NAME

       deb-version - Debian package version number format

SYNOPSIS

       [epoch:]upstream-version[-debian-revision]

DESCRIPTION

       Version numbers as used for Debian binary and source packages consist of three components. These are:

       epoch  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.

       upstream-version
              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 scheme.

              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 allowed.

       debian-revision
              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 upstream-version is.

              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).

   Sorting algorithm
       The upstream-version and debian-revision parts are compared by the package management  system  using  the
       same algorithm:

       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 as zero.

       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 silly orderings.

NOTES

       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.

SEE ALSO

       deb-control(5), deb(5), dpkg(1)

1.19.7                                             2022-05-25                                     deb-version(7)