How to execute a file within the Python interpreter?

Several ways.

• From the shell

  python someFile.py
  

• From inside IDLE, hit F5.

• If you're typing interactively, try this (Python3):

  >>> exec(open("filename.py").read())
  

• For Python 2:

  >>> variables= {}
  >>> execfile( "someFile.py", variables )
  >>> print variables # globals from the someFile module
  

For Python 2:

>>> execfile('filename.py')

For Python 3:

>>> exec(open("filename.py").read())
# or
>>> from pathlib import Path
>>> exec(Path("filename.py").read_text())

See the documentation. If you are using Python 3.0, see this question.

See answer by @S.Lott for an example of how you access globals from filename.py after executing it.

Python 2 + Python 3

exec(open("./path/to/script.py").read(), globals())

This will execute a script and put all it's global variables in the interpreter's global scope (the normal behavior in most scripting environments).

Python 3 exec Documentation

I'm trying to use variables and settings from that file, not to invoke a separate process.

Well, simply importing the file with import filename (minus .py, needs to be in the same directory or on your PYTHONPATH) will run the file, making its variables, functions, classes, etc. available in the filename.variable namespace.

So if you have cheddar.py with the variable spam and the function eggs – you can import them with import cheddar, access the variable with cheddar.spam and run the function by calling cheddar.eggs()

If you have code in cheddar.py that is outside a function, it will be run immediately, but building applications that runs stuff on import is going to make it hard to reuse your code. If a all possible, put everything inside functions or classes.