"New" Idea: maybe belongs in programming forum...

[polypagan]

Alright, I've got this idea that really only applies to laptops (I believe).

AND, in particular to laptops like my old Dell Inspiron 6400 with a battery that will power the machine for a few (like 5) minutes, at most.

(BTW, openSUSE 11.4 Xfce, not that it matters.)

In /etc/inittab there are the following lines:

pf:owerwait:/etc/init.d/powerfail start
pn:owerfailnow:/etc/init.d/powerfail now

I know these are there to allow UPS software to tell init to do a shutdown if and when the power fails. How does that work? What triggers these events?

What I'd like is for the pf: line to get kicked if the AC power fails, giving the machine time to shutdown gracefully.

Does anyone know how to write something that does that? Alternatively, of course, a script could just execute shutdown (provided it had enough privilege.) So, really, the question is, how do I find out if we're running on AC, or get a poke when that ceases to be the case?

What I'm envisioning is a bash/perl/python script or C program that runs as a daemon, gets the signal from APM or ACPI and either uses inittab or not to shut the machine down.

Any pointers would be greatly appreciated. Thanks!

[polypagan]

Okay, having received no reply... and after a bit more research, here's what I tried:


$ cat /etc/acpi/events/battery
event=battery.*
action=/etc/acpi/actions/battery.sh


$ cat /etc/acpi/actions/battery.sh
#!/bin/bash
# ac/battery event handler
#
status=`awk '/^state: / { print $2 }' /proc/acpi/ac_adapter/AC/state`

if [ "$status" = "off-line" ]
then
## following line still contains -k option (just kidding...)
/sbin/shutdown -k now "AC Adapter Unplugged... Shutting system down now!!!!"
else
#
/sbin/shutdown -c now "AC Power Restored... System continues"
fi

and:
$ ls -l /etc/acpi/actions/battery.sh
-rwxr-xr-x 1 root root 626 Aug 16 17:43 /etc/acpi/actions/battery.sh

/var/log/messages shows acpid getting the correct number of rules.

I pull the plug and NOTHING HAPPENS.

I run the battery.sh script explicitly (as root) and it complains it can't find the pid of running shutdown (fair enough since there isn't one.)
I can also test the awk line on the cl and it works fine.

so: acpid isn't triggering the script.

How to debug?

[atreyu]

Have you tried running the acpid daemon in the foreground, with the debug flag on?

service acpid stop
acpid -d -f

maybe that will turn up something.

[polypagan]

That was a very useful reply, thank you!

I found that acpid -f -d -l was needed to get acpid to 'log' to STDERR. That showed me that the 'event' was not a battery event, but an 'ac_adapter' event.

So:

$ cat /etc/acpi/events/ac_adapter
event=ac_adapter.*
action=/etc/acpi/actions/ac_adapter.sh

and;

$ cat /etc/acpi/actions/ac_adapter.sh
#!/bin/bash
# ac/battery event handler
#                                                                                                                                   
status=`awk '/^state: / { print $2 }' /proc/acpi/ac_adapter/AC/state`
                                                                                                                                    
if [ "$status" = "off-line" ]
then
	/sbin/shutdown -h now "AC Adapter Unplugged... Shutting system down now!!!!"
else   
	/sbin/shutdown -c now "AC Power Restored... System continues"
fi

works beautifully!

Thanks again!
Daniel