[Gambas-user] Saving settings on system shutdown

[bb]

On Sun, 2021-10-03 at 11:59 +0100, Bruce Steers wrote:
> I have a program that starts with my system and runs in the
> background.
> 
> It has icons i can move and on exit it saves the positions.
> 
> I have noticed if i do not exit the program but shutdown the computer
> the
> settings do not save.
> 
> Of course i could just save the settings on moving icons but i
> wondered if
> there is a recommended method to catch an application exit due to a
> shutdown?
> Does the system just kill the program?
> 
> I guessed DBus would probably be the best alternative way but
> wouldn't hurt
> to ask the experts if there is already an easier way.
> 
> Thanks for any advice :)
> 
> BruceS
> ----[ http://gambaswiki.org/wiki/doc/netiquette ]----
This is an "I think" answer.
IT it depends on the distro.
IT most shutdowns for sysvinit systems use /etc/rc0.d/ scripts one of
which (say "K02sendsigs") controls the ending of "all" processes in
some manner, e.g. by sending them a SIGxxx (usually? a SIGHUP) signal
and then possibly waiting until "them" exits (or if they dont, then
killing them).
IT I dont know how systemd does it but hopefully it involves a signals
based method as well.

So, IT you should implement signal handling for your program via
gb.signal, find out whether you can trap the shutdown SIG used and then
do whatever you need.

Interested in the answer btw.

cheers
bruce