Merge branch 'sv/objfixes'
[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--------
11'git-rev-parse' [ --option ] <args>...
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--revs-only::
27 Do not output flags and parameters not meant for
28 `git-rev-list` command.
29
30--no-revs::
31 Do not output flags and parameters meant for
32 `git-rev-list` command.
33
34--flags::
35 Do not output non-flag parameters.
36
37--no-flags::
38 Do not output flag parameters.
39
40--default <arg>::
41 If there is no parameter given by the user, use `<arg>`
42 instead.
43
44--verify::
45 The parameter given must be usable as a single, valid
46 object name. Otherwise barf and abort.
47
48--sq::
49 Usually the output is made one line per flag and
50 parameter. This option makes output a single line,
51 properly quoted for consumption by shell. Useful when
52 you expect your parameter to contain whitespaces and
53 newlines (e.g. when using pickaxe `-S` with
54 `git-diff-\*`).
55
56--not::
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57 When showing object names, prefix them with '{caret}' and
58 strip '{caret}' prefix from the object names that already have
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59 one.
60
61--symbolic::
62 Usually the object names are output in SHA1 form (with
babfaba2 63 possible '{caret}' prefix); this option makes them output in a
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64 form as close to the original input as possible.
65
66
67--all::
68 Show all refs found in `$GIT_DIR/refs`.
69
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70--branches::
71 Show branch refs found in `$GIT_DIR/refs/heads`.
72
73--tags::
74 Show tag refs found in `$GIT_DIR/refs/tags`.
75
76--remotes::
77 Show tag refs found in `$GIT_DIR/refs/remotes`.
78
5077fa9c 79--show-prefix::
5f94c730 80 When the command is invoked from a subdirectory, show the
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81 path of the current directory relative to the top-level
82 directory.
7fc9d69f 83
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84--show-cdup::
85 When the command is invoked from a subdirectory, show the
86 path of the top-level directory relative to the current
87 directory (typically a sequence of "../", or an empty string).
88
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89--git-dir::
90 Show `$GIT_DIR` if defined else show the path to the .git directory.
91
5102349c 92--short, --short=number::
735d80b3 93 Instead of outputting the full SHA1 values of object names try to
abda1ef5 94 abbreviate them to a shorter unique name. When no length is specified
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95 7 is used. The minimum length is 4.
96
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97--since=datestring, --after=datestring::
98 Parses the date string, and outputs corresponding
99 --max-age= parameter for git-rev-list command.
100
101--until=datestring, --before=datestring::
102 Parses the date string, and outputs corresponding
103 --min-age= parameter for git-rev-list command.
104
7fc9d69f 105<args>...::
5077fa9c 106 Flags and parameters to be parsed.
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107
108
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109SPECIFYING REVISIONS
110--------------------
111
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112A revision parameter typically, but not necessarily, names a
113commit object. They use what is called an 'extended SHA1'
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114syntax. Here are various ways to spell object names. The
115ones listed near the end of this list are to name trees and
116blobs contained in a commit.
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117
118* The full SHA1 object name (40-byte hexadecimal string), or
119 a substring of such that is unique within the repository.
120 E.g. dae86e1950b1277e545cee180551750029cfe735 and dae86e both
121 name the same commit object if there are no other object in
122 your repository whose object name starts with dae86e.
123
6b09c788 124* An output from `git-describe`; i.e. a closest tag, followed by a
0ac30568 125 dash, a `g`, and an abbreviated object name.
6b09c788 126
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127* A symbolic ref name. E.g. 'master' typically means the commit
128 object referenced by $GIT_DIR/refs/heads/master. If you
129 happen to have both heads/master and tags/master, you can
72e9340c 130 explicitly say 'heads/master' to tell git which one you mean.
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131 When ambiguous, a `<name>` is disambiguated by taking the
132 first match in the following rules:
3a45f625 133
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134 . if `$GIT_DIR/<name>` exists, that is what you mean (this is usually
135 useful only for `HEAD`, `FETCH_HEAD` and `MERGE_HEAD`);
136
137 . otherwise, `$GIT_DIR/refs/<name>` if exists;
138
139 . otherwise, `$GIT_DIR/refs/tags/<name>` if exists;
140
141 . otherwise, `$GIT_DIR/refs/heads/<name>` if exists;
142
143 . otherwise, `$GIT_DIR/refs/remotes/<name>` if exists;
144
145 . otherwise, `$GIT_DIR/refs/remotes/<name>/HEAD` if exists.
146
147* A ref followed by the suffix '@' with a date specification
148 enclosed in a brace
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149 pair (e.g. '\{yesterday\}', '\{1 month 2 weeks 3 days 1 hour 1
150 second ago\}' or '\{1979-02-26 18:30:00\}') to specify the value
151 of the ref at a prior point in time. This suffix may only be
152 used immediately following a ref name and the ref must have an
153 existing log ($GIT_DIR/logs/<ref>).
d556fae2 154
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155* A ref followed by the suffix '@' with an ordinal specification
156 enclosed in a brace pair (e.g. '\{1\}', '\{15\}') to specify
157 the n-th prior value of that ref. For example 'master@\{1\}'
158 is the immediate prior value of 'master' while 'master@\{5\}'
159 is the 5th prior value of 'master'. This suffix may only be used
160 immediately following a ref name and the ref must have an existing
161 log ($GIT_DIR/logs/<ref>).
