A revision parameter <rev> typically, but not necessarily, names
a commit object. It uses what is called an extended SHA-1 syntax.
Here are various ways to spell object names. The ones listed near
the end of this list name trees and blobs contained in a commit.
Note
This document shows the "raw" syntax as seen by git. The
shell and other UIs might require additional quoting to
protect special characters and to avoid word splitting.
<sha1>, e.g. dae86e1950b1277e545cee180551750029cfe735, dae86e
The full SHA-1 object name (40-byte hexadecimal string), or a
leading substring that is unique within the repository. E.g.
dae86e1950b1277e545cee180551750029cfe735 and dae86e both name
the same commit object if there is no other object in your
repository whose object name starts with dae86e.
<describeOutput>, e.g. v1.7.4.2-679-g3bee7fb
Output from git describe; i.e. a closest tag, optionally
followed by a dash and a number of commits, followed by a
dash, a g, and an abbreviated object name.
<refname>, e.g. master, heads/master, refs/heads/master
A symbolic ref name. E.g. master typically means the commit
object referenced by refs/heads/master. If you happen to have
both heads/master and tags/master, you can explicitly say
heads/master to tell Git which one you mean. When ambiguous,
a <refname> is disambiguated by taking the first match in the
following rules:
1. If $GIT_DIR/<refname> exists, that is what you mean (this
is usually useful only for HEAD, FETCH_HEAD, ORIG_HEAD,
MERGE_HEAD and CHERRY_PICK_HEAD);
2. otherwise, refs/<refname> if it exists;
3. otherwise, refs/tags/<refname> if it exists;
4. otherwise, refs/heads/<refname> if it exists;
5. otherwise, refs/remotes/<refname> if it exists;
6. otherwise, refs/remotes/<refname>/HEAD if it exists.
HEAD names the commit on which you based the changes in
the working tree. FETCH_HEAD records the branch which
you fetched from a remote repository with your last git
fetch invocation. ORIG_HEAD is created by commands that
move your HEAD in a drastic way, to record the position
of the HEAD before their operation, so that you can
easily change the tip of the branch back to the state
before you ran them. MERGE_HEAD records the commit(s)
which you are merging into your branch when you run git
merge. CHERRY_PICK_HEAD records the commit which you are
cherry-picking when you run git cherry-pick.
Note that any of the refs/* cases above may come either
from the $GIT_DIR/refs directory or from the
$GIT_DIR/packed-refs file. While the ref name encoding is
unspecified, UTF-8 is preferred as some output processing
may assume ref names in UTF-8.
@
@ alone is a shortcut for HEAD.
[<refname>]@{<date>}, e.g. master@{yesterday}, HEAD@{5 minutes
ago}
A ref followed by the suffix @ with a date specification
enclosed in a brace pair (e.g. {yesterday}, {1 month 2 weeks
3 days 1 hour 1 second ago} or {1979-02-26 18:30:00})
specifies the value of the ref at a prior point in time. This
suffix may only be used immediately following a ref name and
the ref must have an existing log ($GIT_DIR/logs/<ref>). Note
that this looks up the state of your local ref at a given
time; e.g., what was in your local master branch last week.
If you want to look at commits made during certain times, see
--since and --until.
<refname>@{<n>}, e.g. master@{1}
A ref followed by the suffix @ with an ordinal specification
enclosed in a brace pair (e.g. {1}, {15}) specifies the n-th
prior value of that ref. For example master@{1} is the
immediate prior value of master while master@{5} is the 5th
prior value of master. This suffix may only be used
immediately following a ref name and the ref must have an
existing log ($GIT_DIR/logs/<refname>).
@{<n>}, e.g. @{1}
You can use the @ construct with an empty ref part to get at
a reflog entry of the current branch. For example, if you are
on branch blabla then @{1} means the same as blabla@{1}.
@{-<n>}, e.g. @{-1}
The construct @{-<n>} means the <n>th branch/commit checked
out before the current one.
[<branchname>]@{upstream}, e.g. master@{upstream}, @{u}
The suffix @{upstream} to a branchname (short form
<branchname>@{u}) refers to the branch that the branch
specified by branchname is set to build on top of (configured
with branch.<name>.remote and branch.<name>.merge). A missing
branchname defaults to the current one. These suffixes are
also accepted when spelled in uppercase, and they mean the
same thing no matter the case.
[<branchname>]@{push}, e.g. master@{push}, @{push}
The suffix @{push} reports the branch "where we would push
to" if git push were run while branchname was checked out (or
the current HEAD if no branchname is specified). Since our
push destination is in a remote repository, of course, we
report the local tracking branch that corresponds to that
branch (i.e., something in refs/remotes/).
