use strict;
use warnings;

my $t = '\\t';
print "$t:\n";

my $evaled = eval "qq/$t/";
print "$evaled:\n"

##</code><code>##

\t:
	:

##</code><code>##

my %seps = (
  '\\t' => "\t",
  '\\n' => "\n",
   # etc
);

my $input = <>;
my $separator = $seps{$input};