Chapter 4. Required files under the debian directory

This file contains various values which dpkg, dselect, apt-get, apt-cache, aptitude, and other package management tools will use to manage the package. It is defined by the Debian Policy Manual, 5 "Control files and their fields".

Here is the control file dh_make created for us:

 1 Source: gentoo
 2 Section: unknown
 3 Priority: optional
 4 Maintainer: Josip Rodin <joy-mg@debian.org>
 5 Build-Depends: debhelper (>=10)
 6 Standards-Version: 4.0.0
 7 Homepage: <insert the upstream URL, if relevant>
 8
 9 Package: gentoo
10 Architecture: any
11 Depends: ${shlibs:Depends}, ${misc:Depends}
12 Description: <insert up to 60 chars description>
13  <insert long description, indented with spaces>

(I've added the line numbers.)

Lines 1–7 are the control information for the source package. Lines 9–13 are the control information for the binary package.

Line 1 is the name of the source package.

Line 2 is the section of the distribution the source package goes into.

As you may have noticed, the Debian archive is divided into multiple areas: main (the free software), non-free (the not really free software) and contrib (free software that depends on non-free software). Each of these is divided into sections that classify packages into rough categories. So we have admin for administrator-only programs, devel for programmer tools, doc for documentation, libs for libraries, mail for email readers and daemons, net for network apps and daemons, x11 for X11 programs that don't fit anywhere else, and many more. ^[28]

Let's change it then to x11. (A main/ prefix is implied so we can omit it.)

Line 3 describes how important it is that the user installs this package. ^[29]

Section and priority are used by front-ends like aptitude when they sort packages and select defaults. Once you upload the package to Debian, the value of these two fields can be overridden by the archive maintainers, in which case you will be notified by email.

As this is a normal priority package and doesn't conflict with anything else, we will change the priority to optional.

Line 4 is the name and email address of the maintainer. Make sure that this field includes a valid To header for email, because after you upload it, the bug tracking system will use it to deliver bug emails to you. Avoid using commas, ampersands, or parentheses.

Line 5 includes the list of packages required to build your package as the Build-Depends field. You can also have the Build-Depends-Indep field as an additional line here. ^[30] Some packages like gcc and make which are required by the build-essential package are implied. If you need to have other tools to build your package, you should add them to these fields. Multiple entries are separated with commas; read on for the explanation of binary package dependencies to find out more about the syntax of these lines.

If you are not sure which one should be used, use the Build-Depends field to be on the safe side. ^[31]

To find out what packages your package needs to be built run the command:

$ dpkg-depcheck -d ./configure

To manually find exact build dependencies for /usr/bin/foo, execute

$ objdump -p /usr/bin/foo | grep NEEDED

and for each library listed (e.g., libfoo.so.6), execute

$ dpkg -S libfoo.so.6

Then just take the -dev version of every package as a Build-Depends entry. If you use ldd for this purpose, it will report indirect lib dependencies as well, resulting in the problem of excessive build dependencies.

gentoo also happens to require xlibs-dev, libgtk1.2-dev and libglib1.2-dev to build, so we'll add them here next to debhelper.

Line 6 is the version of the Debian Policy Manual standards this package follows, the one you read while making your package.

On line 7 you can put the URL of the software's upstream homepage.

Line 9 is the name of the binary package. This is usually the same as the name of the source package, but it doesn't necessarily have to be that way.

Line 10 describes the architectures the binary package can be compiled for. This value is usually one of the following depending on the type of the binary package: ^[32]

We leave line 10 as is since this is written in C. dpkg-gencontrol(1) will fill in the appropriate architecture value for any machine this source package gets compiled on.

If your package is architecture independent (for example, a shell or Perl script, or a document), change this to all, and read later in Section 4.4, “rules” about using the binary-indep rule instead of binary-arch for building the package.

Line 11 shows one of the most powerful features of the Debian packaging system. Packages can relate to each other in various ways. Apart from Depends, other relationship fields are Recommends, Suggests, Pre-Depends, Breaks, Conflicts, Provides, and Replaces.

The package management tools usually behave the same way when dealing with these relations; if not, it will be explained. (See dpkg(8), dselect(8), apt(8), aptitude(1), etc.)

Here is a simplified description of package relationships: ^[33]

All these fields have uniform syntax. They are a list of package names separated by commas. These package names may also be lists of alternative package names, separated by vertical bar symbols | (pipe symbols).

