Documentation: be consistent about "git-" versus "git "
[git/git.git] / Documentation / git-rev-parse.txt
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1git-rev-parse(1)
2================
3
4NAME
5----
7bd7f280 6git-rev-parse - Pick out and massage parameters
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7
8
9SYNOPSIS
10--------
b1889c36 11'git rev-parse' [ --option ] <args>...
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12
13DESCRIPTION
14-----------
5077fa9c 15
abda1ef5 16Many git porcelainish commands take mixture of flags
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17(i.e. parameters that begin with a dash '-') and parameters
18meant for underlying `git-rev-list` command they use internally
19and flags and parameters for other commands they use as the
20downstream of `git-rev-list`. This command is used to
21distinguish between them.
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22
23
24OPTIONS
25-------
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26--parseopt::
27 Use `git-rev-parse` in option parsing mode (see PARSEOPT section below).
28
29--keep-dash-dash::
30 Only meaningful in `--parseopt` mode. Tells the option parser to echo
31 out the first `--` met instead of skipping it.
32
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33--revs-only::
34 Do not output flags and parameters not meant for
35 `git-rev-list` command.
36
37--no-revs::
38 Do not output flags and parameters meant for
39 `git-rev-list` command.
40
41--flags::
42 Do not output non-flag parameters.
43
44--no-flags::
45 Do not output flag parameters.
46
47--default <arg>::
48 If there is no parameter given by the user, use `<arg>`
49 instead.
50
51--verify::
52 The parameter given must be usable as a single, valid
53 object name. Otherwise barf and abort.
54
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55-q::
56--quiet::
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57 Only meaningful in `--verify` mode. Do not output an error
58 message if the first argument is not a valid object name;
59 instead exit with non-zero status silently.
60
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61--sq::
62 Usually the output is made one line per flag and
63 parameter. This option makes output a single line,
64 properly quoted for consumption by shell. Useful when
65 you expect your parameter to contain whitespaces and
66 newlines (e.g. when using pickaxe `-S` with
67 `git-diff-\*`).
68
69--not::
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70 When showing object names, prefix them with '{caret}' and
71 strip '{caret}' prefix from the object names that already have
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72 one.
73
74--symbolic::
75 Usually the object names are output in SHA1 form (with
babfaba2 76 possible '{caret}' prefix); this option makes them output in a
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77 form as close to the original input as possible.
78
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79--symbolic-full-name::
80 This is similar to \--symbolic, but it omits input that
81 are not refs (i.e. branch or tag names; or more
82 explicitly disambiguating "heads/master" form, when you
83 want to name the "master" branch when there is an
84 unfortunately named tag "master"), and show them as full
85 refnames (e.g. "refs/heads/master").
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86
87--all::
88 Show all refs found in `$GIT_DIR/refs`.
89
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90--branches::
91 Show branch refs found in `$GIT_DIR/refs/heads`.
92
93--tags::
94 Show tag refs found in `$GIT_DIR/refs/tags`.
95
96--remotes::
97 Show tag refs found in `$GIT_DIR/refs/remotes`.
98
5077fa9c 99--show-prefix::
5f94c730 100 When the command is invoked from a subdirectory, show the
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101 path of the current directory relative to the top-level
102 directory.
7fc9d69f 103
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104--show-cdup::
105 When the command is invoked from a subdirectory, show the
106 path of the top-level directory relative to the current
107 directory (typically a sequence of "../", or an empty string).
108
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109--git-dir::
110 Show `$GIT_DIR` if defined else show the path to the .git directory.
111
c9bf7be2 112--is-inside-git-dir::
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113 When the current working directory is below the repository
114 directory print "true", otherwise "false".
115
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116--is-inside-work-tree::
117 When the current working directory is inside the work tree of the
118 repository print "true", otherwise "false".
