Environment Variables not in Python interpreter

Question

HI i just run over a curious thing.

In my .bashrc looks like this:

PYTHONPATH=$PYTHONPATH:/home/pschu/ParaView-3.14.1-Build/Utilities/VTKPythonWrapping/site-packages:home/pschu/ParaView-3.14.1-Build/bin

ParaView_DIR=/home/pschu/ParaView-3.14.1-Build

LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/home/pschu/ParaView-3.14.1-Builds/bin

So now when i start the python interpreter and type following:

>>>os.environ['PYTHONPATH']
 Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
 File "/usr/lib64/python2.7/UserDict.py", line 23, in __getitem__
 raise KeyError(key)
KeyError: 'PYTHONPATH'

same error with ParaView_DIR, but LD_LIBRARY_PATH has the additional Path.

in the shell they exist.

echo $PYTHONPATH
:/home/pschu/ParaView-3.14.1-Build/Utilities/VTKPythonWrapping/site-packages:home/pschu/ParaView-3.14.1-Build/bin

now when i do

export PYTHONPATH=$PYTHONPATH

before I run the python interpreter it works.

What's happening?

user647772 · Accepted Answer · 2012-10-23 10:40:06Z

2

This works:

% PYTHONPATH=$PYTHONPATH:/tmp python

In Python:

>>> import os
>>> os.environ["PYTHONPATH"]
':/tmp'

answered Oct 23, 2012 at 10:40

user647772

Sign up to request clarification or add additional context in comments.

2 Comments

cdarke Over a year ago

What, without an export or setenv?

user647772 Over a year ago

Yes, since the environment variable and the started python programm are on the same line. In this case no export is needed.

cdarke · Accepted Answer · 2012-10-23 10:45:45Z

1

Did you export the variables?

export PYTHONPATH ParaView_DIR

LD_LIBRARY_PATH was probably already exported in one of your other startup files. Once a variable is exported it stays that way.

Exporting a variable makes it an environment variable, if you don't export then it is just local to the shell and a child process does not get a copy.

If you are using the C-shell (often indicated by the % prompt) then the syntax is different:

setenv PYTHONPATH $PYTHONPATH

edited Oct 23, 2012 at 10:45

answered Oct 23, 2012 at 10:40

cdarke

44.8k8 gold badges85 silver badges86 bronze badges

Collectives™ on Stack Overflow

Environment Variables not in Python interpreter

2 Answers 2

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related