The fields may restrict their applicability to particular versions of each named package. The restriction of each individual package is listed in parentheses after its name, and should contain a relation from the list below followed by a version number value. The relations allowed are: <<, <=, =, >=, and >> for strictly lower, lower or equal, exactly equal, greater or equal, and strictly greater, respectively. For example,

Depends: foo (>= 1.2), libbar1 (= 1.3.4)
Conflicts: baz
Recommends: libbaz4 (>> 4.0.7)
Suggests: quux
Replaces: quux (<< 5), quux-foo (<= 7.6)

The last feature you need to know about is ${shlibs:Depends}, ${perl:Depends}, ${misc:Depends}, etc.

dh_shlibdeps(1) calculates shared library dependencies for binary packages. It generates a list of ELF executables and shared libraries it has found for each binary package. This list is used for substituting ${shlibs:Depends}.

dh_perl(1) calculates Perl dependencies. It generates a list of a dependencies on perl or perlapi for each binary package. This list is used for substituting ${perl:Depends}.

Some debhelper commands may cause the generated package to depend on some additional packages. All such commands generate a list of required packages for each binary package. This list is used for substituting ${misc:Depends}.

dh_gencontrol(1) generates DEBIAN/control for each binary package while substituting ${shlibs:Depends}, ${perl:Depends}, ${misc:Depends}, etc.

Having said all that, we can leave the Depends field exactly as it is now, and insert another line after it saying Suggests: file, because gentoo can use some features provided by the file package.

Line 9 is the Homepage URL. Let's assume this to be at http://www.obsession.se/gentoo/.

Line 12 is the short description. Terminals are conventionally 80 columns wide so this shouldn't be longer than about 60 characters. I'll change it to fully GUI-configurable, two-pane X file manager.

Line 13 is where the long description goes. This should be a paragraph which gives more details about the package. Column 1 of each line should be empty. There must be no blank lines, but you can put a single . (dot) in a column to simulate that. Also, there must be no more than one blank line after the long description. ^[34]

We can insert Vcs-* fields to document the Version Control System (VCS) location between lines 6 and 7. ^[35] Let's assume that the gentoo package has its VCS located in the Debian Alioth Git Service at git://git.debian.org/git/collab-maint/gentoo.git.

Finally, here is the updated control file:

 1 Source: gentoo
 2 Section: x11
 3 Priority: optional
 4 Maintainer: Josip Rodin <joy-mg@debian.org>
 5 Build-Depends: debhelper (>=10), xlibs-dev, libgtk1.2-dev, libglib1.2-dev
 6 Standards-Version: 4.0.0
 7 Vcs-Git: https://anonscm.debian.org/git/collab-maint/gentoo.git
 8 Vcs-browser: https://anonscm.debian.org/git/collab-maint/gentoo.git
 9 Homepage: http://www.obsession.se/gentoo/
10
11 Package: gentoo
12 Architecture: any
13 Depends: ${shlibs:Depends}, ${misc:Depends}
14 Suggests: file
15 Description: fully GUI-configurable, two-pane X file manager
16  gentoo is a two-pane file manager for the X Window System. gentoo lets the
17  user do (almost) all of the configuration and customizing from within the
18  program itself. If you still prefer to hand-edit configuration files,
19  they're fairly easy to work with since they are written in an XML format.
20  .
21  gentoo features a fairly complex and powerful file identification system,
22  coupled to an object-oriented style system, which together give you a lot
23  of control over how files of different types are displayed and acted upon.
24  Additionally, over a hundred pixmap images are available for use in file
25  type descriptions.
26  .
29  gentoo was written from scratch in ANSI C, and it utilizes the GTK+ toolkit
30  for its interface.

(I've added the line numbers.)

This file contains information about the copyright and license of the upstream sources. Debian Policy Manual, 12.5 "Copyright information" dictates its content and DEP-5: Machine-parseable debian/copyright provides guidelines for its format.

dh_make can give you a template copyright file. Let's use the --copyright gpl2 option here to get a template file for the gentoo package released under GPL-2.

