Git Hooks Setup

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You are a Git automation specialist. The user wants to set up pre-commit, pre-push, and commit-msg hooks to automate validation and prevent bad commits/pushes.

What to check first

• .git/hooks/ directory exists and is readable in your repo
• Current Git version (git --version) supports hooks you plan to use
• Whether you need hooks to run in all local clones or via a shared tool like Husky

Steps

1. Navigate to .git/hooks/ directory and list existing hook templates with ls -la .git/hooks/ to see what's already there
2. Create the pre-commit hook by creating file .git/hooks/pre-commit with touch .git/hooks/pre-commit
3. Make the pre-commit hook executable with chmod +x .git/hooks/pre-commit so Git can run it
4. Create the pre-push hook by creating file .git/hooks/pre-push with touch .git/hooks/pre-push
5. Make the pre-push hook executable with chmod +x .git/hooks/pre-push
6. Create the commit-msg hook by creating file .git/hooks/commit-msg with touch .git/hooks/commit-msg
7. Make the commit-msg hook executable with chmod +x .git/hooks/commit-msg
8. Test hooks by running git commit --allow-empty -m "test" to trigger pre-commit and commit-msg, and git push --dry-run to test pre-push

Code

#!/bin/bash
# .git/hooks/pre-commit
# Runs before commit is created; exit with non-zero to block commit

set -e

echo "🔍 Running pre-commit checks..."

# Check for staged files
if git diff --cached --quiet; then
    echo "❌ No staged changes to commit"
    exit 1
fi

# Lint staged JavaScript/TypeScript files
STAGED_FILES=$(git diff --cached --name-only --diff-filter=ACM | grep -E '\.(js|ts|jsx|tsx)$' || true)
if [ ! -z "$STAGED_FILES" ]; then
    echo "📋 Linting staged files..."
    echo "$STAGED_FILES" | xargs npx eslint --fix || exit 1
    git add $STAGED_FILES
fi

# Check for large files (> 5MB)
LARGE_FILES=$(git diff --cached --name-only | while read file; do
    if [ -f "$file" ]; then
        size=$(stat -f%z "$file" 2>/dev/null || stat -c%s "$file" 2>/dev/null)
        if [ "$size" -gt 5242880 ]; then
            echo "$file"
        fi
    fi
done)

if [ ! -z "$LARGE_FILES" ]; then
    echo "⚠️  Large files detected (>5MB

Note: this example was truncated in the source. See the GitHub repo for the latest full version.

Common Pitfalls

• Treating this skill as a one-shot solution — most workflows need iteration and verification
• Skipping the verification steps — you don't know it worked until you measure
• Applying this skill without understanding the underlying problem — read the related docs first

When NOT to Use This Skill

• When a simpler manual approach would take less than 10 minutes
• On critical production systems without testing in staging first
• When you don't have permission or authorization to make these changes

How to Verify It Worked

• Run the verification steps documented above
• Compare the output against your expected baseline
• Check logs for any warnings or errors — silent failures are the worst kind

Production Considerations

• Test in staging before deploying to production
• Have a rollback plan — every change should be reversible
• Monitor the affected systems for at least 24 hours after the change