I'm not sure line separators differ with TEXTAREA fields no matter what OS is running on the machine with the Browser.

In my own (less than vast) experience, I have had no problem using code like the following (AFAIK, has worked with Mac-, UNIX- and Windows-based browsers):

# assuming text is in $_
my @lines = split /\n/;
my $text = join '||', @lines;
print "||$lines||\n";
[download]

Or, in one line,

print '||'. join('||', split( /\n/ )) .'||' ."\n";
[download]

dmm

If you GIVE a man a fish you feed him for a day
But, TEACH him to fish and you feed him for a lifetime