Heres an easy way to compile processing apps to jar files!
Note: This doesnt work for FX2D and / or libraries, this works for processing server & client tho.
Step 1:
Export your processing sketch with Linux 64x selected
Step 2:
Go into the exported folder, go to lib. Copy all of its contents into a new folder.
Step 3:
Now select every .jar file, that is in the new folder. Right click → extract → extract here. It will ask you if you want to replace or skip, press replace. Then delete the old .jar files, you don’t need them anymore.
Step 4:
Select every file in the folder. Right click → compress → Compress to .zip. Rename the .zip to a .jar
Now your file will be able to be executed!