Python Commands Cheat Sheet: Terminal, pip, venv, REPL, and Python Syntax

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Python commands depend on where you type them. Terminal commands launch Python, run scripts, create virtual environments, and manage packages. Python expressions and statements run inside the Python REPL or a .py file. This cheat sheet separates those contexts and includes macOS/Linux, Windows Command Prompt, and PowerShell examples.

Examples target modern Python 3. As of August 18, 2026, the official documentation covers Python 3.14.6, released June 10, 2026. Executable names, shell quoting, package availability, and some options can vary by operating system, shell, installation method, and Python version.

Quick-reference Python commands

Task	macOS/Linux	Windows
Check Python	python3 --version	py --version
Start the REPL	python3	py
Run a file	python3 script.py	py script.py
Create an environment	python3 -m venv .venv	py -m venv .venv
Install a package	python3 -m pip install package	py -m pip install package
List packages	python3 -m pip list	py -m pip list

Once a virtual environment is activated, use python and python -m pip so both commands refer to that environment.

1. Terminal commands for Python

Check whether Python is installed

python --version
python3 --version

On Windows, also try the Python launcher:

py --version

To display detailed interpreter information:

python -c "import sys; print(sys.version)"

To find the executable selected by your shell:

# macOS/Linux
which python
which python3

# Windows
where python
where py

python, python3, and py are not interchangeable on every computer. python may point to Python 3, another installation, or nothing at all. python3 is common on Unix-like systems, while py is the Windows Python launcher and can select a particular installed version.

Start and exit the Python REPL

The interactive interpreter, commonly called the REPL, lets you enter Python one line at a time:

# macOS/Linux
python3

# Windows
py

Inside the REPL, exit with:

exit()
quit()

Keyboard alternatives are Ctrl-D on macOS/Linux and Ctrl-Z followed by Enter on Windows. These are terminal control sequences, not Python statements. See the official command-line documentation.

Run a Python file

python script.py
python3 script.py
py script.py

Use the form that matches your installation. Pass command-line arguments after the filename:

python script.py first second

Read them in Python with:

import sys

print(sys.argv)

Run a module with -m

python -m module_name
python -m package.module

-m asks the selected interpreter to locate and run a module. This is especially useful for package-aware execution and for built-in tools such as pip, unittest, and http.server.

Execute a short command with -c

python -c "print('Hello, Python')"
python -c "import sys; print(sys.version)"
python -c "import os; print(os.getcwd())"
python -c "from pathlib import Path; print(Path.cwd())"

Quoting rules differ between Bash, zsh, PowerShell, and Command Prompt, so a command copied from another operating system may need adjustment.

Run code from standard input

echo "print('Hello')" | python
printf "print(2 + 2)n" | python

This is mainly useful in Unix-style shell pipelines and is less important for beginners.

Useful interpreter options

Command	Purpose
python --help	Show interpreter help
python --version	Show the Python version
python -c "..."	Execute a short command
python -m module	Run a module as a script
python -i script.py	Run a script, then stay interactive
python -B script.py	Do not write bytecode files
python -u script.py	Use unbuffered standard output and error
python -O script.py	Enable basic optimization mode
python -X ...	Select implementation-specific options
python -W ...	Configure warning behavior

The last five options are operational tools rather than everyday beginner commands. Options can change between Python versions; consult the version-specific command-line reference.

2. Virtual-environment commands

A virtual environment isolates a project’s packages from other projects and from the operating system’s Python installation. Python’s built-in venv module is the standard-library choice for modern Python 3 projects.

Create an environment

# macOS/Linux
mkdir my-project
cd my-project
python3 -m venv .venv

# Windows PowerShell
mkdir my-project
cd my-project
py -m venv .venv

.venv is a conventional project-local directory name. Add it to Git’s ignore file:

.venv/

Activate it

# macOS/Linux with Bash or zsh
source .venv/bin/activate

# Windows Command Prompt
.venvScriptsactivate

# Windows PowerShell
.venvScriptsActivate.ps1

Fish, csh, and other shells use different activation scripts. Activation changes the current shell’s PATH; it is convenient but not required. You can call the environment’s interpreter directly:

# macOS/Linux
.venv/bin/python app.py
.venv/bin/python -m pip install requests

# Windows PowerShell
.venvScriptspython.exe app.py
.venvScriptspython.exe -m pip install requests

Verify the active interpreter

# macOS/Linux
which python
python -c "import sys; print(sys.executable)"

# Windows
where python
python -c "import sys; print(sys.executable)"

The path should contain .venv/bin/python on Unix-like systems or .venvScriptspython.exe on Windows.

