82045a2522799ccf3a03479bf4f4cd1fa1809879
[git/git.git] / Documentation / git-rev-parse.txt
1 git-rev-parse(1)
2 ================
3
4 NAME
5 ----
6 git-rev-parse - Pick out and massage parameters
7
8
9 SYNOPSIS
10 --------
11 'git rev-parse' [ --option ] <args>...
12
13 DESCRIPTION
14 -----------
15
16 Many git porcelainish commands take mixture of flags
17 (i.e. parameters that begin with a dash '-') and parameters
18 meant for the underlying 'git-rev-list' command they use internally
19 and flags and parameters for the other commands they use
20 downstream of 'git-rev-list'. This command is used to
21 distinguish between them.
22
23
24 OPTIONS
25 -------
26 --parseopt::
27 Use 'git-rev-parse' in option parsing mode (see PARSEOPT section below).
28
29 --keep-dashdash::
30 Only meaningful in `--parseopt` mode. Tells the option parser to echo
31 out the first `--` met instead of skipping it.
32
33 --stop-at-non-option::
34 Only meaningful in `--parseopt` mode. Lets the option parser stop at
35 the first non-option argument. This can be used to parse sub-commands
36 that take options themself.
37
38 --sq-quote::
39 Use 'git-rev-parse' in shell quoting mode (see SQ-QUOTE
40 section below). In contrast to the `--sq` option below, this
41 mode does only quoting. Nothing else is done to command input.
42
43 --revs-only::
44 Do not output flags and parameters not meant for
45 'git-rev-list' command.
46
47 --no-revs::
48 Do not output flags and parameters meant for
49 'git-rev-list' command.
50
51 --flags::
52 Do not output non-flag parameters.
53
54 --no-flags::
55 Do not output flag parameters.
56
57 --default <arg>::
58 If there is no parameter given by the user, use `<arg>`
59 instead.
60
61 --verify::
62 The parameter given must be usable as a single, valid
63 object name. Otherwise barf and abort.
64
65 -q::
66 --quiet::
67 Only meaningful in `--verify` mode. Do not output an error
68 message if the first argument is not a valid object name;
69 instead exit with non-zero status silently.
70
71 --sq::
72 Usually the output is made one line per flag and
73 parameter. This option makes output a single line,
74 properly quoted for consumption by shell. Useful when
75 you expect your parameter to contain whitespaces and
76 newlines (e.g. when using pickaxe `-S` with
77 'git-diff-\*'). In contrast to the `--sq-quote` option,
78 the command input is still interpreted as usual.
79
80 --not::
81 When showing object names, prefix them with '{caret}' and
82 strip '{caret}' prefix from the object names that already have
83 one.
84
85 --symbolic::
86 Usually the object names are output in SHA1 form (with
87 possible '{caret}' prefix); this option makes them output in a
88 form as close to the original input as possible.
89
90 --symbolic-full-name::
91 This is similar to \--symbolic, but it omits input that
92 are not refs (i.e. branch or tag names; or more
93 explicitly disambiguating "heads/master" form, when you
94 want to name the "master" branch when there is an
95 unfortunately named tag "master"), and show them as full
96 refnames (e.g. "refs/heads/master").
97
98 --abbrev-ref[={strict|loose}]::
99 A non-ambiguous short name of the objects name.
100 The option core.warnAmbiguousRefs is used to select the strict
101 abbreviation mode.
102
103 --all::
104 Show all refs found in `$GIT_DIR/refs`.
105
106 --branches::
107 Show branch refs found in `$GIT_DIR/refs/heads`.
108
109 --tags::
110 Show tag refs found in `$GIT_DIR/refs/tags`.
111
112 --remotes::
113 Show tag refs found in `$GIT_DIR/refs/remotes`.
114
115 --show-prefix::
116 When the command is invoked from a subdirectory, show the
117 path of the current directory relative to the top-level
118 directory.
119
120 --show-cdup::
121 When the command is invoked from a subdirectory, show the
122 path of the top-level directory relative to the current
123 directory (typically a sequence of "../", or an empty string).
124
125 --git-dir::
126 Show `$GIT_DIR` if defined else show the path to the .git directory.
127
128 --is-inside-git-dir::
129 When the current working directory is below the repository
130 directory print "true", otherwise "false".
131
132 --is-inside-work-tree::
133 When the current working directory is inside the work tree of the
134 repository print "true", otherwise "false".
