Yup. Don't do anything silly like system("tar cvf - $my_user_input_from_a_form");, unless you want to hand out tar files of your server's passwords, though.
andramoiennepemousapolutropon
Comment on Re: Re: HTTP/CGI Backup interface w/Perl
This is very good advice and I was remiss in not noting such myself. That said, you should also know that, if you did so, you might risk a whole lot worse than the loss of your password file. It would permit a user to run any arbitrary command on your system with privileges the same as those that the cgi script runs with.
Know the risks, understand the issues, and use the -T option to help you catch dangerous code.