Enterprise Mac Administrator's Guide

8.1. The Basics

Every shell has some built-in functions that it performs directly, but most commands you enter cause the shell to execute programs that are external to the shell. This sets the shell apart from other command interpreters, as its primary mechanism for invoking functionality is largely dependent upon other programs. That's not to say that shells don't have built-in capabilities. They do; they can read, create, and append files, manipulate data through globbing and variable mangling and, they can utilize looping constructs. However, the ability to parse and extend that data will more often than not require external calls. This chapter seeks to arm you with the ability to fully utilize the Bash shell's internal functions, as well ...