Weblogic Portal 10.3.6 generic installer on Mac OS X – Insufficient Disk Space error

Trying to use the portal103_generic.jar installer on Mac OS X 10.11.1 gives this error even though you have plenty of free space:

A quick Google turns up this question and answer. Quick fix, run passing this option: -Dos.name=unix, so:

java -Dos.name=unix -jar portal103_generic.jar

Although others reported this avoided the issue, I then got this issue instead:

Exception in thread "chmodFile" java.lang.Error: Unix is not a supported OS platform.
 at java.lang.UNIXProcess$Platform.get(UNIXProcess.java:164)

Following additional suggestion here, using -Dspace.detection=false instead avoided the issue.