use strict;
use warnings;

use feature 'say';

my $file = 'test_file.txt';

open(my $fh, "<", $file) or die "Unable to open file '$file': $!";
my $data;
{
    local $/;
    undef $/;
    $data = <$fh>;
}
close($fh);
my @lines = split /\n/,$data;

my $line_number = 1;
foreach my $line (@lines) {
    say "$line_number: $line";
    $line_number++;
}