Recipe 7.12. Shutting Down Automatically
7.12.1 Problem
Your
users are careless watt-wasters who refuse to develop the habit of
shutting down their PCs at night, or maybe you think it would be nice
to have your machine turn itself off at night, so you can just walk
away and not worry about it.
7.12.2 Solution
It's easy as pie, thanks to cron.
Add this line to
/etc/crontab to automatically shut down your
machine every night at 11p.m.:
# m h dom mon dow user command
00 23 * * * root /sbin/shutdown -h now
7.12.3 Discussion
/etc/crontab is perfect for simple
cron setups. Note that it has a name field, so
any user can have entries in this file. However, only root can edit
/etc/crontab.
Another way is to use the crontab command:
# crontab -u root -e
This opens the root user's
crontab. Edit and save, and
you're done. Don't try to name the
file yourself—during editing, it's a
/tmp file, which is automatically renamed by
crontab when you save it. It will end up in
/var/spool/cron/crontabs, or somewhere close by.
7.12.4 A Brief Word on Uptimes
You've probably noticed Linux users bragging and
obsessing about their uptimes. There's even an
uptime command. There is nothing sacred about
uptimes. Yes, I too love that Linux is stable as a table, and that
most software installations and system upgrades never require a
reboot. But let's not go nuts. If a particular
machine does not need to be running 24 7, turn it off. It saves
electricity, reduces the risk of something bad happening, and extends
the life of your hardware.
7.12.5 See Also
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