receive-pack: refactor updateInstead codepath
[git/git.git] / Documentation / githooks.txt
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1githooks(5)
2===========
3
4NAME
5----
2de9b711 6githooks - Hooks used by Git
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7
8SYNOPSIS
9--------
10$GIT_DIR/hooks/*
11
12
13DESCRIPTION
14-----------
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15
16Hooks are little scripts you can place in `$GIT_DIR/hooks`
17directory to trigger action at certain points. When
0b444cdb 18'git init' is run, a handful of example hooks are copied into the
6d35cc76 19`hooks` directory of the new repository, but by default they are
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20all disabled. To enable a hook, rename it by removing its `.sample`
21suffix.
6d35cc76 22
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23NOTE: It is also a requirement for a given hook to be executable.
24However - in a freshly initialized repository - the `.sample` files are
25executable by default.
26
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27This document describes the currently defined hooks.
28
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29HOOKS
30-----
31
6d35cc76 32applypatch-msg
6d71c1dc 33~~~~~~~~~~~~~~
6d35cc76 34
0b444cdb 35This hook is invoked by 'git am' script. It takes a single
6d35cc76 36parameter, the name of the file that holds the proposed commit
45ad9b50 37log message. Exiting with non-zero status causes
0b444cdb 38'git am' to abort before applying the patch.
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39
40The hook is allowed to edit the message file in place, and can
41be used to normalize the message into some project standard
42format (if the project has one). It can also be used to refuse
43the commit after inspecting the message file.
44
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45The default 'applypatch-msg' hook, when enabled, runs the
46'commit-msg' hook, if the latter is enabled.
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47
48pre-applypatch
6d71c1dc 49~~~~~~~~~~~~~~
6d35cc76 50
0b444cdb 51This hook is invoked by 'git am'. It takes no parameter, and is
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52invoked after the patch is applied, but before a commit is made.
53
54If it exits with non-zero status, then the working tree will not be
55committed after applying the patch.
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56
57It can be used to inspect the current working tree and refuse to
58make a commit if it does not pass certain test.
59
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60The default 'pre-applypatch' hook, when enabled, runs the
61'pre-commit' hook, if the latter is enabled.
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62
63post-applypatch
6d71c1dc 64~~~~~~~~~~~~~~~
6d35cc76 65
0b444cdb 66This hook is invoked by 'git am'. It takes no parameter,
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67and is invoked after the patch is applied and a commit is made.
68
69This hook is meant primarily for notification, and cannot affect
0b444cdb 70the outcome of 'git am'.
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71
72pre-commit
6d71c1dc 73~~~~~~~~~~
6d35cc76 74
0b444cdb 75This hook is invoked by 'git commit', and can be bypassed
6cf378f0 76with `--no-verify` option. It takes no parameter, and is
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77invoked before obtaining the proposed commit log message and
78making a commit. Exiting with non-zero status from this script
0b444cdb 79causes the 'git commit' to abort.
6d35cc76 80
45ad9b50 81The default 'pre-commit' hook, when enabled, catches introduction
6d35cc76 82of lines with trailing whitespaces and aborts the commit when
45ad9b50 83such a line is found.
6d35cc76 84
0b444cdb 85All the 'git commit' hooks are invoked with the environment
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86variable `GIT_EDITOR=:` if the command will not bring up an editor
87to modify the commit message.
88
8089c85b 89prepare-commit-msg
6d71c1dc 90~~~~~~~~~~~~~~~~~~
8089c85b 91
0b444cdb 92This hook is invoked by 'git commit' right after preparing the
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93default log message, and before the editor is started.
94
95It takes one to three parameters. The first is the name of the file
99686960 96that contains the commit log message. The second is the source of the commit
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97message, and can be: `message` (if a `-m` or `-F` option was
98given); `template` (if a `-t` option was given or the
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99configuration option `commit.template` is set); `merge` (if the
100commit is a merge or a `.git/MERGE_MSG` file exists); `squash`
101(if a `.git/SQUASH_MSG` file exists); or `commit`, followed by
d5fa1f1a 102a commit SHA-1 (if a `-c`, `-C` or `--amend` option was given).
