Running Hudson from OS X: the .war.zip Fiasco

It took me a while to figure this out and maybe it's just because I'm not a java guy, but I couldn't figure out how to start the Hudson continuous integration tool on my Mac. I downloaded the 2.0.0 version from the Hudson site (http://hudson-ci.org/). The file was hudson-2.0.0.war.zip. The instructions say to run

java -jar hudson-2.0.0.war

to start up the service. I unzipped the file and ended up with a bunch of .class files and no .war. Ah, looks like I also unzipped the .war file. So then I found this nice post (http://superuser.com/questions/159260/in-mac-os-x-how-can-i-unzip-a-zip-file-without-unzipping-its-contents) on how to unzip a file without unzipping its contents. Now I have a

hudson-2.0.0.war/

directory. I ran

$ java -jar hudson-2.0.0.war
Invalid or corrupt jarfile hudson-2.0.0.war

Hmm, not sure what to do next. Somewhere in my search I read that a .war is basically just a zip file. So I tried

$ java -jar hudson-2.0.0.war.zip

on the original file, which worked. I renamed hudson-2.0.0.war.zip

$ mv hudson-2.0.0.war.zip hudson-2.0.0.war

and I was off and running.

So I hope this helps some other java n00bs who may have run into this. The moral of the story is .war == .zip