Linux Utilities | Part 2

Regular expressions:

• The character '^' is special at the beginning of a string
• The character '$' is special at the end of the string
• If you want to use a special character in a apttern, you must quote it, in effect, by escaping it with a preceding backslash (\)
• . => (dot character) matches any single character
• * =>A single character followe by * matches 0 or more occurences of that character
• [set] => A set of charactres in square bracketsmatches any single character from the set

Subexpressions:

You can enclose a portion of a regex between the markers '\(' and '\)'. The entire construct is called a s sub-expression

Interval Expressions:

• \{m\}
• \{m,\}
• \{m,n\}
• The first form denotes exactly m occurences belonging to String
• The second form denotes at least m characters belongihng to String
• The third form denotes between m and n characters belonging to String

The precedence of the operators is as follows:

• []
• * + ?
• /