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
History traversing commands such as git log operate on a set of commits,
not just a single commit.
For these commands, specifying a single revision, using the
notation described in the previous section, means the set of commits
reachable from the given commit.
Specifying several revisions means the set of commits reachable
from any of the given commits.
A commit’s reachable set is the commit itself and the
commits in its ancestry chain.
There are several notations to specify a set of connected commits
(called a "revision range"), illustrated below.
^<rev> (caret) Notation
To exclude commits reachable from a commit, a prefix
^ notation is used. E.g. ^r1 r2 means commits reachable from
r2 but exclude the ones reachable from r1 (i.e. r1 and
its ancestors).
The .. (two-dot) Range Notation
The ^r1 r2 set operation appears so often that
there is a shorthand for it. When you have two commits r1 and r2
(named according to the syntax explained in SPECIFYING REVISIONS above), you
can ask for commits that are reachable from r2 excluding those that are
reachable from r1 by ^r1 r2 and it can be written as
r1..r2.
The ... (three-dot) Symmetric Difference Notation
A similar notation r1...r2 is called symmetric
difference of r1 and r2 and is defined as r1 r2 --not $(git
merge-base --all r1 r2). It is the set of commits that are reachable from
either one of r1 (left side) or r2 (right side) but not from
both.
In these two shorthand notations, you can omit one end and let it
default to HEAD. For example, origin.. is a shorthand for
origin..HEAD and asks "What did I do since I forked from the
origin branch?" Similarly, ..origin is a shorthand for
HEAD..origin and asks "What did the origin do since I forked
from them?" Note that .. would mean HEAD..HEAD which is
an empty range that is both reachable and unreachable from HEAD.
Commands that are specifically designed to take two distinct
ranges (e.g. "git range-diff R1 R2" to compare two ranges) do
exist, but they are exceptions. Unless otherwise noted, all "git"
commands that operate on a set of commits work on a single revision range.
In other words, writing two "two-dot range notation" next to each
other, e.g.
does not specify two revision ranges for most commands.
Instead it will name a single connected set of commits, i.e. those that are
reachable from either B or D but are reachable from neither A or C. In a
linear history like this:
because A and B are reachable from C, the revision range specified
by these two dotted ranges is a single commit D.
Three other shorthands exist, particularly useful for merge commits, for naming
a set that is formed by a commit and its parent commits.
The r1^@ notation means all parents of r1.
The r1^! notation includes commit r1 but excludes
all of its parents. By itself, this notation denotes the single commit
r1.
The <rev>^-[<n>] notation includes
<rev> but excludes the <n>th parent (i.e. a shorthand for
<rev>^<n>..<rev>), with <n> = 1 if not
given. This is typically useful for merge commits where you can just pass
<commit>^- to get all the commits in the branch that was merged
in merge commit <commit> (including <commit>
itself).
While <rev>^<n> was about specifying a single
commit parent, these three notations also consider its parents. For example
you can say HEAD^2^@, however you cannot say HEAD^@^2.