gitrevisions(7)
NAME
gitrevisions - specifying revisions and ranges for Git
SYNOPSIS
gitrevisions
DESCRIPTION
Many Git commands take revision parameters as arguments. Depending on the command, they denote a specific commit or, for commands which walk the revision graph (such as git-log(1)), all commits which are reachable from that commit. For commands that walk the revision graph one can also specify a range of revisions explicitly. In addition, some Git commands (such as git-show(1)) also take revision parameters which denote other objects than commits, e.g. blobs ("files") or trees ("directories of files").
SPECIFYING REVISIONS
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.
<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.
<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 checkout -b 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.
<rev>^, 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. master~3
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. 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.
<rev>:<path>, e.g. HEAD:README, :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.
:path (with an empty part before the colon) is a special case of
the syntax described next: content recorded in the index at the
given path. 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 = 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
SPECIFYING RANGES
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.
A commit's reachable set is the commit itself and the commits in its
ancestry chain.
Commit Exclusions
^<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).
Dotted Range Notations
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.
Other <rev>^ Parent Shorthand Notations
Two 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.
While <rev>^<n> was about specifying a single commit parent, these two
notations consider all its parents. For example you can say HEAD^2^@,
however you cannot say HEAD^@^2.
REVISION RANGE SUMMARY
<rev>
Include commits that are reachable from <rev> (i.e. <rev> and its
ancestors).
^<rev>
Exclude commits that are reachable from <rev> (i.e. <rev> and its
ancestors).
<rev1>..<rev2>
Include commits that are reachable from <rev2> but exclude those
that are reachable from <rev1>. When either <rev1> or <rev2> is
omitted, it defaults to HEAD.
<rev1>...<rev2>
Include commits that are reachable from either <rev1> or <rev2> but
exclude those that are reachable from both. When either <rev1> or
<rev2> is omitted, it defaults to HEAD.
<rev>^@, e.g. HEAD^@
A suffix ^ followed by an at sign is the same as listing all
parents of <rev> (meaning, include anything reachable from its
parents, but not the commit itself).
<rev>^!, e.g. HEAD^!
A suffix ^ followed by an exclamation mark is the same as giving
commit <rev> and then all its parents prefixed with ^ to exclude
them (and their ancestors).
Here are a handful of examples using the Loeliger illustration above,
with each step in the notation's expansion and selection carefully
spelt out:
Args Expanded arguments Selected commits
D G H D
D F G H I J D F
^G D H D
^D B E I J F B
^D B C E I J F B C
C I J F C
B..C = ^B C C
B...C = B ^F C G H D E B C
C^@ = C^1
= F I J F
B^@ = B^1 B^2 B^3
= D E F D G H E F I J
C^! = C ^C^@
= C ^C^1
= C ^F C
B^! = B ^B^@
= B ^B^1 ^B^2 ^B^3
= B ^D ^E ^F B
F^! D = F ^I ^J D G H D F
SEE ALSO
git-rev-parse(1)
GIT
Part of the git(1) suite
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