Recently I've been getting the error
error: Setup script exited with error: command 'clang' failed with exit status 1
when trying to install various Python libraries using Easy Install on OSX Mountain Lion (with Server.app installed). This happened recently trying to install psycopg2, but I've seen it before when trying to install lxml.
server:Desktop shellperson$ sudo easy_install psycopg2 Password: Searching for psycopg2 Reading http://pypi.python.org/simple/psycopg2/ Reading http://initd.org/psycopg/ Reading http://initd.org/projects/psycopg2 Best match: psycopg2 2.4.5 Downloading http://initd.org/psycopg/tarballs/PSYCOPG-2-4/psycopg2-2.4.5.tar.gz Processing psycopg2-2.4.5.tar.gz Running psycopg2-2.4.5/setup.py -q bdist_egg --dist-dir /tmp/easy_install-TUzBu0/psycopg2-2.4.5/egg-dist-tmp-wjxjYJ no previously-included directories found matching 'doc/src/_build' unable to execute clang: No such file or directory error: Setup script exited with error: command 'clang' failed with exit status 1
Fixed the problem by first installing Xcode from the App Store, then installing Command Line Tools from the Downloads section of Xcode's Preferences screen.
UPDATE: Now on Mavericks you can install Command Line Tools using the following command: