To execute a Python file in the python shell, you could use either the execfile method or the exec method.
Example
For example, you want to run a script called my_script.py that only contains the line:
print("Greetings from my_script")
from the python shell, you could simply enter:
>>> execfile('my_script.py') Greetings from my_script
Or you could use the exec method as follows:
>>> exec(open("my_script.py").read()) Greetings from my_script