8089c85b 103
0b444cdb 104If the exit status is non-zero, 'git commit' will abort.
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105
106The purpose of the hook is to edit the message file in place, and
6cf378f0 107it is not suppressed by the `--no-verify` option. A non-zero exit
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108means a failure of the hook and aborts the commit. It should not
109be used as replacement for pre-commit hook.
110
2de9b711 111The sample `prepare-commit-msg` hook that comes with Git comments
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112out the `Conflicts:` part of a merge's commit message.
113
6d35cc76 114commit-msg
6d71c1dc 115~~~~~~~~~~
6d35cc76 116
0b444cdb 117This hook is invoked by 'git commit', and can be bypassed
6cf378f0 118with `--no-verify` option. It takes a single parameter, the
6d35cc76 119name of the file that holds the proposed commit log message.
0b444cdb 120Exiting with non-zero status causes the 'git commit' to
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121abort.
122
123The hook is allowed to edit the message file in place, and can
124be used to normalize the message into some project standard
125format (if the project has one). It can also be used to refuse
126the commit after inspecting the message file.
127
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128The default 'commit-msg' hook, when enabled, detects duplicate
129"Signed-off-by" lines, and aborts the commit if one is found.
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130
131post-commit
6d71c1dc 132~~~~~~~~~~~
6d35cc76 133
0b444cdb 134This hook is invoked by 'git commit'. It takes no
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135parameter, and is invoked after a commit is made.
136
137This hook is meant primarily for notification, and cannot affect
0b444cdb 138the outcome of 'git commit'.
6d35cc76 139
00e5d48a 140pre-rebase
6d71c1dc 141~~~~~~~~~~
00e5d48a 142
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143This hook is called by 'git rebase' and can be used to prevent a
144branch from getting rebased. The hook may be called with one or
145two parameters. The first parameter is the upstream from which
146the series was forked. The second parameter is the branch being
147rebased, and is not set when rebasing the current branch.
00e5d48a 148
1abbe475 149post-checkout
6d71c1dc 150~~~~~~~~~~~~~
1abbe475 151
0b444cdb 152This hook is invoked when a 'git checkout' is run after having updated the
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153worktree. The hook is given three parameters: the ref of the previous HEAD,
154the ref of the new HEAD (which may or may not have changed), and a flag
155indicating whether the checkout was a branch checkout (changing branches,
156flag=1) or a file checkout (retrieving a file from the index, flag=0).
0b444cdb 157This hook cannot affect the outcome of 'git checkout'.
1abbe475 158
0b444cdb 159It is also run after 'git clone', unless the --no-checkout (-n) option is
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160used. The first parameter given to the hook is the null-ref, the second the
161ref of the new HEAD and the flag is always 1.
162
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163This hook can be used to perform repository validity checks, auto-display
164differences from the previous HEAD if different, or set working dir metadata
165properties.
166
46232915 167post-merge
6d71c1dc 168~~~~~~~~~~
46232915 169
0b444cdb 170This hook is invoked by 'git merge', which happens when a 'git pull'
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171is done on a local repository. The hook takes a single parameter, a status
172flag specifying whether or not the merge being done was a squash merge.
0b444cdb 173This hook cannot affect the outcome of 'git merge' and is not executed,
2b3e60c2 174if the merge failed due to conflicts.
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175
176This hook can be used in conjunction with a corresponding pre-commit hook to
177save and restore any form of metadata associated with the working tree
f745acb0 178(e.g.: permissions/ownership, ACLS, etc). See contrib/hooks/setgitperms.perl
af6fb4c8 179for an example of how to do this.
46232915 180
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181pre-push
182~~~~~~~~
183
184This hook is called by 'git push' and can be used to prevent a push from taking
185place. The hook is called with two parameters which provide the name and
186location of the destination remote, if a named remote is not being used both
187values will be the same.
