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On a Ubuntu (10.10) system, I have a Python package that installs itself into /usr/local/lib/python2.6/site-packages/. This isn't contained in the default path (sys.path). How do I add this directory to the path?

Setting the $PYTHONPATH environment variable is a solution, of course, but I'm looking for a more elegant way to do this. For example easy_install also puts installed packages in it, my sys.path looks something like this:

['', '/usr/local/lib/python2.6/dist-packages/keyring-0.5.1-py2.6.egg', 
'/usr/lib/python2.6', '/usr/lib/python2.6/plat-linux2', '/usr/lib/python2.6/lib-tk',  
'/usr/lib/python2.6/lib-old', '/usr/lib/python2.6/lib-dynload', 
'/usr/local/lib/python2.6/dist-packages', '/usr/lib/python2.6/dist-packages', 
'/usr/lib/python2.6/dist-packages/PIL', '/usr/lib/pymodules/python2.6', 
'/usr/lib/pymodules/python2.6/gtk-2.0']

so the path is obviously not the default built into the Python binary.

Is there a single config file that contains the entries above? Or in what ways is it possible to modify it?

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4 Answers 4

Reset to default
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+50

The site module documentation and Modifying Python's Search Path seem to be what you're looking for.

As far as I understand it, those entries are being added to sys.path by:

  • /usr/lib/python2.6/site.py
  • /usr/lib/python2.6/dist-packages/site.py
    (Change 2.6 to your version of Python.)

The easiest way to change it is to add a file /usr/local/lib/python2.6/dist-packages/site-packages.pth containing ../site-packages.

Alternatively, maybe you can teach the package to use site.getsitepackages()?

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  • 1
    thanks, works perfectly :) (I ended up adding a .pth file to /usr/local/python2.6/dist-packages, containing "../site-packages")
    – Latanius
    Feb 18, 2011 at 21:40
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    You can also create a module called sitecustomize.py which site.py tries to import and modify sys.path there.
    – TestUser16418
    Feb 18, 2011 at 22:11
8

I'd like to summarize my findings about python's path modification. There are two ways to do it.

  • .pth file
  • PYTHONPATH

Any .pth file which is found on the default path (see bellow) will get its content included into sys.path. Format of said .pth file is simple: one (folder) path per line. Surprisingly, the paths can be absolute or relative to the .pth file.

Default path is where the interpreter resides and <some-prefix>/lib/python<version>/site-packages where <some-prefix> is usually /usr/.

PYTHONPATH is environmental variable of your operating system. On unix systems you list them by env. Global modification of such variables is done through .sh scripts inside /etc/profile.d/ folder as mentioned by @TestUser16418.

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  • 2
    It is PYTHONPATH without "_"
    – heroxbd
    Jul 9, 2017 at 4:57
6

You might create a new file called /etc/profile.d/local_python.sh with the contents

PYTHONPATH="/usr/local/lib/python2.6/site-packages/":"${PYTHONPATH}"
export PYTHONPATH

Which will set the PYTHONPATH variable for all logged in users on your system.

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2
  • 7
    This really isn't universal. The /etc/profile.d mechanism will only work for login shells for people with shells that use /etc/profile.d (bash/ksh/zsh). I'm sure csh users won't see this change. Also, will be ignored in cron/at jobs.
    – Rich Homolka
    Feb 18, 2011 at 21:43
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    this is a nice way to set global environment variables (yet another thing I learned today), but as I mentioned in the post, I was looking for a more Pythonic way :)
    – Latanius
    Feb 18, 2011 at 21:45
1

For example, if you want to import the suds module which is available as an .egg file:

egg_path = '/home/shahid/suds_2.4.egg'

sys.path.append(egg_path)

import suds
# ... rest of code
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