Java - No Main Manifest Attribute, in App.jar error even though MANIFEST.MF file is in /META-INF

Question

I have been trying to get this to work, but it won't. I went through the Archive Manager and found the MANIFEST.MF file in App.jar/META-INF/ so I don't know why it says there isn't one!

chmod -ing it with chmod +x./App.jar and running ./App.jar returns

bash: ./App.jar: cannot execute binary file: Exec format error

Running Linux Mint 20 (Based on Ubuntu 20.04) With OpenJDK 11.

Answer 1

Use java -jar App.jar to run the executable JAR file.

There is a way to make JAR files directly executable using the binfmt_misc kernel feature but most users/linux distributions don't bother to set it up.