1Hooks used by git 2================= 3 4Hooks are little scripts you can place in `$GIT_DIR/hooks` 5directory to trigger action at certain points. When 6`git-init` is run, a handful example hooks are copied in the 7`hooks` directory of the new repository, but by default they are 8all disabled. To enable a hook, make it executable with `chmod +x`. 9 10This document describes the currently defined hooks. 11 12applypatch-msg 13-------------- 14 15This hook is invoked by `git-am` script. It takes a single 16parameter, the name of the file that holds the proposed commit 17log message. Exiting with non-zero status causes 18`git-am` to abort before applying the patch. 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 25The default 'applypatch-msg' hook, when enabled, runs the 26'commit-msg' hook, if the latter is enabled. 27 28pre-applypatch 29-------------- 30 31This hook is invoked by `git-am`. It takes no parameter, 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 39The default 'pre-applypatch' hook, when enabled, runs the 40'pre-commit' hook, if the latter is enabled. 41 42post-applypatch 43--------------- 44 45This hook is invoked by `git-am`. It takes no parameter, 46and is invoked after the patch is applied and a commit is made. 47 48This hook is meant primarily for notification, and cannot affect 49the outcome of `git-am`. 50 51pre-commit 52---------- 53 54This hook is invoked by `git-commit`, and can be bypassed 55with `\--no-verify` option. It takes no parameter, and is 56invoked before obtaining the proposed commit log message and 57making a commit. Exiting with non-zero status from this script 58causes the `git-commit` to abort. 59 60The default 'pre-commit' hook, when enabled, catches introduction 61of lines with trailing whitespaces and aborts the commit when 62such a line is found. 63 64commit-msg 65---------- 66 67This hook is invoked by `git-commit`, and can be bypassed 68with `\--no-verify` option. It takes a single parameter, the 69name of the file that holds the proposed commit log message. 70Exiting with non-zero status causes the `git-commit` to 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 78The default 'commit-msg' hook, when enabled, detects duplicate 79"Signed-off-by" lines, and aborts the commit if one is found. 80 81post-commit 82----------- 83 84This hook is invoked by `git-commit`. It takes no 85parameter, and is invoked after a commit is made. 86 87This hook is meant primarily for notification, and cannot affect 88the outcome of `git-commit`. 89 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 100(eg: permissions/ownership, ACLS, etc). See contrib/hooks/setgitperms.perl 101for an example of how to do this. 102 103[[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 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. 131 132[[update]] 133update 134------ 135 136This hook is invoked by `git-receive-pack` on the remote repository, 137which happens when a `git push` is done on a local repository. 138Just before updating the ref on the remote repository, the update hook 139is invoked. Its exit status determines the success or failure of 140the ref update. 141 142The hook executes once for each ref to be updated, and takes 143three parameters: 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. 148 149A zero exit from the update hook allows the ref to be updated. 150Exiting with a non-zero status prevents `git-receive-pack` 151from updating that ref. 152 153This hook can be used to prevent 'forced' update on certain refs by 154making sure that the object name is a commit object that is a 155descendant of the commit object named by the old object name. 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 160firing one e-mail per ref when used naively, though. The 161<<post-receive,'post-receive'>> hook is more suited to that. 162 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 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. 170 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------------ 178 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 185arguments, but gets the same information as the 186<<pre-receive,'pre-receive'>> 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 192This supersedes the <<post-update,'post-update'>> hook in that it gets 193both old and new values of all the refs in addition to their 194names. 195 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. 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]] 206post-update 207----------- 208 209This hook is invoked by `git-receive-pack` on the remote repository, 210which happens when a `git push` is done on a local repository. 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. 216 217This hook is meant primarily for notification, and cannot affect 218the outcome of `git-receive-pack`. 219 220The 'post-update' hook can tell what are the heads that were pushed, 221but it does not know what their original and updated values are, 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. 226 227When enabled, the default 'post-update' hook runs 228`git-update-server-info` to keep the information used by dumb 229transports (e.g., HTTP) up-to-date. If you are publishing 230a git repository that is accessible via HTTP, you should 231probably enable this hook. 232 233Both standard output and standard error output are forwarded to 234`git-send-pack` on the other end, so you can simply `echo` messages 235for the user.