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[git/git.git] / Documentation / githooks.txt
1 githooks(5)
2 ===========
3
4 NAME
5 ----
6 githooks - Hooks used by Git
7
8 SYNOPSIS
9 --------
10 $GIT_DIR/hooks/*
11
12
13 DESCRIPTION
14 -----------
15
16 Hooks are little scripts you can place in `$GIT_DIR/hooks`
17 directory to trigger action at certain points. When
18 'git init' is run, a handful of example hooks are copied into the
19 `hooks` directory of the new repository, but by default they are
20 all disabled. To enable a hook, rename it by removing its `.sample`
21 suffix.
22
23 NOTE: It is also a requirement for a given hook to be executable.
24 However - in a freshly initialized repository - the `.sample` files are
25 executable by default.
26
27 This document describes the currently defined hooks.
28
29 HOOKS
30 -----
31
32 applypatch-msg
33 ~~~~~~~~~~~~~~
34
35 This hook is invoked by 'git am' script. It takes a single
36 parameter, the name of the file that holds the proposed commit
37 log message. Exiting with non-zero status causes
38 'git am' to abort before applying the patch.
39
40 The hook is allowed to edit the message file in place, and can
41 be used to normalize the message into some project standard
42 format (if the project has one). It can also be used to refuse
43 the commit after inspecting the message file.
44
45 The default 'applypatch-msg' hook, when enabled, runs the
46 'commit-msg' hook, if the latter is enabled.
47
48 pre-applypatch
49 ~~~~~~~~~~~~~~
50
51 This hook is invoked by 'git am'. It takes no parameter, and is
52 invoked after the patch is applied, but before a commit is made.
53
54 If it exits with non-zero status, then the working tree will not be
55 committed after applying the patch.
56
57 It can be used to inspect the current working tree and refuse to
58 make a commit if it does not pass certain test.
59
60 The default 'pre-applypatch' hook, when enabled, runs the
61 'pre-commit' hook, if the latter is enabled.
62
63 post-applypatch
64 ~~~~~~~~~~~~~~~
65
66 This hook is invoked by 'git am'. It takes no parameter,
67 and is invoked after the patch is applied and a commit is made.
68
69 This hook is meant primarily for notification, and cannot affect
70 the outcome of 'git am'.
71
72 pre-commit
73 ~~~~~~~~~~
74
75 This hook is invoked by 'git commit', and can be bypassed
76 with `--no-verify` option. It takes no parameter, and is
77 invoked before obtaining the proposed commit log message and
78 making a commit. Exiting with non-zero status from this script
79 causes the 'git commit' to abort.
80
81 The default 'pre-commit' hook, when enabled, catches introduction
82 of lines with trailing whitespaces and aborts the commit when
83 such a line is found.
84
85 All the 'git commit' hooks are invoked with the environment
86 variable `GIT_EDITOR=:` if the command will not bring up an editor
87 to modify the commit message.
88
89 prepare-commit-msg
90 ~~~~~~~~~~~~~~~~~~
91
92 This hook is invoked by 'git commit' right after preparing the
93 default log message, and before the editor is started.
94
95 It takes one to three parameters. The first is the name of the file
96 that contains the commit log message. The second is the source of the commit
97 message, and can be: `message` (if a `-m` or `-F` option was
98 given); `template` (if a `-t` option was given or the
99 configuration option `commit.template` is set); `merge` (if the
100 commit is a merge or a `.git/MERGE_MSG` file exists); `squash`
101 (if a `.git/SQUASH_MSG` file exists); or `commit`, followed by
102 a commit SHA-1 (if a `-c`, `-C` or `--amend` option was given).
103
104 If the exit status is non-zero, 'git commit' will abort.
105
106 The purpose of the hook is to edit the message file in place, and
107 it is not suppressed by the `--no-verify` option. A non-zero exit
108 means a failure of the hook and aborts the commit. It should not
109 be used as replacement for pre-commit hook.
