grep and Egrep Regular expressions

An expression	Meaning
C	Any non-special character c that matches itself
\c	Remove any special meaning of character C
^	Header
$	End of Line
.	Any single character
[...]	... Any character in a character, a range like a-Z is legal
[^...]	Not... Any single character in the
\ n	Characters matching the nth \ (... \) (in grep only)
r*	R appears 0 or more times
r+	R appears one or more times (only in Egrep)
R?	R appears 0 or once (in Egrep only)
R1r2	R2 followed R1
R1|r2	R1 or R2 (in Egrep only)
\ (r\)	Tagged regular expression r (in grep only), can be nested
(r)	Regular expression R (in Egrep only), can be nested

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grep and Egrep Regular expressions