Section: dpkg suite (7)
deb-version - Debian package version number format
Version numbers as used for Debian binary and source packages
consist of three components. These are:
This is a single (generally small) unsigned integer. It
may be omitted, in which case zero is assumed. If it is
omitted then the upstream-version may not
contain any colons.
It is provided to allow mistakes in the version numbers
of older versions of a package, and also a package's
previous version numbering schemes, to be left behind.
This is the main part of the version number. It is
usually the version number of the original ("upstream")
package from which the .deb file has been made,
if this is applicable. Usually this will be in the same
format as that specified by the upstream author(s);
however, it may need to be reformatted to fit into the
package management system's format and comparison
The comparison behavior of the package management system
with respect to the upstream-version is
described below. The upstream-version
portion of the version number is mandatory.
The upstream-version may contain only
alphanumerics ("A-Za-z0-9") and the characters
. + - : ~
(full stop, plus, hyphen, colon, tilde) and should
start with a digit. If there is no
debian-revision then hyphens are not allowed;
if there is no epoch then colons are not
This part of the version number specifies the version of
the Debian package based on the upstream version. It
may contain only alphanumerics and the characters
+ . ~
(plus, full stop, tilde) and is
compared in the same way as the
It is optional; if it isn't present then the
upstream-version may not contain a hyphen.
This format represents the case where a piece of
software was written specifically to be turned into a
Debian package, and so there is only one "debianization"
of it and therefore no revision indication is required.
It is conventional to restart the
debian-revision at '1' each time the
upstream-version is increased.
Dpkg will break the version
number apart at the last hyphen in the string (if there
is one) to determine the upstream-version and
debian-revision. The absence of a
debian-revision compares earlier than the
presence of one (but note that the debian-revision
is the least significant part of the version number).
parts are compared by the package management system using the
The strings are compared from left to right.
First the initial part of each string consisting entirely of
non-digit characters is determined. These two parts (one of
which may be empty) are compared lexically. If a difference
is found it is returned. The lexical comparison is a
comparison of ASCII values modified so that all the letters
sort earlier than all the non-letters and so that a tilde
sorts before anything, even the end of a part. For example,
the following parts are in sorted order: '~~', '~~a', '~',
the empty part, 'a'.
Then the initial part of the remainder of each string which
consists entirely of digit characters is determined. The
numerical values of these two parts are compared, and any
difference found is returned as the result of the comparison.
For these purposes an empty string (which can only occur at
the end of one or both version strings being compared) counts
These two steps (comparing and removing initial non-digit
strings and initial digit strings) are repeated until a
difference is found or both strings are exhausted.
Note that the purpose of epochs is to allow us to leave behind
mistakes in version numbering, and to cope with situations
where the version numbering scheme changes. It is
not intended to cope with version numbers containing
strings of letters which the package management system cannot
interpret (such as 'ALPHA' or 'pre-'), or with
The tilde character and its special sorting properties were introduced
in dpkg 1.10 and some parts of the dpkg build scripts only gained
support for it later in the 1.10.x series.