But what if you need some sort of confirmation that your command have been received and the system is in the shutdown cycle?
Well, all you have to do is to tweak the action parameter from /etc/acpi/events/power.conf and my suggestion could be found bellow.
Let's take a Centos or any RHEL based distribution and test it!
yum install acpid
- comment the default action (inserting # as the first character of the line)
- add the following line at the end of the file
action=/bin/ps awwux | /bin/grep gnome-power-manager | /bin/grep -qv grep || (/bin/echo -e \\a >> /dev/console;/bin/sleep 0.25;/bin/echo -e \\aPower button event ! >> /dev/console;/bin/sleep 0.25;/bin/echo -e \\a >> /dev/console;/sbin/shutdown -h now)
All we have now is to restart the acpid service:
service acpid restart
In this way, when the case power button will be pressed shortly, 3 short beeps will be heard (in case your machine have an internal speaker) before the final shutdown command is triggered.