Using awk to capture first line of a multiline output?

Question

I have this output, which is the PID of all processes running matching a grep for fcgi:

# ps ax | grep fcgi | cut -f1 -d' '
21065
21066
21067
21068
21069
21070
24801

I want to cut out the very first number (i.e. 21065) so I can pass it to the kill function to kill the parent process (the parent process is returned as the first PID).

Any ideas on how to do this?

Answer 1

Use:

to get the pid number

PARENT_PID=`ps ax | grep fcgi | cut -f1 -d' ' | head -1`

to directly kill:

kill `ps ax | grep fcgi | cut -f1 -d' ' | head -1`

Answer 2

Don't use ps ax | grep... to kill a process, if you can avoid it. See here

Instead use pidof

Answer 3

There is no need to jump through all the hoops of running ps, grep, cut, head, and kill yourself. That's what pkill is for.

pkill fcgi

Also see pgrep for future reference.