I highly recommend argparse which comes with Python 2.7 and later.

The argparse module reduces boiler plate code and makes your code more robust, because the module handles all standard use cases (including subcommands), generates the help and usage for you, checks and sanitize the user input - all stuff you have to worry about when you are using sys.argv approach. And it is for free (built-in).

Here a small example:

import argparse

parser = argparse.ArgumentParser("simple_example")
parser.add_argument("counter", help="An integer will be increased by 1 and printed.", type=int)
args = parser.parse_args()
print(args.counter + 1)

and the output for python prog.py -h

usage: simple_example [-h] counter
    
positional arguments:
  counter     counter will be increased by 1 and printed.
    
optional arguments:
  -h, --help  show this help message and exit

and the output for python prog.py 1 As one would expect:

2

I realize I already have a question that is answered.

You can find it here: How do you have an input statement with multiple arguments that are stored into a variable?

Here is the correct code:

def command_split(text:str) -> (str,str):
    """Split a string in a command and any optional arugments"""
    text = text.strip() # basic sanitize input
    space = text.find(' ')
    if space > 0:
        return text[:space],text[space+1:]
    return text,None

x = input(":>")
command,args = command_split(x)
# print (f'command: "{command:}", args: "{args}"')

if command == 'echo':
    if args == None:
        raise SyntaxError
    print (args)

A more simple way:

x = input(":>")
if x.split(" ")[0] == 'echo':
    echoreturn = ' '.join(x.split(" ")[1:])
    print(echoreturn)

My version to @rgov 's post: (Thank you!)

import argparse
import shlex

def do_say(args):
    print(args.what)

parser = argparse.ArgumentParser()
subparsers = parser.add_subparsers()
say_command = subparsers.add_parser('say')
say_command.add_argument('what')
say_command.set_defaults(func=do_say)

while True:
    try:

        command = input(":>")

        args = parser.parse_args(shlex.split(command))
        args.func(args)
    except SyntaxError:
        print("Syntax Error")
    except ValueError:
        print("Value Error")
    except:
        print("")

var = raw_input("Please enter something: ")
print "you entered", var

Or for Python 3:

var = input("Please enter something: ")
print("You entered: " + var)