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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 14:47:53 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 14:47:53 +0000
commitc8bae7493d2f2910b57f13ded012e86bdcfb0532 (patch)
tree24e09d9f84dec336720cf393e156089ca2835791 /Documentation/revisions.txt
parentInitial commit. (diff)
downloadgit-upstream.tar.xz
git-upstream.zip
Adding upstream version 1:2.39.2.upstream/1%2.39.2upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+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.
+
+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:
+
+ . If '$GIT_DIR/<refname>' exists, that is what you mean (this is usually
+ useful only for `HEAD`, `FETCH_HEAD`, `ORIG_HEAD`, `MERGE_HEAD`
+ and `CHERRY_PICK_HEAD`);
+
+ . otherwise, 'refs/<refname>' if it exists;
+
+ . otherwise, 'refs/tags/<refname>' if it exists;
+
+ . otherwise, 'refs/heads/<refname>' if it exists;
+
+ . otherwise, 'refs/remotes/<refname>' if it exists;
+
+ . otherwise, 'refs/remotes/<refname>/HEAD' if it exists.
++
+`HEAD` names the commit on which you based the changes in the working tree.
+`FETCH_HEAD` records the branch which you fetched from a remote repository
+with your last `git fetch` invocation.
+`ORIG_HEAD` is created by commands that move your `HEAD` in a drastic
+way, to record the position of the `HEAD` before their operation, so that
+you can easily change the tip of the branch back to the state before you ran
+them.
+`MERGE_HEAD` records the commit(s) which you are merging into your branch
+when you run `git merge`.
+`CHERRY_PICK_HEAD` records the commit which you are cherry-picking
+when you run `git cherry-pick`.
++
+Note that any of the 'refs/*' cases above may come either from
+the `$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 ('$GIT_DIR/logs/<refname>').
+
+'@{<n>}', e.g. '@\{1\}'::
+ You can use the '@' construct with an empty ref part to get at a
+ reflog entry of the current branch. For example, if you are on
+ branch 'blabla' then '@\{1\}' means the same as 'blabla@\{1\}'.
+
+'@{-<n>}', e.g. '@{-1}'::
+ The construct '@{-<n>}' means the <n>th branch/commit checked out
+ before the current one.
+
+'[<branchname>]@\{upstream\}', e.g. 'master@\{upstream\}', '@\{u\}'::
+ A branch B may be set up to build on top of a branch X (configured with
+ `branch.<name>.merge`) at a remote R (configured with
+ `branch.<name>.remote`). B@{u} refers to the remote-tracking branch for
+ the branch X taken from remote R, typically found at `refs/remotes/R/X`.
+
+'[<branchname>]@\{push\}', e.g. 'master@\{push\}', '@\{push\}'::
+ The suffix '@\{push}' reports the branch "where we would push to" if
+ `git push` were run while `branchname` was checked out (or the current
+ `HEAD` if no branchname is specified). Like for '@\{upstream\}', we report
+ the remote-tracking branch that corresponds to that branch at the remote.
++
+Here's an example to make it more clear:
++
+------------------------------
+$ 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>{caret}[<n>]', e.g. 'HEAD{caret}, v1.5.1{caret}0'::
+ A suffix '{caret}' to a revision parameter means the first parent of
+ that commit object. '{caret}<n>' means the <n>th parent (i.e.
+ '<rev>{caret}'
+ is equivalent to '<rev>{caret}1'). As a special rule,
+ '<rev>{caret}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>{tilde}[<n>]', e.g. 'HEAD{tilde}, master{tilde}3'::
+ A suffix '{tilde}' to a revision parameter means the first parent of
+ that commit object.
+ A suffix '{tilde}<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>{tilde}3' is
+ equivalent to '<rev>{caret}{caret}{caret}' which is equivalent to
+ '<rev>{caret}1{caret}1{caret}1'. See below for an illustration of
+ the usage of this form.
+
+'<rev>{caret}{<type>}', e.g. 'v0.99.8{caret}\{commit\}'::
+ A suffix '{caret}' 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>{caret}\{commit\}'
+ describes the corresponding commit object.
+ Similarly, if '<rev>' is a tree-ish, '<rev>{caret}\{tree\}'
+ describes the corresponding tree object.
+ '<rev>{caret}0'
+ is a short-hand for '<rev>{caret}\{commit\}'.
++
+'<rev>{caret}\{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>{caret}\{tag\}' can be used to ensure that '<rev>' identifies an
+existing tag object.
+
+'<rev>{caret}{}', e.g. 'v0.99.8{caret}{}'::
+ A suffix '{caret}' 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>{caret}{/<text>}', e.g. 'HEAD^{/fix nasty bug}'::
+ A suffix '{caret}' 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 '{caret}'.
+
+':/<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
+
+
+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.
+
+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.
+
+
+Commit Exclusions
+~~~~~~~~~~~~~~~~~
+
+'{caret}<rev>' (caret) Notation::
+ To exclude commits reachable from a commit, a prefix '{caret}'
+ notation is used. E.g. '{caret}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 '{caret}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 '{caret}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.
+
+ $ git log A..B C..D
+
+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:
+
+ ---A---B---o---o---C---D
+
+because A and B are reachable from C, the revision range specified
+by these two dotted ranges is a single commit D.
+
+
+Other <rev>{caret} Parent Shorthand Notations
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+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{caret}@' notation means all parents of 'r1'.
+
+The 'r1{caret}!' notation includes commit 'r1' but excludes all of its parents.
+By itself, this notation denotes the single commit 'r1'.
+
+The '<rev>{caret}-[<n>]' notation includes '<rev>' but excludes the <n>th
+parent (i.e. a shorthand for '<rev>{caret}<n>..<rev>'), with '<n>' = 1 if
+not given. This is typically useful for merge commits where you
+can just pass '<commit>{caret}-' to get all the commits in the branch
+that was merged in merge commit '<commit>' (including '<commit>'
+itself).
+
+While '<rev>{caret}<n>' was about specifying a single commit parent, these
+three notations also consider its parents. For example you can say
+'HEAD{caret}2{caret}@', however you cannot say 'HEAD{caret}@{caret}2'.
+
+Revision Range Summary
+----------------------
+
+'<rev>'::
+ Include commits that are reachable from <rev> (i.e. <rev> and its
+ ancestors).
+
+'{caret}<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>{caret}@', e.g. 'HEAD{caret}@'::
+ A suffix '{caret}' 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>{caret}!', e.g. 'HEAD{caret}!'::
+ A suffix '{caret}' followed by an exclamation mark is the same
+ as giving commit '<rev>' and all its parents prefixed with
+ '{caret}' to exclude them (and their ancestors).
+
+'<rev>{caret}-<n>', e.g. 'HEAD{caret}-, HEAD{caret}-2'::
+ Equivalent to '<rev>{caret}<n>..<rev>', with '<n>' = 1 if not
+ given.
+
+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
+ B^- = B^..B
+ = ^B^1 B E I J F B
+ 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
+....