>perl -wMstrict -le
"$_ = 'Goodbye\; Good luck\, and thanks for all the fish!\n\n';
 my %conv = ( ',' => ',',  ';' => ';',  n => qq{\n} );
 print qq{[[$_]]};
 s{ \\([,;n]) }{$conv{$1}}xmsg;
 print qq{[[$_]]};;
"
[[Goodbye\; Good luck\, and thanks for all the fish!\n\n]]
[[Goodbye; Good luck, and thanks for all the fish!

]]