Merge branch 'gr/smtp'
[git/git.git] / Documentation / hooks.txt
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72e9340c 1Hooks used by git
6d35cc76 2=================
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3
4Hooks are little scripts you can place in `$GIT_DIR/hooks`
5directory to trigger action at certain points. When
5c94f87e 6`git-init` is run, a handful example hooks are copied in the
6d35cc76 7`hooks` directory of the new repository, but by default they are
45ad9b50 8all disabled. To enable a hook, make it executable with `chmod +x`.
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9
10This document describes the currently defined hooks.
11
12applypatch-msg
13--------------
14
59c8e2cb 15This hook is invoked by `git-am` script. It takes a single
6d35cc76 16parameter, the name of the file that holds the proposed commit
45ad9b50 17log message. Exiting with non-zero status causes
59c8e2cb 18`git-am` to abort before applying the patch.
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19
20The hook is allowed to edit the message file in place, and can
21be used to normalize the message into some project standard
22format (if the project has one). It can also be used to refuse
23the commit after inspecting the message file.
24
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25The default 'applypatch-msg' hook, when enabled, runs the
26'commit-msg' hook, if the latter is enabled.
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27
28pre-applypatch
29--------------
30
59c8e2cb 31This hook is invoked by `git-am`. It takes no parameter,
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32and is invoked after the patch is applied, but before a commit
33is made. Exiting with non-zero status causes the working tree
34after application of the patch not committed.
35
36It can be used to inspect the current working tree and refuse to
37make a commit if it does not pass certain test.
38
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39The default 'pre-applypatch' hook, when enabled, runs the
40'pre-commit' hook, if the latter is enabled.
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41
42post-applypatch
43---------------
44
59c8e2cb 45This hook is invoked by `git-am`. It takes no parameter,
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46and is invoked after the patch is applied and a commit is made.
47
48This hook is meant primarily for notification, and cannot affect
59c8e2cb 49the outcome of `git-am`.
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50
51pre-commit
52----------
53
215a7ad1 54This hook is invoked by `git-commit`, and can be bypassed
e1ccf53a 55with `\--no-verify` option. It takes no parameter, and is
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56invoked before obtaining the proposed commit log message and
57making a commit. Exiting with non-zero status from this script
215a7ad1 58causes the `git-commit` to abort.
6d35cc76 59
45ad9b50 60The default 'pre-commit' hook, when enabled, catches introduction
6d35cc76 61of lines with trailing whitespaces and aborts the commit when
45ad9b50 62such a line is found.
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63
64commit-msg
65----------
66
215a7ad1 67This hook is invoked by `git-commit`, and can be bypassed
e1ccf53a 68with `\--no-verify` option. It takes a single parameter, the
6d35cc76 69name of the file that holds the proposed commit log message.
215a7ad1 70Exiting with non-zero status causes the `git-commit` to
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71abort.
72
73The hook is allowed to edit the message file in place, and can
74be used to normalize the message into some project standard
75format (if the project has one). It can also be used to refuse
76the commit after inspecting the message file.
77
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78The default 'commit-msg' hook, when enabled, detects duplicate
79"Signed-off-by" lines, and aborts the commit if one is found.
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80
81post-commit
82-----------
83
215a7ad1 84This hook is invoked by `git-commit`. It takes no
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85parameter, and is invoked after a commit is made.
86
87This hook is meant primarily for notification, and cannot affect
215a7ad1 88the outcome of `git-commit`.
6d35cc76 89
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90post-merge
91-----------
92
93This hook is invoked by `git-merge`, which happens when a `git pull`
94is done on a local repository. The hook takes a single parameter, a status
95flag specifying whether or not the merge being done was a squash merge.
96This hook cannot affect the outcome of `git-merge`.
97
98This hook can be used in conjunction with a corresponding pre-commit hook to
99save and restore any form of metadata associated with the working tree
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100(eg: permissions/ownership, ACLS, etc). See contrib/hooks/setgitperms.perl
101for an example of how to do this.
46232915 102
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103[[pre-receive]]
104pre-receive
105-----------
106
107This hook is invoked by `git-receive-pack` on the remote repository,
108which happens when a `git push` is done on a local repository.
109Just before starting to update refs on the remote repository, the
110pre-receive hook is invoked. Its exit status determines the success
111or failure of the update.
