Trouble getting Forge to work on server

[TimJSwan]

I have a mac. I used jar xf and jar uf commands to extract the classes from minecraft_server.jar and for compressing them back with the forge files copied in. I tried this by dragging and dropping them in to mix them, and, in case their order was being mixed up, I also tried using jar xf command after renaming the forge zip into a jar. Neither way works. Every time, somehow, when I go to actually run my minecraft_server.jar it cannot run and the terminal says "Invalid or corrupt jarfile minecraft_server.jar" I did not delete META_INF as is stated in the directions for the server. However, I even tried deleting that after dragging and dropping the forge files in case that would work. Single player with forge works fine for me. I downloaded the latest server from minecraft.net and I used the latest recommended download of forge universal. If you can diagnose what the issue is, please let me know. Thanks!

[LexManos]

Dont do anything fancy

Just run the downloaded universal zip as a jar

java -jar minecraftforge-universal.zip

As long as minecraft_server.jar is in the same folder it'll run.