Perl Best Practices

Chapter 14. Command-Line Processing

The demiurge sits at his teletype, pounding out one command line after another, specifying the values of fundamental constants of physics: universe -G 6.672e-11 -e 1.602e-19 -h 6.626e-34…. and when he's finished typing out the command line, his right pinky hesitates above the ENTER key for an aeon or two, wondering what's going to happen; then down it comes—and the WHACK you hear is another Big Bang.

—Neal StephensonIn the Beginning was the Command Line

Perl started out as a language that was "also good for many system administration tasks"^[82]. In the beginning, Larry created it to help him write utility programs for data mining, report generation, text munging, stream filtering, and pattern matching; as an easy way to build new command-line tools, without the constraints of shell scripting or the burdens of C programming.

Nearly two decades on, Perl is still beloved by sysadmins, toolsmiths, and other denizens of the shell, as a fast and powerful way to create new testaceous utilities. And for most of these utility programs, the command line is still the primary user interface.

If you're designing a new tool, script, utility, application, or suite, chances are it will need some kind of command-line interface. If it does, make sure that interface is convenient, powerful, flexible, mnemonic, consistent, and predictable.

Sounds difficult? It is. In fact, it's even more difficult ...