tcp ping script using netcat

tcp-pinger.sh

#!/bin/bash

pinghost="${1}"
pingport="${2}"
pingtimeout=10
pingcmd="nc -w ${pingtimeout} ${pinghost} ${pingport}"
pingret=0

echo "$(date -Iseconds) - connecting to ${pinghost} ${pingport}"

while true; do
  while [[ ${pingret} = 0 ]]; do
    pingout="$(${pingcmd} 2>&1)"; pingret=${?}
    sleep 1
  done

  echo "$(date -Iseconds) - app failure"

  while [[ ${pingret} != 0 ]]; do
    pingout="$(${pingcmd} 2>&1)"; pingret=${?}
    sleep 1
  done

  echo "$(date -Iseconds) - app ok"
done