Get window PID with xprop

[haarp]

Hello,

xprop _NET_WM_PID allows to get the PID of the window clicked upon under X.

However this doesn't work for firejail windows, as I'm only getting very low PIDs, presumably those within the jail. They do not correspond to any PIDs seen in firejail <--list|--tree|--top>.

Is there any way to get a mapping from the in-jail PIDs to system-wide PIDs?

(Background: I want to SIGSTOP processes by clicking on them, powered by xprop)

Thanks!

[rusty-snake]

Is there any way to get a mapping from the in-jail PIDs to system-wide PIDs?

If you know the jail (precisely: the pid-namespace), there could be a way. But without you try to find the parent of 2 in the following tree:

2463: 1, 2, 3
83644: 1, 4
1293: 2, 5

Short: Even if you have a mapping, the input key is not unique.

[haarp]

Hmmmm, yeah, that makes things difficult. Not seeing an easy way around this. Thanks for the info!