#!/usr/bin/perl

my $FILE = $ARGV[0];
my $MAXSIZE=10;

exit -1 if ! -f $FILE;

$num_lines = 0;
open FILE, ">$FILE";
for (;;) {
        chomp($mytime=`date +%T`);
        my $line = "$mytime";
        $line .= ";" . sprintf "%.2f", rand(10);
        $line .= ";" . sprintf "%.2f", rand(20);
        $line .= ";" . sprintf "%.2f", rand(30);
        $line .= ";" . sprintf "%.2f", rand(40);
        if($num_lines < $MAXSIZE){
                push @array, "$line\n";
                $num_lines++;
        }else{
                shift @array;
                push @array, "$line\n";
        }
        #Get the end position of the file
        seek(FILE, 0, 2);
        $endpos = tell(FILE);

        seek(FILE, 0, 0);#Seek to start
        print FILE @array;

        #For the rest of the bytes print " "
        $curpos = tell(FILE);
        for(my $cnt=$curpos;$cnt<$endpos;$cnt++){
                print FILE " ";
        }

        sleep 1;
}