I have a multiseat Ubuntu setup and I need to identify which processes of a graphical application are running in each X.Org display.
For example, I have two X.Org displays, :0 and :1, and two instances of Firefox running, one on each display. How do I find the PIDs of the processes of Firefox running on display :0 only?
Neither ps -e nor ps -T helped me. In both cases, I have a single "?" in TTY column for my Firefox processes.