ipython reads wrong python version, (ipython3 Mac OS)

Okay quick fix:

which python

gives you /usr/bin/python, right? Do

which ipython

and I bet that'll be /usr/local/bin/ipython. Let's look inside:

cat /usr/local/bin/ipython

#!/usr/bin/python
# EASY-INSTALL-ENTRY-SCRIPT: 'ipython==0.12.1','console_scripts','ipython'
__requires__ = 'ipython==0.12.1'
import sys
from pkg_resources import load_entry_point

if __name__ == '__main__':
    sys.exit(
        load_entry_point('ipython==0.12.1', 'console_scripts', 'ipython')()
    )

Aha - open /usr/local/bin/ipython in your editor (with privileges), and change the first line to

#!/usr/local/bin/python

save, start iPython, should say it's using 2.7.2 now.

同样的solution， 对于ipython3 

(尤其当python3.4 转成了3.5之后）