Bash Cookbook

Linking commands, pipes, and input/output

This section is probably one of the most important in the book because it describes a fundamental and powerful feature on Linux and Unix: the ability to use pipes and redirect input or output. By themselves, pipes are a fairly trivial feature - commands and scripts can redirect their output to files or commands. So what? This could be considered a massive understatement in the Bash scripting world, because pipes and redirection allow you to enhance commands with the functionality of other commands or features. 

Let's look into this with an example using commands called tail and grep. In this example, the user, Bob, wants to look at his logs in real time (live), but he only wants to find the entries ...