Headless Mode Beginner

# Basic one-shot usage
$ claude -p "What files are in the src/ directory?"

# With a specific task
$ claude -p "Add input validation to the signup form in src/components/SignupForm.tsx"

# Quick code generation
$ claude -p "Generate a Python function to validate email addresses"

# Pipe file contents for review
$ cat src/auth.js | claude -p "Review this code for security vulnerabilities"

# Pipe error logs for analysis
$ tail -100 /var/log/app/error.log | claude -p "What's causing these errors?"

# Pipe test output
$ npm test 2>&1 | claude -p "Analyze the test failures and suggest fixes"

# Pipe git diff
$ git diff --staged | claude -p "Write a commit message for these changes"

# Use echo for quick prompts
$ echo "fix the login bug" | claude

# Default text output
$ claude -p "List all API endpoints"

# JSON output for programmatic parsing
$ claude -p "List all API endpoints" --output-format json

# Stream output in JSON format
$ claude -p "Refactor the database module" --output-format stream-json

# Parse JSON output with jq
$ claude -p "Analyze code complexity" --output-format json | jq '.result'

#!/bin/bash
# Use exit codes in scripts
claude -p "Fix the failing tests in src/utils/"

if [ $? -eq 0 ]; then
    echo "Claude successfully fixed the tests"
    npm test
else
    echo "Claude encountered an error"
    exit 1
fi

#!/bin/bash
# Script: auto-review.sh
# Automatically review all changed files

for file in $(git diff --name-only HEAD~1); do
    echo "Reviewing: $file"
    claude -p "Review this file for bugs and improvements: $file" >> review-report.txt
    echo "---" >> review-report.txt
done

echo "Review complete. See review-report.txt"

#!/bin/bash
# Add JSDoc comments to all JavaScript files

find src/ -name "*.js" | while read file; do
    echo "Processing: $file"
    claude -p "Add JSDoc comments to all exported functions in $file"
done

# Process files in parallel (use with caution - API rate limits)
find src/ -name "*.ts" | xargs -P 3 -I {} claude -p "Add TypeScript type annotations to {}"

# crontab -e
# Daily code health check at 6 AM
0 6 * * * cd /home/user/project && claude -p "Run a code health check: look for unused imports, dead code, and potential bugs" > /tmp/daily-report.txt 2>&1

# Weekly dependency audit on Mondays
0 9 * * 1 cd /home/user/project && claude -p "Check for outdated dependencies and security vulnerabilities" > /tmp/weekly-audit.txt 2>&1

# Generate changelog every Friday
0 17 * * 5 cd /home/user/project && git log --since='1 week ago' --oneline | claude -p "Generate a changelog from these commits" >> CHANGELOG.md

#!/bin/bash
# smart-deploy.sh - AI-assisted deployment script
set -e

PROJECT_DIR="/home/user/my-app"
cd "$PROJECT_DIR"

# Step 1: Pre-deployment check
echo "Running pre-deployment analysis..."
ANALYSIS=$(claude -p "Analyze the current git diff against main. Are there any risky changes that could break production?" --output-format json)

# Step 2: Run tests
echo "Running tests..."
TEST_OUTPUT=$(npm test 2>&1) || {
    echo "Tests failed. Asking Claude for help..."
    echo "$TEST_OUTPUT" | claude -p "These tests failed. Fix them."
    npm test || exit 1
}

# Step 3: Generate release notes
echo "Generating release notes..."
git log --since="last week" --oneline | claude -p "Generate professional release notes from these commits" > RELEASE_NOTES.md

echo "Deployment preparation complete!"