$a="\$a=\"gn\";\$b=\$a;\$b=~s/([\\\$\\\"\\\\])/\\\\\$1/g;\$a=~s/gn/\$b/;print \$a;";$b=$a;$b=~s/([\$\"\\])/\\$1/g;$a=~s/gn/$b/;print $a;