String Manipulation

You could do a "ends_with" comparison before your check for the slash. if you know the valid extensions that you don't want appended with slashes this should work.

While you are at it you could use the ends_with in place of your string index command as well.

elseif { $uri starts_with "/nexus/" } {
  pool pool1
} elseif { $uri starts_with "/earth/" } {
  pool pool2
} elseif { [HTTP::uri] ends_with ".html" } {
  pool pool3
} elseif { not ([HTTP::uri] ends_with "/") } {
  HTTP::redirect "http://[HTTP::host][HTTP::uri]/"
} else {
  pool pool3
}

Is this what you are going for? If not, if you could provide a clear set of inputs and expected results, it will be easier for us to figure out a solution.

-Joe