Add 'git rev-parse --show-toplevel' option.
[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-toplevel::
116 Show the absolute path of the top-level directory.
117
118 --show-prefix::
119 When the command is invoked from a subdirectory, show the
120 path of the current directory relative to the top-level
121 directory.
122
123 --show-cdup::
124 When the command is invoked from a subdirectory, show the
125 path of the top-level directory relative to the current
126 directory (typically a sequence of "../", or an empty string).
127
128 --git-dir::
129 Show `$GIT_DIR` if defined else show the path to the .git directory.
130
131 --is-inside-git-dir::
132 When the current working directory is below the repository
133 directory print "true", otherwise "false".
134
135 --is-inside-work-tree::
136 When the current working directory is inside the work tree of the
137 repository print "true", otherwise "false".
138
139 --is-bare-repository::
140 When the repository is bare print "true", otherwise "false".
141
142 --short::
143 --short=number::
144 Instead of outputting the full SHA1 values of object names try to
145 abbreviate them to a shorter unique name. When no length is specified
146 7 is used. The minimum length is 4.
147
148 --since=datestring::
149 --after=datestring::
150 Parse the date string, and output the corresponding
151 --max-age= parameter for 'git-rev-list'.
152
153 --until=datestring::
154 --before=datestring::
155 Parse the date string, and output the corresponding
156 --min-age= parameter for 'git-rev-list'.
157
158 <args>...::
159 Flags and parameters to be parsed.
160
161
162 SPECIFYING REVISIONS
163 --------------------
164
165 A revision parameter typically, but not necessarily, names a
166 commit object. They use what is called an 'extended SHA1'
167 syntax. Here are various ways to spell object names. The
168 ones listed near the end of this list are to name trees and
169 blobs contained in a commit.
170
171 * The full SHA1 object name (40-byte hexadecimal string), or
172 a substring of such that is unique within the repository.
173 E.g. dae86e1950b1277e545cee180551750029cfe735 and dae86e both
174 name the same commit object if there are no other object in
175 your repository whose object name starts with dae86e.
176
177 * An output from 'git-describe'; i.e. a closest tag, optionally
178 followed by a dash and a number of commits, followed by a dash, a
179 `g`, and an abbreviated object name.
180
181 * A symbolic ref name. E.g. 'master' typically means the commit
182 object referenced by $GIT_DIR/refs/heads/master. If you
183 happen to have both heads/master and tags/master, you can
184 explicitly say 'heads/master' to tell git which one you mean.
185 When ambiguous, a `<name>` is disambiguated by taking the
186 first match in the following rules:
187
188 . if `$GIT_DIR/<name>` exists, that is what you mean (this is usually
189 useful only for `HEAD`, `FETCH_HEAD`, `ORIG_HEAD` and `MERGE_HEAD`);
190
191 . otherwise, `$GIT_DIR/refs/<name>` if exists;
192
193 . otherwise, `$GIT_DIR/refs/tags/<name>` if exists;
194
195 . otherwise, `$GIT_DIR/refs/heads/<name>` if exists;
196
197 . otherwise, `$GIT_DIR/refs/remotes/<name>` if exists;
198
199 . otherwise, `$GIT_DIR/refs/remotes/<name>/HEAD` if exists.
200 +
201 HEAD names the commit your changes in the working tree is based on.
202 FETCH_HEAD records the branch you fetched from a remote repository
203 with your last 'git-fetch' invocation.
204 ORIG_HEAD is created by commands that moves your HEAD in a drastic
205 way, to record the position of the HEAD before their operation, so that
206 you can change the tip of the branch back to the state before you ran
207 them easily.
208 MERGE_HEAD records the commit(s) you are merging into your branch
209 when you run 'git-merge'.
210
211 * A ref followed by the suffix '@' with a date specification
212 enclosed in a brace
213 pair (e.g. '\{yesterday\}', '\{1 month 2 weeks 3 days 1 hour 1
214 second ago\}' or '\{1979-02-26 18:30:00\}') to specify the value
215 of the ref at a prior point in time. This suffix may only be
216 used immediately following a ref name and the ref must have an
217 existing log ($GIT_DIR/logs/<ref>). Note that this looks up the state
218 of your *local* ref at a given time; e.g., what was in your local
219 `master` branch last week. If you want to look at commits made during
220 certain times, see `--since` and `--until`.
221
222 * A ref followed by the suffix '@' with an ordinal specification
223 enclosed in a brace pair (e.g. '\{1\}', '\{15\}') to specify
224 the n-th prior value of that ref. For example 'master@\{1\}'
225 is the immediate prior value of 'master' while 'master@\{5\}'
226 is the 5th prior value of 'master'. This suffix may only be used
227 immediately following a ref name and the ref must have an existing
228 log ($GIT_DIR/logs/<ref>).