112
113This hook executes once for the receive operation. It takes no
114arguments, but for each ref to be updated it receives on standard
115input a line of the format:
116
117 <old-value> SP <new-value> SP <ref-name> LF
118
119where `<old-value>` is the old object name stored in the ref,
120`<new-value>` is the new object name to be stored in the ref and
121`<ref-name>` is the full name of the ref.
122When creating a new ref, `<old-value>` is 40 `0`.
123
124If the hook exits with non-zero status, none of the refs will be
125updated. If the hook exits with zero, updating of individual refs can
126still be prevented by the <<update,'update'>> hook.
127
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128Both standard output and standard error output are forwarded to
129`git-send-pack` on the other end, so you can simply `echo` messages
130for the user.
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131
132[[update]]
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133update
134------
135
6250ad1e 136This hook is invoked by `git-receive-pack` on the remote repository,
45ad9b50 137which happens when a `git push` is done on a local repository.
6250ad1e 138Just before updating the ref on the remote repository, the update hook
37425065 139is invoked. Its exit status determines the success or failure of
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140the ref update.
141
142The hook executes once for each ref to be updated, and takes
143three parameters:
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144
145 - the name of the ref being updated,
146 - the old object name stored in the ref,
147 - and the new objectname to be stored in the ref.
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148
149A zero exit from the update hook allows the ref to be updated.
150Exiting with a non-zero status prevents `git-receive-pack`
cbb84e5d 151from updating that ref.
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152
153This hook can be used to prevent 'forced' update on certain refs by
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154making sure that the object name is a commit object that is a
155descendant of the commit object named by the old object name.
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156That is, to enforce a "fast forward only" policy.
157
158It could also be used to log the old..new status. However, it
159does not know the entire set of branches, so it would end up
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160firing one e-mail per ref when used naively, though. The
161<<post-receive,'post-receive'>> hook is more suited to that.
6250ad1e 162
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163Another use suggested on the mailing list is to use this hook to
164implement access control which is finer grained than the one
165based on filesystem group.
166
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167Both standard output and standard error output are forwarded to
168`git-send-pack` on the other end, so you can simply `echo` messages
169for the user.
3aadad1b 170
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171The default 'update' hook, when enabled--and with
172`hooks.allowunannotated` config option turned on--prevents
173unannotated tags to be pushed.
174
175[[post-receive]]
176post-receive
177------------
6250ad1e 178
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179This hook is invoked by `git-receive-pack` on the remote repository,
180which happens when a `git push` is done on a local repository.
181It executes on the remote repository once after all the refs have
182been updated.
183
184This hook executes once for the receive operation. It takes no
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185arguments, but gets the same information as the
186<<pre-receive,'pre-receive'>>
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187hook does on its standard input.
188
189This hook does not affect the outcome of `git-receive-pack`, as it
190is called after the real work is done.
191
02783075 192This supersedes the <<post-update,'post-update'>> hook in that it gets
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193both old and new values of all the refs in addition to their
194names.
cbb84e5d 195
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196Both standard output and standard error output are forwarded to
197`git-send-pack` on the other end, so you can simply `echo` messages
198for the user.
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199
200The default 'post-receive' hook is empty, but there is
201a sample script `post-receive-email` provided in the `contrib/hooks`
202directory in git distribution, which implements sending commit
203emails.
204
205[[post-update]]
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206post-update
207-----------
208
6250ad1e 209This hook is invoked by `git-receive-pack` on the remote repository,
45ad9b50 210which happens when a `git push` is done on a local repository.
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211It executes on the remote repository once after all the refs have
212been updated.
213
214It takes a variable number of parameters, each of which is the
215name of ref that was actually updated.
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216
217This hook is meant primarily for notification, and cannot affect
218the outcome of `git-receive-pack`.
219
45ad9b50 220The 'post-update' hook can tell what are the heads that were pushed,
6250ad1e 221but it does not know what their original and updated values are,
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222so it is a poor place to do log old..new. The
223<<post-receive,'post-receive'>> hook does get both original and
224updated values of the refs. You might consider it instead if you need
225them.
cbb84e5d 226
45ad9b50 227When enabled, the default 'post-update' hook runs
6d35cc76 228`git-update-server-info` to keep the information used by dumb
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229transports (e.g., HTTP) up-to-date. If you are publishing
230a git repository that is accessible via HTTP, you should
6250ad1e 231probably enable this hook.
3aadad1b 232
cbb84e5d 233Both standard output and standard error output are forwarded to
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234`git-send-pack` on the other end, so you can simply `echo` messages
235for the user.