110
111 The sample `prepare-commit-msg` hook that comes with Git comments
112 out the `Conflicts:` part of a merge's commit message.
113
114 commit-msg
115 ~~~~~~~~~~
116
117 This hook is invoked by 'git commit', and can be bypassed
118 with `--no-verify` option. It takes a single parameter, the
119 name of the file that holds the proposed commit log message.
120 Exiting with non-zero status causes the 'git commit' to
121 abort.
122
123 The hook is allowed to edit the message file in place, and can
124 be used to normalize the message into some project standard
125 format (if the project has one). It can also be used to refuse
126 the commit after inspecting the message file.
127
128 The default 'commit-msg' hook, when enabled, detects duplicate
129 "Signed-off-by" lines, and aborts the commit if one is found.
130
131 post-commit
132 ~~~~~~~~~~~
133
134 This hook is invoked by 'git commit'. It takes no
135 parameter, and is invoked after a commit is made.
136
137 This hook is meant primarily for notification, and cannot affect
138 the outcome of 'git commit'.
139
140 pre-rebase
141 ~~~~~~~~~~
142
143 This hook is called by 'git rebase' and can be used to prevent a
144 branch from getting rebased. The hook may be called with one or
145 two parameters. The first parameter is the upstream from which
146 the series was forked. The second parameter is the branch being
147 rebased, and is not set when rebasing the current branch.
148
149 post-checkout
150 ~~~~~~~~~~~~~
151
152 This hook is invoked when a 'git checkout' is run after having updated the
153 worktree. The hook is given three parameters: the ref of the previous HEAD,
154 the ref of the new HEAD (which may or may not have changed), and a flag
155 indicating whether the checkout was a branch checkout (changing branches,
156 flag=1) or a file checkout (retrieving a file from the index, flag=0).
157 This hook cannot affect the outcome of 'git checkout'.
158
159 It is also run after 'git clone', unless the --no-checkout (-n) option is
160 used. The first parameter given to the hook is the null-ref, the second the
161 ref of the new HEAD and the flag is always 1.
162
163 This hook can be used to perform repository validity checks, auto-display
164 differences from the previous HEAD if different, or set working dir metadata
165 properties.
166
167 post-merge
168 ~~~~~~~~~~
169
170 This hook is invoked by 'git merge', which happens when a 'git pull'
171 is done on a local repository. The hook takes a single parameter, a status
172 flag specifying whether or not the merge being done was a squash merge.
173 This hook cannot affect the outcome of 'git merge' and is not executed,
174 if the merge failed due to conflicts.
175
176 This hook can be used in conjunction with a corresponding pre-commit hook to
177 save and restore any form of metadata associated with the working tree
178 (e.g.: permissions/ownership, ACLS, etc). See contrib/hooks/setgitperms.perl
179 for an example of how to do this.
180
181 pre-push
182 ~~~~~~~~
183
184 This hook is called by 'git push' and can be used to prevent a push from taking
185 place. The hook is called with two parameters which provide the name and
186 location of the destination remote, if a named remote is not being used both
187 values will be the same.
188
189 Information about what is to be pushed is provided on the hook's standard
190 input with lines of the form:
191
192 <local ref> SP <local sha1> SP <remote ref> SP <remote sha1> LF
193
194 For instance, if the command +git push origin master:foreign+ were run the
195 hook would receive a line like the following:
196
197 refs/heads/master 67890 refs/heads/foreign 12345
198
199 although the full, 40-character SHA-1s would be supplied. If the foreign ref
200 does not yet exist the `<remote SHA-1>` will be 40 `0`. If a ref is to be
201 deleted, the `<local ref>` will be supplied as `(delete)` and the `<local
202 SHA-1>` will be 40 `0`. If the local commit was specified by something other
203 than a name which could be expanded (such as `HEAD~`, or a SHA-1) it will be
204 supplied as it was originally given.
