a* match zero or more a s
[ab] match an a or b, other handy items a-z,
A-Z, 0-9
\x0D Match a cntrl/control character like ^M
[^ab] Don't match an a or b
[-a-z] match hypen and a thru z, [a-z-] works
too
[]a-z] match [ and a-z
[ab\*] match a, b or *
\(RE\) subexpresion (saved for use via \# where
# is a number)
Extended option
+ one or more (* is zero or more)
? zero or one
| or
() groupsing
\{min,max\} control number of matches
re is greedy!
precedence
[] highest
*+?
^$
concatenation
alternation
Allen notes from the Saint Louis Unix Users Group meeting Apr 8th 2002