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| -rw-r--r-- | Documentation/revisions.txt | 198 |
1 files changed, 107 insertions, 91 deletions
diff --git a/Documentation/revisions.txt b/Documentation/revisions.txt index 04fceee253..b290b617d4 100644 --- a/Documentation/revisions.txt +++ b/Documentation/revisions.txt @@ -1,147 +1,163 @@ SPECIFYING REVISIONS -------------------- -A revision parameter typically, but not necessarily, names a -commit object. They use what is called an 'extended SHA1' +A revision parameter '<rev>' typically, but not necessarily, names a +commit object. It uses what is called an 'extended SHA1' syntax. Here are various ways to spell object names. The -ones listed near the end of this list are to name trees and +ones listed near the end of this list name trees and blobs contained in a commit. -* The full SHA1 object name (40-byte hexadecimal string), or - a substring of such that is unique within the repository. +'<sha1>', e.g. 'dae86e1950b1277e545cee180551750029cfe735', 'dae86e':: + The full SHA1 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 are no other object in + name the same commit object if there is no other object in your repository whose object name starts with dae86e. -* An output from 'git describe'; i.e. a closest tag, optionally +'<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. + 'g', and an abbreviated object name. -* 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 +'<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 `<name>` is disambiguated by taking the + When ambiguous, a '<name>' is disambiguated by taking the first match in the following rules: - . if `$GIT_DIR/<name>` exists, that is what you mean (this is usually - useful only for `HEAD`, `FETCH_HEAD`, `ORIG_HEAD`, `MERGE_HEAD` - and `CHERRY_PICK_HEAD`); + . If '$GIT_DIR/<name>' 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/<name>` if exists; + . otherwise, 'refs/<name>' if it exists; - . otherwise, `refs/tags/<name>` if exists; + . otherwise, 'refs/tags/<refname>' if it exists; - . otherwise, `refs/heads/<name>` if exists; + . otherwise, 'refs/heads/<name>' if it exists; - . otherwise, `refs/remotes/<name>` if exists; + . otherwise, 'refs/remotes/<name>' if it exists; - . otherwise, `refs/remotes/<name>/HEAD` if exists. + . otherwise, 'refs/remotes/<name>/HEAD' if it exists. + -HEAD names the commit your changes in the working tree is based on. -FETCH_HEAD records the branch you fetched from a remote repository -with your last 'git fetch' invocation. -ORIG_HEAD is created by commands that moves your HEAD in a drastic -way, to record the position of the HEAD before their operation, so that -you can change the tip of the branch back to the state before you ran -them easily. -MERGE_HEAD records the commit(s) you are merging into your branch -when you run 'git merge'. -CHERRY_PICK_HEAD records the commit you are cherry-picking -when you run 'git cherry-pick'. +'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. +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. -* A ref followed by the suffix '@' with a date specification +'<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\}') to specify the value + 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 ($GIT_DIR/logs/<ref>). Note that this looks up the state + existing log ('$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`. + 'master' branch last week. If you want to look at commits made during + certain times, see '--since' and '--until'. -* A ref followed by the suffix '@' with an ordinal specification - enclosed in a brace pair (e.g. '\{1\}', '\{15\}') to specify +'<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 ($GIT_DIR/logs/<ref>). + log ('$GIT_DIR/logs/<refname>'). -* You can use the '@' construct with an empty ref part to get at a - reflog of the current branch. For example, if you are on the - branch 'blabla', then '@\{1\}' means the same as 'blabla@\{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\}'. -* The special construct '@\{-<n>\}' means the <n>th branch checked out +'@\{-<n>\}', e.g. '@\{-1\}':: + The construct '@\{-<n>\}' means the <n>th branch checked out before the current one. -* The suffix '@\{upstream\}' to a ref (short form 'ref@\{u\}') refers to - the branch the ref is set to build on top of. Missing ref defaults +'<refname>@\{upstream\}', e.g. 'master@\{upstream\}', '@\{u\}':: + The suffix '@\{upstream\}' to a ref (short form '<refname>@\{u\}') refers to + the branch the ref is set to build on top of. A missing ref defaults to the current branch. -* A suffix '{caret}' to a revision parameter (e.g. 'HEAD{caret}') means the first parent of +'<rev>{caret}', 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 + '<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. -* A suffix '{tilde}<n>' to a revision parameter means the commit +'<rev>{tilde}<n>', e.g. 'master{tilde}3':: + A suffix '{tilde}<n>' to a revision parameter means the commit object that is the <n>th generation grand-parent of the named - commit object, following only the first parent. I.e. rev~3 is - equivalent to rev{caret}{caret}{caret} which is equivalent to - rev{caret}1{caret}1{caret}1. See below for a illustration of + 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. -* A suffix '{caret}' followed by an object type name enclosed in - brace pair (e.g. `v0.99.8{caret}\{commit\}`) means the object +'<rev>{caret}\{<type>\}', e.g. 'v0.99.8{caret}\{commit\}':: + A suffix '{caret}' followed by an object type name enclosed in + brace pair means the object could be a tag, and dereference the tag recursively until an object of that type is found or the object cannot be - dereferenced anymore (in which case, barf). `rev{caret}0` - introduced earlier is a short-hand for `rev{caret}\{commit\}`. + dereferenced anymore (in which case, barf). '<rev>{caret}0' + is a short-hand for '<rev>{caret}\{commit\}'. -* A suffix '{caret}' followed by an empty brace pair - (e.g. `v0.99.8{caret}\{\}`) means the object could be a tag, +'<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. -* A suffix '{caret}' to a revision parameter followed by a brace - pair that contains a text led by a slash (e.g. `HEAD^{/fix nasty bug}`): - this is the same as `:/fix nasty bug` syntax below except that +'<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 ref before '{caret}'. + the '<rev>' before '{caret}'. -* A colon, followed by a slash, followed by a text (e.g. `:/fix nasty bug`): this names +':/<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. If the commit message starts with a - '!', you have to repeat that; the special sequence ':/!', - followed by something else than '!' is reserved for now. + '!' 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`. + match messages starting with a string, one can use e.g. ':/^foo'. -* A suffix ':' followed by a path (e.g. `HEAD:README`); this names the blob or tree +'<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, e.g. `:README`) + ':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 current working directory. - The given path will be converted to be relative to working tree's root directory. + 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 with the working tree. + the same tree structure as the working tree. -* A colon, optionally followed by a stage number (0 to 3) and a - colon, followed by a path (e.g. `:0:README`); this names a blob object in the - index at the given path. Missing stage number (and the colon - that follows it, e.g. `:README`) names a stage 0 entry. During a merge, stage +':<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 being merged. + 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 @@ -175,31 +191,31 @@ G H I J SPECIFYING RANGES ----------------- -History traversing commands such as 'git log' operate on a set +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`. +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 +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`. +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)`. +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. +'r1' or 'r2' but not from both. 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 +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. Here are a handful of examples: |