push options: {pre,post}-receive hook learns about push options
[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 $GIT_DIR/hooks/* (or \`git config core.hooksPath`/*)
11
12
13 DESCRIPTION
14 -----------
15
16 Hooks are programs you can place in a hooks directory to trigger
17 actions at certain points in git's execution. Hooks that don't have
18 the executable bit set are ignored.
19
20 By default the hooks directory is `$GIT_DIR/hooks`, but that can be
21 changed via the `core.hooksPath` configuration variable (see
22 linkgit:git-config[1]).
23
24 Before Git invokes a hook, it changes its working directory to either
25 the root of the working tree in a non-bare repository, or to the
26 $GIT_DIR in a bare repository.
27
28 Hooks can get their arguments via the environment, command-line
29 arguments, and stdin. See the documentation for each hook below for
30 details.
31
32 'git init' may copy hooks to the new repository, depending on its
33 configuration. See the "TEMPLATE DIRECTORY" section in
34 linkgit:git-init[1] for details. When the rest of this document refers
35 to "default hooks" it's talking about the default template shipped
36 with Git.
37
38 The currently supported hooks are described below.
39
40 HOOKS
41 -----
42
43 applypatch-msg
44 ~~~~~~~~~~~~~~
45
46 This hook is invoked by 'git am'. It takes a single
47 parameter, the name of the file that holds the proposed commit
48 log message. Exiting with a non-zero status causes 'git am' to abort
49 before applying the patch.
50
51 The hook is allowed to edit the message file in place, and can
52 be used to normalize the message into some project standard
53 format. It can also be used to refuse the commit after inspecting
54 the message file.
55
56 The default 'applypatch-msg' hook, when enabled, runs the
57 'commit-msg' hook, if the latter is enabled.
58
59 pre-applypatch
60 ~~~~~~~~~~~~~~
61
62 This hook is invoked by 'git am'. It takes no parameter, and is
63 invoked after the patch is applied, but before a commit is made.
64
65 If it exits with non-zero status, then the working tree will not be
66 committed after applying the patch.
67
68 It can be used to inspect the current working tree and refuse to
69 make a commit if it does not pass certain test.
70
71 The default 'pre-applypatch' hook, when enabled, runs the
72 'pre-commit' hook, if the latter is enabled.
73
74 post-applypatch
75 ~~~~~~~~~~~~~~~
76
77 This hook is invoked by 'git am'. It takes no parameter,
78 and is invoked after the patch is applied and a commit is made.
79
80 This hook is meant primarily for notification, and cannot affect
81 the outcome of 'git am'.
82
83 pre-commit
84 ~~~~~~~~~~
85
86 This hook is invoked by 'git commit', and can be bypassed
87 with the `--no-verify` option. It takes no parameters, and is
88 invoked before obtaining the proposed commit log message and
89 making a commit. Exiting with a non-zero status from this script
90 causes the 'git commit' command to abort before creating a commit.
91
92 The default 'pre-commit' hook, when enabled, catches introduction
93 of lines with trailing whitespaces and aborts the commit when
94 such a line is found.
95
96 All the 'git commit' hooks are invoked with the environment
97 variable `GIT_EDITOR=:` if the command will not bring up an editor
98 to modify the commit message.
99
100 prepare-commit-msg
101 ~~~~~~~~~~~~~~~~~~
102
103 This hook is invoked by 'git commit' right after preparing the
104 default log message, and before the editor is started.
105
106 It takes one to three parameters. The first is the name of the file
107 that contains the commit log message. The second is the source of the commit
108 message, and can be: `message` (if a `-m` or `-F` option was
109 given); `template` (if a `-t` option was given or the
110 configuration option `commit.template` is set); `merge` (if the
111 commit is a merge or a `.git/MERGE_MSG` file exists); `squash`
112 (if a `.git/SQUASH_MSG` file exists); or `commit`, followed by
113 a commit SHA-1 (if a `-c`, `-C` or `--amend` option was given).
114
115 If the exit status is non-zero, 'git commit' will abort.
116
117 The purpose of the hook is to edit the message file in place, and
118 it is not suppressed by the `--no-verify` option. A non-zero exit
119 means a failure of the hook and aborts the commit. It should not
120 be used as replacement for pre-commit hook.
