These example files are not triggered because they are not executable and do not have the right name.
Git Hooks
Learn the basics of Git hooks.
You will need
- A Unix CLI
- Git
Recommended reading
What is a Git hook?
A Git hook is an executable file that can be triggered when certain actions occur. Hooks can be any kind of executable file, e.g. a compiled binary program, a shell script, a Ruby script, a Python script, etc.
Hooks must be executable files with a specific name in the hooks directory
inside a repository’s Git directory (inside the .git directory in a normal
repository).
You can find example hook files in most Git repositores:
$> cd /path/to/a/git/repository
$> cat .git/hooks/pre-commit.sample
#!/bin/sh
#
# An example hook script to verify what is about to be committed.
...
More information
What kind of hooks are there?
Hook scripts must have a specific name (and be executable) to be triggered.
These hook scripts are only limited by a developer’s imagination. Some example hook scripts include:
| Hook | Example usage |
|---|---|
pre-commit |
Check the commit message for spelling errors. |
pre-receive |
Enforce project coding standards. |
post-commit |
Email/SMS team members of a new commit. |
post-receive |
Push the code to production. |
You can type the git help hooks command to get the full list of hooks and
their documentation. A full list is also available here.
How can I create a hook?
Create a new repository:
$> cd /path/to/projects
$> mkdir git-hook-example
$> cd git-hook-example
$> git init
Create a hook script named pre-commit that will be executed before every
commit:
$> echo '#!/bin/bash' > .git/hooks/pre-commit
$> echo 'echo You are about to commit...' >> .git/hooks/pre-commit
$> chmod +x .git/hooks/pre-commit
You now have a pre-commit hook script:
$> cat .git/hooks/pre-commit
#!/bin/bash
echo You are about to commit...
Hooks are not under version control
Note that hooks are not part of the working tree and thus cannot be put under version control:
$> git status
On branch main
No commits yet
nothing to commit (create/copy files and use "git add" to track)
This is a good thing, as you don’t want people to be able to send malicious hook scripts to your machine every time you clone a repository from the Internet.
How do I use a hook?
Following the previous example, make a commit and the pre-commit hook will be
automatically triggered:
$> echo content > file.txt
$> git add .
$> git commit -m "Test"
You are about to commit...
[main 14b306d] Test
1 file changed, 1 insertion(+), 1 deletion(-)
What are hooks good for?
Hooks can be a way to automate repetitive or mundane tasks, like removing trailing spaces at each commit.
Or they can be used to automate deployments, for example to run the latest version of a server-side application every time new commits are pushed.
References
On this page
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