"Every Unix system offers several useful commands for finding files and searching them for strings. Together with programming techniques such as streams, pipes, redirections, and regular expressions they comprise very powerful tools ideal for administrative tasks.
"Regular expressions are descriptive patterns dealing with text strings. They have been part of Unix systems from their beginnings. They were invented by Mr Ken Thompson, one of Unix's creators. Regular expressions are very effective tools for processing text information and they are decidedly worth the effort it takes to master them, but even a passing familiarity will pay dividends..."
