Aug 21, 2020
How to Use Git Hooks?
Developing a quality application is a complex process. To do it, we use tools that complement the coding process. One of these processes is automation. This is due to the need for developers and sysadmins to reduce deployment time. Git is one of the most popular tools for this specific purpose. That’s why in this tutorial, we’ll show you how to use Git hooks to enhance your VPS project!
Git hooks are an internal utility that will improve the way Git is used. Let’s learn exactly how they work!
What is Git?
Before tackling the subject of Hooks, let’s quickly cover what Git is.
Git is an open source version control application. With it, we can monitor the development of software in detail.
Git is very popular among developers, and most open source projects use it.
What are Git Hooks
With Git we will be able to create branches of development, register changes and have absolute control over the versions. However, it is possible to automate this process. Git automation works at the level of programs and deployment. That is what Hooks are for.
Git hooks are shell scripts that run automatically before or after Git executes an important command like Commit or Push. For a Hook to work, it is necessary to give the Unix system the execution permissions. By using these scripts, we can automate certain things.
Git includes examples of Git hooks as soon as a local repository is started. It should be noted that sites like Github or Gitlab do not allow their use in the first instance. That is why they are mainly used in local or private instances.
How to Use Git Hooks
Hooks are stored in the .git/hooks/ folder of each cloned project, or in a newly created local repository. There we will find a series of example Hooks, which are a good starting point.
To activate a hook, it is only necessary to create a file and save it in the .git/hooks/ folder. However, the name of the file is predefined by Git. Some of the Hooks we can use are:
|Git Hook||Git Command||Description|
|applypatch-msg.sample||git am||When a patch message is changed|
|commit-msg.sample||git commit||To set the message of a commit action|
|fsmonitor-watchman.sample||launch watchman||To integrate watchman|
|post-update.sample||git push||By updating all data after the push|
|pre-applypatch.sample||git am||Before applying a patch|
|pre-commit.sample||git commit||Before committing|
|prepare-commit-msg.sample||git commit||When a commit message is set|
|pre-push.sample||git push||Before making a push|
|pre-rebase.sample||git rebase||Before making a pass or merge|
|pre-receive.sample||git push||When we push and get the data from the remote repository|
|update.sample||git push||By updating the remote data in a push|
As we can see, every Hook carries a command in Git. With that, we can take it into account when it is convenient to make a Hook.
Git Hook Examples
The use of Hooks is very wide, but knowledge of Bash and other languages such as Python or Ruby are needed to use their full potential. Here are some basic examples:
Showing Information About a Commit Action
This example shows the information of a commit action. Make a file called prepare-commit-msg in the .git/hooks/ folder of our repository. Then, write the following script:
#!/bin/sh SOB=$(git config github.user) grep -qs "^$SOB" "$1" || echo ". Cambio por @$SOB" >> "$1"
Then, save it. And set the execution permissions to the file.
:~$ chmod +x prepare-commit-msg
With this simple Hook, when a commit action is made, we’ll instantly receive relevant information about it.
Generate Documentation as Changes are Uploaded
This pre-push Hook allows generating the documentation of our code if we have a generator. Every time we make a change, the documentation will be performed automatically.
Create pre-push in the same folder as before and add the script:
#!/bin/bash doxygen Doxyfile git add docs/ git commit -m "Update documentation ($(date +%F@%R))"
Save the file, and finally, set the execution permission.
:~$ chmod +x pre-push
Find and Fix Trailing Whitespace in Commits
This pre-commit type Git hook is quite simple to make. Make a file called pre-commit and add the following:
#!/bin/bash -l .git/hooks/pre-commit-master-no-no if [[ $? == 1 ]] then exit 1 fi .git/hooks/pre-commit-debugger .git/hooks/pre-commit-trailing-spaces .git/hooks/pre-commit-images .git/hooks/pre-commit-pair
Now trailing whitespace will be found and fixed in all commits.
Git is a vital tool for today’s developers. Git hooks are a great way to improve it even further! In this tutorial, we reviewed the fundamental concept of automating Git processes with hooks.
Making a script for Git Hooks can be complicated if you don’t have a solid base of programming language knowledge, like bash.
Luckily here you have taken the first step towards learning how to use Git Hooks. We recommend to follow the official documentation and continue the learning process!