121
122 The sample `prepare-commit-msg` hook that comes with Git comments
123 out the `Conflicts:` part of a merge's commit message.
124
125 commit-msg
126 ~~~~~~~~~~
127
128 This hook is invoked by 'git commit', and can be bypassed
129 with the `--no-verify` option. It takes a single parameter, the
130 name of the file that holds the proposed commit log message.
131 Exiting with a non-zero status causes the 'git commit' to
132 abort.
133
134 The hook is allowed to edit the message file in place, and can be used
135 to normalize the message into some project standard format. It
136 can also be used to refuse the commit after inspecting the message
137 file.
138
139 The default 'commit-msg' hook, when enabled, detects duplicate
140 "Signed-off-by" lines, and aborts the commit if one is found.
141
142 post-commit
143 ~~~~~~~~~~~
144
145 This hook is invoked by 'git commit'. It takes no parameters, and is
146 invoked after a commit is made.
147
148 This hook is meant primarily for notification, and cannot affect
149 the outcome of 'git commit'.
150
151 pre-rebase
152 ~~~~~~~~~~
153
154 This hook is called by 'git rebase' and can be used to prevent a
155 branch from getting rebased. The hook may be called with one or
156 two parameters. The first parameter is the upstream from which
157 the series was forked. The second parameter is the branch being
158 rebased, and is not set when rebasing the current branch.
159
160 post-checkout
161 ~~~~~~~~~~~~~
162
163 This hook is invoked when a 'git checkout' is run after having updated the
164 worktree. The hook is given three parameters: the ref of the previous HEAD,
165 the ref of the new HEAD (which may or may not have changed), and a flag
166 indicating whether the checkout was a branch checkout (changing branches,
167 flag=1) or a file checkout (retrieving a file from the index, flag=0).
168 This hook cannot affect the outcome of 'git checkout'.
169
170 It is also run after 'git clone', unless the --no-checkout (-n) option is
171 used. The first parameter given to the hook is the null-ref, the second the
172 ref of the new HEAD and the flag is always 1.
173
174 This hook can be used to perform repository validity checks, auto-display
175 differences from the previous HEAD if different, or set working dir metadata
176 properties.
177
178 post-merge
179 ~~~~~~~~~~
180
181 This hook is invoked by 'git merge', which happens when a 'git pull'
182 is done on a local repository. The hook takes a single parameter, a status
183 flag specifying whether or not the merge being done was a squash merge.
184 This hook cannot affect the outcome of 'git merge' and is not executed,
185 if the merge failed due to conflicts.
186
187 This hook can be used in conjunction with a corresponding pre-commit hook to
188 save and restore any form of metadata associated with the working tree
189 (e.g.: permissions/ownership, ACLS, etc). See contrib/hooks/setgitperms.perl
190 for an example of how to do this.
191
192 pre-push
193 ~~~~~~~~
194
195 This hook is called by 'git push' and can be used to prevent a push from taking
196 place. The hook is called with two parameters which provide the name and
197 location of the destination remote, if a named remote is not being used both
198 values will be the same.
199
200 Information about what is to be pushed is provided on the hook's standard
201 input with lines of the form:
202
203 <local ref> SP <local sha1> SP <remote ref> SP <remote sha1> LF
204
205 For instance, if the command +git push origin master:foreign+ were run the
206 hook would receive a line like the following:
207
208 refs/heads/master 67890 refs/heads/foreign 12345
209
210 although the full, 40-character SHA-1s would be supplied. If the foreign ref
211 does not yet exist the `<remote SHA-1>` will be 40 `0`. If a ref is to be
212 deleted, the `<local ref>` will be supplied as `(delete)` and the `<local
213 SHA-1>` will be 40 `0`. If the local commit was specified by something other
214 than a name which could be expanded (such as `HEAD~`, or a SHA-1) it will be
215 supplied as it was originally given.
216
217 If this hook exits with a non-zero status, 'git push' will abort without
218 pushing anything. Information about why the push is rejected may be sent
219 to the user by writing to standard error.
220
221 [[pre-receive]]
222 pre-receive
223 ~~~~~~~~~~~
224
225 This hook is invoked by 'git-receive-pack' on the remote repository,
226 which happens when a 'git push' is done on a local repository.
