GNUStep

"Before you can execute this makefile you must first set your GNUstep environment variables. Among other things this defines the GNUSTEP_MAKEFILES variable referenced above. The simplest way to do this is to execute one of the following commands (you must first locate your GNUstep installation manually):

C shell:

source /System/Library/Makefiles/GNUstep.csh

Bourne shell:

. /System/Library/Makefiles/GNUstep.sh On most Unix systems, GNUstep is installed in /usr/lib/GNUstep. (Directory layout documentation.)"