Why hooks automate workflows in Git - See It in Action

Why hooks automate workflows

📖 Scenario: You are working on a team project using Git. Your team wants to make sure that every time someone tries to commit code, a check runs automatically to prevent mistakes. This helps keep the project clean and error-free.

🎯 Goal: Learn how to use Git hooks to automate a simple workflow that checks commit messages before saving them.

📋 What You'll Learn

Create a Git hook script file

Add a simple check in the hook script

Make the hook script executable

Test the hook by making a commit

💡 Why This Matters

🌍 Real World

Teams use Git hooks to automate checks like code style, tests, or commit message rules to keep code quality high.

💼 Career

Knowing how to create and use Git hooks is useful for developers and DevOps engineers to enforce workflow rules automatically.

1

Create the Git hook script file

Create a file named pre-commit inside the .git/hooks/ directory with the following first line: #!/bin/sh

Git

# Create the pre-commit hook file with the shebang line
# Your code here

Hint

The first line of a shell script is usually #!/bin/sh to tell the system how to run it.

2

Add a simple commit message check

Add a line to the pre-commit script that checks if the commit message file contains the word WIP. Use grep -q WIP .git/COMMIT_EDITMSG and if found, print "Commit message contains WIP, please finish your work before committing." and exit with status 1.

Git

#!/bin/sh
# Add a check for 'WIP' in the commit message
# Your code here

Hint

Use grep -q to quietly check for a word, and if found, print a message and exit with 1 to stop the commit.

3

Make the hook script executable

Run the command chmod +x .git/hooks/pre-commit to make the pre-commit script executable.

Git

#!/bin/sh
grep -q WIP .git/COMMIT_EDITMSG && { echo "Commit message contains WIP, please finish your work before committing."; exit 1; }
# Your code here

Hint

Use chmod +x to allow the script to run as a program.

4

Test the hook by making a commit

Try to commit with a message containing WIP and observe the output. Use git commit -m "WIP: work in progress" and check that the commit is blocked with the message Commit message contains WIP, please finish your work before committing.

Git

#!/bin/sh
grep -q WIP .git/COMMIT_EDITMSG && { echo "Commit message contains WIP, please finish your work before committing."; exit 1; }
# Test the hook by running:
# git commit -m "WIP: work in progress"
# Your code here

Hint

Try committing with a message that includes 'WIP' to see the hook stop the commit.

Practice

1. What is the main purpose of Git hooks in a project?

easy

A. To create new branches automatically

B. To store large files outside the repository

C. To merge branches without conflicts

D. To automatically run scripts during Git actions

Solution

1. Step 1: Understand what Git hooks do

   Git hooks are scripts that run automatically when certain Git events happen, like committing or pushing.

2. Step 2: Identify the main purpose

   The main purpose is to automate tasks during Git actions, such as checks or notifications.

3. Final Answer:

   To automatically run scripts during Git actions -> Option D

4. Quick Check:

   Git hooks automate scripts = A [OK]

Hint: Hooks run scripts automatically on Git events [OK]

Common Mistakes:

• Confusing hooks with branch management
• Thinking hooks store files
• Assuming hooks merge branches

2. Which of the following is the correct way to enable a Git hook script?

easy

A. Push the script to the remote repository

B. Add the script to the .gitignore file

C. Rename the script to remove the .sample extension in .git/hooks/

D. Create a new branch named hooks

Solution

1. Step 1: Locate Git hooks directory

   Git hooks are stored in the .git/hooks/ folder, usually with .sample extensions.

2. Step 2: Enable a hook script

   To enable a hook, you rename the script to remove the .sample extension so Git can run it.

3. Final Answer:

   Rename the script to remove the .sample extension in .git/hooks/ -> Option C

4. Quick Check:

   Remove .sample to enable hook = C [OK]

Hint: Remove .sample extension to activate hook scripts [OK]

Common Mistakes:

• Adding hooks to .gitignore disables them
• Pushing hooks doesn't enable them locally
• Creating branches does not enable hooks

3. Given a pre-commit hook script that checks for TODO comments and rejects the commit if found, what will happen if you try to commit a file containing 'TODO: fix this'?

medium

A. The commit will be rejected with a warning about TODO comments

B. The commit will delete the TODO comments automatically

C. The commit will succeed but add a warning in the commit message

D. The commit will succeed without any message

Solution

1. Step 1: Understand the pre-commit hook behavior

   The pre-commit hook runs before the commit is finalized and can reject commits based on conditions.

2. Step 2: Analyze the effect of TODO comments

   If the script finds 'TODO' comments, it rejects the commit and shows a warning message.

3. Final Answer:

   The commit will be rejected with a warning about TODO comments -> Option A

4. Quick Check:

   Pre-commit rejects TODO commits = D [OK]

Hint: Pre-commit hooks can block commits with errors [OK]

Common Mistakes:

• Assuming commit succeeds silently
• Thinking commit adds warnings instead of blocking
• Believing hooks modify code automatically

4. You wrote a post-commit hook script but it does not run after commits. What is the most likely reason?

medium

A. The script is named post-commit.sample

B. All of the above

C. The script file is missing execute permissions

D. The script is located outside the .git/hooks directory

Solution

1. Step 1: Check script permissions

   Git requires hook scripts to have execute permissions to run.

2. Step 2: Check script name and location

   The script must be named exactly (no .sample) and be inside .git/hooks/ folder.

3. Step 3: Combine all issues

   Any of these issues (wrong name, wrong location, no execute permission) will prevent the hook from running.

4. Final Answer:

   All of the above -> Option B

5. Quick Check:

   Permissions, name, location all matter = D [OK]

Hint: Check permissions, name, and location for hooks [OK]

Common Mistakes:

• Ignoring execute permissions
• Leaving .sample extension
• Placing script outside hooks folder

5. You want to automate sending a notification email after every successful push to the remote repository. Which Git hook should you use and why?

hard

A. post-push hook, because it runs after the push completes successfully

B. pre-push hook, because it runs before pushing and can stop the push

C. post-commit hook, because it runs after each commit locally

D. pre-commit hook, because it runs before committing changes

Solution

1. Step 1: Identify when to send notification

   The notification should be sent after a successful push to the remote repository.

2. Step 2: Understand available hooks

   Git does not have a built-in post-push hook, but the server-side post-receive hook runs after a successful push on the remote repository.

3. Step 3: Choose the best hook

   To send notification after a successful push, use the server-side post-receive hook, which runs after the push completes successfully.

4. Final Answer:

   post-push hook, because it runs after the push completes successfully -> Option A

5. Quick Check:

   Use post-push (server-side post-receive) for notifications after push = A [OK]

Hint: Use post-receive hook on server to notify after push [OK]

Common Mistakes:

• Assuming post-push hook exists locally in Git
• Using pre-push which runs before push
• Using post-commit which runs too early