run-on-output

Execute tasks when CLI output patterns are detected

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Features • Installation • Usage • Examples

A lightweight Node.js CLI tool that monitors command output in real-time and triggers actions when specific patterns are found. Perfect for automation workflows, development environments, and CI/CD pipelines.

Features

• 🎯 Pattern Matching - Monitor stdout/stderr for regex patterns or plain strings
• ⚡ Real-time Monitoring - Output is forwarded in real-time while monitoring
• 🔧 Flexible Actions - Display messages or execute commands when patterns match
• 📝 Multiple Patterns - Wait for multiple patterns before triggering actions
• 🚀 Zero Dependencies - Built with Node.js built-in modules only

Installation

npm install -g run-on-output

Or use without installing:

npx run-on-output [options] <command> [args...]

Usage

Basic Examples

Display a message when server starts:

run-on-output -s "Server started" -m "🚀 Server is ready" npm start

Execute a health check when server is listening:

run-on-output -p "listening on port \\d+" -r "curl http://localhost:3000/health" node server.js

Monitor development environment startup:

run-on-output -s "webpack compiled,server ready" -m "✅ Development environment ready" npm run dev

Multiple actions - show message and open browser:

run-on-output -s "ready" -m "Server is up" -r "open http://localhost:3000" npm start

Run npm script when server is ready:

run-on-output -s "Server running" -n "test" node server.js

[!TIP] You can use the short alias roo instead of run-on-output for faster typing:

roo -s "Server started" -m "🚀 Server is ready" npm start

Command Line Options

run-on-output [OPTIONS] <command> [args...]

OPTIONS:
  -p, --patterns <patterns>    Comma-separated list of regex patterns to watch for
  -s, --strings <strings>      Comma-separated list of plain strings to watch for
  -r, --run <command>          Command to execute after all patterns are found
  -n, --npm <script>           npm script to run after all patterns are found
  -m, --message <text>         Message to display after all patterns are found
  -h, --help                   Show this help message

REQUIREMENTS:
  - Either --patterns or --strings must be specified (but not both)
  - At least one of --run, --npm, or --message must be specified

Pattern Types

Plain Strings (-s, --strings)

• Matches exact text (case-insensitive)
• Easier to use for simple text matching
• Example: -s "Server started,Database connected"

Regex Patterns (-p, --patterns)

• Use regular expressions for complex matching
• Supports all JavaScript regex features
• Example: -p "listening on port \\d+,ready in \\d+ms"

Examples

Development Workflow

# Wait for both webpack and server, then open browser
run-on-output -s "webpack compiled,Local:" -r "open http://localhost:3000" npm run dev

# Monitor test runner and show completion message
run-on-output -s "Tests completed" -m "✅ All tests passed" npm test

CI/CD Pipeline

# Wait for deployment completion and run smoke tests
run-on-output -p "deployment.*complete" -r "./scripts/smoke-test.sh" deploy.sh

# Monitor build process and trigger notifications
run-on-output -s "Build successful" -r "slack-notify '#dev' 'Build completed'" npm run build

Docker & Containers

# Wait for container health check and run integration tests
run-on-output -s "healthy" -r "npm run test:integration" docker-compose up

# Monitor database initialization
run-on-output -p "database.*ready" -m "📁 Database initialized" ./start-db.sh

API Development

# Wait for API server and run endpoint tests
run-on-output -p "server.*listening.*port" -r "npm run test:api" node api.js

# Monitor microservices startup and run deployment script
run-on-output -s "auth-service ready,user-service ready" -n "deploy" ./start-services.sh

# Combine message, command and npm script
run-on-output -s "Database connected" -m "🎉 Ready for testing" -n "test:integration" npm start