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From: Peter Otten <__peter__@web.de>
Subject: Re: Flag control variable
Date: Tue, 11 Feb 2014 18:46:40 +0100
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Xref: csiph.com comp.lang.python:65933

luke.geelen@gmail.com wrote:

> i'd like to know how to set up a flag to change a variable,
> for example, i want a simple script to combine 2 numbers,
> 
> 
> sum = num + another_num
> print "Now the sum of the numbers equals : ", sum
> 
> how could i make it so that if i type python ./script.py 21 41
> that i get the sum of 21 and 41 ?

You seem to be looking for sys.argv which contains the script name and the 
command-line arguments.

$ cat script.py
import sys
a = int(sys.argv[1])
b = int(sys.argv[2])
print a, "+", b, "=", a + b
$ python script.py 21 41
21 + 41 = 62

The conversion to int (or float etc.) is necessary because in python

>>> "21" + "41"
'2141'