Cisco Cisco Web Security Appliance S170 Guía Del Usuario
9-22
AsyncOS 8.7 for Cisco Web Security Appliances User Guide
Chapter 9 Classify URLs for Policy Application
Regular Expressions
Regular Expression Character Table
Meta-
character
character
Description
.
Matches any single character, except the newline character (0x0A). For example, the
regular expression
regular expression
r.t
matches the strings rat, rut, r t, but not root.
Be wary of using unescaped dots in long patterns, and especially in the middle of longer
patterns. See
patterns. See
for more information.
*
Matches zero or more occurrences of the character immediately preceding. For example,
the regular expression
the regular expression
.*
means match any string of characters, and
[0-9]*
matches any
string of digits.
Be wary of using this meta-character, especially in conjunction with the dot character. Any
pattern containing an unescaped dot that returns more than 63 characters after the dot will be
disabled. See
pattern containing an unescaped dot that returns more than 63 characters after the dot will be
disabled. See
for more information.
\
The escape character; it means treat the following meta-character as an ordinary character.
For example,
For example,
\^
is used to match the caret character (^) rather than the beginning of a line.
Similarly, the expression
\.
is used to match an actual dot rather than any single character.
^
Matches the beginning of a line. For example, the regular expression
^When in matches
the beginning of the string “When in the course of human events” but not the string “What
and when in the”.
and when in the”.
$
Matches the end of a line or string. For example,
b$\.
matches any line or string that ends
with “b.”
+
Matches one or more occurrences of the character or regular expression immediately
preceding. For example, the regular expression
preceding. For example, the regular expression
9+
matches 9, 99, and 999.
?
Matches zero or one occurrence of the preceding pattern element. For example,
colou?r
matches both “colour” and “color” since the “u” is optional.
( )
Treat the expression between the left and right parens as a group, limiting the scope of
other meta-characters. For example,
other meta-characters. For example,
(abc)+
matches one or more occurrences of the string
“abc”; such as, “abcabcabc” or “abc123” but not “abab” or “ab123”.
|
Logical OR: matches the preceding pattern or the following pattern. For example
(him|her)
matches the line “it belongs to him” and the line “it belongs to her” but does
not match the line “it belongs to them.”
[ ]
Matches any one of the characters between the brackets. For example, the regular
expression
expression
r[aou]t
matches “rat”, “rot”, and “rut”, but not “ret”.
Ranges of characters are specified by a beginning character, a hyphen, and an ending
character. For example, the pattern
character. For example, the pattern
[0-9]
means match any digit. Multiple ranges can be
specified as well. The pattern
[A-Za-z]
means match any upper- or lower-case letter. To
match any character except those in the range (that is, the complementary range), use a
caret as the first character after the opening bracket. For example, the expression
caret as the first character after the opening bracket. For example, the expression
[^269A-Z]
matches any characters except 2, 6, 9, and uppercase letters.