CMake 3.X

CMake 3.X offers a 'clean' target.

cmake --build C:/foo/build/ --target clean

From the CMake docs for 3.0.2:

--clean-first  = Build target 'clean' first, then build.
                 (To clean only, use --target 'clean'.)

CMake 2.X

There is no cmake clean in CMake version 2.X

I usually build the project in a single folder like "build". So if I want to make clean, I can just rm -rf build.

The "build" folder in the same directory as the root "CMakeLists.txt" is usually a good choice. To build your project, you simply give cmake the location of the CMakeLists.txt as an argument. For example: cd <location-of-cmakelists>/build && cmake ... (From @ComicSansMS)

Thanks to everybody's help, I was able to solve my issue.

For other people who may suffer from the same problem in the future, this is what I did:

it was because my $PATH was messed up (I think it happened when I tried to add Android SDK to $PATH)

I cleared the .bash_profile and added C++ and make and /opt/local/bin, /opt/local/sbin

like this

export PATH=$PATH:/opt/local/bin:/opt/local/sbin:/usr/bin/c++:/usr/bin/make

and it worked like charm.