sys.argv[1] meaning in script

Question

I'm currently teaching myself Python and was just wondering (In reference to my example below) in simplified terms what the sys.argv[1] represents. Is it simply asking for an input?

#!/usr/bin/python3.1

# import modules used here -- sys is a very standard one
import sys

# Gather our code in a main() function
def main():
  print ('Hello there', sys.argv[1])
  # Command line args are in sys.argv[1], sys.argv[2] ..
  # sys.argv[0] is the script name itself and can be ignored

# Standard boilerplate to call the main() function to begin
# the program.
if __name__ == '__main__':
  main()

Answer 1

Just adding to Frederic's answer, for example if you call your script as follows:

./myscript.py foo bar

sys.argv[0] would be "./myscript.py" sys.argv[1] would be "foo" and sys.argv[2] would be "bar" ... and so forth.

In your example code, if you call the script as follows ./myscript.py foo , the script's output will be "Hello there foo".

Answer 2

sys.argv[1] contains the first command line argument passed to your script.

For example, if your script is named hello.py and you issue:

$ python3.1 hello.py foo

or:

$ chmod +x hello.py  # make script executable
$ ./hello.py foo

Your script will print:

Hello there foo