Is my virtual environment (python) causing my PYTHONPATH to break?

Question

In my /etc/profile, I set PYTHONPATH as something.

But when I source myvirtual-env

And then do this in python:

>>> import sys
>>> print sys.path

I don't see my paths anywhere.

Answer 1

That's the point of the virtualenv. It doesn't inherit from the rest of your setup. If you want a PYTHONPATH, you need to explicitly set one.

This djangousers post is probably helpful, you want to use virtualenvwrapper to solve this problem.

More info in this other SO post on a similar problem.

Answer 2

I don't observe the problem with Python 2.7, virtualenv 1.7.1.2 on Windows XP and I suspect Paul McMillan's answer is wrong.

# PYTHONPATH not set
# output from python -c "import sys; print sys.path" (edited for clarity)

'',
'C:\\Program Files\\python\\2.7\\lib\\site-packages\\pip-1.1-py2.7.egg',
'C:\\WINDOWS\\system32\\python27.zip',
'C:\\Program Files\\python\\2.7\\DLLs',
'C:\\Program Files\\python\\2.7\\lib',
'C:\\Program Files\\python\\2.7\\lib\\plat-win',
'C:\\Program Files\\python\\2.7\\lib\\lib-tk',
'C:\\Program Files\\python\\2.7',
'C:\\Program Files\\python\\2.7\\lib\\site-packages',
'C:\\Program Files\\python\\2.7\\lib\\site-packages\\setuptools-0.6c11-py2.7.egg-info'

# PYTHONPATH not set, virtualenv activated
# output from python -c "import sys; print sys.path" (edited for clarity)

'',
'c:\\python\\virtualenv\\2.7\\lib\\site-packages\\distribute-0.6.24-py2.7.egg',
'c:\\python\\virtualenv\\2.7\\lib\\site-packages\\pip-1.1-py2.7.egg',
'C:\\WINDOWS\\system32\\python27.zip',
'c:\\python\\virtualenv\\2.7\\DLLs',
'c:\\python\\virtualenv\\2.7\\lib',
'c:\\python\\virtualenv\\2.7\\lib\\plat-win',
'c:\\python\\virtualenv\\2.7\\lib\\lib-tk',
'c:\\python\\virtualenv\\2.7\\Scripts',
'C:\\Program Files\\python\\2.7\\Lib',
'C:\\Program Files\\python\\2.7\\DLLs',
'C:\\Program Files\\python\\2.7\\Lib\\lib-tk',
'c:\\python\\virtualenv\\2.7',
'c:\\python\\virtualenv\\2.7\\lib\\site-packages'

# PYTHONPATH set to c:\pythonpath_sample_dir
# output from python -c "import sys; print sys.path" (edited for clarity)

''
'C:\\Program Files\\python\\2.7\\lib\\site-packages\\pip-1.1-py2.7.egg'
'c:\\pythonpath_sample_dir'   <--- value from PYTHONPATH
'C:\\WINDOWS\\system32\\python27.zip'
'C:\\Program Files\\python\\2.7\\DLLs'
'C:\\Program Files\\python\\2.7\\lib'
'C:\\Program Files\\python\\2.7\\lib\\plat-win'
'C:\\Program Files\\python\\2.7\\lib\\lib-tk'
'C:\\Program Files\\python\\2.7'
'C:\\Program Files\\python\\2.7\\lib\\site-packages'
'C:\\Program Files\\python\\2.7\\lib\\site-packages\\setuptools-0.6c11-py2.7.egg-info'

# PYTHONPATH set to c:\pythonpath_sample_dir, virtualenv activated
# output from python -c "import sys; print sys.path" (edited for clarity)

''
'c:\\python\\virtualenv\\2.7\\lib\\site-packages\\distribute-0.6.24-py2.7.egg'
'c:\\python\\virtualenv\\2.7\\lib\\site-packages\\pip-1.1-py2.7.egg'
'c:\\pythonpath_sample_dir'   <--- value from PYTHONPATH
'C:\\WINDOWS\\system32\\python27.zip'
'c:\\python\\virtualenv\\2.7\\DLLs'
'c:\\python\\virtualenv\\2.7\\lib'
'c:\\python\\virtualenv\\2.7\\lib\\plat-win'
'c:\\python\\virtualenv\\2.7\\lib\\lib-tk'
'c:\\python\\virtualenv\\2.7\\Scripts'
'C:\\Program Files\\python\\2.7\\Lib'
'C:\\Program Files\\python\\2.7\\DLLs'
'C:\\Program Files\\python\\2.7\\Lib\\lib-tk'
'c:\\python\\virtualenv\\2.7'
'c:\\python\\virtualenv\\2.7\\lib\\site-packages'

Also python virtualenv: why can I still import old modules in clean/new virtualenv seems to confirm PYTHONPATH is being used to construct sys.path also when virtual environment is activated.