Metacharacter What It Matches
x?? Matches 0 or 1 occurrences of x
(xyz)?? Matches 0 or 1 occurrences of pattern xyz
x*? Matches 0 or more occurrences of x
(xyz)*? Matches 0 or more occurrences of pattern xyz
x+? Matches 1 or more occurrences of x
(xyz)+? Matches 1 or more occurrences of pattern xyz
x{m,n}? Matches at least m occurrences of x and no more than n occurrences of x
x{m}? Matches at least m occurrences of x
x{m,}? Matches at least m times