It seems that problem is not in Getopt::Long, but in that the substitution string has to be a plain string not escape sequence when taken from outside (of the program). Escape sequence as replacement, however, does work when hard coded in the s///. Or, something like that.

The following code -- tested in genuine xterm, bash3, perl 5.8.7, and Getopt::Long 2.68 -- will put \n as itself not as a newline if i specified the -out as an escape sequence. It did the expected when i specified the replacement string as Ctrl-J.

use warnings; use strict;

use Getopt::Long
  qw(:config
      gnu_compat no_ignore_case
      no_debug
    );

#  Get regexen|strings for substitution.
my ($in ,  $out);
GetOptions( 'i|in=s' => \$in , 'o|out=s' => \$out) or usage();
usage() unless defined $in && defined $out;

printf "in: '%s'  out: '%s'\n" , $in , $out;

my $text;
while (<STDIN>) { $text .= $_; }
chomp $text;

printf "before:\n'%s'\n" , $text;

$text =~ s/$in/$out/g;

printf "after:\n'%s'\n" , $text;

sub usage { die "specify strings for -in & -out options.\n"; }
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Update: For a user to be able to specify/use escape sequnce in replacement, use a hash, somthing like the last message in Regular Expression To Match Escape Sequences thread.

- Parv