Also make sure that none of the commands you are sending to the system make use of tainted user data; e.g.: data that you have recieved from the user and have not checked for obvious problems (i.e. rm -r -f). This could be a big door to script kiddies of the world. You can make the interpreter get *really* paranoid about input by adding the -t option to your shebang line (just like turning -w warnings on). This will make you *have* to pass all user supplied input thru a regex to keep perl from horking it.