Citrix Systems Network Router 9.2 User Manual

The following table describes operations that use regular expressions.
Operations That Apply Regular Expressions to Text and HTTP Headers

text.BEFORE_REGEX(regular 

expression)

Selects text that precedes the string that matches 
the regular expression argument. If the regular 
expression does not match any data in the target, 
the expression returns a text object of length of 0.

The following expression selects the string "text" 
from "text/plain".

http.res.header("content-

type").before_regex(re#/#) 

text.AFTER_REGEX(regular 

expression)

Selects text that follows the string that matches the 
regular expression argument. If the regular 
expression does not match any text in the target, 
the expression returns a text object of length of 0.

The following expression extracts "Example" from 
"myExample":

http.req.header("etag").after_
regex(re/my/)

text.REGEX_SELECT(regular 

expression)

Selects a string that matches the regular expression 
argument. If the regular expression does not match 
the target, a text object of length of 0 is returned.

The following example extracts the string "NS-
CACHE-9.0: 90" from a Via header:

http.req.header("via").regex_

select(re!NS-CACHE-

\d\.\d:\s*\d{1,3}!)