Are there suspend\resume signals in Linux?

Question

My application needs to react on hibernation mode so it can do some action on suspending and other actions on resuming. I've found some distributive-specific ways to achieve it(Upower + DBus) but didn't find anything universal. Is there a way to do it?

Thanks!

This might bee something http://www.mjmwired.net/kernel/Documentation/power/freezing-of-tasks.txt — Kristofer, May 26 '11 at 11:13
@Kristofer, thanks for clue I have found more appropriate: http://www.mjmwired.net/kernel/Documentation/power/notifiers.txt But it seems that it is only possible in the kernel mode but I need to be notified in the user space without writing any kernel modules — ixSci, May 28 '11 at 09:54

score 5 · Answer 1 · answered Aug 04 '11 at 05:42

A simple solution to this is to use a self-pipe. Open up a pipe and periodically write timestamps to it. select on this pipe to read the timestamps and compare them to the current time. When there is a big gap, that means you have just woken up from system suspension or hibernate mode.

As for the other way around, there is not much time when the lid is closed and it flips the switch.

If you really need to act on suspend, then you will need to set powersave hooks like this https://help.ubuntu.com/community/PowerManagement/ReducedPower in pm-utils. It could be as simple as

kill -1 `cat mypid` ; sleep 1

Your process would then trap SIGHUP and do what needs to be done to prepare for suspension. The sleep delays the process long enough for your program to react to the signal.

I wonder if this is still applicable to this very day – matanster Sep 29 '20 at 18:43 — matanster, Sep 29 '20 at 18:43

score 1 · Answer 2 · answered Mar 04 '19 at 21:10

1

I believe you are looking for SIGSTOP and SIGCONT signals. You can send these to a running process like so:

kill -STOP pid
sleep 60
kill -CONT pid

answered Mar 04 '19 at 21:10

macetw

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This is irrelevant to the original question which is about system power modes. – medoc Jun 16 '22 at 14:47

Are there suspend\resume signals in Linux?

2 Answers2

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