Posix and Unicode Classes
Shortcut Expansion Description [[:alpha:]] [a-zA-Z] An alphabetic character. [[:alnum:]] [0-9A-Za-z] An alphabetic or numeric character. [[:digit:]] \d A digit, 0-9. [[:lower:]] [a-z] A lower case letter. [[:upper:]] [A-Z] An upper case letter. [[:punct:]] [!"#$%&'()*+,-./:;<=>?@\[\\\]^_`{|}~] A punctuation character note the escaped characters [, \, and ]. /bea?t/ Matches either 'beat' or 'bet' /bea+t/ Matches 'beat', 'beaat', 'beaaat' /bea*t/ Matches 'bet', 'beat', 'beaat'