Eggs in path before PYTHONPATH environment variable

Question

If I have packages installed from easy_install, the eggs are prepended to sys.path before the items in the PYTHONPATH variable.

Fo

Answer 1

Consider using the -S command-line option to suppress *.pth processing:

python -c 'import sys; print("\n".join(sys.path))'
python -S -c 'import sys; print("\n".join(sys.path))'

https://docs.python.org/3/library/site.html#site.main

You can also use -S with site.main() to delay *.pth processing until runtime, say to capture the original sys.path for appending:

export PYTHONPATH=$(
  PYTHONPATH='' \
  python -c 'import sys; \
    sys.path.extend(sys.argv[1:]); old=list(sys.path); \
    import site; site.main(); \
    [ old.append(p) for p in sys.path if p not in old ]; \
    sys.path=old; \
    print ":".join(sys.path)' \
  $EXTRA_PATH $ANOTHER_PATH)

python -S ... # using explicit PYTHONPATH

• Start from explicit empty PYTHONPATH
• Append to sys.path explicitly with extend
• Import site and call site.main()
• Append new paths to old path and then install it in sys.path
• Print with ":" for PYTHONPATH
• python -S is desirable for later runs only using $PYTHONPATH
• python -S may or may not be desirable while setting PYTHONPATH (depending on if you need sys.path expanded before extending)