How can I ask ps to display only user processes and not kernel threads?See this question to see what I mean... 
Can ps display only non kernel processes on Linux?
linux;process;linux kernel;ps;filter
This should do (under Linux):ps --ppid 2 -p 2 --deselectkthreadd (PID 2) has PPID 0 (on Linux 2.6+) but ps does not allow to filter for PPID 0; thus this work-around.