Java arguments

output

-Doutput=<filePath>
This is an environment variable that is used to set an output directory. If you don't set one when launching that application then the default output will be a folder named output in the world folder the jar file is in.
To set the option place it before the name of the jar file as below and specify a path to the file either as an absolute path or a relative path.
relative
java -jar -Doutput=<OutputFolderName> smallWorld.jar raduis 0,0 500
Absolute
java -jar -Doutput=c:/<OutputFolderName> smallWorld.jar raduis 0,0 500
in your minecraft directory
java -jar -Doutput=$saves/.minecraft/<OutputFolderName> smallWorld.jar raduis 0,0 500
The $saves output option will place you in your save folder in your .minecraft folder. To place your output folder anywhere else use the other options.

dim

You can output other dimensions with another environment variable. This one is quite simple, you can either use the dimension number or for the 3 vanilla dimensions the name.

• end = 1
• overworld = 0
• nether = -1

If you don't specify a dimension the program will default to getting files from the overworld.
java -jar -Ddim=nether smallWorld.jar raduis 0,0 500