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). 101 102[[pre-receive]] 103pre-receive 104----------- 105 106This hook is invoked by `git-receive-pack` on the remote repository, 107which happens when a `git push` is done on a local repository. 108Just before starting to update refs on the remote repository, the 109pre-receive hook is invoked. Its exit status determines the success 110or failure of the update. 111 112This hook executes once for the receive operation. It takes no 113arguments, but for each ref to be updated it receives on standard 114input a line of the format: 115 116 <old-value> SP <new-value> SP <ref-name> LF 117 118where `<old-value>` is the old object name stored in the ref, 119`<new-value>` is the new object name to be stored in the ref and 120`<ref-name>` is the full name of the ref. 121When creating a new ref, `<old-value>` is 40 `0`. 122 123If the hook exits with non-zero status, none of the refs will be 124updated. If the hook exits with zero, updating of individual refs can 125still be prevented by the <<update,'update'>> hook. 126 127Both standard output and standard error output are forwarded to 128`git-send-pack` on the other end, so you can simply `echo` messages 129for the user. 130 131[[update]] 132update 133------ 134 135This hook is invoked by `git-receive-pack` on the remote repository, 136which happens when a `git push` is done on a local repository. 137Just before updating the ref on the remote repository, the update hook 138is invoked. Its exit status determines the success or failure of 139the ref update. 140 141The hook executes once for each ref to be updated, and takes 142three parameters: 143 144 - the name of the ref being updated, 145 - the old object name stored in the ref, 146 - and the new objectname to be stored in the ref. 147 148A zero exit from the update hook allows the ref to be updated. 149Exiting with a non-zero status prevents `git-receive-pack` 150from updating that ref. 151 152This hook can be used to prevent 'forced' update on certain refs by 153making sure that the object name is a commit object that is a 154descendant of the commit object named by the old object name. 155That is, to enforce a "fast forward only" policy. 156 157It could also be used to log the old..new status. However, it 158does not know the entire set of branches, so it would end up 159firing one e-mail per ref when used naively, though. The 160<<post-receive,'post-receive'>> hook is more suited to that. 161 162Another use suggested on the mailing list is to use this hook to 163implement access control which is finer grained than the one 164based on filesystem group. 165 166Both standard output and standard error output are forwarded to 167`git-send-pack` on the other end, so you can simply `echo` messages 168for the user. 169 170The default 'update' hook, when enabled--and with 171`hooks.allowunannotated` config option turned on--prevents 172unannotated tags to be pushed. 173 174[[post-receive]] 175post-receive 176------------ 177 178This hook is invoked by `git-receive-pack` on the remote repository, 179which happens when a `git push` is done on a local repository. 180It executes on the remote repository once after all the refs have 181been updated. 182 183This hook executes once for the receive operation. It takes no 184arguments, but gets the same information as the 185<<pre-receive,'pre-receive'>> 186hook does on its standard input. 187 188This hook does not affect the outcome of `git-receive-pack`, as it 189is called after the real work is done. 190 191This supersedes the <<post-update,'post-update'>> hook in that it gets 192both old and new values of all the refs in addition to their 193names. 194 195Both standard output and standard error output are forwarded to 196`git-send-pack` on the other end, so you can simply `echo` messages 197for the user. 198 199The default 'post-receive' hook is empty, but there is 200a sample script `post-receive-email` provided in the `contrib/hooks` 201directory in git distribution, which implements sending commit 202emails. 203 204[[post-update]] 205post-update 206----------- 207 208This hook is invoked by `git-receive-pack` on the remote repository, 209which happens when a `git push` is done on a local repository. 210It executes on the remote repository once after all the refs have 211been updated. 212 213It takes a variable number of parameters, each of which is the 214name of ref that was actually updated. 215 216This hook is meant primarily for notification, and cannot affect 217the outcome of `git-receive-pack`. 218 219The 'post-update' hook can tell what are the heads that were pushed, 220but it does not know what their original and updated values are, 221so it is a poor place to do log old..new. The 222<<post-receive,'post-receive'>> hook does get both original and 223updated values of the refs. You might consider it instead if you need 224them. 225 226When enabled, the default 'post-update' hook runs 227`git-update-server-info` to keep the information used by dumb 228transports (e.g., HTTP) up-to-date. If you are publishing 229a git repository that is accessible via HTTP, you should 230probably enable this hook. 231 232Both standard output and standard error output are forwarded to 233`git-send-pack` on the other end, so you can simply `echo` messages 234for the user.