#!/bin/sh

# IsHostAlive.sh
# Mon Dec  8 22:41:56 PST 2008
# Chieh Cheng
# http://www.CynosureX.com/

# GNU General Public License (GPL) Version 2, June 1991

  scriptName=`basename "$0"`

checkAllHosts ()
{
  while read host
  do
    result=`checkHost "${host}"`
    printf "${host} is "

    if [ ${result} -eq 1 ]
    then
      echo "alive"
    else
      echo "dead"
    fi
  done
}

checkHost ()
{
  host="$1"
  os=`uname -s`

  case "${os}" in
    "Darwin")
      output=`ping -c 1 -t 1 ${host} 2>&1`
      ;;

    "Linux")
      output=`ping -c 1 -W 1 ${host} 2>&1`
      ;;

    "SunOS")
      output=`ping "${host}" 1 1 2>&1`
      result=`echo "${output}" | grep -c " is alive"`
      if [ ${result} -eq 1 ]
      then
        output=" 0% packet loss"
      else
        output=" 100% packet loss"
      fi
      ;;

    *)
      output="Unsupported operating system."
      echo "${output}"
      ;;
  esac

  # Darwin shows 0.0% packet loss.
  # Linux shows 0% packet loss.
  result=`echo "${output}" | grep -c ' \(0.\)*0% packet loss'`
  echo ${result}
}

usage ()
{
  echo "  Usage:  ${scriptName} host"
  echo "            or"
  echo "          ${scriptName} -"
  echo
  echo "            With the '-', you can pipe in a list of hosts."
}

if [ $# -eq 1 ]
then
  host="$1"

  if [ "${host}" = "-" ]
  then
    checkAllHosts
  else
    checkHost "${host}"
  fi
else
  usage
fi