Script to force shutdown

You can't force a shutdown without an administrator's password, so either your script is going to need to prompt, or you'll need to embed your admin password in your script (which leaves it vulnerable since scripts are not encrypted by default).

Something like:

do shell script "/sbin/shutdown" user name "admin" password "supersecret" with administrator privileges

Omit the 'password' parameter to have the OS prompt for the admin credentials at runtime.

You could also edit /etc/sudoers to give your standard user's unfettered access to /sbin/shutdown without requiring a password, but that's an even hairier prospect in my book.

Another trick is setting up a no-passphrase ssh-keygen key for the root account, then putting the root's public ssh key in the normal account's .ssh/authorized_keys file. Now you can "ssh root@localhost /sbin/shutdown -h now"

NOTE: It is NOT necessary to enable the root account to use this trick. You can become root via "sudo su -" and then perform the necessary ssh-keygen setup all without enabling root.

However, it is on par with Camelot's suggestion about /etc/sudoers, and at least Camelot's sudoers suggestion limits the destructive damage that can be done.

OK, I have the ssh-keygen steps backwards. You create an ssh-keygen key pair with no-passphrase in the normal account, then you copy the .pub file into the root's .ssh/authorized_keys file.