shutdown (string command[, integer minutes]) ⇒ void
Runs the shutdown command, given a parameter, command, which specifies the shutdown request (e.g. -r for restart).
The shutdown command was improved in version 1.8.1 to make it work with time based
minutes argument was added to allow the program
to specify in how many minutes the system should shutdown. This is based on the operating
system and runs an appropriate Unix or win32 shell command to do this.