Merge branch 'maint'
[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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90[[pre-receive]]
91pre-receive
92-----------
93
94This hook is invoked by `git-receive-pack` on the remote repository,
95which happens when a `git push` is done on a local repository.
96Just before starting to update refs on the remote repository, the
97pre-receive hook is invoked. Its exit status determines the success
98or failure of the update.
99
100This hook executes once for the receive operation. It takes no
101arguments, but for each ref to be updated it receives on standard
102input a line of the format:
103
104 <old-value> SP <new-value> SP <ref-name> LF
105
106where `<old-value>` is the old object name stored in the ref,
107`<new-value>` is the new object name to be stored in the ref and
108`<ref-name>` is the full name of the ref.
109When creating a new ref, `<old-value>` is 40 `0`.
110
111If the hook exits with non-zero status, none of the refs will be
112updated. If the hook exits with zero, updating of individual refs can
113still be prevented by the <<update,'update'>> hook.
114
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115Both standard output and standard error output are forwarded to
116`git-send-pack` on the other end, so you can simply `echo` messages
117for the user.
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118
119[[update]]
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120update
121------
122
6250ad1e 123This hook is invoked by `git-receive-pack` on the remote repository,
45ad9b50 124which happens when a `git push` is done on a local repository.
6250ad1e 125Just before updating the ref on the remote repository, the update hook
37425065 126is invoked. Its exit status determines the success or failure of
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127the ref update.
128
129The hook executes once for each ref to be updated, and takes
130three parameters:
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131
132 - the name of the ref being updated,
133 - the old object name stored in the ref,
134 - and the new objectname to be stored in the ref.
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135
136A zero exit from the update hook allows the ref to be updated.
137Exiting with a non-zero status prevents `git-receive-pack`
cbb84e5d 138from updating that ref.
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139
140This hook can be used to prevent 'forced' update on certain refs by
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141making sure that the object name is a commit object that is a
142descendant of the commit object named by the old object name.
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143That is, to enforce a "fast forward only" policy.
144
145It could also be used to log the old..new status. However, it
146does not know the entire set of branches, so it would end up
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147firing one e-mail per ref when used naively, though. The
148<<post-receive,'post-receive'>> hook is more suited to that.
6250ad1e 149
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150Another use suggested on the mailing list is to use this hook to
151implement access control which is finer grained than the one
152based on filesystem group.
153
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154Both standard output and standard error output are forwarded to
155`git-send-pack` on the other end, so you can simply `echo` messages
156for the user.
3aadad1b 157
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158The default 'update' hook, when enabled--and with
159`hooks.allowunannotated` config option turned on--prevents
160unannotated tags to be pushed.
161
162[[post-receive]]
163post-receive
164------------
6250ad1e 165
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166This hook is invoked by `git-receive-pack` on the remote repository,
167which happens when a `git push` is done on a local repository.
168It executes on the remote repository once after all the refs have
169been updated.
170
171This hook executes once for the receive operation. It takes no
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172arguments, but gets the same information as the
173<<pre-receive,'pre-receive'>>
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174hook does on its standard input.
175
176This hook does not affect the outcome of `git-receive-pack`, as it
177is called after the real work is done.
178
02783075 179This supersedes the <<post-update,'post-update'>> hook in that it gets
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180both old and new values of all the refs in addition to their
181names.
cbb84e5d 182
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183Both standard output and standard error output are forwarded to
184`git-send-pack` on the other end, so you can simply `echo` messages
185for the user.
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186
187The default 'post-receive' hook is empty, but there is
188a sample script `post-receive-email` provided in the `contrib/hooks`
189directory in git distribution, which implements sending commit
190emails.
191
192[[post-update]]
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193post-update
194-----------
195
6250ad1e 196This hook is invoked by `git-receive-pack` on the remote repository,
45ad9b50 197which happens when a `git push` is done on a local repository.
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198It executes on the remote repository once after all the refs have
199been updated.
200
201It takes a variable number of parameters, each of which is the
202name of ref that was actually updated.
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203
204This hook is meant primarily for notification, and cannot affect
205the outcome of `git-receive-pack`.
206
45ad9b50 207The 'post-update' hook can tell what are the heads that were pushed,
6250ad1e 208but it does not know what their original and updated values are,
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209so it is a poor place to do log old..new. The
210<<post-receive,'post-receive'>> hook does get both original and
211updated values of the refs. You might consider it instead if you need
212them.
cbb84e5d 213
45ad9b50 214When enabled, the default 'post-update' hook runs
6d35cc76 215`git-update-server-info` to keep the information used by dumb
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216transports (e.g., HTTP) up-to-date. If you are publishing
217a git repository that is accessible via HTTP, you should
6250ad1e 218probably enable this hook.
3aadad1b 219
cbb84e5d 220Both standard output and standard error output are forwarded to
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221`git-send-pack` on the other end, so you can simply `echo` messages
222for the user.