diff options
Diffstat (limited to 'Documentation/revisions.txt')
| -rw-r--r-- | Documentation/revisions.txt | 222 |
1 files changed, 150 insertions, 72 deletions
diff --git a/Documentation/revisions.txt b/Documentation/revisions.txt index 5a286d0d61..ba11b9c95e 100644 --- a/Documentation/revisions.txt +++ b/Documentation/revisions.txt @@ -28,8 +28,8 @@ blobs contained in a commit. 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'); + useful only for `HEAD`, `FETCH_HEAD`, `ORIG_HEAD`, `MERGE_HEAD` + and `CHERRY_PICK_HEAD`); . otherwise, 'refs/<refname>' if it exists; @@ -41,16 +41,16 @@ blobs contained in a commit. . 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 +`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 +`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 +`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 +`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 @@ -59,21 +59,21 @@ 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'. + '@' alone is a shortcut for `HEAD`. -'<refname>@\{<date>\}', e.g. 'master@\{yesterday\}', 'HEAD@\{5 minutes ago\}':: +'<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 + 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'. + certain times, see `--since` and `--until`. -'<refname>@\{<n>\}', e.g. 'master@\{1\}':: +'<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\}' @@ -82,19 +82,46 @@ some output processing may assume ref names in UTF-8. immediately following a ref name and the ref must have an existing log ('$GIT_DIR/logs/<refname>'). -'@\{<n>\}', e.g. '@\{1\}':: +'@{<n>}', e.g. '@\{1\}':: You can use the '@' construct with an empty ref part to get at a reflog entry of the current branch. For example, if you are on branch 'blabla' then '@\{1\}' means the same as 'blabla@\{1\}'. -'@\{-<n>\}', e.g. '@\{-1\}':: - The construct '@\{-<n>\}' means the <n>th branch/commit checked out +'@{-<n>}', e.g. '@{-1}':: + The construct '@{-<n>}' means the <n>th branch/commit checked out before the current one. '<branchname>@\{upstream\}', e.g. 'master@\{upstream\}', '@\{u\}':: The suffix '@\{upstream\}' to a branchname (short form '<branchname>@\{u\}') refers to the branch that the branch specified by branchname is set to build on - top of. A missing branchname defaults to the current one. + top of (configured with `branch.<name>.remote` and + `branch.<name>.merge`). A missing branchname defaults to the + current one. + +'<branchname>@\{push\}', e.g. 'master@\{push\}', '@\{push\}':: + The suffix '@\{push}' reports the branch "where we would push to" if + `git push` were run while `branchname` was checked out (or the current + `HEAD` if no branchname is specified). Since our push destination is + in a remote repository, of course, we report the local tracking branch + that corresponds to that branch (i.e., something in 'refs/remotes/'). ++ +Here's an example to make it more clear: ++ +------------------------------ +$ 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>{caret}', e.g. 'HEAD{caret}, v1.5.1{caret}0':: A suffix '{caret}' to a revision parameter means the first parent of @@ -112,7 +139,7 @@ some output processing may assume ref names in UTF-8. '<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\}':: +'<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 @@ -132,13 +159,13 @@ 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}\{\}':: +'<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}':: +'<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 @@ -149,11 +176,12 @@ existing tag object. 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. If the commit message starts with a - '!' you have to repeat that; the special sequence ':/!', - followed by something else than '!', is reserved for now. - The regular expression can match any part of the commit message. To - match messages starting with a string, one can use e.g. ':/^foo'. + 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 @@ -209,58 +237,91 @@ SPECIFYING RANGES ----------------- History traversing commands such as `git log` operate on a set -of commits, not just a single commit. To these commands, -specifying a single revision with the notation described in the -previous section means the set of commits reachable from that -commit, following the commit ancestry chain. - -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'. - -This 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'. - -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' or 'r2' but not from both. - -In these two shorthands, you can omit one end and let it default to HEAD. +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 +~~~~~~~~~~~~~~~~~ + +'{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. -Two other shorthands for naming a set that is formed by a commit -and its parent commits exist. The 'r1{caret}@' notation means all -parents of 'r1'. 'r1{caret}!' includes commit 'r1' but excludes -all of its parents. +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'. -To summarize: +Revision Range Summary +---------------------- '<rev>':: - Include commits that are reachable from (i.e. ancestors of) - <rev>. + Include commits that are reachable from <rev> (i.e. <rev> and its + ancestors). '{caret}<rev>':: - Exclude commits that are reachable from (i.e. ancestors of) - <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'. + <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'. + 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 @@ -272,16 +333,33 @@ To summarize: as giving commit '<rev>' and then all its parents prefixed with '{caret}' to exclude them (and their ancestors). -Here are a handful of examples: - - D G H D - D F G H I J D F - ^G D H D - ^D B E I J F B - B..C C - B...C G H D E B C - ^D B C E I J F B C - C I J F C - C^@ I J F - C^! C - F^! D G H D F +'<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 |