my $dataFile = $ARGV[0];
tear_down($dataFile);

sub tear_down{
    my ($dataFile) = @_;
    open my $file, '<', $dataFile || die "$!";

    my count = 3;

    for ( my $i = 1 ; $i <= $count ; $i++ ) {
        seek to bytes in file;
        read x bytes in file;
    }
}

sub parse_file_1{
    my ($file) = @_;
    ...do stuff....
}

sub parse_file_2{
    my ($file) = @_;
    ...do stuff...
}

sub parse_file_3{
    my ($file) = @_;
    ...do stuff...
}