deb(5) dpkg suite deb(5)
deb - Debian binary package format
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).
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 (new style long
pathnames and long linknames, supported since dpkg 126.96.36.199; large file
metadata since dpkg 1.18.24), and the POSIX ustar format (long names
supported since dpkg 1.15.0). Unrecognized tar typeflags are
considered an error. Each tar entry size inside a tar archive is
limited to 11 ASCII octal digits, allowing for up to 8 GiB tar entries.
The GNU large file metadata support permits 95-bit tar entry sizes and
negative timestamps, and 63-bit UID, GID and device numbers.
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 188.8.131.52ubuntu2), as a series of
plain files, of which the file control is mandatory and contains the
core control information, the conffiles, triggers, shlibs and symbols
files contain optional control information, and the preinst, postinst,
prerm and postrm files are optional maintainer scripts. 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 184.108.40.206ubuntu2), bzip2 (with .bz2 extension, supported
since dpkg 1.10.24) or lzma (with .lzma extension, supported since dpkg
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
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
deb-old(5), dpkg-deb(1), deb-control(5), deb-conffiles(5)
deb-triggers(5), deb-shlibs(5), deb-symbols(5), deb-preinst(5),
deb-postinst(5), deb-prerm(5), deb-postrm(5).
1.19.7 2022-05-25 deb(5)
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