135
136 --is-bare-repository::
137 When the repository is bare print "true", otherwise "false".
138
139 --short::
140 --short=number::
141 Instead of outputting the full SHA1 values of object names try to
142 abbreviate them to a shorter unique name. When no length is specified
143 7 is used. The minimum length is 4.
144
145 --since=datestring::
146 --after=datestring::
147 Parse the date string, and output the corresponding
148 --max-age= parameter for 'git-rev-list'.
149
150 --until=datestring::
151 --before=datestring::
152 Parse the date string, and output the corresponding
153 --min-age= parameter for 'git-rev-list'.
154
155 <args>...::
156 Flags and parameters to be parsed.
157
158
159 SPECIFYING REVISIONS
160 --------------------
161
162 A revision parameter typically, but not necessarily, names a
163 commit object. They use what is called an 'extended SHA1'
164 syntax. Here are various ways to spell object names. The
165 ones listed near the end of this list are to name trees and
166 blobs contained in a commit.
167
168 * The full SHA1 object name (40-byte hexadecimal string), or
169 a substring of such that is unique within the repository.
170 E.g. dae86e1950b1277e545cee180551750029cfe735 and dae86e both
171 name the same commit object if there are no other object in
172 your repository whose object name starts with dae86e.
173
174 * An output from 'git-describe'; i.e. a closest tag, optionally
175 followed by a dash and a number of commits, followed by a dash, a
176 `g`, and an abbreviated object name.
177
178 * A symbolic ref name. E.g. 'master' typically means the commit
179 object referenced by $GIT_DIR/refs/heads/master. If you
180 happen to have both heads/master and tags/master, you can
181 explicitly say 'heads/master' to tell git which one you mean.
182 When ambiguous, a `<name>` is disambiguated by taking the
183 first match in the following rules:
184
185 . if `$GIT_DIR/<name>` exists, that is what you mean (this is usually
186 useful only for `HEAD`, `FETCH_HEAD`, `ORIG_HEAD` and `MERGE_HEAD`);
187
188 . otherwise, `$GIT_DIR/refs/<name>` if exists;
189
190 . otherwise, `$GIT_DIR/refs/tags/<name>` if exists;
191
192 . otherwise, `$GIT_DIR/refs/heads/<name>` if exists;
193
194 . otherwise, `$GIT_DIR/refs/remotes/<name>` if exists;
195
196 . otherwise, `$GIT_DIR/refs/remotes/<name>/HEAD` if exists.
197 +
198 HEAD names the commit your changes in the working tree is based on.
199 FETCH_HEAD records the branch you fetched from a remote repository
200 with your last 'git-fetch' invocation.
201 ORIG_HEAD is created by commands that moves your HEAD in a drastic
202 way, to record the position of the HEAD before their operation, so that
203 you can change the tip of the branch back to the state before you ran
204 them easily.
205 MERGE_HEAD records the commit(s) you are merging into your branch
206 when you run 'git-merge'.
207
208 * A ref followed by the suffix '@' with a date specification
209 enclosed in a brace
210 pair (e.g. '\{yesterday\}', '\{1 month 2 weeks 3 days 1 hour 1
211 second ago\}' or '\{1979-02-26 18:30:00\}') to specify the value
212 of the ref at a prior point in time. This suffix may only be
213 used immediately following a ref name and the ref must have an
214 existing log ($GIT_DIR/logs/<ref>). Note that this looks up the state
215 of your *local* ref at a given time; e.g., what was in your local
216 `master` branch last week. If you want to look at commits made during
217 certain times, see `--since` and `--until`.
218
219 * A ref followed by the suffix '@' with an ordinal specification
220 enclosed in a brace pair (e.g. '\{1\}', '\{15\}') to specify
221 the n-th prior value of that ref. For example 'master@\{1\}'
222 is the immediate prior value of 'master' while 'master@\{5\}'
223 is the 5th prior value of 'master'. This suffix may only be used
224 immediately following a ref name and the ref must have an existing
225 log ($GIT_DIR/logs/<ref>).
226
227 * You can use the '@' construct with an empty ref part to get at a
228 reflog of the current branch. For example, if you are on the
229 branch 'blabla', then '@\{1\}' means the same as 'blabla@\{1\}'.
230
231 * The special construct '@\{-<n>\}' means the <n>th branch checked out
232 before the current one.
