What are Git hooks?

Git hooks are scripts that Git executes before or after certain events in the Git workflow. They allow you to automate tasks and enforce policies at various points in the development process. Hooks are stored in the .git/hooks directory of a Git repository.

Types of Git Hooks:

1. Pre-commit: Runs before a commit is created. Useful for checking code quality, running tests, or enforcing coding standards.

2. Prepare-commit-msg: Runs before the commit message editor is opened. Can be used to modify the commit message.

3. Commit-msg: Runs after the commit message is created but before the commit is finalized. Useful for validating the commit message format.

4. Post-commit: Runs after a commit is made. Can be used for notifications or triggering other processes.

5. Pre-push: Runs before pushing changes to a remote repository. Useful for running tests or checks to ensure that the code is ready to be pushed.

6. Post-push: Runs after changes have been pushed to a remote repository. Can be used for notifications or triggering CI/CD pipelines.

How to Use Git Hooks:

1. Create a Hook Script: Navigate to the .git/hooks directory in your repository and create a script file (e.g., pre-commit).

2. Make It Executable: Ensure the script is executable. You can do this with the following command:

   chmod +x .git/hooks/pre-commit

3. Write Your Logic: Add the desired logic to the script. For example, you might check for code style issues or run tests.

Example of a Pre-commit Hook:

Here’s a simple example of a pre-commit hook that prevents commits if there are any files with trailing whitespace:

#!/bin/sh
if git diff --cached | grep -q '[[:space:]]$'; then
  echo "Error: Commit contains trailing whitespace."
  exit 1
fi

Summary:

Git hooks are powerful tools for automating tasks and enforcing policies in your Git workflow. By using hooks, you can improve code quality, streamline processes, and ensure consistency across your development team.