dpkg/doc/deb.5

.\" Hey, Emacs!  This is an -*- nroff -*- source file.
.\" Authors: Raul Miller, Ian Jackson
.TH DEB 5 "1st July 1996" "Debian Project" "Debian GNU/Linux"
.SH NAME 
deb - Debian GNU/Linux binary package format
.SH SYNOPSIS
.IB filename .deb
.SH DESCRIPTION
The
.B .deb
format is the Debian binary package file format.  The format has
changed since Debian 0.93 and the new format is being phased in.  It
is understood by dpkg 0.93.76 and later, and is generated by default
by all versions of dpkg since 1.2.0 and all i386/ELF versions since
1.1.1elf.

The new format is described here.  Please see
.BR deb-old (5)
for details of the old format.
.SH FORMAT
The file is an
.B ar
archive with a magic number of
.BR !<arch> .
Note that many modern versions of
.B ar
create archives with different magic numbers.  Archives created in
this way will not be recognised by
.BR dpkg\-deb ,
though these
.B ar
programs do understand the magic number used by
.BR dpkg\-deb .

The first member is named
.B debian-binary
and contains a series of lines, separated by newlines.  Currently only
one line is present, the format version number, which is currently
.BR 2.0 .
Programs which read new-format archives should be prepared for the
minor number to be increased and new lines to be present, and should
ignore these if this is the case.

If the major number has changed an incompatible change has been made
and the program should stop; if it has not then the program can safely
continue, unless it encounters an unexpected member in the archive
(except at the end), as described below.

The second required member is named
.B control.tar.gz
and is a gzipped ustar containing the package control information, as
a series of plain files, of which the file
.B control
is mandatory and contains the core control information.  See the
.I dpkg Programmers' manual
for details of these files.  The control tarfile may optionally
contain an entry for
.RB ` . ',
the current directory.

The third and final required member is named
.B data.tar.gz
and contains the filesystem archive as a gzipped ustar.

These members must occur in this order.  Further members may be
defined in the future, and will if possible be placed after these
three.  Current implementations should ignore any additional members
after
.BR data.tar.gz .
Additional members defined in the future which need to be inserted
before
.B data.tar.gz
and which can safely be ignored by older programs will have names
starting with an underscore
.RB ` _ '.

New members which cannot safely be ignored will be inserted before
.B data.tar.gz
with names starting with something other than underscores, or will
cause the major version number to be increased.
.SH SEE ALSO
.BR deb (5),
.BR deb\-control (5),
.IR "dpkg Programmers' manual" ,
.BR dpkg\-deb (8)