227 Just before starting to update refs on the remote repository, the
228 pre-receive hook is invoked. Its exit status determines the success
229 or failure of the update.
230
231 This hook executes once for the receive operation. It takes no
232 arguments, but for each ref to be updated it receives on standard
233 input a line of the format:
234
235 <old-value> SP <new-value> SP <ref-name> LF
236
237 where `<old-value>` is the old object name stored in the ref,
238 `<new-value>` is the new object name to be stored in the ref and
239 `<ref-name>` is the full name of the ref.
240 When creating a new ref, `<old-value>` is 40 `0`.
241
242 If the hook exits with non-zero status, none of the refs will be
243 updated. If the hook exits with zero, updating of individual refs can
244 still be prevented by the <<update,'update'>> hook.
245
246 Both standard output and standard error output are forwarded to
247 'git send-pack' on the other end, so you can simply `echo` messages
248 for the user.
249
250 The number of push options given on the command line of
251 `git push --push-option=...` can be read from the environment
252 variable `GIT_PUSH_OPTION_COUNT`, and the options themselves are
253 found in `GIT_PUSH_OPTION_0`, `GIT_PUSH_OPTION_1`,...
254 If it is negotiated to not use the push options phase, the
255 environment variables will not be set. If the client selects
256 to use push options, but doesn't transmit any, the count variable
257 will be set to zero, `GIT_PUSH_OPTION_COUNT=0`.
258
259 [[update]]
260 update
261 ~~~~~~
262
263 This hook is invoked by 'git-receive-pack' on the remote repository,
264 which happens when a 'git push' is done on a local repository.
265 Just before updating the ref on the remote repository, the update hook
266 is invoked. Its exit status determines the success or failure of
267 the ref update.
268
269 The hook executes once for each ref to be updated, and takes
270 three parameters:
271
272 - the name of the ref being updated,
273 - the old object name stored in the ref,
274 - and the new object name to be stored in the ref.
275
276 A zero exit from the update hook allows the ref to be updated.
277 Exiting with a non-zero status prevents 'git-receive-pack'
278 from updating that ref.
279
280 This hook can be used to prevent 'forced' update on certain refs by
281 making sure that the object name is a commit object that is a
282 descendant of the commit object named by the old object name.
283 That is, to enforce a "fast-forward only" policy.
284
285 It could also be used to log the old..new status. However, it
286 does not know the entire set of branches, so it would end up
287 firing one e-mail per ref when used naively, though. The
288 <<post-receive,'post-receive'>> hook is more suited to that.
289
290 In an environment that restricts the users' access only to git
291 commands over the wire, this hook can be used to implement access
292 control without relying on filesystem ownership and group
293 membership. See linkgit:git-shell[1] for how you might use the login
294 shell to restrict the user's access to only git commands.
295
296 Both standard output and standard error output are forwarded to
297 'git send-pack' on the other end, so you can simply `echo` messages
298 for the user.
299
300 The default 'update' hook, when enabled--and with
301 `hooks.allowunannotated` config option unset or set to false--prevents
302 unannotated tags to be pushed.
303
304 [[post-receive]]
305 post-receive
306 ~~~~~~~~~~~~
307
308 This hook is invoked by 'git-receive-pack' on the remote repository,
309 which happens when a 'git push' is done on a local repository.
310 It executes on the remote repository once after all the refs have
311 been updated.
312
313 This hook executes once for the receive operation. It takes no
314 arguments, but gets the same information as the
315 <<pre-receive,'pre-receive'>>
316 hook does on its standard input.
317
318 This hook does not affect the outcome of 'git-receive-pack', as it
319 is called after the real work is done.
320
321 This supersedes the <<post-update,'post-update'>> hook in that it gets
322 both old and new values of all the refs in addition to their
323 names.
324
325 Both standard output and standard error output are forwarded to
326 'git send-pack' on the other end, so you can simply `echo` messages
327 for the user.
328
329 The default 'post-receive' hook is empty, but there is
330 a sample script `post-receive-email` provided in the `contrib/hooks`
331 directory in Git distribution, which implements sending commit
332 emails.
