# type: perl average.pl  <trace file>  > file$infile = $ARGV[0];   # the trace file for flow ID and E2E delay of each flow    $totalDelay=0.0;    $flowNum=0;        open (DATA, "<$infile") || die "Can't open $infile";    while (<DATA>) {      $line = $_;      @x = split(' ');            $flowNum = $flowNum + 1;      $totalDelay = $totalDelay + $x[1] ;	      }   $AvgDelay = $totalDelay / $flowNum;   print STDOUT "total flow Num = $flowNum, average delay = $AvgDelay \n";   close DATA;   exit(0);