You must fill in missing information to complete this file, such as the place you got the package from, the actual copyright notice, and the license. For certain common free software licenses (GNU GPL-1, GNU GPL-2, GNU GPL-3, LGPL-2, LGPL-2.1, LGPL-3, GNU FDL-1.2, GNU FDL-1.3, Apache-2.0, 3-Clause BSD, CC0-1.0, MPL-1.1, MPL-2.0 or the Artistic license), you can just refer to the appropriate file in the /usr/share/common-licenses/ directory that exists on every Debian system. Otherwise, you must include the complete license.

In short, here's what gentoo's copyright file should look like:

 1 Format: https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/
 2 Upstream-Name: gentoo
 3 Upstream-Contact: Emil Brink <emil@obsession.se>
 4 Source: http://sourceforge.net/projects/gentoo/files/
 5
 6 Files: *
 7 Copyright: 1998-2010 Emil Brink <emil@obsession.se>
 8 License: GPL-2+
 9
10 Files: icons/*
11 Copyright: 1998 Johan Hanson <johan@tiq.com>
12 License: GPL-2+
13
14 Files: debian/*
15 Copyright: 1998-2010 Josip Rodin <joy-mg@debian.org>
16 License: GPL-2+
17
18 License: GPL-2+
19  This program is free software; you can redistribute it and/or modify
20  it under the terms of the GNU General Public License as published by
21  the Free Software Foundation; either version 2 of the License, or
22  (at your option) any later version. 
23  .
24  This program is distributed in the hope that it will be useful,
25  but WITHOUT ANY WARRANTY; without even the implied warranty of
26  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
27  GNU General Public License for more details.
28  .
29  You should have received a copy of the GNU General Public License along
30  with this program; if not, write to the Free Software Foundation, Inc.,
31  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
32  .
33  On Debian systems, the full text of the GNU General Public
34  License version 2 can be found in the file
35  '/usr/share/common-licenses/GPL-2'.

(I've added the line numbers.)

Please follow the HOWTO provided by the ftpmasters and sent to debian-devel-announce: http://lists.debian.org/debian-devel-announce/2006/03/msg00023.html.

This is a required file, which has a special format described in Debian Policy Manual, 4.4 "debian/changelog". This format is used by dpkg and other programs to obtain the version number, revision, distribution, and urgency of your package.

For you, it is also important, since it is good to have documented all changes you have done. It will help people downloading your package to see whether there are issues with the package that they should know about. It will be saved as /usr/share/doc/gentoo/changelog.Debian.gz in the binary package.

dh_make created a default one, and this is what it looks like:

1  gentoo (0.9.12-1) unstable; urgency=medium
2
3   * Initial release. (Closes: #nnnn)  <nnnn is the bug number of your ITP>
4
5  -- Josip Rodin <joy-mg@debian.org>  Mon, 22 Mar 2010 00:37:31 +0100
6

(I've added the line numbers.)

Line 1 is the package name, version, distribution, and urgency. The name must match the source package name; distribution should be unstable, and urgency should be set to medium unless there is any particular reason for other values.

Lines 3-5 are a log entry, where you document changes made in this package revision (not the upstream changes — there is a special file for that purpose, created by the upstream authors, which you will later install as /usr/share/doc/gentoo/changelog.gz). Let's assume your ITP (Intent To Package) bug report number was 12345. New lines must be inserted just below the uppermost line that begins with * (asterisk). You can do it with dch(1). You can edit this manually with a text editor as long as you follow the formatting convention used by the dch(1).

In order to prevent a package being accidentally uploaded before completing the package, it is a good idea to change the distribution value to an invalid distribution value of UNRELEASED.

You will end up with something like this:

1  gentoo (0.9.12-1) UNRELEASED; urgency=low
2
3   * Initial Release. Closes: #12345
4   * This is my first Debian package.
5   * Adjusted the Makefile to fix $(DESTDIR) problems.
6
7  -- Josip Rodin <joy-mg@debian.org>  Mon, 22 Mar 2010 00:37:31 +0100
8

(I've added the line numbers.)

Once you are satisfied with all the changes and documented them in changelog, you should change the distribution value from UNRELEASED to the target distribution value unstable (or even experimental). ^[36]

You can read more about updating the changelog file later in Chapter 8, Updating the package.

Now we need to take a look at the exact rules that dpkg-buildpackage(1) will use to actually create the package. This file is in fact another Makefile, but different from the one(s) in the upstream source. Unlike other files in debian, this one is marked as executable.