Cisco Cisco Web Security Appliance S390 Betriebsanweisung

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/downloads/.*\.(exe|zip|bin)

Avoid using regular expressions strings that are redundant because they can cause higher 
CPU usage on the Web Security appliance. A redundant regular expression is one that starts 
or ends with “.*”. 

Note — You must enclose regular expressions that contain blank spaces or non-alphanumeric 
characters in ASCII quotation marks.

Table 13-5 describes characters that are commonly used to form regular expressions: 

Table 13-5 Regular Expression Character Descriptions

Character

Description

.

Matches a single character.

*

Matches zero or more occurrences of the preceding regular expression. 
For example:
[0-9]* matches any number of digits
“.*” matches any arbitrary string of characters

^

Matches the beginning of a line as the first character of a regular expression.

$

Matches the end of a line as the last character of a regular expression.

+

Matches one or more occurrences of the preceding regular expression.

?

Matches zero or one occurrence of the preceding regular expression.

|

Matches the preceding regular expression or the following regular expression. 
For example:
x|y matches either x or y
abc|xyz matches either of the strings abc or xyz

[ ]

Matches the characters or digits that are enclosed within the brackets. 
For example:
[a-z] matches any character between a and z
[r-u] matches any of the characters r, s, t, or u
[0-3] matches any of the single digits 0, 1, 2, 3

{ }

Specifies the number of times to match the previous pattern. 
For example:
D{1,3} matches one to three occurrences of the letter D