Linux
displaying all processes for certain user
ps -U username (with u you can use numerical uid) --> ps U username
ps -e -H  --> ps axf
ps -eljH - (e everything, l long, j job control, H hierarchy)
ps -s 1234 - show processes with session leader 1234

ps -Ho "pid,rss,pmem,vsize,cmd" -s 25323 custom format shows pid, rss, pmem, vsize, and cmd

ps -eo "pid,rss,vsize,cmd" --sort rss - shows everything and sorts by resident memory use