Deactivate, reactivate, or recreate

deactivate

To use the environment again in a new terminal, activate it again. If an environment is corrupted, deactivate it, remove the .venv directory, and recreate it with python -m venv .venv. Do not delete it while its interpreter is running.

3. pip package commands

The safest general pattern is:

python -m pip install package

This binds pip to the interpreter selected by python. On systems where Python 3 is named separately, use python3 -m pip; on Windows, py -m pip or a version-specific launcher such as py -3.14 -m pip.

Install and upgrade packages

python -m pip install requests
python -m pip install requests flask pandas
python -m pip install requests==2.32.4
python -m pip install "requests>=2.32"
python -m pip install --upgrade requests

Quote version constraints because shells can interpret characters such as > and <.

Install from a requirements file

python -m pip install -r requirements.txt

Inspect installed packages

python -m pip list
python -m pip show requests
python -m pip freeze
python -m pip check
python -m pip inspect

• list displays installed packages.
• show displays metadata and installation details for one package.
• freeze prints installed distributions and versions.
• check reports incompatible dependency requirements.
• inspect produces environment metadata for deeper inspection.

Uninstall packages and upgrade pip

python -m pip uninstall requests
python -m pip install --upgrade pip

Do not upgrade every package indiscriminately: newer versions can introduce incompatibilities. For a project, define and review dependency constraints deliberately.

Create a requirements snapshot

python -m pip freeze > requirements.txt
python -m pip install -r requirements.txt

pip freeze records what is installed in the current environment. It can include transitive dependencies and unrelated packages, so it is a useful snapshot but not always an ideal direct-dependency manifest. Platform-specific dependencies may also require different specifications.

Less frequent pip commands

python -m pip cache info
python -m pip config list
python -m pip debug

These help inspect pip’s cache, configuration, and environment. The pip command reference contains the current command inventory. Older guides may recommend pip search; do not treat it as a universally reliable discovery workflow. Direct package indexes and project documentation are generally better starting points.

4. When pip is missing or installs into the wrong place

If pip is unavailable, try:

python -m ensurepip --default-pip
python -m pip --version

This is not the correct fix for every operating-system-managed Python installation. Some Linux distributions package Python and pip components separately. Prefer a virtual environment or the distribution’s package manager, and do not use sudo pip install ... as a universal solution.

When a script reports ModuleNotFoundError after a successful installation, compare the interpreter and pip paths:

python -c "import sys; print(sys.executable)"
python -m pip --version

Both should refer to the same installation or virtual environment. Also remember that a package’s pip distribution name and its Python import name are not guaranteed to match.

5. Python REPL commands and inspection

The following are Python functions, not terminal commands. Type them after starting the REPL or place them in a .py file:

import math
help()
help(math)
help(math.sqrt)
dir(math)
exit()
quit()

help() opens Python’s built-in documentation system. dir() lists attributes available on an object or module.

To see where an installed module came from:

import requests
print(requests.__file__)

6. Essential Python built-ins

Function	Example	Purpose
print()	print("Hi")	Display output
input()	name = input("Name: ")	Read text input
len()	len(items)	Count items
type()	type(value)	Get an object’s type
isinstance()	isinstance(x, int)	Test type membership
int()	int("42")	Convert to an integer
float()	float("3.14")	Convert to floating point
str()	str(42)	Convert to a string
list()	list(range(3))	Create a list
dict()	dict(a=1)	Create a dictionary
set()	set(values)	Create a set
range()	range(5)	Represent an integer sequence
enumerate()	enumerate(items)	Add indexes during iteration
zip()	zip(names, scores)	Iterate over sequences together
sorted()	sorted(items)	Return sorted data
sum()	sum(numbers)	Add numeric values
min(), max()	max(scores)	Find extreme values
abs()	abs(-4)	Return absolute value
round()	round(3.14159, 2)	Round a number
open()	open("data.txt")	Open a file
help(), dir()	help(str)	Read documentation or inspect attributes

See the Python built-in function reference for version-specific behavior.

7. Python language constructs

if, for, while, def, and class are Python language constructs, not commands typed directly into your operating-system shell.

