test for a specific port from Linux or Unix command line

  
# check for tcp port ##
  
## need bash shell
  
echo >/dev/tcp/{host}/{port}

(echo >/dev/tcp/{host}/{port}) &>/dev/null && echo "open" || echo "close"
  
(echo >/dev/udp/{host}/{port}) &>/dev/null && echo "open" || echo "close"
  
(echo >/dev/tcp/www.cyberciti.biz/22) &>/dev/null && echo "Open 22" || echo "Close 22"
  
(echo >/dev/tcp/www.cyberciti.biz/443) &>/dev/null && echo "Open 443" || echo "Close 443"