git-describe(1)
NAME
git-describe - Describe a commit using the most recent tag reachable
from it
SYNOPSIS
git describe [--all] [--tags] [--contains] [--abbrev=<n>] [<commit-ish>...]
git describe [--all] [--tags] [--contains] [--abbrev=<n>] --dirty[=<mark>]
DESCRIPTION
The command finds the most recent tag that is reachable from a commit.
If the tag points to the commit, then only the tag is shown. Otherwise,
it suffixes the tag name with the number of additional commits on top
of the tagged object and the abbreviated object name of the most recent
commit.
By default (without --all or --tags) git describe only shows annotated
tags. For more information about creating annotated tags see the -a and
-s options to git-tag(1).
OPTIONS
<commit-ish>...
Commit-ish object names to describe. Defaults to HEAD if omitted.
--dirty[=<mark>]
Describe the working tree. It means describe HEAD and appends
<mark> (-dirty by default) if the working tree is dirty.
--all
Instead of using only the annotated tags, use any ref found in
refs/ namespace. This option enables matching any known branch,
remote-tracking branch, or lightweight tag.
--tags
Instead of using only the annotated tags, use any tag found in
refs/tags namespace. This option enables matching a lightweight
(non-annotated) tag.
--contains
Instead of finding the tag that predates the commit, find the tag
that comes after the commit, and thus contains it. Automatically
implies --tags.
--abbrev=<n>
Instead of using the default 7 hexadecimal digits as the
abbreviated object name, use <n> digits, or as many digits as
needed to form a unique object name. An <n> of 0 will suppress long
format, only showing the closest tag.
--candidates=<n>
Instead of considering only the 10 most recent tags as candidates
to describe the input commit-ish consider up to <n> candidates.
Increasing <n> above 10 will take slightly longer but may produce a
more accurate result. An <n> of 0 will cause only exact matches to
be output.
--exact-match
Only output exact matches (a tag directly references the supplied
commit). This is a synonym for --candidates=0.
--debug
Verbosely display information about the searching strategy being
employed to standard error. The tag name will still be printed to
standard out.
--long
Always output the long format (the tag, the number of commits and
the abbreviated commit name) even when it matches a tag. This is
useful when you want to see parts of the commit object name in
"describe" output, even when the commit in question happens to be a
tagged version. Instead of just emitting the tag name, it will
describe such a commit as v1.2-0-gdeadbee (0th commit since tag
v1.2 that points at object deadbee....).
--match <pattern>
Only consider tags matching the given glob(7) pattern, excluding
the "refs/tags/" prefix. This can be used to avoid leaking private
tags from the repository.
--always
Show uniquely abbreviated commit object as fallback.
--first-parent
Follow only the first parent commit upon seeing a merge commit.
This is useful when you wish to not match tags on branches merged
in the history of the target commit.
EXAMPLES
With something like git.git current tree, I get:
[torvalds@g5 git]$ git describe parent
v1.0.4-14-g2414721
i.e. the current head of my "parent" branch is based on v1.0.4, but
since it has a few commits on top of that, describe has added the
number of additional commits ("14") and an abbreviated object name for
the commit itself ("2414721") at the end.
The number of additional commits is the number of commits which would
be displayed by "git log v1.0.4..parent". The hash suffix is "-g" +
7-char abbreviation for the tip commit of parent (which was
2414721b194453f058079d897d13c4e377f92dc6). The "g" prefix stands for
"git" and is used to allow describing the version of a software
depending on the SCM the software is managed with. This is useful in an
environment where people may use different SCMs.
Doing a git describe on a tag-name will just show the tag name:
[torvalds@g5 git]$ git describe v1.0.4
v1.0.4
With --all, the command can use branch heads as references, so the
output shows the reference path as well:
[torvalds@g5 git]$ git describe --all --abbrev=4 v1.0.5^2
tags/v1.0.0-21-g975b
[torvalds@g5 git]$ git describe --all --abbrev=4 HEAD^
heads/lt/describe-7-g975b
With --abbrev set to 0, the command can be used to find the closest
tagname without any suffix:
[torvalds@g5 git]$ git describe --abbrev=0 v1.0.5^2
tags/v1.0.0
Note that the suffix you get if you type these commands today may be
longer than what Linus saw above when he ran these commands, as your
Git repository may have new commits whose object names begin with 975b
that did not exist back then, and "-g975b" suffix alone may not be
sufficient to disambiguate these commits.
SEARCH STRATEGY
For each commit-ish supplied, git describe will first look for a tag
which tags exactly that commit. Annotated tags will always be preferred
over lightweight tags, and tags with newer dates will always be
preferred over tags with older dates. If an exact match is found, its
name will be output and searching will stop.
If an exact match was not found, git describe will walk back through
the commit history to locate an ancestor commit which has been tagged.
The ancestor's tag will be output along with an abbreviation of the
input commit-ish's SHA-1. If --first-parent was specified then the walk
will only consider the first parent of each commit.
If multiple tags were found during the walk then the tag which has the
fewest commits different from the input commit-ish will be selected and
output. Here fewest commits different is defined as the number of
commits which would be shown by git log tag..input will be the smallest
number of commits possible.
GIT
Part of the git(1) suite
Free and Open Source Software