updates-pacman-aurhelper needs synchronization when used with multiple bars.

[Deleted user]

Because it uses the "checkupdates" script, the updates-pacman-aurhelper script will fail when executed in very short succession (as with e.g. 2 bars on 2 monitors).

checkupdates will fail if more than one instance of it is running:

$ checkupdates & checkupdates

-> This likely outputs something like

➜  ~ checkupdates & checkupdates
[1] 4287
==> ERROR: Cannot fetch updates
➜  ~ apparmor 3.0.0-2 -> 3.0.0-3
arandr 0.1.10-4 -> 0.1.10-5
...

Possible workarounds would probably be a lockfile or a loop that checks the exit status of checkupdates and sleeps for a short amount of time.

[x70b1]

Yes, its a problem. A simpler hack could be a random sleep.

On the other hand its an edge case I would say. So I don't want to change the existing scripts for this.

[Deleted user]

I actually have a solution, which would look like this:

while true; do
	updates_arch=$(((((checkupdates 2>/dev/null; echo $? >&3) | wc -l >&4) 3>&1) | (read xs; exit $xs)) 4>&1)
	exitstatus=$?

	if [ $exitstatus -eq 2 ]; then
		updates_arch=0
		break
	fi

	if [ $exitstatus -eq 0 ]; then
		break
	fi
done

This would work 100% of the time.

[Deleted user]

involves a bit of file descriptor magic in order to get the exitstatus of checkupdates and the output of wc at the same time.