sys.argv

Learn command-line arguments with sys.argv.

sys.argv

sys.argv is a list holding command-line arguments. It is used by importing the sys module:

import sys
print(sys.argv)
# python script.py Ayşe 25
# ["script.py", "Ayşe", "25"]

sys.argv[0] is always the script name. Real arguments start at sys.argv[1]. Each argument is a string — convert if you need a number.

It is the way to read parameters given when the script starts.

argv and IndexError

If the user does not give enough arguments, accessing sys.argv[1] raises IndexError. So you must first check that the list has enough elements:

import sys
if len(sys.argv) > 1:
    name = sys.argv[1]
else:
    name = "misafir"
print(name)

This pattern — first a length check, then access — prevents IndexError. Providing a default value makes the script robust.

This check is standard in command-line scripts.

Exercise Greet with sys.argv

Write import sys. Assign sys.argv[1] if len(sys.argv) > 1 else "misafir" to name. Then write print("Merhaba, " + name). The script runs with no arguments.

Show example solution

import sys
name = sys.argv[1] if len(sys.argv) > 1 else "misafir"
print("Merhaba, " + name)

Test yourself

Complete the sys.argv access

import sys
name = sys.____[1]

Show answer

import sys
name = sys.argv[1]

What does sys.argv[0] contain?
- An empty string
- The first argument
- The argument count
- The script name
Show answer

The script name — sys.argv[0] is always the name of the script being run.
Match sys.argv concepts

sys.argv[0]

Script name
sys.argv[1]

First argument
len(sys.argv)

Argument count
import sys

Required import

Next lesson: Summary - Input and output

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