229
230 * You can use the '@' construct with an empty ref part to get at a
231 reflog of the current branch. For example, if you are on the
232 branch 'blabla', then '@\{1\}' means the same as 'blabla@\{1\}'.
233
234 * The special construct '@\{-<n>\}' means the <n>th branch checked out
235 before the current one.
236
237 * A suffix '{caret}' to a revision parameter means the first parent of
238 that commit object. '{caret}<n>' means the <n>th parent (i.e.
239 'rev{caret}'
240 is equivalent to 'rev{caret}1'). As a special rule,
241 'rev{caret}0' means the commit itself and is used when 'rev' is the
242 object name of a tag object that refers to a commit object.
243
244 * A suffix '{tilde}<n>' to a revision parameter means the commit
245 object that is the <n>th generation grand-parent of the named
246 commit object, following only the first parent. I.e. rev~3 is
247 equivalent to rev{caret}{caret}{caret} which is equivalent to
248 rev{caret}1{caret}1{caret}1. See below for a illustration of
249 the usage of this form.
250
251 * A suffix '{caret}' followed by an object type name enclosed in
252 brace pair (e.g. `v0.99.8{caret}\{commit\}`) means the object
253 could be a tag, and dereference the tag recursively until an
254 object of that type is found or the object cannot be
255 dereferenced anymore (in which case, barf). `rev{caret}0`
256 introduced earlier is a short-hand for `rev{caret}\{commit\}`.
257
258 * A suffix '{caret}' followed by an empty brace pair
259 (e.g. `v0.99.8{caret}\{\}`) means the object could be a tag,
260 and dereference the tag recursively until a non-tag object is
261 found.
262
263 * A colon, followed by a slash, followed by a text: this names
264 a commit whose commit message starts with the specified text.
265 This name returns the youngest matching commit which is
266 reachable from any ref. If the commit message starts with a
267 '!', you have to repeat that; the special sequence ':/!',
268 followed by something else than '!' is reserved for now.
269
270 * A suffix ':' followed by a path; this names the blob or tree
271 at the given path in the tree-ish object named by the part
272 before the colon.
273
274 * A colon, optionally followed by a stage number (0 to 3) and a
275 colon, followed by a path; this names a blob object in the
276 index at the given path. Missing stage number (and the colon
277 that follows it) names a stage 0 entry. During a merge, stage
278 1 is the common ancestor, stage 2 is the target branch's version
279 (typically the current branch), and stage 3 is the version from
280 the branch being merged.
281
282 Here is an illustration, by Jon Loeliger. Both commit nodes B
283 and C are parents of commit node A. Parent commits are ordered
284 left-to-right.
285
286 ........................................
287 G H I J
288 \ / \ /
289 D E F
290 \ | / \
291 \ | / |
292 \|/ |
293 B C
294 \ /
295 \ /
296 A
297 ........................................
298
299 A = = A^0
300 B = A^ = A^1 = A~1
301 C = A^2 = A^2
302 D = A^^ = A^1^1 = A~2
303 E = B^2 = A^^2
304 F = B^3 = A^^3
305 G = A^^^ = A^1^1^1 = A~3
306 H = D^2 = B^^2 = A^^^2 = A~2^2
307 I = F^ = B^3^ = A^^3^
308 J = F^2 = B^3^2 = A^^3^2
309
310
311 SPECIFYING RANGES
312 -----------------
313
314 History traversing commands such as 'git-log' operate on a set
315 of commits, not just a single commit. To these commands,
316 specifying a single revision with the notation described in the
317 previous section means the set of commits reachable from that
318 commit, following the commit ancestry chain.
319
320 To exclude commits reachable from a commit, a prefix `{caret}`
321 notation is used. E.g. `{caret}r1 r2` means commits reachable
322 from `r2` but exclude the ones reachable from `r1`.
323
324 This set operation appears so often that there is a shorthand
325 for it. When you have two commits `r1` and `r2` (named according
326 to the syntax explained in SPECIFYING REVISIONS above), you can ask
327 for commits that are reachable from r2 excluding those that are reachable
328 from r1 by `{caret}r1 r2` and it can be written as `r1..r2`.
329
330 A similar notation `r1\...r2` is called symmetric difference
331 of `r1` and `r2` and is defined as
332 `r1 r2 --not $(git merge-base --all r1 r2)`.
333 It is the set of commits that are reachable from either one of
334 `r1` or `r2` but not from both.
