Python launching problems OS X I'm trying to install python on mac OS X 10.7.5. I installed it from MacPort and I think before I did, I screwed up $PATH somehow. It seems to install fine but then when I try to run ipython I get 

-bash: ipython: command not found.


I thought it had something to do with the path and when I do /bin/echo $PATH I get something that seems really weird to me: 

opt/local/bin:/opt/local/sbin:/opt/local/bin:/opt/local/sbin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin
You need to install ipython in addition to python:

$ port search ipython

py-ipython @0.13.2 (python)
An enhanced Interactive Python shell


With

$ sudo port select --set ipython ipython24


you can then select the version you want.

It ill be installed in

$ type ipython
ipython is /opt/local/bin/ipython


Check that your PATH begins with /opt/local/bin and not with opt/local/bin/ (notice the beginning /)