119
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120--is-bare-repository::
121 When the repository is bare print "true", otherwise "false".
c9bf7be2 122
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123--short::
124--short=number::
735d80b3 125 Instead of outputting the full SHA1 values of object names try to
abda1ef5 126 abbreviate them to a shorter unique name. When no length is specified
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127 7 is used. The minimum length is 4.
128
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129--since=datestring::
130--after=datestring::
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131 Parses the date string, and outputs corresponding
132 --max-age= parameter for git-rev-list command.
133
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134--until=datestring::
135--before=datestring::
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136 Parses the date string, and outputs corresponding
137 --min-age= parameter for git-rev-list command.
138
7fc9d69f 139<args>...::
5077fa9c 140 Flags and parameters to be parsed.
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141
142
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143SPECIFYING REVISIONS
144--------------------
145
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146A revision parameter typically, but not necessarily, names a
147commit object. They use what is called an 'extended SHA1'
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148syntax. Here are various ways to spell object names. The
149ones listed near the end of this list are to name trees and
150blobs contained in a commit.
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151
152* The full SHA1 object name (40-byte hexadecimal string), or
153 a substring of such that is unique within the repository.
154 E.g. dae86e1950b1277e545cee180551750029cfe735 and dae86e both
155 name the same commit object if there are no other object in
156 your repository whose object name starts with dae86e.
157
6b09c788 158* An output from `git-describe`; i.e. a closest tag, followed by a
0ac30568 159 dash, a `g`, and an abbreviated object name.
6b09c788 160
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161* A symbolic ref name. E.g. 'master' typically means the commit
162 object referenced by $GIT_DIR/refs/heads/master. If you
163 happen to have both heads/master and tags/master, you can
72e9340c 164 explicitly say 'heads/master' to tell git which one you mean.
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165 When ambiguous, a `<name>` is disambiguated by taking the
166 first match in the following rules:
3a45f625 167
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168 . if `$GIT_DIR/<name>` exists, that is what you mean (this is usually
169 useful only for `HEAD`, `FETCH_HEAD` and `MERGE_HEAD`);
170
171 . otherwise, `$GIT_DIR/refs/<name>` if exists;
172
173 . otherwise, `$GIT_DIR/refs/tags/<name>` if exists;
174
175 . otherwise, `$GIT_DIR/refs/heads/<name>` if exists;
176
177 . otherwise, `$GIT_DIR/refs/remotes/<name>` if exists;
178
179 . otherwise, `$GIT_DIR/refs/remotes/<name>/HEAD` if exists.
180
181* A ref followed by the suffix '@' with a date specification
182 enclosed in a brace
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183 pair (e.g. '\{yesterday\}', '\{1 month 2 weeks 3 days 1 hour 1
184 second ago\}' or '\{1979-02-26 18:30:00\}') to specify the value
185 of the ref at a prior point in time. This suffix may only be
186 used immediately following a ref name and the ref must have an
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187 existing log ($GIT_DIR/logs/<ref>). Note that this looks up the state
188 of your *local* ref at a given time; e.g., what was in your local
189 `master` branch last week. If you want to look at commits made during
190 certain times, see `--since` and `--until`.
d556fae2 191
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192* A ref followed by the suffix '@' with an ordinal specification
193 enclosed in a brace pair (e.g. '\{1\}', '\{15\}') to specify
194 the n-th prior value of that ref. For example 'master@\{1\}'
195 is the immediate prior value of 'master' while 'master@\{5\}'
196 is the 5th prior value of 'master'. This suffix may only be used
197 immediately following a ref name and the ref must have an existing
198 log ($GIT_DIR/logs/<ref>).
199
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200* You can use the '@' construct with an empty ref part to get at a
201 reflog of the current branch. For example, if you are on the
202 branch 'blabla', then '@\{1\}' means the same as 'blabla@\{1\}'.
203
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204* A suffix '{caret}' to a revision parameter means the first parent of
205 that commit object. '{caret}<n>' means the <n>th parent (i.e.