188
189Information about what is to be pushed is provided on the hook's standard
190input with lines of the form:
191
192 <local ref> SP <local sha1> SP <remote ref> SP <remote sha1> LF
193
194For instance, if the command +git push origin master:foreign+ were run the
195hook would receive a line like the following:
196
197 refs/heads/master 67890 refs/heads/foreign 12345
198
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199although the full, 40-character SHA-1s would be supplied. If the foreign ref
200does not yet exist the `<remote SHA-1>` will be 40 `0`. If a ref is to be
ec55559f 201deleted, the `<local ref>` will be supplied as `(delete)` and the `<local
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202SHA-1>` will be 40 `0`. If the local commit was specified by something other
203than a name which could be expanded (such as `HEAD~`, or a SHA-1) it will be
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204supplied as it was originally given.
205
206If this hook exits with a non-zero status, 'git push' will abort without
207pushing anything. Information about why the push is rejected may be sent
208to the user by writing to standard error.
209
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210[[pre-receive]]
211pre-receive
6d71c1dc 212~~~~~~~~~~~
cbb84e5d 213
ba020ef5 214This hook is invoked by 'git-receive-pack' on the remote repository,
0b444cdb 215which happens when a 'git push' is done on a local repository.
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216Just before starting to update refs on the remote repository, the
217pre-receive hook is invoked. Its exit status determines the success
218or failure of the update.
219
220This hook executes once for the receive operation. It takes no
221arguments, but for each ref to be updated it receives on standard
222input a line of the format:
223
224 <old-value> SP <new-value> SP <ref-name> LF
225
226where `<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.
229When creating a new ref, `<old-value>` is 40 `0`.
230
231If the hook exits with non-zero status, none of the refs will be
232updated. If the hook exits with zero, updating of individual refs can
233still be prevented by the <<update,'update'>> hook.
234
24a0d61e 235Both standard output and standard error output are forwarded to
0b444cdb 236'git send-pack' on the other end, so you can simply `echo` messages
24a0d61e 237for the user.
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238
239[[update]]
6d35cc76 240update
6d71c1dc 241~~~~~~
6d35cc76 242
ba020ef5 243This hook is invoked by 'git-receive-pack' on the remote repository,
0b444cdb 244which happens when a 'git push' is done on a local repository.
6250ad1e 245Just before updating the ref on the remote repository, the update hook
37425065 246is invoked. Its exit status determines the success or failure of
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247the ref update.
248
249The hook executes once for each ref to be updated, and takes
250three parameters:
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251
252 - the name of the ref being updated,
253 - the old object name stored in the ref,
5fe8f49b 254 - and the new object name to be stored in the ref.
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255
256A zero exit from the update hook allows the ref to be updated.
ba020ef5 257Exiting with a non-zero status prevents 'git-receive-pack'
cbb84e5d 258from updating that ref.
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259
260This hook can be used to prevent 'forced' update on certain refs by
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261making sure that the object name is a commit object that is a
262descendant of the commit object named by the old object name.
a75d7b54 263That is, to enforce a "fast-forward only" policy.
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264
265It could also be used to log the old..new status. However, it
266does not know the entire set of branches, so it would end up
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267firing one e-mail per ref when used naively, though. The
268<<post-receive,'post-receive'>> hook is more suited to that.
6250ad1e 269
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270Another use suggested on the mailing list is to use this hook to
271implement access control which is finer grained than the one
272based on filesystem group.
273
24a0d61e 274Both standard output and standard error output are forwarded to
0b444cdb 275'git send-pack' on the other end, so you can simply `echo` messages
24a0d61e 276for the user.
3aadad1b 277
cbb84e5d 278The default 'update' hook, when enabled--and with
39c448c1 279`hooks.allowunannotated` config option unset or set to false--prevents
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280unannotated tags to be pushed.
281
282[[post-receive]]
283post-receive
6d71c1dc 284~~~~~~~~~~~~
6250ad1e 285
ba020ef5 286This hook is invoked by 'git-receive-pack' on the remote repository,
0b444cdb 287which happens when a 'git push' is done on a local repository.
