A shebang (also called a hashbang) is the first line in a script file that tells the operating system which interpreter to use to run the file. In Python scripts, adding a shebang line is optional but useful, especially when running scripts on Unix-like systems (Linux, macOS).
Why Use a Shebang in Python?
It lets you execute the script directly from the terminal without explicitly typing python script.py.
Instead of:
python3 myscript.py
You can run:
./myscript.py
...assuming the file is executable.
Common Shebang Forms for Python
These are the common shebang formats in Python scripts, each with different levels of portability and usage scenarios.
1. Recommended (Portable)
#!/usr/bin/env python3
- Uses the environment to locate the Python interpreter.
- Works across systems where python3 is properly configured in the user's PATH.
- Best for portability and virtual environments.
Also Read: Python Performance Tips for Scalable Applications
2. Fixed Path (Less Portable)
#!/usr/bin/python3
- Specifies the absolute path to the Python binary.
- Works reliably if you know the interpreter path.
- Not ideal for cross-platform or shared codebases.
| Shebang |
Use Case |
Portability |
| #!/usr/bin/env python3 |
Best for most use cases |
✅ High |
| #!/usr/bin/python3 |
Hardcoded path, controlled systems |
⚠️ Medium |
| (No shebang) |
When importing or running in IDE |
🚫 N/A |
When to Include It?
Add a shebang when:
- You're writing scripts for Unix/Linux/macOS environments.
- You want users to run the script like a command (./myscript.py).
- You plan to distribute the script or use it in cron jobs or shell automation.
You can skip it when:
- Your script is intended to be imported as a module.
- It's only run manually via an IDE or python script.py.
Tip
Don’t forget to make your Python script executable:
chmod +x myscript.py
Also, avoid using just #!/usr/bin/env python, as python could point to Python 2 on some systems. Prefer python3. 
