> Can I make Cron to automaticly shutdown my computer?
Yes!
>And if how do I do it? Must a user be loged in to run cron jobs?
No, you don't have to be logged in. You can do it via the use of cron jobs. They're scripts / programs which can be scheduled to run at certain times (hourly, daily, weekly, once a year.. what have you).
To shudown your machine you can use :
shutdown -h now
or more recently
halt
halt will call shutdown anyway, but may be easier to remember. I like to use the shutdown command because you won't find halt on other unix's (and I started on AIX so it's ingrained)
To make this happen automatically :
crontab -e
- pulls up a blank editor for you to edit your cron jobs :
15 23 * * * /sbin/shutdown -h now
- tells cron to execute the shutdown at 11:15pm every day
:wq
- writes the file.
You're set.
When you run crontab -e you're writing the crontab for that user and so they are the user who will execute the commands. So, you'll need to be root, or someone who has the privs to /sbin/shutdown.
Shutdown has a couple of other flags instead of -h (halt). The other useful one -r does a reboot. And it can take a time as argument so, you might want to shutdown in 30 minutes you could
shutdown -h +30
see man shutdown, man halt, man cron for all of the above.
Slick.
