\askforoverwritefalse
\generate{\file{man-ja.tex}{\from{manual.dtx}{ja}}
\file{man-en.tex}{\from{manual.dtx}{en}}}
-%\immediate\write18{lualatex man-ja}
+\immediate\write18{lualatex man-ja}
\immediate\write18{lualatex man-en}
- \endbatchfile
+\endbatchfile