my $x = "foo";
my $y = 'abc $x def\\/';

escape_slashes($y);
$y = eval "qq/$y/";
unescape_slashes($y);

print "y=$y\n";

sub escape_slashes {
    $_[0] =~ s#(\\|/)#\\\\$1#g;
}

sub unescape_slashes {
    $_[0] =~ s#(\\\\|\\/)#substr($1, 1, 1)#eg;
}