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
Opportunity
Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.
Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.
Free Software
Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.
Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.
Free Books
The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.
Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.
Education
Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.
Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.
