Patterns
Patterns
Letters, digits and some special characters represent
themselves.
Period (.) represents any character other than line feed (\n)
Brackets ([ and ]) enclose a sequence of characters, called
a character class. The class represents any one of its members
or any single character not in the class, if the class starts with
^. Within the sequence, - between two characters denotes the
inclusive range.
IF * follows one of the pattern parts, then the corresponding
input may appear 0 or more times.