open(DATAOUT, ">variable")||die"$!\n";

for(my $count=0.9; $count<=1; $count=$count+0.01)
{
    open(DATAIN, "<$ARGV[0]")||die"cannot open \"ARGV[0]\":$!";
    while(<DATAIN>)
    {
        my @line = split (/\t/);

        if($line[2] >= $count)
        {
            print DATAOUT;
        }
    }
    close DATAIN;
}