162
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163* You can use the '@' construct with an empty ref part to get at a
164 reflog of the current branch. For example, if you are on the
165 branch 'blabla', then '@\{1\}' means the same as 'blabla@\{1\}'.
166
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167* A suffix '{caret}' to a revision parameter means the first parent of
168 that commit object. '{caret}<n>' means the <n>th parent (i.e.
169 'rev{caret}'
170 is equivalent to 'rev{caret}1'). As a special rule,
171 'rev{caret}0' means the commit itself and is used when 'rev' is the
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172 object name of a tag object that refers to a commit object.
173
54bd2558 174* A suffix '{tilde}<n>' to a revision parameter means the commit
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175 object that is the <n>th generation grand-parent of the named
176 commit object, following only the first parent. I.e. rev~3 is
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177 equivalent to rev{caret}{caret}{caret} which is equivalent to
178 rev{caret}1{caret}1{caret}1. See below for a illustration of
179 the usage of this form.
3a45f625 180
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181* A suffix '{caret}' followed by an object type name enclosed in
182 brace pair (e.g. `v0.99.8{caret}\{commit\}`) means the object
183 could be a tag, and dereference the tag recursively until an
184 object of that type is found or the object cannot be
185 dereferenced anymore (in which case, barf). `rev{caret}0`
186 introduced earlier is a short-hand for `rev{caret}\{commit\}`.
187
188* A suffix '{caret}' followed by an empty brace pair
189 (e.g. `v0.99.8{caret}\{\}`) means the object could be a tag,
190 and dereference the tag recursively until a non-tag object is
191 found.
192
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193* A colon, followed by a slash, followed by a text: this names
194 a commit whose commit message starts with the specified text.
195 This name returns the youngest matching commit which is
196 reachable from any ref. If the commit message starts with a
197 '!', you have to repeat that; the special sequence ':/!',
198 followed by something else than '!' is reserved for now.
199
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200* A suffix ':' followed by a path; this names the blob or tree
201 at the given path in the tree-ish object named by the part
202 before the colon.
203
204* A colon, optionally followed by a stage number (0 to 3) and a
205 colon, followed by a path; this names a blob object in the
206 index at the given path. Missing stage number (and the colon
207 that follows it) names an stage 0 entry.
208
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209Here is an illustration, by Jon Loeliger. Both node B and C are
210a commit parents of commit node A. Parent commits are ordered
211left-to-right.
212
213 G H I J
214 \ / \ /
215 D E F
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216 \ | / \
217 \ | / |
218 \|/ |
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219 B C
220 \ /
221 \ /
222 A
223
224 A = = A^0
225 B = A^ = A^1 = A~1
226 C = A^2 = A^2
227 D = A^^ = A^1^1 = A~2
228 E = B^2 = A^^2
229 F = B^3 = A^^3
230 G = A^^^ = A^1^1^1 = A~3
231 H = D^2 = B^^2 = A^^^2 = A~2^2
232 I = F^ = B^3^ = A^^3^
233 J = F^2 = B^3^2 = A^^3^2
234
3a45f625 235
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236SPECIFYING RANGES
237-----------------
238
239History traversing commands such as `git-log` operate on a set
240of commits, not just a single commit. To these commands,
241specifying a single revision with the notation described in the
242previous section means the set of commits reachable from that
243commit, following the commit ancestry chain.
244
245To exclude commits reachable from a commit, a prefix `{caret}`
246notation is used. E.g. "`{caret}r1 r2`" means commits reachable
247from `r2` but exclude the ones reachable from `r1`.
248
249This set operation appears so often that there is a shorthand
250for it. "`r1..r2`" is equivalent to "`{caret}r1 r2`". It is
251the difference of two sets (subtract the set of commits
252reachable from `r1` from the set of commits reachable from
253`r2`).
254
255A similar notation "`r1\...r2`" is called symmetric difference
256of `r1` and `r2` and is defined as
257"`r1 r2 --not $(git-merge-base --all r1 r2)`".
e18ee576 258It is the set of commits that are reachable from either one of
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259`r1` or `r2` but not from both.
260
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261Two other shorthands for naming a set that is formed by a commit
262and its parent commits exists. `r1{caret}@` notation means all
263parents of `r1`. `r1{caret}!` includes commit `r1` but excludes
264its all parents.
265
266Here are a handful examples:
be4c7014 267
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268 D G H D
269 D F G H I J D F
270 ^G D H D
271 ^D B E I J F B
272 B...C G H D E B C
273 ^D B C E I J F B C
274 C^@ I J F
275 F^! D G H D F
be4c7014 276
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277Author
278------
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279Written by Linus Torvalds <torvalds@osdl.org> and
280Junio C Hamano <junkio@cox.net>
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281
282Documentation
283--------------
284Documentation by Junio C Hamano and the git-list <git@vger.kernel.org>.
285
286GIT
287---
a7154e91 288Part of the gitlink:git[7] suite
7fc9d69f 289