Variables and comments

name = "Ada"
count = 3

# This is a comment

Conditionals and loops

if score >= 60:
    print("Pass")
else:
    print("Try again")

for item in items:
    print(item)

while count > 0:
    count -= 1

Functions and exceptions

def greet(name):
    return f"Hello, {name}"

try:
    value = int(user_input)
except ValueError:
    print("Enter a whole number")

Context managers and comprehensions

with open("data.txt", encoding="utf-8") as file:
    text = file.read()

squares = [n * n for n in range(10)]

8. Files and directories with pathlib

pathlib is the preferred modern standard-library interface for many path operations:

from pathlib import Path

path = Path("data.txt")
print(path.exists())
print(path.name)
print(path.suffix)

text = Path("input.txt").read_text(encoding="utf-8")
Path("output.txt").write_text("Donen", encoding="utf-8")

for path in Path(".").iterdir():
    print(path)

Older code often uses os.path; it remains valid, but new code can usually use pathlib for clearer path handling.

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9. Validation, testing, and standard-library tools

Check syntax without running a file

python -m py_compile script.py
python -m compileall .

The first command compiles one file. The second searches a directory tree for Python files to compile.

Run tests

python -m unittest

unittest is included in Python’s standard library. pytest is third-party:

python -m pip install pytest
python -m pytest

Start a local web server

python -m http.server
python -m http.server 8000

This serves the current directory for local testing. Do not expose it to an untrusted network or use it as a production web server.

Use built-in modules from the terminal

python -m json.tool data.json
python -m zipfile -l archive.zip
python -m http.server 8000
python -m calendar

These examples demonstrate the general python -m module mechanism: a module can provide a command-line interface even when it is primarily a Python library.

10. Run a script as an executable

On Unix-like systems, add a shebang at the top of the file:

#!/usr/bin/env python3

Then make it executable and run it:

chmod +x script.py
./script.py

This depends on file permissions, the shell, and the installed interpreter. Windows generally uses file associations or an explicit command such as py script.py.

11. A practical project workflow

macOS/Linux

mkdir my-project
cd my-project
python3 -m venv .venv
source .venv/bin/activate
python -m pip install --upgrade pip
python -m pip install requests
python -m pip freeze > requirements.txt
python app.py
deactivate

Windows PowerShell

mkdir my-project
cd my-project
py -m venv .venv
.venvScriptsActivate.ps1
python -m pip install --upgrade pip
python -m pip install requests
python -m pip freeze > requirements.txt
python app.py
deactivate

Upgrading pip is a common maintenance step, not a mandatory prerequisite before every installation.

12. Troubleshooting common errors

“python is not recognized” or “command not found”

Try the alternative executable name:

python3 --version
py --version

If none works, install Python through an appropriate official or operating-system channel and ensure the executable is available to your shell. The Python downloads page provides official installers, although some organizations require an approved distribution channel.

PowerShell blocks activation

Rather than casually changing a machine-wide execution policy, bypass activation and call the environment directly:

.venvScriptspython.exe app.py
.venvScriptspython.exe -m pip install requests

“No module named venv”

Some operating-system distributions package the venv component separately. Install the matching package through that distribution’s package manager, then retry python3 -m venv .venv. There is no single package name that applies to every Linux distribution.

“No module named pip”

Try python -m ensurepip --default-pip, but check your operating system’s Python packaging policy first. A virtual environment or distribution-specific package may be the appropriate solution.

pip and Python use different installations

Do not switch randomly between pip, pip3, and multiple Python commands. Use:

python -c "import sys; print(sys.executable)"
python -m pip --version

Then install with that same interpreter.

Permission errors

Install inside a virtual environment. A per-user installation may be appropriate in some cases:

python -m pip install --user package

--user is not a replacement for a virtual environment in every situation, and some managed environments prohibit user-site installation. Avoid treating sudo pip install as the default repair.

The script works in an IDE but not the terminal

The IDE may use a different interpreter. Compare its selected interpreter with:

python -c "import sys; print(sys.executable)"

Also check the IDE’s project interpreter and the terminal’s virtual-environment state. Opening an integrated terminal does not guarantee that the project environment is selected.

Printable condensed reference

Need to	Command
Check version	python --version
Locate interpreter	python -c "import sys; print(sys.executable)"
Run a file	python script.py
Run a module	python -m module
Run a one-liner	python -c "..."
Create venv	python -m venv .venv
Activate POSIX	source .venv/bin/activate
Activate Windows CMD	.venvScriptsactivate
Activate PowerShell	.venvScriptsActivate.ps1
Install package	python -m pip install package
Install requirements	python -m pip install -r requirements.txt
List packages	python -m pip list
Check dependencies	python -m pip check
Export snapshot	python -m pip freeze > requirements.txt
Compile-check	python -m py_compile script.py
Run tests	python -m unittest
Serve local files	python -m http.server 8000
Leave venv or REPL	deactivate or exit()

For the complete, current syntax and option details, use the official Python 3 documentation, the Python installation guide, and the Python Packaging User Guide.

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