How do I modify the dependencies and rules of a GNU makefile target depending upon the platform (Linux vs. OS X)?

I have a (GNU) makefile with an all target that looks like this:

.PHONY: all
all: $(unittest++_tests_exe) $(cmockery_tests_exe)
 @echo Running UnitTest++ tests...
 @./$(unittest++_tests_exe)
 @echo Running Cmockery tests...
 @./$(cmockery_tests_exe)

The UnitTest++ 开发者_JAVA百科tests run on both Linux and Mac OS X, and the Cmockery tests run only on Linux.

How do I modify the dependencies and rules so that make all only builds and runs $(unittest++_tests_exe) on Mac OS X?

---

T.E.D.'s answer triggered me to come up with the following:

ifeq ($(uname),Linux)
cmockery_tests_exe = cmockery_tests
else
cmockery_tests_exe = $()
endif

.PHONY: all
all: $(unittest++_tests_exe) $(cmockery_tests_exe)
 @echo Running UnitTest++ tests...
 @./$(unittest++_tests_exe)
ifeq ($(uname),Linux)
 @echo Running Cmockery tests...
 @./$(cmockery_tests_exe)
endif

It seems to work, but I welcome your suggestions.

---

I believe the Right Way to do this is to use something like autoconf.

If you want to hack it, try calling uname and putting the result in a symbol. You can then parse out the relevant parts