ps: Clean way to only get parent processes?

Question

I use ps ef and ps rf a lot.

Here is a sample output for ps rf:

  PID TTY      STAT   TIME COMMAND
 3476 pts/0         


        

Answer 1

/usr/bin/pgrep -o <process_name>

where '-o' is the oldest (least recently started) of the matching processes

Answer 2

how about ps fuxa | grep 'PID\|[0-9] /' for all parents, or: ps fuxa | grep '[0-9] /' | grep 'PID\|<commandname>' for single process?

Answer 3

From key words KEYWORD

ps aux | grep -i KEYWORD | grep -v grep | awk '{print $2}'|sort -h|head -1|xargs kill

BTW, is this assumption that parent process ID is the smallest ID valid？？？？