[CentOS] halt versus shutdown

On Mon, 2020-06-15 at 01:32 +0200, Leon Fauster via CentOS wrote:
> Working with different OSs can be quite challenging (mentally :-)).
> 
> I wonder why the command "halt" has not same result between EL6 and EL8.
> 
> To shutdown the vm or workstation in EL8 i must use "shutdown now".
> 
> Who mandates this behavior in terms of configuration file?
> 

It's to do with systemd. EL6 used SysV based init and runlevels, EL7 &
EL8 use systemd targets.

If you look at the halt and shutdown commands they are symlinks to
/usr/bin/systemctl now and they are implemented as shims that replicate
the effect of the old SysV processes.

So the following have the same effect:

  "systemctl isolate halt.target"
  "halt"
  "shutdown -H now"
  "systemctl halt"

there are equivalents for "poweroff" and "reboot" as well.

P.