debhelper scripts: $!";

=head2 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 L<dh_installdebconf(1)>, your
package will generally need to depend on debconf. Or if you use
L<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
B<${misc:Depends}>. If you put that token into your F<debian/control> file, it
will be expanded to the dependencies debhelper figures you need. 

This is entirely independent of the standard B<${shlibs:Depends}> generated by
L<dh_makeshlibs(1)>, and the B<${perl:Depends}> generated by L<dh_perl(1)>.
You can choose not to use any of these, if debhelper's guesses don't match
reality.

=head2 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/I<package>.

Sometimes, you might want to use some other temporary directory. This is
supported by the B<-P> flag. For example, "B<dh_installdocs -Pdebian/tmp>", will
use B<debian/tmp> as the temporary directory. Note that if you use B<-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 B<-p> flag to specify which binary package the debhelper program will
act on.

=head2 udebs

Debhelper includes support for udebs. To create a udeb with debhelper,
add "B<Package-Type: udeb>" to the package's stanza in F<debian/control>, and
build-depend on debhelper (>= 4.2). Debhelper will try to create udebs that
comply with debian-installer policy, by making the generated package files
end in F<.udeb>, not installing any documentation into a udeb, skipping over
F<preinst>, F<postrm>, F<prerm>, and F<config> scripts, etc.

=head2 Build depends

Once your package uses debhelper to build, be sure to add
debhelper to your Build-Depends line in F<debian/control>. You should
build-depend on a version of debhelper equal to (or greater than) the
debhelper compatibility level your package uses. So if your package used
compatibility level 7:

  Build-Depends: debhelper (>= 7)

=head1 ENVIRONMENT

=over 4

=item B<DH_VERBOSE>

Set to B<1> to enable verbose mode. Debhelper will output every command it runs
that modifies files on the build system.

=item B<DH_COMPAT>

Temporarily specifies what compatibility level debhelper should run at,
overriding any value in F<debian/compat>.

=item B<DH_NO_ACT>

Set to B<1> to enable no-act mode.

=item B<DH_OPTIONS>

Anything in this variable will be prepended to the command line arguments
of all debhelper commands. Command-specific options will be ignored by 
commands that do not support them. 

This is useful in some situations, for example, if you need to pass B<-p> to
all debhelper commands that will be run. One good way to set B<DH_OPTIONS> is
by using "Target-specific Variable Values" in your F<debian/rules> file. See
the make documentation for details on doing this.

=item B<DH_ALWAYS_EXCLUDE>

If set, this adds the value the variable is set to to the B<-X> options of all
commands that support the B<-X> option. Moreover, B<dh_builddeb> will B<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 B<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
B<DH_ALWAYS_EXCLUDE=CVS> in F<debian/rules>, to make it take effect wherever
your package is built.

Multiple things to exclude can be separated with colons, as in
B<DH_ALWAYS_EXCLUDE=CVS:.svn>

=back

=head1 SEE ALSO

=over 4

=item F</usr/share/doc/debhelper/examples/>

A set of example F<debian/rules> files that use debhelper.

=item L<http://kitenet.net/~joey/code/debhelper/>

Debhelper web site.

=back

=head1 AUTHOR

Joey Hess <joeyh@debian.org>

=cut