Git Hooks – Overview

Like many other Version Control Systems, Git has a way to fire off custom scripts when certain important actions occur. There are two groups of these hooks: client-side and server-side. Client-side hooks are triggered by operations such as committing and merging, while server-side hooks run on network operations such as receiving pushed commits. You can use these hooks for all sorts of reasons.

– ref: Git – 8.3 Customizing Git - Git Hooks

If you use git init to initialise an empty directory, you’ll find some files with the .sample suffix, these are example hooks provided by git, if you wish to make any of them actually executable, you can simply remove the .sample suffix, and make it executable via chmod +x hook-name command.

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Some of the hooks are client-side, running on your local; and few hooks are server-side, and will be ran on server:

  • Client-side hooks: pre-commit, post-commit, pre-push (for pre commit/push) prepare-commit-msg, commit-msg (for commit message), etc
  • Server-side hooks: pre-receive, update, post-receive

Example – Checking Formatting Before Committing

Let’s take this scenario as a practical example, let’s say, I want to check the formatting of my code before committing:

  1. Firstly, I have previously setup prettier already, which can execute a format check using the command npm run format:check (basically runs prettier --check .) you can find out more about this at: prettier.io – install.

  2. Secondly, I’ll create the pre-commit hook file at .git/hooks/pre-commit and make it executable using the chmod command:

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    #!/bin/sh

# Check if the npm is installed and available
if command -v npm >/dev/null 2>&1; then
  # Run the format:check command and store the exit status in $?
  npm run format:check
  # This test checks if the exit code is not zero, which means the formatting check failed.
  if [ $? -ne 0 ]; then
    # stop and signal failure
    echo -e "\n\033[31m Commit aborted: Formatting check failed. \033[0m\n" >&2
    exit 1
  fi
else
  # stop and signal failure
  echo -e "\n\033[31m Pre-commit: npm not found; skipping format check. \033[0m\n" >&2
  exit 1
fi

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    > chmod +x .git/hooks/post-commit

  3. Thirdly, I’ll make a intentional mis-format in my codebase, and attempt to make the commit; As you can see in the following GIF, either directly using git command in terminal or in lazygit, the pre-commit hook will be triggered, to check the formatting; And when it fails (using exit 1) it will prevent the commit from happening.2026-04-22T155459

  4. Finally, let’s fix the mal-formatting using prettier --write . command and try to commit again; As you can see in the below GIF, both will trigger the pre-commit hook, and check the format again; But this time both will succeed and make the commit. 2026-04-22T155737

Reference & Extension

  • GIT documentation – Git Hooks: link
  • Atlassian Git Tutorial – Git Hooks: link
  • Medium – Mastering Client-Side Git Hooks: A Guide for Teams: link