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Associated Information

- none

Useful Links

- GAWK Manual
- Sed resources

Basic Metacharacters

• . any single character except newline

• * any number (including zero) of the single character that immediately preceeds it

• [...] matches any one of the characters (known as a class) enclosed in the brackets.
  If the first character in the brackets is a ^ i.e. [^...] , this reverse the match, i.e. anything but the characters in the brackets
  A - specifies a range e.g. [a-z]

• ^ As the first character of a regular expression matches the start of a line

• \{n,m}\ matches a range of occurrences of the single character that preceeds it e.g. a\{4\} matches four a`s , a\{4,\} matches at lease 4 a`s , a\{4,8\} matches between 4 to 8 a`s.

• \ Escape special meaning

Extended Metacharacters

• + matches one or more occurrences of character (or regular expression)

• ? matches zero or one occurrences of character (or regular expression)

• | matches either/or (alternation)

• () groups regular expressions e.g. (abc)* matches " " , "abc " , "abcabc" etc.

• {n,m} matches a range of occurrences of the single character that immediately precceds it