3. Package Structure

Let's examine one example package a little bit closer. E.g. file 'parted_1.4.24-4_i386.deb' contains these three files:

$ ar tv parted_1.4.24-4_i386.deb
rw-r--r-- 0/0      4 Mar 28 13:46 2002 debian-binary
rw-r--r-- 0/0   1386 Mar 28 13:46 2002 control.tar.gz
rw-r--r-- 0/0  39772 Mar 28 13:46 2002 data.tar.gz

Now we can start to extract all files including the content of the tar files.

3.1. debian-binary

The content of this file is "2.0\n". This states the version of the deb file format. For 2.0 all other lines get ignored.

3.2. data.tar.gz

The 'data.tar.gz' file contains all the files that will be installed with their destination paths:

drwxr-xr-x root/root         0 2002-03-28 13:44:57 ./
drwxr-xr-x root/root         0 2002-03-28 13:44:49 ./sbin/
-rwxr-xr-x root/root     31656 2002-03-28 13:44:49 ./sbin/parted
drwxr-xr-x root/root         0 2002-03-28 13:44:38 ./usr/
drwxr-xr-x root/root         0 2002-03-28 13:44:41 ./usr/share/
drwxr-xr-x root/root         0 2002-03-28 13:44:38 ./usr/share/man/
drwxr-xr-x root/root         0 2002-03-28 13:44:52 ./usr/share/man/man8/
-rw-r--r-- root/root      1608 2002-03-28 13:44:37 ./usr/share/man/man8/parted.8.gz
drwxr-xr-x root/root         0 2002-03-28 13:44:41 ./usr/share/doc/
drwxr-xr-x root/root         0 2002-03-28 13:44:52 ./usr/share/doc/parted/
-rw-r--r-- root/root      1880 2002-03-07 14:20:08 ./usr/share/doc/parted/README.Debian
-rw-r--r-- root/root      1347 2002-02-27 01:40:50 ./usr/share/doc/parted/copyright
-rw-r--r-- root/root      6444 2002-03-28 13:37:33 ./usr/share/doc/parted/changelog.Debian.gz
-rw-r--r-- root/root     15523 2002-03-28 02:36:43 ./usr/share/doc/parted/changelog.gz

It must be the last file in the deb archive.

3.3. control.tar.gz

In our example this file has the following content:

-rw-r--r--    1 root     root         1336 Mar 28  2002 control
-rw-r--r--    1 root     root          388 Mar 28  2002 md5sums
-rwxr-xr-x    1 root     root          253 Mar 28  2002 postinst
-rwxr-xr-x    1 root     root          194 Mar 28  2002 prerm

'md5sums' contains for each file in data.tar.gz the md5sum. In our example the content looks like this:

1d15dcfb6bb23751f76a2b7b844d3c57  sbin/parted
4eb9cc2e192f1b997cf13ff0b921af74  usr/share/man/man8/parted.8.gz
2f356768104a09092e26a6abb012c95e  usr/share/doc/parted/README.Debian
a6259bd193f8f150c171c88df2158e3e  usr/share/doc/parted/copyright
7f8078127a689d647586420184fc3953  usr/share/doc/parted/changelog.Debian.gz
98f217a3bf8a7407d66fd6ac8c5589b7  usr/share/doc/parted/changelog.gz

Don't worry, the 'md5sum' file as well as the 'postinst' and 'prerm' files are not mandatory for your first package. But please take a note of their existence, every proper official Debian package has them for good reasons.

'prerm' and 'postinst' seem to take care of removing old documentation files and adding a link from doc to share/doc.

$ cat postinst
set -e
# Automatically added by dh_installdocs
if [ "$1" = "configure" ]; then
  if [ -d /usr/doc -a ! -e /usr/doc/parted -a -d /usr/share/doc/parted ]; then
    ln -sf ../share/doc/parted /usr/doc/parted
# End automatically added section

$ cat prerm
set -e
# Automatically added by dh_installdocs
if [ \( "$1" = "upgrade" -o "$1" = "remove" \) -a -L /usr/doc/parted ]; then
  rm -f /usr/doc/parted
# End automatically added section

And finally the most interesting file:

$ cat control
Package: parted
Version: 1.4.24-4
Section: admin
Priority: optional
Architecture: i386
Depends: e2fsprogs (>= 1.27-2), libc6 (>= 2.2.4-4), libncurses5 (>= \
5.2.20020112a-1), libparted1.4 (>= 1.4.13+14pre1), libreadline4 (>= \
4.2a-4), libuuid1
Suggests: parted-doc
Conflicts: fsresize
Replaces: fsresize
Installed-Size: 76
Maintainer: Timshel Knoll <timshel@debian.org>
Description: The GNU Parted disk partition resizing program
 GNU Parted is a program that allows you to create, destroy,
 resize, move and copy hard disk partitions. This is useful
 for creating space for new operating systems, reorganizing
 disk usage, and copying data to new hard disks.
 This package contains the Parted binary and manual page.
 Parted currently supports DOS, Mac, Sun, BSD, GPT and PC98
 disklabels/partition tables, as well as a 'loop' (raw disk)
 type which allows use on RAID/LVM. Filesystems supported are
 ext2, ext3, FAT (FAT16 and FAT32) and linux-swap. Parted can
 also detect HFS (Mac OS), JFS, NTFS, ReiserFS, UFS and XFS
 filesystems, but cannot create/remove/resize/check these
 filesystems yet.
 The nature of this software means that any bugs could cause
 massive data loss. While there are no known bugs at the moment,
 they could exist, so please back up all important files before
 running it, and do so at your own risk.

Further information about the control file can be obtained via 'man 5 deb-control'.