Chapter 11. Writing command-line applications

This chapter covers

Designing command-line applications by using common conventions
Communicating with pipes
Using exit codes

Node command-line utilities are used everywhere, from project automation tools, such as Gulp and Yeoman, to XML and JSON parsers. If you’ve ever wondered how to build command-line tools with Node, this chapter will show you everything you need to know to get started. You’ll learn how Node programs accept command-line arguments and how to handle I/O with pipes. We’ve also included shell tips that will help you use the command line more effectively.

Although writing command-line tools with Node isn’t hard, it’s important to follow community conventions. This chapter includes many of these conventions so you’ll be able to write tools that other people can use, without too much documentation.

11.1. Understanding conventions and philosophy

A big part of command-line development is understanding the conventions used by established programs. As a real-world example, take a look at Babel:

Usage: babel [options] <files ...>

Options:

  -h, --help                           output usage information
  -f, --filename [filename]            filename to use when reading from stdin
[ ... ]
  -q, --quiet                          Don't log anything
  -V, --version                        output the version number

Chapter 11. Writing command-line applications

This chapter covers

11.1. Understanding conventions and philosophy

11.2. Introducing parse-json

11.3. Using command-line arguments

11.4. Sharing command-line tools with npm

11.5. Connecting scripts with pipes

11.6. Interpreting real-world scripts

11.7. Summary