tangetools/w4it-for-port-open/w4it-for-port-open

#!/bin/bash

HOST=$1
PORT=$2

NC=$( which nc )

usage () {
  echo "Usage:"
  echo "  $0 host [port]"
  echo "  port defaults to 22 (ssh)"
  exit 1
}

print_not_reachable () {
  echo -n .
}

is_port_open () {
    $NC -z -w 2 $HOST $PORT 2>&1
    return $?
}

if [ -z "$HOST" ] ; then
  usage
fi
if [ -z "$PORT" ] ; then
  PORT=22
fi
if [ -z "$NC" ] ; then
  echo "Error, 'nc' not installed."
  exit 2
fi

while ! is_port_open ; do
  print_not_reachable
done
echo