Changes

<i>A '''regular expression''' is a combination of two types of characters: '''literals''' and '''special characters'''.<br>In combination, these characters define a logical pattern. Strings of text can be compared to this pattern<br>to see if they fit the pattern defined by the expression.</i>

This usually refers to text that is <u>contained</u> inside a '''file''' or text as a result<br>of issuing Linux commands using a '''Linux pipeline command'''.

===Literal (Simple) Regular Expressions===