> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/python/cpython/llms.txt
> Use this file to discover all available pages before exploring further.

# Using the Python Interpreter

> Learn how to invoke and use the Python interpreter

The Python interpreter is your gateway to running Python code. This guide covers how to start the interpreter, pass arguments, and understand its interactive mode.

## Invoking the Interpreter

The Python interpreter is usually installed as `/usr/local/bin/python3.15` on Unix systems. You can start it by typing:

```bash theme={null}
python3.15
```

On Windows, if you've installed Python from the Microsoft Store, use:

```bash theme={null}
python
```

Or with the py launcher:

```bash theme={null}
py
```

### Exiting the Interpreter

To exit the interpreter:

* **Unix/Linux**: Press `Ctrl-D`
* **Windows**: Press `Ctrl-Z` then Enter
* **All platforms**: Type `quit()`

### Command Line Editing

The interpreter supports:

* Interactive line editing
* History substitution
* Code completion on most systems

Test if command line editing works by typing a word and pressing the Left arrow key. If the cursor moves, editing is enabled.

## Running Python Scripts

You can run Python code in several ways:

### Execute a File

```bash theme={null}
python script.py
```

### Execute a Command

```bash theme={null}
python -c "print('Hello, World!')"
```

<Warning>
  Since Python statements often contain spaces or special characters, quote the entire command.
</Warning>

### Execute a Module

```bash theme={null}
python -m http.server
```

### Interactive Mode After Script

Run a script and then enter interactive mode:

```bash theme={null}
python -i script.py
```

## Argument Passing

When you run a Python script, command-line arguments are available in `sys.argv`:

```python theme={null}
import sys

print("Script name:", sys.argv[0])
print("Arguments:", sys.argv[1:])
```

**Special cases:**

* No script: `sys.argv[0]` is an empty string
* With `-c`: `sys.argv[0]` is `'-c'`
* With `-m`: `sys.argv[0]` is the full module name

## Interactive Mode

When you start the interpreter without a script, it enters interactive mode:

```python theme={null}
$ python3.15
Python 3.15 (default, May 7 2025, 15:46:04)
[GCC 10.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>>
```

### Prompts

* **Primary prompt** (`>>>`): Ready for a new statement
* **Secondary prompt** (`...`): Continuation of a multi-line statement

```python theme={null}
>>> the_world_is_flat = True
>>> if the_world_is_flat:
...     print("Be careful not to fall off!")
...
Be careful not to fall off!
```

## Source Code Encoding

By default, Python source files are treated as UTF-8 encoded. This allows using characters from most languages:

```python theme={null}
# UTF-8 is the default
name = "François"
greeting = "你好"
```

### Declaring a Different Encoding

To use a different encoding, add a special comment as the **first line**:

```python theme={null}
# -*- coding: encoding -*-
```

Example for Windows-1252:

```python theme={null}
# -*- coding: cp1252 -*-
```

### With a Shebang Line

If your script starts with a shebang, the encoding goes on the **second line**:

```python theme={null}
#!/usr/bin/env python3
# -*- coding: cp1252 -*-
```

<Info>
  For portable code, stick to UTF-8 encoding and ASCII identifiers even if you can use non-ASCII characters in strings and comments.
</Info>

## Next Steps

Now that you know how to invoke the interpreter, let's explore Python basics in the [Introduction to Python](/tutorial/introduction).