The Unix Shell - Part II - page 3
Introduction,Standard Input and Output.Summary
This article has illustrated some of the powerful features a Unix shell has to offer. Redirecting output of commands for later use or filtering data with pipes are just two of the many tasks readily accomplished in the Unix environment. These same taks require significantly more effort in any operating system with a less powerful command line. The shell also provides facilities for looping and conditional execution (if statements). For more about the Unix shell and associated tools, read the main page for your favourite shell, or pick up a copy of O'Reilly's "Unix in a NutShell".