Executing modules as scripts

Question

I am learn python now, and today, i met a problem in http://docs.python.org/release/2.5.4/tut/node8.html

6.1.1 Executing modules as scripts

When you run a Python module with

python fibo.py <arguments>

the code in the module will be executed, just as if you imported it, but with the __name__ set to "__main__". That means that by adding this code at the end of your module:

if __name__ == "__main__":
    import sys`
    fib(int(sys.argv[1]))

you can make the file usable as a script as well as an importable module, because the code that parses the command line only runs if the module is executed as the "main" file:

$ python fibo.py 50 1 1 2 3 5 8 13 21 34

but when i do this in shell, i got

File "<input>", line 1
python fibo.py 222
SyntaxError: invalid syntax

how to execute script correctly?

fibo.py is

def fib(n):
    a,b=0,1
    while b<n:
        print b,
        a,b = b,a+b


def fib2(n):
    result=[]
    a,b=0,1
    while b<n:
        result.append(b)
        a,b=b,a+b
    return result

if __name__ =="__main__":
    import sys
    fib(int(sys.argv[1]))

Answer 1

What exactly did you do in the shell? What is the code you are running?

It sounds like you made a mistake in your script - perhaps missing the colon or getting the indentation wrong. Without seeing the file you are running it is impossible to say more.

edit:

I have figured out what is going wrong. You are trying to run python fibo.py 222 in the python shell. I get the same error when I do that:

[138] % python
Python 2.6.1 (r261:67515, Apr  9 2009, 17:53:24)
[GCC 4.1.2 20080704 (Red Hat 4.1.2-44)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> python fibo.py 222
  File "<stdin>", line 1
    python fibo.py 222
              ^
SyntaxError: invalid syntax
>>>

You need to run it from the operating system's command line prompt NOT from within Python's interactive shell.

Make sure to change to Python home directory first. For example, from the Operating system's command line, type: cd C:\Python33\ -- depending on your python version. Mine is 3.3. And then type: python fibo.py 200 (for example)