$ perl -de0

Loading DB routines from perl5db.pl version 1.0402
Emacs support available.

Enter h or `h h' for help.

main::(-e:1):   0
  DB<1> my $string = '\\this is a test on \ escapes . ';

  DB<2> print $string
\this is a test on \ escapes . 
  DB<3> x $string
0  '\\this is a test on \\ escapes . '
  DB<4> $string =~ s/\\/\\\\/g;

  DB<5> print $string
\\this is a test on \\ escapes .