question about :matches_regex

Hi,

I think both of those regexes would have the same exact matching. The parentheses would capture a match into a backreference which wouldn't be usable. If you wanted to match a literal ( or ), I think you'd need to escape them with backslashes.

Regardless, if you're just trying to check if the URI starts wtih /cjj or /(cjj), you could use a string pattern instead. This would be significantly more efficient than a regex.

switch -glob [HTTP::path] {
   "/(cjj)*" { pool cjj01-BRO }
   "/cjj*" { pool cjj01-WSE }
}

Aaron

Thanks for your answer

 

"The parentheses would capture a match into a backreference which wouldn't be usable. "

 

 

can you give me an example to make me understand this better

 

you mean a variable?

 

like $cjj ,and this cjj is set an value at the begining of the irule

 

($cjj)

Normally you could use a capturing group defined by the expression in the parentheses to capture the matched characters. Here's an example:

 

 

regexp -inline {test([0-9]} "test321654654" original match

 

 

$original would be set to the original string of test321654654 and $match would be set to 321654654. See the TCL wiki page for regexp for details: http://www.tcl.tk/man/tcl8.4/TclCmd/regexp.htm

 

 

In your example, matches_regex doesn't support saving the matches. And it's much more efficient to use a string function to do the HTTP path checking anyhow.

 

 

Aaron

oh

 

got it

 

 

It is not me who use this matches_regex

 

 

Another engineer use this and I need to maintanian this irule ,but confused by ()

 

So you mean we use a capturing group by the expression in () to capture the matched characters

 

 

for example ([0-9]) test321654654

 

 

so 321654654 will be captured to $match

 

 

and if I use () in matches_regex ,because matches_regex doesn't support saving the matches,so it is useless.it will only work like a normal character without ()

 

 

I mean matches_regex will ignore () in my case

 

 

right?

 

That's it exactly. I'd still suggest using a switch statement instead of a regex.

 

 

Aaron

we will ,haha

 

 

but this irule is commerical ,should replace it later

 

 

so matches_regex will cost more bigip resource?like CPU or memory?

 

 

right?

it is so late in USA,you are still up

 

haha

 

 

you have high spirits in respecting work

matches_regex will cost more in CPU than a string function like switch.

 

 

Aaron