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grep and egrep Regular Expressions (decreasing order of precedence)

c

any non-special character c matches itself

\c

turn off any special meaning of character c

^

beginning of line

$

end of line

.

any single character

[...]

any one of characters in ...; ranges like a-z are legal

[^...]

any single character not in ...; ranges are legal

\n

with the n'th \(...\) matched (grep only)

r*

zero or more occurrences of r

r+

one or more occurrences of r (egrep only)

r?

zero or one occurrences of r (egrep only)

r1r2

r1 followed by r2

r1|r2

r1 or r2 (egrep only)

\(r\)

tagged regular expression r (grep only); can be nested

(r)

regular expression r (egrep only); can be nested

No regular expression matches a newline