Ping in Perl

#!/usr/bin/perl

use Net::Ping;
use Time::HiRes;
$host = $ARGV[0];

if($host eq "") { 
  print "usage: ping.pl (host|ip)\n";
  exit(0);
}

while(1) {
  $p = Net::Ping->new();
  $p->hires();
  ($ret, $duration, $ip) = $p->ping($host, 5.5);

  printf("$host [ip: $ip] is alive (packet return time: %.2f ms)\n", 1000 * $duration) if $ret;
  $p->close();
  sleep 1;
}