while (defined(my $line = <$in>)) {
        chomp $line;  # Zap trailing "\n" efficiently 
        print $out $line,"\r";
    }

##</code><code>##

#!/usr/bin/perl

use strict;
use warnings;
use autodie;

open my $out,'>:raw',"file.tmp";
print $out "a line\na second line\n0";
close $out;

open my $in,'<:raw',"file.tmp";
while (my $line=<$in>) {
	chomp $line;
	print "read: $line\n";
}
close $in;

##</code><code>##

>perl foo.pl
read: a line
read: a second line
read: 0
>

##</code><code>##

>perl -E '"0\n" and say "true"'
true
>perl -E '"\n" and say "true"'
true
>perl -E '"0" or say "false"'
false
> perl -E '"" or say "false"'
false
>perl -E 'undef or say "false"'
false
>