how to change a string ,such as add a number after some letters

Hi,all friends,I use irule below to achieve this:

 

switch -glob [string tolower [HTTP::host]] {

 

"srwd29.com" -

 

"www.srwd29.com" {

 

scan [HTTP::host] {%[^.]%s} domainfirst domainleft

 

set num 2

 

HTTP::redirect "http://$domainfirst$num$domainleft[HTTP::uri]"

 

}

 

I try to add "2" after $domainfirst( HTTP::redirect "http://$domainfirst2$domainleft[HTTP::uri]"),but it doesn't work ,that is why there is a num variable

 

Thank you for your great help