335
336 Two other shorthands for naming a set that is formed by a commit
337 and its parent commits exist. The `r1{caret}@` notation means all
338 parents of `r1`. `r1{caret}!` includes commit `r1` but excludes
339 all of its parents.
340
341 Here are a handful of examples:
342
343 D G H D
344 D F G H I J D F
345 ^G D H D
346 ^D B E I J F B
347 B...C G H D E B C
348 ^D B C E I J F B C
349 C^@ I J F
350 F^! D G H D F
351
352 PARSEOPT
353 --------
354
355 In `--parseopt` mode, 'git-rev-parse' helps massaging options to bring to shell
356 scripts the same facilities C builtins have. It works as an option normalizer
357 (e.g. splits single switches aggregate values), a bit like `getopt(1)` does.
358
359 It takes on the standard input the specification of the options to parse and
360 understand, and echoes on the standard output a line suitable for `sh(1)` `eval`
361 to replace the arguments with normalized ones. In case of error, it outputs
362 usage on the standard error stream, and exits with code 129.
363
364 Input Format
365 ~~~~~~~~~~~~
366
367 'git-rev-parse --parseopt' input format is fully text based. It has two parts,
368 separated by a line that contains only `--`. The lines before the separator
369 (should be more than one) are used for the usage.
370 The lines after the separator describe the options.
371
372 Each line of options has this format:
373
374 ------------
375 <opt_spec><flags>* SP+ help LF
376 ------------
377
378 `<opt_spec>`::
379 its format is the short option character, then the long option name
380 separated by a comma. Both parts are not required, though at least one
381 is necessary. `h,help`, `dry-run` and `f` are all three correct
382 `<opt_spec>`.
383
384 `<flags>`::
385 `<flags>` are of `*`, `=`, `?` or `!`.
386 * Use `=` if the option takes an argument.
387
388 * Use `?` to mean that the option is optional (though its use is discouraged).
389
390 * Use `*` to mean that this option should not be listed in the usage
391 generated for the `-h` argument. It's shown for `--help-all` as
392 documented in linkgit:gitcli[7].
393
394 * Use `!` to not make the corresponding negated long option available.
395
396 The remainder of the line, after stripping the spaces, is used
397 as the help associated to the option.
398
399 Blank lines are ignored, and lines that don't match this specification are used
400 as option group headers (start the line with a space to create such
401 lines on purpose).
402
403 Example
404 ~~~~~~~
405
406 ------------
407 OPTS_SPEC="\
408 some-command [options] <args>...
409
410 some-command does foo and bar!
411 --
412 h,help show the help
413
414 foo some nifty option --foo
415 bar= some cool option --bar with an argument
416
417 An option group Header
418 C? option C with an optional argument"
419
420 eval `echo "$OPTS_SPEC" | git rev-parse --parseopt -- "$@" || echo exit $?`
421 ------------
422
423 SQ-QUOTE
424 --------
425
426 In `--sq-quote` mode, 'git-rev-parse' echoes on the standard output a
427 single line suitable for `sh(1)` `eval`. This line is made by
428 normalizing the arguments following `--sq-quote`. Nothing other than
429 quoting the arguments is done.
430
431 If you want command input to still be interpreted as usual by
432 'git-rev-parse' before the output is shell quoted, see the `--sq`
433 option.
434
435 Example
436 ~~~~~~~
437
438 ------------
439 $ cat >your-git-script.sh <<\EOF
440 #!/bin/sh
441 args=$(git rev-parse --sq-quote "$@") # quote user-supplied arguments
442 command="git frotz -n24 $args" # and use it inside a handcrafted
443 # command line
444 eval "$command"
445 EOF
446
447 $ sh your-git-script.sh "a b'c"
448 ------------
449
450 EXAMPLES
451 --------
452
453 * Print the object name of the current commit:
454 +
455 ------------
456 $ git rev-parse --verify HEAD
457 ------------
458
459 * Print the commit object name from the revision in the $REV shell variable:
460 +
461 ------------
462 $ git rev-parse --verify $REV
463 ------------
464 +
465 This will error out if $REV is empty or not a valid revision.
466
467 * Same as above:
468 +
469 ------------
470 $ git rev-parse --default master --verify $REV
471 ------------
472 +
473 but if $REV is empty, the commit object name from master will be printed.
474
475
476 Author
477 ------
478 Written by Linus Torvalds <torvalds@osdl.org> .
479 Junio C Hamano <gitster@pobox.com> and Pierre Habouzit <madcoder@debian.org>
480
481 Documentation
482 --------------
483 Documentation by Junio C Hamano and the git-list <git@vger.kernel.org>.
484
485 GIT
486 ---
487 Part of the linkgit:git[1] suite