Read environment variables in Python
Question: I have set some environment variables in `~/.profile`:

    
    
    SOMEVAR=/some/custom/path
    

and already did `source ~/.profile`. So when I do:

    
    
    echo $SOMEVAR
    

it prints the correct directory:

    
    
    /some/custom/path
    

However, when I try to read this variable in a Python script, it fails:

    
    
    import os
    
    print(os.environ["SOMEVAR"])
    

I get:

    
    
    Traceback (most recent call last):
      File "environment_test.py", line 3, in <module>
        print os.environ["SOMEVAR"]
      File "/usr/lib64/python2.7/UserDict.py", line 23, in __getitem__
        raise KeyError(key)
    KeyError: 'SOMEVAR'
    

What's wrong there?


Answer: You don't want the launched processes see all the crap (= variables) you've
created. Hence regular variables are only visible in this shell you're
executing.

You have to export the variable:

    
    
    export SOMEVAR=/some/custom/path
    