333
334 The number of push options given on the command line of
335 `git push --push-option=...` can be read from the environment
336 variable `GIT_PUSH_OPTION_COUNT`, and the options themselves are
337 found in `GIT_PUSH_OPTION_0`, `GIT_PUSH_OPTION_1`,...
338 If it is negotiated to not use the push options phase, the
339 environment variables will not be set. If the client selects
340 to use push options, but doesn't transmit any, the count variable
341 will be set to zero, `GIT_PUSH_OPTION_COUNT=0`.
342
343 [[post-update]]
344 post-update
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.
349 It executes on the remote repository once after all the refs have
350 been updated.
351
352 It takes a variable number of parameters, each of which is the
353 name of ref that was actually updated.
354
355 This hook is meant primarily for notification, and cannot affect
356 the outcome of 'git-receive-pack'.
357
358 The 'post-update' hook can tell what are the heads that were pushed,
359 but it does not know what their original and updated values are,
360 so it is a poor place to do log old..new. The
361 <<post-receive,'post-receive'>> hook does get both original and
362 updated values of the refs. You might consider it instead if you need
363 them.
364
365 When enabled, the default 'post-update' hook runs
366 'git update-server-info' to keep the information used by dumb
367 transports (e.g., HTTP) up-to-date. If you are publishing
368 a Git repository that is accessible via HTTP, you should
369 probably enable this hook.
370
371 Both standard output and standard error output are forwarded to
372 'git send-pack' on the other end, so you can simply `echo` messages
373 for the user.
374
375 push-to-checkout
376 ~~~~~~~~~~~~~~~~
377
378 This hook is invoked by 'git-receive-pack' on the remote repository,
379 which happens when a 'git push' is done on a local repository, when
380 the push tries to update the branch that is currently checked out
381 and the `receive.denyCurrentBranch` configuration variable is set to
382 `updateInstead`. Such a push by default is refused if the working
383 tree and the index of the remote repository has any difference from
384 the currently checked out commit; when both the working tree and the
385 index match the current commit, they are updated to match the newly
386 pushed tip of the branch. This hook is to be used to override the
387 default behaviour.
388
389 The hook receives the commit with which the tip of the current
390 branch is going to be updated. It can exit with a non-zero status
391 to refuse the push (when it does so, it must not modify the index or
392 the working tree). Or it can make any necessary changes to the
393 working tree and to the index to bring them to the desired state
394 when the tip of the current branch is updated to the new commit, and
395 exit with a zero status.
396
397 For example, the hook can simply run `git read-tree -u -m HEAD "$1"`
398 in order to emulate 'git fetch' that is run in the reverse direction
399 with `git push`, as the two-tree form of `read-tree -u -m` is
400 essentially the same as `git checkout` that switches branches while
401 keeping the local changes in the working tree that do not interfere
402 with the difference between the branches.
403
404
405 pre-auto-gc
406 ~~~~~~~~~~~
407
408 This hook is invoked by 'git gc --auto'. It takes no parameter, and
409 exiting with non-zero status from this script causes the 'git gc --auto'
410 to abort.
411
412 post-rewrite
413 ~~~~~~~~~~~~
414
415 This hook is invoked by commands that rewrite commits (`git commit
416 --amend`, 'git-rebase'; currently 'git-filter-branch' does 'not' call
417 it!). Its first argument denotes the command it was invoked by:
418 currently one of `amend` or `rebase`. Further command-dependent
419 arguments may be passed in the future.
420
421 The hook receives a list of the rewritten commits on stdin, in the
422 format
423
424 <old-sha1> SP <new-sha1> [ SP <extra-info> ] LF
425
426 The 'extra-info' is again command-dependent. If it is empty, the
427 preceding SP is also omitted. Currently, no commands pass any
428 'extra-info'.
429
430 The hook always runs after the automatic note copying (see
431 "notes.rewrite.<command>" in linkgit:git-config[1]) has happened, and
432 thus has access to these notes.
433
434 The following command-specific comments apply:
435
436 rebase::
437 For the 'squash' and 'fixup' operation, all commits that were
438 squashed are listed as being rewritten to the squashed commit.
439 This means that there will be several lines sharing the same
440 'new-sha1'.
441 +
442 The commits are guaranteed to be listed in the order that they were
443 processed by rebase.
444
445
446 GIT
447 ---
448 Part of the linkgit:git[1] suite