205
206 If this hook exits with a non-zero status, 'git push' will abort without
207 pushing anything. Information about why the push is rejected may be sent
208 to the user by writing to standard error.
209
210 [[pre-receive]]
211 pre-receive
212 ~~~~~~~~~~~
213
214 This hook is invoked by 'git-receive-pack' on the remote repository,
215 which happens when a 'git push' is done on a local repository.
216 Just before starting to update refs on the remote repository, the
217 pre-receive hook is invoked. Its exit status determines the success
218 or failure of the update.
219
220 This hook executes once for the receive operation. It takes no
221 arguments, but for each ref to be updated it receives on standard
222 input a line of the format:
223
224 <old-value> SP <new-value> SP <ref-name> LF
225
226 where `<old-value>` is the old object name stored in the ref,
227 `<new-value>` is the new object name to be stored in the ref and
228 `<ref-name>` is the full name of the ref.
229 When creating a new ref, `<old-value>` is 40 `0`.
230
231 If the hook exits with non-zero status, none of the refs will be
232 updated. If the hook exits with zero, updating of individual refs can
233 still be prevented by the <<update,'update'>> hook.
234
235 Both standard output and standard error output are forwarded to
236 'git send-pack' on the other end, so you can simply `echo` messages
237 for the user.
238
239 [[update]]
240 update
241 ~~~~~~
242
243 This hook is invoked by 'git-receive-pack' on the remote repository,
244 which happens when a 'git push' is done on a local repository.
245 Just before updating the ref on the remote repository, the update hook
246 is invoked. Its exit status determines the success or failure of
247 the ref update.
248
249 The hook executes once for each ref to be updated, and takes
250 three parameters:
251
252 - the name of the ref being updated,
253 - the old object name stored in the ref,
254 - and the new object name to be stored in the ref.
255
256 A zero exit from the update hook allows the ref to be updated.
257 Exiting with a non-zero status prevents 'git-receive-pack'
258 from updating that ref.
259
260 This hook can be used to prevent 'forced' update on certain refs by
261 making sure that the object name is a commit object that is a
262 descendant of the commit object named by the old object name.
263 That is, to enforce a "fast-forward only" policy.
264
265 It could also be used to log the old..new status. However, it
266 does not know the entire set of branches, so it would end up
267 firing one e-mail per ref when used naively, though. The
268 <<post-receive,'post-receive'>> hook is more suited to that.
269
270 Another use suggested on the mailing list is to use this hook to
271 implement access control which is finer grained than the one
272 based on filesystem group.
273
274 Both standard output and standard error output are forwarded to
275 'git send-pack' on the other end, so you can simply `echo` messages
276 for the user.
277
278 The default 'update' hook, when enabled--and with
279 `hooks.allowunannotated` config option unset or set to false--prevents
280 unannotated tags to be pushed.
281
282 [[post-receive]]
283 post-receive
284 ~~~~~~~~~~~~
285
286 This hook is invoked by 'git-receive-pack' on the remote repository,
287 which happens when a 'git push' is done on a local repository.
288 It executes on the remote repository once after all the refs have
289 been updated.
290
291 This hook executes once for the receive operation. It takes no
292 arguments, but gets the same information as the
293 <<pre-receive,'pre-receive'>>
294 hook does on its standard input.
295
296 This hook does not affect the outcome of 'git-receive-pack', as it
297 is called after the real work is done.
298
299 This supersedes the <<post-update,'post-update'>> hook in that it gets
300 both old and new values of all the refs in addition to their
301 names.
302
303 Both standard output and standard error output are forwarded to
304 'git send-pack' on the other end, so you can simply `echo` messages
305 for the user.
306
307 The default 'post-receive' hook is empty, but there is
308 a sample script `post-receive-email` provided in the `contrib/hooks`
309 directory in Git distribution, which implements sending commit
310 emails.
311
312 [[post-update]]
313 post-update
314 ~~~~~~~~~~~
315
316 This hook is invoked by 'git-receive-pack' on the remote repository,
317 which happens when a 'git push' is done on a local repository.
