set pythonpath before import statements

Question

My code is   import scriptlib abc import scriptlib xyz  def foo          some operations   but the scriptlib is in some other directory  so I will have to include that directory in environment variable  PYTHONPATH    Is there anyway in which I can first add the scriptlib directory in environment variable  PYTHONPATH  before import statement getting executed like    import sys sys path append   mypath scriptlib   import scriptlib abc import scriptlib xyz  def foo          some operations   If so  is the value only for that command prompt or is it global    Thanks in advance

User · Accepted Answer

This will add a path to your Python process / instance (i.e. the running executable). The path will not be modified for any other Python processes. Another running Python program will not have its path modified, and if you exit your program and run again the path will not include what you added before. What are you are doing is generally correct.

set.py:

import sys
sys.path.append("/tmp/TEST")

loop.py

import sys
import time
while True:
  print sys.path
  time.sleep(1)

run: python loop.py &

This will run loop.py, connected to your STDOUT, and it will continue to run in the background. You can then run python set.py. Each has a different set of environment variables. Observe that the output from loop.py does not change because set.py does not change loop.py's environment.

A note on importing

Python imports are dynamic, like the rest of the language. There is no static linking going on. The import is an executable line, just like sys.path.append....

User · Answer

As also noted in the docs here  Go to Python X X Lib and add these lines to the site py there   import sys sys path append  yourpathstring     This changes your sys path so that on every load  it will have that value in it      As stated here about site py        This module is automatically imported during initialization  Importing this module will append site-specific paths to the module search path and add a few builtins       For other possible methods of adding some path to sys path see these docs

[python] set pythonpath before import statements

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