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So I am working on this project where I take input from the user (a file name ) and then open and check for stuff. the file name is "cur" Now suppose the name of my file is kb.py (Its in python) If I run it on my terminal then first I will do: python kb.y and then there will a prompt and user will give the input. I'll do it this way: 

A = raw_input("Enter File Name: ") b = open(A, 'r+')

I dont want to do that. Instead i want to use it as a command for example: python kb.py cur and it will take it as an input and save to a variable which then will open it. I am confused how to get a input in the same command line.

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2 Answers 2

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Just use sys.argv, like this:

import sys # this part executes when the script is run from the command line if __name__ == '__main__': if len(sys.argv) != 2: # check for the correct number of arguments print 'usage: python kb.py cur' else: call_your_code(sys.argv[1]) # first command line argument

Note: sys.argv[0] is the script's name, and sys.argv[1] is the first command line argument. And so on, if there were more arguments.

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Thanks for the help but can you please explain what if name == 'main': and call_your_code(sys.argv[1]) is doing ?
@Nick First question: take a look at this answer. Second question: that's the part where your program starts, the part where you're going to use the cur argument. It's up to you to decide what to do here!
Ok that helps. Just one more question that suppose I enter python kb.py cur and Now I have to open cur file to see whats in it then how can I assign it to a variable. I mean where exactly is it getting assigned in the above mentioned code, is there any particular variable on which I can call open(VAR, 'r+')
A = raw_input("Enter File Name: ") B =open(call_your_code, 'r+') I am doing something like this in python
No, the value of argv[1] is just the text you entered from the command line. If you executed your program like this: python kb.py cur then in argv[1] you'll have the string 'cur'. It's up to you to decide what to do with this from this point on, for example, opening a file called 'cur', etc. The command line arguments are simply text.
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For simply stuff sys.argv[] is the way to go, for more complicated stuff, have a look at the argparse-module

import argparse parser = argparse.ArgumentParser() parser.add_argument("--verbose", help="increase output verbosity", action="store_true") args = parser.parse_args() if args.verbose: print "verbosity turned on"

output:

$ python prog.py --verbose verbosity turned on $ python prog.py --verbose 1 usage: prog.py [-h] [--verbose] prog.py: error: unrecognized arguments: 1 $ python prog.py --help usage: prog.py [-h] [--verbose] optional arguments: -h, --help show this help message and exit --verbose increase output verbosity
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