GIT-DESCRIBE(1) Git Manual GIT-DESCRIBE(1)

NAME

git-describe - Give an object a human readable name based on an
available ref

SYNOPSIS

git describe [--all] [--tags] [--contains] [--abbrev=<n>] [<commit-ish>...]
git describe [--all] [--tags] [--contains] [--abbrev=<n>] --dirty[=<mark>]
git describe <blob>

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. The result is a "human-readable" object
name which can also be used to identify the commit to other git
commands.

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).

If the given object refers to a blob, it will be described as
<commit-ish>:<path>, such that the blob can be found at <path> in the
<commit-ish>, which itself describes the first commit in which this
blob occurs in a reverse revision walk from HEAD.

OPTIONS

<commit-ish>...
Commit-ish object names to describe. Defaults to HEAD if omitted.

--dirty[=<mark>], --broken[=<mark>]
Describe the state of the working tree. When the working tree
matches HEAD, the output is the same as "git describe HEAD". If
the working tree has local modification "-dirty" is appended to
it. If a repository is corrupt and Git cannot determine if there
is local modification, Git will error out, unless "--broken" is
given, which appends the suffix "-broken" instead.

--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 number of hexadecimal digits (which
will vary according to the number of objects in the repository
with a default of 7) of 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. If used with --all, it also considers
local branches and remote-tracking references matching the
pattern, excluding respectively "refs/heads/" and "refs/remotes/"
prefix; references of other types are never considered. If given
multiple times, a list of patterns will be accumulated, and tags
matching any of the patterns will be considered. Use --no-match
to clear and reset the list of patterns.

--exclude <pattern>
Do not consider tags matching the given glob(7) pattern,
excluding the "refs/tags/" prefix. If used with --all, it also
does not consider local branches and remote-tracking references
matching the pattern, excluding respectively "refs/heads/" and
"refs/remotes/" prefix; references of other types are never
considered. If given multiple times, a list of patterns will be
accumulated and tags matching any of the patterns will be
excluded. When combined with --match a tag will be considered
when it matches at least one --match pattern and does not match
any of the --exclude patterns. Use --no-exclude to clear and
reset the list of patterns.

--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" +
an unambiguous abbreviation for the tip commit of parent (which was
2414721b194453f058079d897d13c4e377f92dc6). The length of the
abbreviation scales as the repository grows, using the approximate
number of objects in the repository and a bit of math around the
birthday paradox, and defaults to a minimum of 7. 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.

BUGS

Tree objects as well as tag objects not pointing at commits, cannot
be described. When describing blobs, the lightweight tags pointing at
blobs are ignored, but the blob is still described as
<commit-ish>:<path> despite the lightweight tag being favorable.

GIT

Part of the git(1) suite

Git 2.48.1 2025-01-13 GIT-DESCRIBE(1)