What's the gnu-netcat's '-z' equivalent option in nmap-ncat?

Question

I check for a listening port on a service prior to running a script using this :

until nc -z $HOST $PORT
do
  echo "waiting for service to be available..."
  sleep 0.5
done

exec "/my/script"

It used to work with gnu-netcat, but now, I've upgraded the Linux distribution, and it uses nmap-ncat for the /usr/bin/nc command.

I'd like to know an equivalent solution to use with nmap-ncat package.

Same question recently asked and answered on ServerFault: http://serverfault.com/q/788934/112426 — bonsaiviking, Jul 15 '16 at 13:34

score 13 · Answer 1 · answered Jul 15 '16 at 03:24

13

--send-only </dev/null seems to do the trick.

answered Jul 15 '16 at 03:24

Jasen

1 Answers1