206 'rev{caret}'
207 is equivalent to 'rev{caret}1'). As a special rule,
208 'rev{caret}0' means the commit itself and is used when 'rev' is the
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209 object name of a tag object that refers to a commit object.
210
54bd2558 211* A suffix '{tilde}<n>' to a revision parameter means the commit
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212 object that is the <n>th generation grand-parent of the named
213 commit object, following only the first parent. I.e. rev~3 is
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214 equivalent to rev{caret}{caret}{caret} which is equivalent to
215 rev{caret}1{caret}1{caret}1. See below for a illustration of
216 the usage of this form.
3a45f625 217
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218* A suffix '{caret}' followed by an object type name enclosed in
219 brace pair (e.g. `v0.99.8{caret}\{commit\}`) means the object
220 could be a tag, and dereference the tag recursively until an
221 object of that type is found or the object cannot be
222 dereferenced anymore (in which case, barf). `rev{caret}0`
223 introduced earlier is a short-hand for `rev{caret}\{commit\}`.
224
225* A suffix '{caret}' followed by an empty brace pair
226 (e.g. `v0.99.8{caret}\{\}`) means the object could be a tag,
227 and dereference the tag recursively until a non-tag object is
228 found.
229
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230* A colon, followed by a slash, followed by a text: this names
231 a commit whose commit message starts with the specified text.
232 This name returns the youngest matching commit which is
233 reachable from any ref. If the commit message starts with a
234 '!', you have to repeat that; the special sequence ':/!',
235 followed by something else than '!' is reserved for now.
236
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237* A suffix ':' followed by a path; this names the blob or tree
238 at the given path in the tree-ish object named by the part
239 before the colon.
240
241* A colon, optionally followed by a stage number (0 to 3) and a
242 colon, followed by a path; this names a blob object in the
243 index at the given path. Missing stage number (and the colon
a5d86f74 244 that follows it) names a stage 0 entry. During a merge, stage
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245 1 is the common ancestor, stage 2 is the target branch's version
246 (typically the current branch), and stage 3 is the version from
247 the branch being merged.
6b09c788 248
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249Here is an illustration, by Jon Loeliger. Both commit nodes B
250and C are parents of commit node A. Parent commits are ordered
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251left-to-right.
252
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253........................................
254G H I J
255 \ / \ /
256 D E F
257 \ | / \
258 \ | / |
259 \|/ |
260 B C
261 \ /
262 \ /
263 A
264........................................
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265
266 A = = A^0
267 B = A^ = A^1 = A~1
268 C = A^2 = A^2
269 D = A^^ = A^1^1 = A~2
270 E = B^2 = A^^2
271 F = B^3 = A^^3
272 G = A^^^ = A^1^1^1 = A~3
273 H = D^2 = B^^2 = A^^^2 = A~2^2
274 I = F^ = B^3^ = A^^3^
275 J = F^2 = B^3^2 = A^^3^2
276
3a45f625 277
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278SPECIFYING RANGES
279-----------------
280
281History traversing commands such as `git-log` operate on a set
282of commits, not just a single commit. To these commands,
283specifying a single revision with the notation described in the
284previous section means the set of commits reachable from that
285commit, following the commit ancestry chain.
286
287To exclude commits reachable from a commit, a prefix `{caret}`
288notation is used. E.g. "`{caret}r1 r2`" means commits reachable
289from `r2` but exclude the ones reachable from `r1`.
290
291This set operation appears so often that there is a shorthand
292for it. "`r1..r2`" is equivalent to "`{caret}r1 r2`". It is
293the difference of two sets (subtract the set of commits
294reachable from `r1` from the set of commits reachable from
295`r2`).
296
297A similar notation "`r1\...r2`" is called symmetric difference
298of `r1` and `r2` and is defined as
b1889c36 299"`r1 r2 --not $(git merge-base --all r1 r2)`".
e18ee576 300It is the set of commits that are reachable from either one of
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301`r1` or `r2` but not from both.
