Cannot install DB2 Express-C 10.1 on Mac OS X 10.7.5
I got it working by completely uninstalling db2 express-c (the db2_deinstall script failed so I manually deleted all directories that involved db2. :P ) .

Then I followed
https://www.ibm.com/developerworks/community/forums/html/topic?id=77777777-0000-0000-0000-000014927797

and it worked. I never ran db2_setup.