A Python script is simply a file containing Python code. Typically, these files have a .py extension and consist of a series of statements and functions that perform tasks when executed. Python scripts can be as simple as a few lines of code or as complex as thousands of lines in large projects. Running a Python script means executing the instructions in the script from start to finish, typically using a Python interpreter.
Before running a Python script, you first need to create one. You can use any text editor or an Integrated Development Environment (IDE) to write your Python code.
Call it something like hello.py and add the following code. The file should be saved with a .py extension.
print("Hello, World!") The above code is a simple Python script that prints "Hello, World!" to the console.
Installing Python
Before running Python scripts, you need to ensure that Python is installed on your system.
Step 1: Download Python
Visit the official Python website at python.org and download the latest version of Python. Make sure to select the correct version for your operating system (Windows, macOS, or Linux).
Step 2: Run the Installer (Windows/macOS)
Windows: Run the downloaded .exe file. During installation, make sure to check the box that says "Add Python to PATH." This ensures that Python is accessible from the command line.
macOS: Run the downloaded .pkg file and follow the installation prompts.
Step 3: Verify the Installation
After installation, verify that Python is installed correctly by opening a command line (Command Prompt on Windows or Terminal on macOS/Linux) and typing:
python --version You should see the installed Python version number. If you see something like Python 3.x.x, then Python is installed correctly.
Step 4: Install pip (Optional but Recommended)
pip is a package manager for Python that allows you to install additional libraries and tools. It usually comes bundled with Python, but if it's not installed, you can install it manually by following instructions from the pip documentation.
Running a Python Script in the Command Line
One of the most common ways to run a Python script is via the command line or terminal.
Step 1: Open the Command Line
First, open the command line interface. On Windows, you can open Command Prompt or PowerShell. On macOS and Linux, open the Terminal.
Step 2: Navigate to Your Script’s Directory
Use the cd (change directory) command to navigate to the directory where your Python script is located.
Example for macOS/Linux:
cd /Users/YourUsername/Documents/PythonScripts Example for Windows:
cd C:\Users\YourUsername\Documents\PythonScripts Step 3: Run the Script
To run the script, type python followed by the script's filename.
python hello.py If Python is installed correctly and the script is in the correct directory, you should see the output:
Et voilà, that's all there is to it!
Common Issues When Running Python Scripts
When running Python scripts, especially as a beginner, you may encounter a few common issues:
1. Python Not Found
If you get an error like python: command not found, it means Python is not installed or not added to your system's PATH. Ensure Python is installed and that the PATH is set up correctly.
2. Incorrect Directory
If your script file is not in the current directory, you'll get a FileNotFoundError. Ensure you are in the correct directory or provide the full path to the script.
3. Syntax Errors
Syntax errors are common when writing Python code. Python will halt execution and provide an error message indicating where the problem occurred. Carefully review your code and correct any issues.
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