Here's an example to make it more clear:
$ git config push.default current
$ git config remote.pushdefault myfork
$ git switch -c mybranch origin/master
$ git rev-parse --symbolic-full-name @{upstream}
refs/remotes/origin/master
$ git rev-parse --symbolic-full-name @{push}
refs/remotes/myfork/mybranch
Note in the example that we set up a triangular workflow,
where we pull from one location and push to another. In a
non-triangular workflow, @{push} is the same as @{upstream},
and there is no need for it.
This suffix is also accepted when spelled in uppercase, and
means the same thing no matter the case.
<rev>^[<n>], e.g. HEAD^, v1.5.1^0
A suffix ^ to a revision parameter means the first parent of
that commit object. ^<n> means the <n>th parent (i.e.
<rev>^ is equivalent to <rev>^1). As a special rule, <rev>^0
means the commit itself and is used when <rev> is the object
name of a tag object that refers to a commit object.
<rev>~[<n>], e.g. HEAD~, master~3
A suffix ~ to a revision parameter means the first parent of
that commit object. A suffix ~<n> to a revision parameter
means the commit object that is the <n>th generation ancestor
of the named commit object, following only the first parents.
I.e. <rev>~3 is equivalent to <rev>^^^ which is equivalent
to <rev>^1^1^1. See below for an illustration of the usage of
this form.
<rev>^{<type>}, e.g. v0.99.8^{commit}
A suffix ^ followed by an object type name enclosed in brace
pair means dereference the object at <rev> recursively until
an object of type <type> is found or the object cannot be
dereferenced anymore (in which case, barf). For example, if
<rev> is a commit-ish, <rev>^{commit} describes the
corresponding commit object. Similarly, if <rev> is a
tree-ish, <rev>^{tree} describes the corresponding tree
object. <rev>^0 is a short-hand for <rev>^{commit}.
<rev>^{object} can be used to make sure <rev> names an object
that exists, without requiring <rev> to be a tag, and without
dereferencing <rev>; because a tag is already an object, it
does not have to be dereferenced even once to get to an
object.
<rev>^{tag} can be used to ensure that <rev> identifies an
existing tag object.
<rev>^{}, e.g. v0.99.8^{}
A suffix ^ followed by an empty brace pair means the object
could be a tag, and dereference the tag recursively until a
non-tag object is found.
<rev>^{/<text>}, e.g. HEAD^{/fix nasty bug}
A suffix ^ to a revision parameter, followed by a brace pair
that contains a text led by a slash, is the same as the :/fix
nasty bug syntax below except that it returns the youngest
matching commit which is reachable from the <rev> before ^.
:/<text>, e.g. :/fix nasty bug
A colon, followed by a slash, followed by a text, names a
commit whose commit message matches the specified regular
expression. This name returns the youngest matching commit
which is reachable from any ref, including HEAD. The regular
expression can match any part of the commit message. To match
messages starting with a string, one can use e.g. :/^foo.
The special sequence :/! is reserved for modifiers to what
is matched. :/!-foo performs a negative match, while :/!!foo
matches a literal ! character, followed by foo. Any other
sequence beginning with :/! is reserved for now. Depending
on the given text, the shell's word splitting rules might
require additional quoting.
<rev>:<path>, e.g. HEAD:README, master:./README
A suffix : followed by a path names the blob or tree at the
given path in the tree-ish object named by the part before
the colon. A path starting with ./ or ../ is relative to the
current working directory. The given path will be converted
to be relative to the working tree's root directory. This is
most useful to address a blob or tree from a commit or tree
that has the same tree structure as the working tree.
:[<n>:]<path>, e.g. :0:README, :README
A colon, optionally followed by a stage number (0 to 3) and a
colon, followed by a path, names a blob object in the index
at the given path. A missing stage number (and the colon that
follows it) names a stage 0 entry. During a merge, stage 1 is
the common ancestor, stage 2 is the target branch's version
(typically the current branch), and stage 3 is the version
from the branch which is being merged.
Here is an illustration, by Jon Loeliger. Both commit nodes B and
C are parents of commit node A. Parent commits are ordered
left-to-right.
G H I J
\ / \ /
D E F
\ | / \
\ | / |
\|/ |
B C
\ /
\ /
A
A = = A^0
B = A^ = A^1 = A~1
C = = A^2
D = A^^ = A^1^1 = A~2
E = B^2 = A^^2
F = B^3 = A^^3
G = A^^^ = A^1^1^1 = A~3
H = D^2 = B^^2 = A^^^2 = A~2^2
I = F^ = B^3^ = A^^3^
J = F^2 = B^3^2 = A^^3^2