318 It executes on the remote repository once after all the refs have
319 been updated.
320
321 It takes a variable number of parameters, each of which is the
322 name of ref that was actually updated.
323
324 This hook is meant primarily for notification, and cannot affect
325 the outcome of 'git-receive-pack'.
326
327 The 'post-update' hook can tell what are the heads that were pushed,
328 but it does not know what their original and updated values are,
329 so it is a poor place to do log old..new. The
330 <<post-receive,'post-receive'>> hook does get both original and
331 updated values of the refs. You might consider it instead if you need
332 them.
333
334 When enabled, the default 'post-update' hook runs
335 'git update-server-info' to keep the information used by dumb
336 transports (e.g., HTTP) up-to-date. If you are publishing
337 a Git repository that is accessible via HTTP, you should
338 probably enable this hook.
339
340 Both standard output and standard error output are forwarded to
341 'git send-pack' on the other end, so you can simply `echo` messages
342 for the user.
343
344 push-to-checkout
345 ~~~~~~~~~~~~~~~~
346
347 This hook is invoked by 'git-receive-pack' on the remote repository,
348 which happens when a 'git push' is done on a local repository, when
349 the push tries to update the branch that is currently checked out
350 and the `receive.denyCurrentBranch` configuration variable is set to
351 `updateInstead`. Such a push by default is refused if the working
352 tree and the index of the remote repository has any difference from
353 the currently checked out commit; when both the working tree and the
354 index match the current commit, they are updated to match the newly
355 pushed tip of the branch. This hook is to be used to override the
356 default behaviour.
357
358 The hook receives the commit with which the tip of the current
359 branch is going to be updated. It can exit with a non-zero status
360 to refuse the push (when it does so, it must not modify the index or
361 the working tree). Or it can make any necessary changes to the
362 working tree and to the index to bring them to the desired state
363 when the tip of the current branch is updated to the new commit, and
364 exit with a zero status.
365
366 For example, the hook can simply run `git read-tree -u -m HEAD "$1"`
367 in order to emulate 'git fetch' that is run in the reverse direction
368 with `git push`, as the two-tree form of `read-tree -u -m` is
369 essentially the same as `git checkout` that switches branches while
370 keeping the local changes in the working tree that do not interfere
371 with the difference between the branches.
372
373
374 pre-auto-gc
375 ~~~~~~~~~~~
376
377 This hook is invoked by 'git gc --auto'. It takes no parameter, and
378 exiting with non-zero status from this script causes the 'git gc --auto'
379 to abort.
380
381 post-rewrite
382 ~~~~~~~~~~~~
383
384 This hook is invoked by commands that rewrite commits (`git commit
385 --amend`, 'git-rebase'; currently 'git-filter-branch' does 'not' call
386 it!). Its first argument denotes the command it was invoked by:
387 currently one of `amend` or `rebase`. Further command-dependent
388 arguments may be passed in the future.
389
390 The hook receives a list of the rewritten commits on stdin, in the
391 format
392
393 <old-sha1> SP <new-sha1> [ SP <extra-info> ] LF
394
395 The 'extra-info' is again command-dependent. If it is empty, the
396 preceding SP is also omitted. Currently, no commands pass any
397 'extra-info'.
398
399 The hook always runs after the automatic note copying (see
400 "notes.rewrite.<command>" in linkgit:git-config[1]) has happened, and
401 thus has access to these notes.
402
403 The following command-specific comments apply:
404
405 rebase::
406 For the 'squash' and 'fixup' operation, all commits that were
407 squashed are listed as being rewritten to the squashed commit.
408 This means that there will be several lines sharing the same
409 'new-sha1'.
410 +
411 The commits are guaranteed to be listed in the order that they were
412 processed by rebase.
413
414
415 GIT
416 ---
417 Part of the linkgit:git[1] suite