How to Run a Python Script from the Command Line

Q: How do I run a Python file in the terminal?

Open a terminal in the file's folder and type `python filename.py`. Use `python3` on macOS and Linux if `python` is not found, or `py` on Windows.

By Yogesh Sharma (LinkedIn) · Every code example is run and checked on Python 3.13 (how we test) · Last updated 21 Oct 2026

Short answer

Save your code in a file such as hello.py, open a terminal in that folder and run python hello.py (or python3 hello.py on macOS and Linux, py hello.py on Windows).

A Python script is a plain text file with the extension .py. When you run it, Python reads the file from top to bottom and executes each statement. You can run scripts from a terminal, from an editor such as VS Code or IDLE, or double-click them on some systems, but the terminal is the most reliable and is what servers and automation use.

This page shows the commands, how to pass arguments, and how if __name__ == "__main__": lets a file work both as a script and as an importable module.

Quick facts
Run a script	`python script.py`
macOS / Linux	`python3 script.py`
Windows launcher	`py script.py`
Run a module	`python -m package.module`
Arguments	Read from `sys.argv`

Run a Python script step by step

Save your code, for example as hello.py.
Open a terminal and change to the folder that holds the file with cd.
Run the file with the command for your system.
If you installed packages into a virtual environment, activate it first.

If the terminal says can't open file, you are in the wrong folder or mistyped the name; use ls (macOS, Linux) or dir (Windows) to see what is there.

# go to the folder
cd path/to/my_project

# run the script
python hello.py          # most systems
python3 hello.py         # macOS / Linux if python is not found
py hello.py              # Windows launcher

# run with arguments
python greet.py Asha 3

Pass command-line arguments with sys.argv

Everything you type after the script name arrives in the list sys.argv as strings. sys.argv[0] is the script's name, so your own arguments start at index 1. Convert numbers with int() yourself; see type casting.

The snippet below parses a pretend argument list so the output is fixed:

Python

argv = ["greet.py", "Asha", "3"]
name = argv[1]
times = int(argv[2])
print(("Hello " + name + "! ") * times)

Use if name == "main" to separate script and module code

When a file is run directly, Python sets its __name__ to "__main__". When another file imports it, __name__ is the module's own name instead. Wrapping the start-up code in this check means it runs only when you execute the file, not when you import it, which is essential for testing and reuse.

Python

def main():
    print("running as a script")

if __name__ == "__main__":
    main()

Other ways to run Python code

Way	Command or action	Good for
Terminal	`python script.py`	Everyday use, automation, servers
Interactive prompt	`python` then type code	Quick experiments
One-liner	`python -c "print(2 + 2)"`	Tiny checks in a shell
Module	`python -m http.server`	Running standard tools and packages
Editor	Run button in VS Code, PyCharm or IDLE	Development with debugging
Executable script (Linux, macOS)	`#!/usr/bin/env python3` then `chmod +x script.py`	Running as `./script.py`

Examples you can run

Press Run, then edit the code and run it again.

Check how the file is being run

Run directly, __name__ is "__main__", so the guarded code executes.

Check how the file is being run

def main():
    print("started")

print(__name__ == "__main__")
if __name__ == "__main__":
    main()

Expected outputTrue
started

Read arguments like sys.argv

sys.argv is a list of strings with the script name first. A fixed list stands in here.

Read arguments like sys.argv

argv = ["total.py", "4", "6", "10"]
numbers = [int(a) for a in argv[1:]]
print("script:", argv[0])
print("sum:", sum(numbers))

Expected outputscript: total.py
sum: 20

sys.argv always has at least the script name

Even with no arguments, sys.argv holds one item, so index 0 is always safe.

sys.argv always has at least the script name

import sys

print(isinstance(sys.argv, list))
print(len(sys.argv) >= 1)

Expected outputTrue
True

Ask for input when a script runs

Interactive scripts read from the keyboard; the sample input is supplied as stdin.

Ask for input when a script runs

name = input("Name: ")
print("Hello,", name)

Input (stdin) — one line per input() call

Expected outputName: Asha
Hello, Asha

Common mistakes

Running the command from the wrong folder

✗ Wrong

python hello.py

python: can't open file 'hello.py': [Errno 2] No such file or directory

✓ Right

cd path/to/my_project
python hello.py

Use cd to move into the folder containing the file, or give the full path, for example python path/to/hello.py.

Typing the script name inside the Python prompt

✗ Wrong

>>> python hello.py

SyntaxError: invalid syntax

✓ Right

python hello.py

python hello.py is a terminal command. Leave the >>> prompt with exit() and type it in the terminal.

Forgetting to convert command-line arguments

✗ Wrong

import sys
total = sys.argv[1] + sys.argv[2]
print(total)

Running `python add.py 2 3` prints 23, because the arguments are strings.

✓ Right

import sys
total = int(sys.argv[1]) + int(sys.argv[2])
print(total)

sys.argv items are always strings. Convert with int() or float() before doing math.