how to lower a part of the URI?

If you know what the first part of the URI is, then it isn't so bad. You can grab everything after that first part of the URI with this:

 

 

set newURI [string range [HTTP::uri] 4 end] this trims off /Bar (4 characters, you can change that value to reflect your actual URI)

 

 

Now, you can redirect to www.foo.com/bar$newURI.

 

 

If the first part of the URI isn't always known, it's still possible but more work.

Thanks Richard, it works perfectly

please feel free to revise.

[root@orchid:Active] config  b virtual bar80 list
virtual bar80 {
   destination 172.28.17.88:http
   ip protocol tcp
   rules myrule1
   profiles
      http
      tcp
}
[root@orchid:Active] config  b rule myrule1 list
rule myrule1 {
   when HTTP_REQUEST {
        scan [HTTP::uri] {/%[^/]%s} para1 para2
        HTTP::redirect "http://[HTTP::host]/[string tolower $para1]$para2"
}
}

[root@orchid:Active] config  curl -I http://www.foo.com/Bar/Xxxxxx
HTTP/1.0 302 Found
Location: http://www.foo.com/bar/Xxxxxx
Server: BigIP
Connection: Keep-Alive
Content-Length: 0

You can grab the 1st folder dynamically regardless of the the length:

set para1 [string tolower [URI::path [HTTP::uri] 1 1]]