13,420
edits
Changes
→Complex / Extended Regular Expressions
'''Complex Regular Expressions''' use symbols to help match text for more <u>precise</u> (complex) patterns.<br>The most common complex regular expression symbols are displayed below:
:*'''Anchors: ''' <span style="font-family:courier;font-weight:bold;">^</span> , <span style="font-family:courier;font-weight:bold;">$</span><br>Match lines the begin (^) or end ($) with a pattern.<br><br>:*'''Single Character:''' <span style="font-family:courier;font-weight:bold;">.</span><br>Represents a single character that can be any type of character.<br><br>:*'''Character Class:''' <span style="font-family:courier;font-weight:bold;">[ ]</span> , <span style="font-family:courier;font-weight:bold;">[^ ]</span><br>Represents a single character but with restrictions.<br><br>:*'''Zero or More Occurrence:''' <span style="font-family:courier;font-weight:bold;">*</span><br>Zero or more occurrences of previous character.<br><br>
Examples of how to use these complex regular expressions with the grep command are displayed below: