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up vote 1 down vote favorite

Something strange and unexpected is happening with the sys.path of any virtual environment I set. For example, a clean env:

$ virtualenv test
$ source test/bin/activate
(test) $

This is the expected PYTHONPATH:

(test) $ python
>>> import sys
>>> print '\n'.join(sys.path)

/home/user/test/local/lib/python2.7/site-packages/setuptools-0.6c11-py2.7.egg
/home/user/test/local/lib/python2.7/site-packages/pip-1.1-py2.7.egg
/home/user/test/lib/python2.7/site-packages/setuptools-0.6c11-py2.7.egg
/home/user/test/lib/python2.7/site-packages/pip-1.1-py2.7.egg
/home/user/test/lib/python2.7
/home/user/test/lib/python2.7/plat-linux2
/home/user/test/lib/python2.7/lib-tk
/home/user/test/lib/python2.7/lib-old
/home/user/test/lib/python2.7/lib-dynload
/usr/lib/python2.7
/usr/lib/python2.7/plat-linux2
/usr/lib/python2.7/lib-tk
/home/user/test/local/lib/python2.7/site-packages
/home/user/test/lib/python2.7/site-packages

But this is the one I really get: 

(test) $ bpython
>>> import sys
>>> print '\n'.join(sys.path)

/usr/bin
/usr/lib/python2.7
/usr/lib/python2.7/plat-linux2
/usr/lib/python2.7/lib-tk
/usr/lib/python2.7/lib-old
/usr/lib/python2.7/lib-dynload
/usr/local/lib/python2.7/dist-packages
/usr/lib/python2.7/dist-packages

I can't figure out the reason of the two different sys.paths. Because of that, no pip installation works! I'm using Virtualenv 1.7.2, Ubuntu 12.04, Python 2.7.3. Any help will be appreciated.

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3 Answers

up vote 2 down vote accepted

My hypothesis is that you have not installed bpython after you have activated the new virtualenv.

I followed it up exactly like you mentioned:

mkvirtualenv bpython
(bpython)~ $ pip install bpython
(bpython)~ $bpython

and then ran the commands:

>>> import sys
>>> print '\n'.join(sys.path)

/Users/xxxx/.virtualenvs/bpython/bin
/Users/xxxx/.virtualenvs/bpython/lib/python2.7/site-packages/setuptools-0.6c11-py2.7.egg
/Users/xxxx/.virtualenvs/bpython/lib/python2.7/site-packages/pip-1.1-py2.7.egg
/Users/xxxx/.virtualenvs/bpython/lib/python27.zip
/Users/xxxx/.virtualenvs/bpython/lib/python2.7
/Users/xxxx/.virtualenvs/bpython/lib/python2.7/plat-darwin
/Users/xxxx/.virtualenvs/bpython/lib/python2.7/plat-mac
/Users/xxxx/.virtualenvs/bpython/lib/python2.7/plat-mac/lib-scriptpackages
/Users/xxxx/.virtualenvs/bpython/lib/python2.7/lib-tk
/Users/xxxx/.virtualenvs/bpython/lib/python2.7/lib-old
/Users/xxxx/.virtualenvs/bpython/lib/python2.7/lib-dynload
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-darwin
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac/lib-scriptpackages
/Users/xxxx/.virtualenvs/bpython/lib/python2.7/site-packages

and did the same thing again by running python under the activated virtualenv

(bpython)~ $ python
.....
>>> import sys
>>> print '\n'.join(sys.path)

/Users/xxxx/.virtualenvs/bpython/lib/python2.7/site-packages/setuptools-0.6c11-py2.7.egg
/Users/xxxx/.virtualenvs/bpython/lib/python2.7/site-packages/pip-1.1-py2.7.egg
/Users/xxxx/.virtualenvs/bpython/lib/python27.zip
/Users/xxxx/.virtualenvs/bpython/lib/python2.7
/Users/xxxx/.virtualenvs/bpython/lib/python2.7/plat-darwin
/Users/xxxx/.virtualenvs/bpython/lib/python2.7/plat-mac
/Users/xxxx/.virtualenvs/bpython/lib/python2.7/plat-mac/lib-scriptpackages
/Users/xxxx/.virtualenvs/bpython/lib/python2.7/lib-tk
/Users/xxxx/.virtualenvs/bpython/lib/python2.7/lib-old
/Users/xxxx/.virtualenvs/bpython/lib/python2.7/lib-dynload
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-darwin
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac/lib-scriptpackages
/Users/xxxx/.virtualenvs/bpython/lib/python2.7/site-packages

I saw no difference in the two results

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You're right. I thought that virtualenv would change PYTHONPATH for any other program since it is active. Thanks. –  andref Jun 23 '12 at 21:46
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up vote 1 down vote

I also discovered that if you have bpython installed locally, you need to create your virtualenv with --no-site-packages for it to work properly. If you created your virtualenv without that flag, you can create an empty file named no-global-site-packages.txt in ~/.virtualenvs/<env-name>/lib/python2.7/ as noted in this Stack Exchange answer.

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up vote 0 down vote

Rather than installing one copy of bpython per virtualenv, I've added this function to my shell profile (for example ~/.bashrc or ~/.zshrc). It wraps the bpython command with some logic to load the virtual environment's python path (if you have an active virtual environment).

bpython() {
    if test -n "$VIRTUAL_ENV"
    then
        PYTHONPATH="$(python -c 'import sys; print ":".join(sys.path)')" \
        command bpython "$@"
    else
        command bpython "$@"
    fi
}
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