233
234 * A suffix '{caret}' to a revision parameter means the first parent of
235 that commit object. '{caret}<n>' means the <n>th parent (i.e.
236 'rev{caret}'
237 is equivalent to 'rev{caret}1'). As a special rule,
238 'rev{caret}0' means the commit itself and is used when 'rev' is the
239 object name of a tag object that refers to a commit object.
240
241 * A suffix '{tilde}<n>' to a revision parameter means the commit
242 object that is the <n>th generation grand-parent of the named
243 commit object, following only the first parent. I.e. rev~3 is
244 equivalent to rev{caret}{caret}{caret} which is equivalent to
245 rev{caret}1{caret}1{caret}1. See below for a illustration of
246 the usage of this form.
247
248 * A suffix '{caret}' followed by an object type name enclosed in
249 brace pair (e.g. `v0.99.8{caret}\{commit\}`) means the object
250 could be a tag, and dereference the tag recursively until an
251 object of that type is found or the object cannot be
252 dereferenced anymore (in which case, barf). `rev{caret}0`
253 introduced earlier is a short-hand for `rev{caret}\{commit\}`.
254
255 * A suffix '{caret}' followed by an empty brace pair
256 (e.g. `v0.99.8{caret}\{\}`) means the object could be a tag,
257 and dereference the tag recursively until a non-tag object is
258 found.
259
260 * A colon, followed by a slash, followed by a text: this names
261 a commit whose commit message starts with the specified text.
262 This name returns the youngest matching commit which is
263 reachable from any ref. If the commit message starts with a
264 '!', you have to repeat that; the special sequence ':/!',
265 followed by something else than '!' is reserved for now.
266
267 * A suffix ':' followed by a path; this names the blob or tree
268 at the given path in the tree-ish object named by the part
269 before the colon.
270
271 * A colon, optionally followed by a stage number (0 to 3) and a
272 colon, followed by a path; this names a blob object in the
273 index at the given path. Missing stage number (and the colon
274 that follows it) names a stage 0 entry. During a merge, stage
275 1 is the common ancestor, stage 2 is the target branch's version
276 (typically the current branch), and stage 3 is the version from
277 the branch being merged.
278
279 Here is an illustration, by Jon Loeliger. Both commit nodes B
280 and C are parents of commit node A. Parent commits are ordered
281 left-to-right.
282
283 ........................................
284 G H I J
285 \ / \ /
286 D E F
287 \ | / \
288 \ | / |
289 \|/ |
290 B C
291 \ /
292 \ /
293 A
294 ........................................
295
296 A = = A^0
297 B = A^ = A^1 = A~1
298 C = A^2 = A^2
299 D = A^^ = A^1^1 = A~2
300 E = B^2 = A^^2
301 F = B^3 = A^^3
302 G = A^^^ = A^1^1^1 = A~3
303 H = D^2 = B^^2 = A^^^2 = A~2^2
304 I = F^ = B^3^ = A^^3^
305 J = F^2 = B^3^2 = A^^3^2
306
307
308 SPECIFYING RANGES
309 -----------------
310
311 History traversing commands such as 'git-log' operate on a set
312 of commits, not just a single commit. To these commands,
313 specifying a single revision with the notation described in the
314 previous section means the set of commits reachable from that
315 commit, following the commit ancestry chain.
316
317 To exclude commits reachable from a commit, a prefix `{caret}`
318 notation is used. E.g. `{caret}r1 r2` means commits reachable
319 from `r2` but exclude the ones reachable from `r1`.
320
321 This set operation appears so often that there is a shorthand
322 for it. When you have two commits `r1` and `r2` (named according
323 to the syntax explained in SPECIFYING REVISIONS above), you can ask
324 for commits that are reachable from r2 excluding those that are reachable
325 from r1 by `{caret}r1 r2` and it can be written as `r1..r2`.
326
327 A similar notation `r1\...r2` is called symmetric difference
328 of `r1` and `r2` and is defined as
329 `r1 r2 --not $(git merge-base --all r1 r2)`.
330 It is the set of commits that are reachable from either one of
331 `r1` or `r2` but not from both.
332
333 Two other shorthands for naming a set that is formed by a commit
334 and its parent commits exist. The `r1{caret}@` notation means all
335 parents of `r1`. `r1{caret}!` includes commit `r1` but excludes
336 all of its parents.
