Provided by: dpkg-dev_1.18.4ubuntu1.7_all 
NAME
deb - Debian binary package format
SYNOPSIS
filename.deb
DESCRIPTION
The .deb format is the Debian binary package file format. It is understood since dpkg 0.93.76, and is
generated by default since dpkg 1.2.0 and 1.1.1elf (i386/ELF builds).
The format described here is used since Debian 0.93; details of the old format are described in
deb-old(5).
FORMAT
The file is an ar archive with a magic value of !<arch>. Only the common ar archive format is supported,
with no long file name extensions, but with file names containing an optional trailing slash, which
limits their length to 15 characters (from the 16 allowed). File sizes are limited to 10 ASCII decimal
digits, allowing for up to approximately 9536.74 MiB member files.
The tar archives currently allowed are, the old-style (v7) format, the pre-POSIX ustar format, a subset
of the GNU format (only the new style long pathnames and long linknames, supported since dpkg 1.4.1.17),
and the POSIX ustar format (long names supported since dpkg 1.15.0). Unrecognized tar typeflags are
considered an error.
The first member is named debian-binary and contains a series of lines, separated by newlines. Currently
only one line is present, the format version number, 2.0 at the time this manual page was written.
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 should be able to safely continue, unless it encounters an unexpected member in
the archive (except at the end), as described below.
The second required member is named control.tar. It is a tar archive containing the package control
information, either not compressed (supported since dpkg 1.17.6), or compressed with gzip (with .gz
extension), xz (with .xz extension, supported since 1.17.6) or zstd (with .zst extension, supported since
1.18.4ubuntu1.7), as a series of plain files, of which the file control is mandatory and contains the
core control information. The control tarball may optionally contain an entry for ‘.’, the current
directory.
The third, last required member is named data.tar. It contains the filesystem as a tar archive, either
not compressed (supported since dpkg 1.10.24), or compressed with gzip (with .gz extension), xz (with .xz
extension, supported since dpkg 1.15.6), zstd (with .zst extension, supported since 1.18.4ubuntu1.7),
bzip2 (with .bz2 extension, supported since dpkg 1.10.24) or lzma (with .lzma extension, supported since
dpkg 1.13.25).
These members must occur in this exact order. Current implementations should ignore any additional
members after data.tar. Further members may be defined in the future, and (if possible) will be placed
after these three. Any additional members that may need to be inserted after debian-binary and before
control.tar or data.tar and which should be safely ignored by older programs, will have names starting
with an underscore, ‘_’.
Those new members which won't be able to be safely ignored will be inserted before data.tar with names
starting with something other than underscores, or will (more likely) cause the major version number to
be increased.
MEDIA TYPE
Current
application/vnd.debian.binary-package
Deprecated
application/x-debian-package
application/x-deb
SEE ALSO
deb-old(5), dpkg-deb(1), deb-control(5).