halt, reboot, poweroff – stop the system.
/sbin/halt [-n] [-w] [-d] [-f] [-i] [-p] [-h]
/sbin/reboot [-n] [-w] [-d] [-f] [-i]
/sbin/poweroff [-n] [-w] [-d] [-f] [-i] [-h]
Halt notes that the system is being brought down in the file /var/log/wtmp, and then either tells the kernel to halt, reboot or poweroff the system.
If halt or reboot is called when the system is not in runlevel 0 or 6, in other words when it’s running normally, shutdown will be invoked instead (with the -h or -r flag). For more info see the shutdown(8) manpage.
The rest of this manpage describes the behaviour in runlevels 0 and 6, that is when the systems shutdown scripts are being run.
Don’t sync before reboot or halt.
Don’t actually reboot or halt but only write the wtmp record (in the /var/log/wtmp file).
Don’t write the wtmp record. The -n flag implies -d.
Force halt or reboot, don’t call shutdown(8).
Shut down all network interfaces just before halt or reboot.
Put all harddrives on the system in standby mode just before halt or poweroff.
When halting the system, do a poweroff. This is the default when halt is called as poweroff.