Command line input in Python

For interactive user input (or piped commands or redirected input)

Use raw_input in Python 2.X, and input in Python 3.

For example:

user_input = raw_input("Some input please: ")

More details can be found here.

So, for example, you might have a script that looks like this

# First, do some work
var1 = 'bik'
var2 = 'bop'

# Now ask for input
user_input = raw_input("Some input please: ")

# Now do something with the above
print(user_input)
print(var1, var2)

If you saved this in foo.py, you could just call the script, then enter bar baz (followed by the enter key).

For command-line arguments

Suppose you have a script named foo.py and want to call it with arguments bar and baz from the command line like

foo.py bar baz

Then, you can do that with the following in your script:

import sys
arg1 = sys.argv[1]
arg2 = sys.argv[2]

Here, arg1 will contain 'bar', and arg2 will contain 'baz'. The object sys.argv is just a list containing everything from the command line. Note that sys.argv[0] is the name of the script.

If you're using Python 3, raw_input has changed to input

Python 3 example:

line = input('Enter a sentence:')

Just Taking Input

the_input = raw_input("Enter input: ")

And that's it.

Moreover, if you want to make a list of inputs, you can do something like:

a = []

for x in xrange(1,10):
    a.append(raw_input("Enter Data: "))

In that case, you'll be asked for data 10 times to store 9 items in a list.

Output:

Enter data: 2
Enter data: 3
Enter data: 4
Enter data: 5
Enter data: 7
Enter data: 3
Enter data: 8
Enter data: 22
Enter data: 5
>>> a
['2', '3', '4', '5', '7', '3', '8', '22', '5']

You can search that list the fundamental way with something like (after making that list):

if '2' in a:
    print "Found"

else: print "Not found."

You can replace '2' with "raw_input()" like this:

if raw_input("Search for: ") in a:
    print "Found"
else: 
    print "Not found"

Taking Raw Data From Input File via Commandline Interface

If you want to take the input from a file you feed through commandline (which is normally what you need when doing code problems for competitions, like Google Code Jam or the ACM/IBM ICPC):

example.py

while(True):
    line = raw_input()
    print "input data: %s" % line

In command line interface:

example.py < input.txt

Hope that helps.