The Simplest Introduction To Sys.Argv As A Way To Pass Arguments From Command Line

The concern is documenting an exemplary implementation of command-line arguments while keeping the code testable also from REPL or module (i.e. code editor). These are notes under the amazing course Core Python: Getting Started

1. at the top of your file import sys module
2. at the bottom of your file, use the pattern to run script immediatelly if called from a shell (if __name__ == "__main__":...)
3. use argv[<n>] to refer to the first, second, and nth positional argument
4. the number must start from 1 not from 0 for example:

# md2med.py
import sys
def main(doc_name, file_to_publish):
    # CODE ACCEPTING THE PARAMS HERE
    #...
        
if __name__ == "__main__":
    main(doc_name=sys.argv[1], file_to_publish=sys.argv[2])

5. when running this, pass the values into the terminal after the name of the script

>>> python md2med.py test-doc ./test-doc.md

1. ISSUE WITH INTGERS

• it is required to pass strings
• TypeError is thrown when working with passed number as an int

>>> python .\pv.py "com-snplow-sales-aws-prod1.collector.snplow.net" 5
TypeError: 'str' object cannot be interpreted as an integer

2. WHAT DOES ARGV MEAN ?

The list of command line arguments passed to a Python script. argv[0] is the script name (it is operating system dependent whether this is a full pathname or not).

• argv means argument vector
• in C, there is also argc, which is argument count

3. SOURCES

• https://realpython.com/python-command-line-arguments/
• https://stackoverflow.com/questions/35302508/how-do-i-pass-command-line-arguments-to-python-from-vs-in-debug-mode
• https://docs.python.org/3/library/sys.html#sys.argv