Cisco Cisco Expressway Maintenance Manual
\
Escapes a regular expression special
character.
character.
^
Signifies the start of a line.
When used immediately after an opening
brace, negates the character set inside the
brace.
brace, negates the character set inside the
brace.
[^abc]
matches any single character that is NOT one of
a, b or c
$
Signifies the end of a line.
^\d\d\d$
matches any string that is exactly 3 digits long
(?!...)
Negative lookahead. Defines a
subexpression that must not be present.
subexpression that must not be present.
(?!.*@example.com$).*
matches any string that does not
end with
@example.com
(?!alice).*
matches any string that does not start with
alice
(?<!...)
Negative lookbehind. Defines a
subexpression that must not be present.
subexpression that must not be present.
.*(?<!net)
matches any string that does not end with
net
Note that regex comparisons are not case sensitive.
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Cisco Expressway Administrator Guide
Reference Material