Command line decompilation for JD-GUI is a highly requested feature but it’s not implemented yet. Perhaps you can use the following workaround in the meantime:
- jar (or zip) all the classes you want decompiled together.
- Launch JD-GUI and open your jar (zip) archive.
- Use “File” – “Save JAR Sources” menu option. It will decompile all classes from your archive and save their sources into another zip file.
I haven’t seen any good open source JD-GUI alternatives with command-line support, unfortunately, so I think the above is as good as it gets for now.