1deb-version(7)                    dpkg suite                    deb-version(7)
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NAME

6       deb-version - Debian package version number format
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SYNOPSIS

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

12       Version numbers as used for Debian binary and source packages consist
13       of three components. These are:
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15       epoch
16           This is a single (generally small) unsigned integer.  It may be
17           omitted, in which case zero is assumed.  If it is omitted then the
18           upstream-version may not contain any colons.
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20           It is provided to allow mistakes in the version numbers of older
21           versions of a package, and also a package's previous version
22           numbering schemes, to be left behind.
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24       upstream-version
25           This is the main part of the version number.  It is usually the
26           version number of the original (“upstream”) package from which the
27           .deb file has been made, if this is applicable.  Usually this will
28           be in the same format as that specified by the upstream author(s);
29           however, it may need to be reformatted to fit into the package
30           management system's format and comparison scheme.
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32           The comparison behavior of the package management system with
33           respect to the upstream-version is described below. The upstream-
34           version portion of the version number is mandatory.
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36           The upstream-version may contain only alphanumerics (“A-Za-z0-9”)
37           and the characters . + - : ~ (full stop, plus, hyphen, colon,
38           tilde) and should start with a digit.  If there is no debian-
39           revision then hyphens are not allowed; if there is no epoch then
40           colons are not allowed.
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42       debian-revision
43           This part of the version number specifies the version of the Debian
44           package based on the upstream version.  It may contain only
45           alphanumerics and the characters + . ~ (plus, full stop, tilde) and
46           is compared in the same way as the upstream-version is.
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48           It is optional; if it isn't present then the upstream-version may
49           not contain a hyphen.  This format represents the case where a
50           piece of software was written specifically to be turned into a
51           Debian package, and so there is only one “debianization” of it and
52           therefore no revision indication is required.
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54           It is conventional to restart the debian-revision at ‘1’ each time
55           the upstream-version is increased.
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57           Dpkg will break the version number apart at the last hyphen in the
58           string (if there is one) to determine the upstream-version and
59           debian-revision. The absence of a debian-revision compares earlier
60           than the presence of one (but note that the debian-revision is the
61           least significant part of the version number).
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63   Sorting algorithm
64       The upstream-version and debian-revision parts are compared by the
65       package management system using the same algorithm:
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67       The strings are compared from left to right.
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69       First the initial part of each string consisting entirely of non-digit
70       characters is determined.  These two parts (one of which may be empty)
71       are compared lexically.  If a difference is found it is returned.  The
72       lexical comparison is a comparison of ASCII values modified so that all
73       the letters sort earlier than all the non-letters and so that a tilde
74       sorts before anything, even the end of a part.  For example, the
75       following parts are in sorted order: ‘~~’, ‘~~a’, ‘~’, the empty part,
76       ‘a’.
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78       Then the initial part of the remainder of each string which consists
79       entirely of digit characters is determined.  The numerical values of
80       these two parts are compared, and any difference found is returned as
81       the result of the comparison.  For these purposes an empty string
82       (which can only occur at the end of one or both version strings being
83       compared) counts as zero.
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85       These two steps (comparing and removing initial non-digit strings and
86       initial digit strings) are repeated until a difference is found or both
87       strings are exhausted.
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89       Note that the purpose of epochs is to allow us to leave behind mistakes
90       in version numbering, and to cope with situations where the version
91       numbering scheme changes.  It is not intended to cope with version
92       numbers containing strings of letters which the package management
93       system cannot interpret (such as ‘ALPHA’ or ‘pre-’), or with silly
94       orderings.
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NOTES

97       The tilde character and its special sorting properties were introduced
98       in dpkg 1.10 and some parts of the dpkg build scripts only gained
99       support for it later in the 1.10.x series.
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SEE ALSO

102       deb-control(5), deb(5), dpkg(1)
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1061.20.9                            2021-04-13                    deb-version(7)
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