A. Regular Expressions

A regular expression defines a set of one or more strings of characters. A simple string of characters is a regular expression that defines one string of characters: itself. A more complex regular expression uses letters, numbers, and special characters to define many different strings of characters. A regular expression is said to match any string it defines.

This appendix describes the regular expressions used by ed, vim, emacs, grep, mawk/gawk, sed, Perl, and many other utilities. The regular expressions used in shell ambiguous file references are different and are ...

Get A Practical Guide to Fedora™ and Red Hat® Enterprise Linux®, Seventh Edition now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.