PYTHONPATH when calling from ipython

[Cecil Westerhof]

Op Saturday 23 May 2015 19:30 CEST schreef Cecil Westerhof:

> I should have checked better. I think I found a bug that made it
> look like PYTHONPATH does not work.
>
> In bash I give:
> echo $PYTHONPATH
> this gives:
> .:/home/cecil/Python/PythonLibrary
>
> Then I start ipython3 and get/do the following:
> Python 3.4.1 (default, May 23 2014, 17:48:28) [GCC]
> Type "copyright", "credits" or "license" for more information.
>
> IPython 2.2.0 -- An enhanced Interactive Python. ? -> Introduction
> and overview of IPython's features. %quickref -> Quick reference.
> help -> Python's own help system. object? -> Details about 'object',
> use 'object??' for extra details.
>
> In [1]: import os
>
> In [2]: os.environ['PYTHONPATH']
> Out[2]: '.:/home/cecil/Python'
>
> And PYTHONPATH has a different value. That is why my module is not
> found.
>
> When I set PYTHONPATH to the correct value, everything works as
> expected: In [3]: os.environ['PYTHONPATH'] =
> '.:/home/cecil/Python/PythonLibrary/'
>
> In [4]: !python2 postOnTwitter.py --used Citation has 50 saved
> messages of 126: [6, 55, 43, 82, 28, 116, 2, 50, 100, 5, 0, 122, 75,
> 51, 121, 60, 114, 13, 102, 78, 31, 107, 73, 109, 54, 119, 72, 90,
> 89, 113, 118, 41, 11, 27, 48, 77, 19, 111, 62, 98, 110, 9, 10, 115,
> 63, 15, 53, 101, 94, 92]
>
> Tips has 30 saved messages of 94:
> [20, 37, 7, 59, 45, 49, 40, 87, 79, 78, 31, 14, 15, 25, 84, 18, 91,
> 53, 8, 35, 80, 92, 34, 42, 74, 69, 64, 22, 86, 62]
>
> That begs the question: what is the reason for the corruption of
> PYTHONPATH?
>
> I already answered it partly myself. When I change PYTHONPATH in
> bash and call ipython3 again, it has the same value as before, so it
> does not take its value from the calling bash as I would expect.

Well it was my fault again. Linux can run very long before you need to
restart it. I work with screen. Before PYTHONPATH was
.:/home/cecil/Python, but later on I changed it to
.:/home/cecil/Python/PythonLibrary. When starting a new shell, the
bash shell had the right value. But when starting ipython it got the
old value. Importing os is not even necessary:
    Python 3.4.1 (default, May 23 2014, 17:48:28) [GCC]
    Type "copyright", "credits" or "license" for more information.

    IPython 2.2.0 -- An enhanced Interactive Python.
    ?         -> Introduction and overview of IPython's features.
    %quickref -> Quick reference.
    help      -> Python's own help system.
    object?   -> Details about 'object', use 'object??' for extra details.

    In [1]: !python2 postOnTwitter.py --used
    python2: can't open file 'postOnTwitter.py': [Errno 2] No such file or directory

    In [2]: !python2 postOnTwitter.py --used
    Citation has 50 saved messages of 126:
    [6, 55, 43, 82, 28, 116, 2, 50, 100, 5, 0, 122, 75, 51, 121, 60, 114, 13, 102, 78, 31, 107, 73, 109, 54, 119, 72, 90, 89, 113, 118, 41, 11, 27, 48, 77, 19, 111, 62, 98, 110, 9, 10, 115, 63, 15, 53, 101, 94, 92]

    Tips has 30 saved messages of 94:
    [20, 37, 7, 59, 45, 49, 40, 87, 79, 78, 31, 14, 15, 25, 84, 18, 91, 53, 8, 35, 80, 92, 34, 42, 74, 69, 64, 22, 86, 62]


Feeling a bit silly at the moment. >:-(


By the way I use python2 because the program uses a library that does
not work with python3.

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof