When reading a Flask tutorial, the author asked me to chmod a+x run.py and then ./run.py, rather than simply python run.py as I usually do. When I ignored the author's instruction and executed python run.py, I got an ImportError.(I suspect this error has something to do with vitrualanv.)
So my question is: What's the difference between
./run.py
and
python run.py
I believe your suspicion is correct. Notice how he creates a virtualenv called flask:
virtualenv flask
run.py contains the following:
#!flask/bin/python
from app import app
app.run(debug=True)
The first line is called a shebang, in which the author defines that the python binary should be executed from flask/bin/python. If you instead execute python run.py, your system's default python binary is used. You could fix this by activating the virtualenv, by calling source bin/activate. Or by explicitly calling flask/bin/python run.py
Take a look at the first line of the file:
#!flask/bin/python
It means that running:
$ ./run.py
is equivalent to:
$ flask/bin/python run.py
and since flask/bin/python is in a virtual environment, it has different modules installed.
