How to access the PID from an lsof.

Question

Given the following command lsof -i:1025 I get:

COMMAND   PID USER   FD   TYPE             DEVICE SIZE/OFF NODE NAME
ruby    12345 john   11u  IPv4 0xb2f4161230e18fd57      0t0  TCP localhost:foobar (LISTEN)

I am trying to write a script to get that PID (12345) and kill it. At the moment I have to run lsof -i:1025, get that PID and then run kill -9 12345.

Answer 1

The lsof(8) man page says:

   -t       specifies that lsof should produce terse output with process
            identifiers only and no header - e.g., so that the output
            may be piped to kill(1).  -t selects the -w option.

You can use lsof -t -i:1025 | xargs kill -9.

Answer 2

And furthermore from @blm's and @Mosh Feu's answers:

lsof -i:1337 -Fp | head -n 1 | sed 's/^p//' | xargs kill

is what ended up doing the trick for me.

I recommend adding this as a bash function and aliasing it

alias kbp='killByPort'
killByPort() {
  lsof -i:$1 -Fp | head -n 1 | sed 's/^p//' | xargs kill
}