302
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303Two other shorthands for naming a set that is formed by a commit
304and its parent commits exists. `r1{caret}@` notation means all
305parents of `r1`. `r1{caret}!` includes commit `r1` but excludes
306its all parents.
307
a5d86f74 308Here are a handful of examples:
be4c7014 309
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310 D G H D
311 D F G H I J D F
312 ^G D H D
313 ^D B E I J F B
314 B...C G H D E B C
315 ^D B C E I J F B C
316 C^@ I J F
317 F^! D G H D F
be4c7014 318
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319PARSEOPT
320--------
321
322In `--parseopt` mode, `git-rev-parse` helps massaging options to bring to shell
323scripts the same facilities C builtins have. It works as an option normalizer
324(e.g. splits single switches aggregate values), a bit like `getopt(1)` does.
325
326It takes on the standard input the specification of the options to parse and
327understand, and echoes on the standard output a line suitable for `sh(1)` `eval`
328to replace the arguments with normalized ones. In case of error, it outputs
329usage on the standard error stream, and exits with code 129.
330
331Input Format
332~~~~~~~~~~~~
333
334`git-rev-parse --parseopt` input format is fully text based. It has two parts,
335separated by a line that contains only `--`. The lines before the separator
336(should be more than one) are used for the usage.
337The lines after the separator describe the options.
338
339Each line of options has this format:
340
341------------
ff962a3f 342<opt_spec><flags>* SP+ help LF
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343------------
344
345`<opt_spec>`::
346 its format is the short option character, then the long option name
347 separated by a comma. Both parts are not required, though at least one
348 is necessary. `h,help`, `dry-run` and `f` are all three correct
349 `<opt_spec>`.
350
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351`<flags>`::
352 `<flags>` are of `*`, `=`, `?` or `!`.
353 * Use `=` if the option takes an argument.
354
355 * Use `?` to mean that the option is optional (though its use is discouraged).
356
357 * Use `*` to mean that this option should not be listed in the usage
358 generated for the `-h` argument. It's shown for `--help-all` as
a5af0e2c 359 documented in linkgit:gitcli[7].
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360
361 * Use `!` to not make the corresponding negated long option available.
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362
363The remainder of the line, after stripping the spaces, is used
364as the help associated to the option.
365
366Blank lines are ignored, and lines that don't match this specification are used
367as option group headers (start the line with a space to create such
368lines on purpose).
369
370Example
371~~~~~~~
372
373------------
374OPTS_SPEC="\
375some-command [options] <args>...
376
377some-command does foo and bar!
378--
379h,help show the help
380
381foo some nifty option --foo
382bar= some cool option --bar with an argument
383
384 An option group Header
385C? option C with an optional argument"
386
b1889c36 387eval `echo "$OPTS_SPEC" | git rev-parse --parseopt -- "$@" || echo exit $?`
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388------------
389
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390EXAMPLES
391--------
392
393* Print the object name of the current commit:
394+
395------------
396$ git rev-parse --verify HEAD
397------------
398
399* Print the commit object name from the revision in the $REV shell variable:
400+
401------------
402$ git rev-parse --verify $REV
403------------
404+
405This will error out if $REV is empty or not a valid revision.
406
407* Same as above:
408+
409------------
410$ git rev-parse --default master --verify $REV
411------------
412+
413but if $REV is empty, the commit object name from master will be printed.
414
21d47835 415
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416Author
417------
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418Written by Linus Torvalds <torvalds@osdl.org> .
419Junio C Hamano <junkio@cox.net> and Pierre Habouzit <madcoder@debian.org>
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420
421Documentation
422--------------
423Documentation by Junio C Hamano and the git-list <git@vger.kernel.org>.
424
425GIT
426---
9e1f0a85 427Part of the linkgit:git[1] suite