path: root/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<-ppackage>] [B<-Npackage] [-Ptmpdir>]

=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 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. Debhelper commands are all named with a "dh_" prefix.
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 dh-make
package, which contains a L<dh_make|dh_make(1)> 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.

=head1 DEBHELPER COMMANDS

Here is the complete list of available debhelper commands. See their man
pages for additional documentation.

=over 4

#LIST#

=back

=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/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.

Note that if a package is the first (or only) binary package listed in
debian/control, debhelper will use debian/foo if no debian/package.foo
file can be found.

In some rare cases, you may want to have different versions of these files
for different architectures. If files named debian/package.foo.arch
exist, where "arch" is the same as the output of "dpkg --print-architecture",
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 ('?' and '*' and '[..]' character classes) in the files.

=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 all architecture dependent packages.

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

Act on all architecture independent packages.

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

Act on the package named "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 is a smarter version of the -a flag, that is used in some rare
circumstances. It understands that if the control file lists "Architecture: i386"
for the package, the package should not be acted on on other architectures. So
this flag makes the command act on all "Architecture: any" packages, as well
as on any packages that have the current architecture explicitly specified.
Contrast to the -a flag, which makes the command work on all packages that
are not architecture independant.

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

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.

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

Use "tmpdir" for package build directory. The default is debian/<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 debian/control, and the
one for which debian/foo files can be used instead of the usual
debian/package.foo files.

=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 postinst/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 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 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
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.

See F</usr/share/doc/debhelper/examples/rules.multi> for an example of how to
use this in a package that generates multiple binary packages.

=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
"#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 $temp="set -e\nset -- @ARGV\n" . << 'EOF';
  #DEBHELPER#
  EOF
  system ($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 dependant 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
L<dh_makeshlibs(1)>, and the ${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/<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.

=head2 Debhelper compatibility 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 compatability levels was 
introduced. You tell debhelper which compatability level it should use, and
it modifies its behavior in various ways.

You tell debhelper what compatability level to use by writing a number to
debian/compat. For example, to turn on V4 mode:

  % echo 4 > debian/compat

These are the available compatablity levels:

=over 4

=item V1

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

=item V2

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

=item V3

This mode works like V2, with the following additions:

=over 8

=item -

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

=item -

dh_makeshlibs makes the postinst and postrm scripts call ldconfig.

=item -

Every file in etc/ is automatically flagged as a conffile by dh_installdeb.

=back

=item V4

This is the reccommended mode of operation. It does everything V3 does,
plus:

=over 8

=item -

dh_makeshlibs -V will not include the debian part of the version number in
the generated dependancy line in the shlibs file.

=item -

You are encouraged to put the new ${misc:Depends} into debian/control to
suppliment the ${shlibs:Depends} field.

=item -

dh_fixperms will make all files in bin/ directories and in etc/init.d 
executable.

=item -

dh_link will correct existing links to conform with policy.

=back

=back

=head2 Doc directory symlinks

Sometimes it is useful to make a package not contain a /usr/share/doc/package
directory at all, instead placing just a dangling symlink in the binary
package, that points to some other doc directory. Policy says this is ok if
your package depends on the package whose doc directory it uses. To
accomplish this, just don't tell debhelper to install any documentation
files into the package, and use dh_link to set up the symlink (or do it by
hand), and debhelper should do the right thing: notice it is a dangling
symlink and not try to install a copyright file or changelog.

=head2 Other notes

In general, if any debhelper program needs a directory to exist under
debian/, it will create it. I haven't bothered to document this in all the
man pages, but for example, dh_installdeb knows to make debian/<package>/DEBIAN/
before trying to put files there, dh_installmenu knows you need a
debian/<package>/usr/lib/menu/ before installing the menu files, etc.

Once your package uses debhelper to build, be sure to add
debhelper to your Build-Depends line in debian/control. You should
build-depend on a verson of debhelper equal to (or greater than) the
debhelper compatability level your package uses. So if your package used
compatability level 4:

  Build-Depends: debhelper (>= 4)

=head1 ENVIRONMENT

=over 4

=item DH_VERBOSE

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

=item DH_COMPAT

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

=item DH_NO_ACT

Set to 1 to enable no-act mode.

=item DH_OPTIONS

Anything in this variable will be prepended to the command line
arguments of all debhelper commands. This is useful in some situations,
for example, if you need to pass -p to all debhelper commands that will be
run. If you use DH_OPTIONS, be sure to build depend on "debhelper >= 1.1.17" --
older debhelpers will ignore it and do things you don't want them to. One very
good way to set DH_OPTIONS is by using "Target-specific Variable Values" in
your debian/rules file. See the make documentation for details on doing this.

=item DH_ALWAYS_EXCLUDE

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.

=back

=head1 SEE ALSO

=over 4

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

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

=item L<http://kitenet.net/programs/debhelper/>

Debhelper web site.

=back

=head1 AUTHOR

Joey Hess <joeyh@debian.org>

=cut