ksh regular expression pattern

Pattern Element 

*      Matches any string, including the nullstring.
?      Matches any single character.
[...]  Matches any one of the enclosedcharacters.
[!...] Any character not enclosed is matched.

Within [ and ], a - can be included in the character set by putting it as the first or last character.

?(pattern-list)          Optionally matches any oneof the given patterns.
*(pattern-list)          Matches zero or moreoccurrences of the given patterns.
+(pattern-list)          Matches one or moreoccurrences of the given patterns.
{n}(pattern-list)        Matches n occurrences ofthe given patterns.
{m,n}(pattern-list)      Matches from m to noccurrences of the given patterns.
@(pattern-list)          Matches exactly one of thegiven patterns.
!(pattern-list)          Matches anything exceptone of the given patterns.

\d     Matches any character in the digit class.
\D     Matches any character not in the digitclass.
\s     Matches any character in the space class.
\S     Matches any character not in the spaceclass.
\w     Matches any character in the word class.
\W     Matches any character not in the wordclass.

[:alnum:]
[:alpha:] 
[:blank:]
[:cntrl:] 
[:digit:] 
[:graph:] 
[:lower:] 
[:print:] 
[:punct:] 
[:space:] 
[:upper:] 
[:word:] 
[:xdigit:]