337
338 Here are a handful of examples:
339
340 D G H D
341 D F G H I J D F
342 ^G D H D
343 ^D B E I J F B
344 B...C G H D E B C
345 ^D B C E I J F B C
346 C^@ I J F
347 F^! D G H D F
348
349 PARSEOPT
350 --------
351
352 In `--parseopt` mode, 'git-rev-parse' helps massaging options to bring to shell
353 scripts the same facilities C builtins have. It works as an option normalizer
354 (e.g. splits single switches aggregate values), a bit like `getopt(1)` does.
355
356 It takes on the standard input the specification of the options to parse and
357 understand, and echoes on the standard output a line suitable for `sh(1)` `eval`
358 to replace the arguments with normalized ones. In case of error, it outputs
359 usage on the standard error stream, and exits with code 129.
360
361 Input Format
362 ~~~~~~~~~~~~
363
364 'git-rev-parse --parseopt' input format is fully text based. It has two parts,
365 separated by a line that contains only `--`. The lines before the separator
366 (should be more than one) are used for the usage.
367 The lines after the separator describe the options.
368
369 Each line of options has this format:
370
371 ------------
372 <opt_spec><flags>* SP+ help LF
373 ------------
374
375 `<opt_spec>`::
376 its format is the short option character, then the long option name
377 separated by a comma. Both parts are not required, though at least one
378 is necessary. `h,help`, `dry-run` and `f` are all three correct
379 `<opt_spec>`.
380
381 `<flags>`::
382 `<flags>` are of `*`, `=`, `?` or `!`.
383 * Use `=` if the option takes an argument.
384
385 * Use `?` to mean that the option is optional (though its use is discouraged).
386
387 * Use `*` to mean that this option should not be listed in the usage
388 generated for the `-h` argument. It's shown for `--help-all` as
389 documented in linkgit:gitcli[7].
390
391 * Use `!` to not make the corresponding negated long option available.
392
393 The remainder of the line, after stripping the spaces, is used
394 as the help associated to the option.
395
396 Blank lines are ignored, and lines that don't match this specification are used
397 as option group headers (start the line with a space to create such
398 lines on purpose).
399
400 Example
401 ~~~~~~~
402
403 ------------
404 OPTS_SPEC="\
405 some-command [options] <args>...
406
407 some-command does foo and bar!
408 --
409 h,help show the help
410
411 foo some nifty option --foo
412 bar= some cool option --bar with an argument
413
414 An option group Header
415 C? option C with an optional argument"
416
417 eval `echo "$OPTS_SPEC" | git rev-parse --parseopt -- "$@" || echo exit $?`
418 ------------
419
420 SQ-QUOTE
421 --------
422
423 In `--sq-quote` mode, 'git-rev-parse' echoes on the standard output a
424 single line suitable for `sh(1)` `eval`. This line is made by
425 normalizing the arguments following `--sq-quote`. Nothing other than
426 quoting the arguments is done.
427
428 If you want command input to still be interpreted as usual by
429 'git-rev-parse' before the output is shell quoted, see the `--sq`
430 option.
431
432 Example
433 ~~~~~~~
434
435 ------------
436 $ cat >your-git-script.sh <<\EOF
437 #!/bin/sh
438 args=$(git rev-parse --sq-quote "$@") # quote user-supplied arguments
439 command="git frotz -n24 $args" # and use it inside a handcrafted
440 # command line
441 eval "$command"
442 EOF
443
444 $ sh your-git-script.sh "a b'c"
445 ------------
446
447 EXAMPLES
448 --------
449
450 * Print the object name of the current commit:
451 +
452 ------------
453 $ git rev-parse --verify HEAD
454 ------------
455
456 * Print the commit object name from the revision in the $REV shell variable:
457 +
458 ------------
459 $ git rev-parse --verify $REV
460 ------------
461 +
462 This will error out if $REV is empty or not a valid revision.
463
464 * Same as above:
465 +
466 ------------
467 $ git rev-parse --default master --verify $REV
468 ------------
469 +
470 but if $REV is empty, the commit object name from master will be printed.
471
472
473 Author
474 ------
475 Written by Linus Torvalds <torvalds@osdl.org> .
476 Junio C Hamano <gitster@pobox.com> and Pierre Habouzit <madcoder@debian.org>
477
478 Documentation
479 --------------
480 Documentation by Junio C Hamano and the git-list <git@vger.kernel.org>.
481
482 GIT
483 ---
484 Part of the linkgit:git[1] suite