I just glanced at it, but you aren't catching or ignoring SIGQUIT. Users could probably drop out of it with a ^\.

Update: Ok in addition to that, you get $server directly from the user and then use it in double quotes in a system call. That's a huge no-no. Consider what might happen if your user enters: || /bin/sh when asked for the server.

-sauoq
"My two cents aren't worth a dime.";