/
/

##</code><code>##

use strict;
use warnings;
use HTML::Entities;
print encode_entities(`cat two-lines-with-one-slash-each.txt`);
__END__

##</code><code>##

$ perl html.entities.pl
Unmatched [ in regex; marked by <-- HERE in m/([ <-- HERE / at (eval 1) line 2.
 while trying to turn range: "/
"
 into code: sub {$_[0] =~ s/([/
])/$char2entity{$1} || num_entity($1)/ge; }
  at /usr/lib/perl5/vendor_perl/5.8.3/i386-linux-thread-multi/HTML/Entities.pm line 428.

##</code><code>##

$ perl -v | head -2

This is perl, v5.8.5 built for i386-linux-thread-multi

$ uname -r
2.6.9-42.0.10.EL

cpan[2]> install HTML::Entities
HTML::Entities is up to date (1.35).