Python Serial Output Works

[sgarber]

Oops, bad title... Better title: Python Serial Output Works Only Conditionally
Hi,
I am working on having python send commands to a microcontroller via the serial port. I want to write a python script that will send a single byte to the serial port and then quit. The script I tried looks like this:

import serial
ser = serial.Serial('/dev/ttyUSB0', 19200, timeout=0)
command = input("Enter command:")
ser.write(chr(command))

This works when typed into python, but not when executed as a script.
The only way I can get a python script to send a byte to the serial port is by having it in a while loop, like so:

import serial
ser = serial.Serial('/dev/ttyUSB0', 19200, timeout=0)
while 1:
   command = input("Enter command:")
   ser.write(chr(command))

I have tried adding sleep() delays, but they never worked.
Questions:
1) Why does my first code block not work as a script, but will work when typed in on the fly?
2) How can I make a script with the functionality I need?
Thank you in advance.