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288It executes on the remote repository once after all the refs have
289been updated.
290
291This hook executes once for the receive operation. It takes no
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292arguments, but gets the same information as the
293<<pre-receive,'pre-receive'>>
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294hook does on its standard input.
295
ba020ef5 296This hook does not affect the outcome of 'git-receive-pack', as it
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297is called after the real work is done.
298
02783075 299This supersedes the <<post-update,'post-update'>> hook in that it gets
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300both old and new values of all the refs in addition to their
301names.
cbb84e5d 302
24a0d61e 303Both standard output and standard error output are forwarded to
0b444cdb 304'git send-pack' on the other end, so you can simply `echo` messages
24a0d61e 305for the user.
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306
307The default 'post-receive' hook is empty, but there is
308a sample script `post-receive-email` provided in the `contrib/hooks`
2de9b711 309directory in Git distribution, which implements sending commit
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310emails.
311
312[[post-update]]
6d35cc76 313post-update
6d71c1dc 314~~~~~~~~~~~
6d35cc76 315
ba020ef5 316This hook is invoked by 'git-receive-pack' on the remote repository,
0b444cdb 317which happens when a 'git push' is done on a local repository.
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318It executes on the remote repository once after all the refs have
319been updated.
320
321It takes a variable number of parameters, each of which is the
322name of ref that was actually updated.
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323
324This hook is meant primarily for notification, and cannot affect
ba020ef5 325the outcome of 'git-receive-pack'.
6d35cc76 326
45ad9b50 327The 'post-update' hook can tell what are the heads that were pushed,
6250ad1e 328but it does not know what their original and updated values are,
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329so it is a poor place to do log old..new. The
330<<post-receive,'post-receive'>> hook does get both original and
331updated values of the refs. You might consider it instead if you need
332them.
cbb84e5d 333
45ad9b50 334When enabled, the default 'post-update' hook runs
0b444cdb 335'git update-server-info' to keep the information used by dumb
45ad9b50 336transports (e.g., HTTP) up-to-date. If you are publishing
2de9b711 337a Git repository that is accessible via HTTP, you should
6250ad1e 338probably enable this hook.
3aadad1b 339
cbb84e5d 340Both standard output and standard error output are forwarded to
0b444cdb 341'git send-pack' on the other end, so you can simply `echo` messages
24a0d61e 342for the user.
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343
344pre-auto-gc
6d71c1dc 345~~~~~~~~~~~
0b85d926 346
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347This hook is invoked by 'git gc --auto'. It takes no parameter, and
348exiting with non-zero status from this script causes the 'git gc --auto'
0b85d926 349to abort.
a5af0e2c 350
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351post-rewrite
352~~~~~~~~~~~~
353
354This hook is invoked by commands that rewrite commits (`git commit
355--amend`, 'git-rebase'; currently 'git-filter-branch' does 'not' call
356it!). Its first argument denotes the command it was invoked by:
357currently one of `amend` or `rebase`. Further command-dependent
358arguments may be passed in the future.
359
360The hook receives a list of the rewritten commits on stdin, in the
361format
362
363 <old-sha1> SP <new-sha1> [ SP <extra-info> ] LF
364
365The 'extra-info' is again command-dependent. If it is empty, the
366preceding SP is also omitted. Currently, no commands pass any
367'extra-info'.
368
6956f858 369The hook always runs after the automatic note copying (see
5e248584 370"notes.rewrite.<command>" in linkgit:git-config.txt[1]) has happened, and
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371thus has access to these notes.
372
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373The following command-specific comments apply:
374
375rebase::
376 For the 'squash' and 'fixup' operation, all commits that were
377 squashed are listed as being rewritten to the squashed commit.
378 This means that there will be several lines sharing the same
379 'new-sha1'.
380+
381The commits are guaranteed to be listed in the order that they were
382processed by rebase.
383
c0fc6869 384
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385GIT
386---
9e1f0a85 387Part of the linkgit:git[1] suite