appstream-compose is a simple app that takes a prefix (default /usr) and a set of application names. It looks for appdata, metainfo, desktop and icon files with that basename in $prefix/share/[appdata|metainfo|applications|icons] and generates appstream xml files and icons in (by default) $prefix/share/app-info.
This manual page was written by Richard Hughes <richard@hughsie.com>.