Using htop to list users. Which is one of my favourite.
% top -U user1
pstree which displays a tree of processes and can include parents and child processes which make it easier to understand.
% pstree -l -a -p -s user1
where
-l : Long format
-a : Show command line args
-p : Display Linux PIDs
-s : See parents of the selected process
pgrep look up or signal processes based on name and other attributes
% pgrep -l -u user1
References:
