What is a shebang?

When you see #! at the start of a file, it's referred to as a "shebang" or "hashbang." This is particularly used at the beginning of a script file that's meant to be run in a Unix-like environment (like Linux or macOS).

This line is not necessary, so if you don't want to learn about it or use it, delete it.

Here’s how it works and why it's useful:

  1. Purpose: The shebang line in a script tells the system which interpreter to use to execute the file. An interpreter is a program that reads and executes code.

  2. Syntax: It starts with #! followed by the path to the interpreter. For example, if you have a Python script, the shebang line might look like #!/usr/bin/python3. This tells the system to use the Python interpreter located at /usr/bin/python3 to run the script.

  3. Practical Use: When you make a script executable (using a command like chmod +x yourscript) and then run it directly from the terminal, the operating system looks at the shebang line to know which interpreter to launch to run the script. This way, you don’t have to type python3 yourscript every time; instead, you can just type ./yourscript, making it simpler and cleaner, especially in automation scripts.

For a mechanical engineer who might be new to coding, think of it like a blueprint specification: just as you'd specify which material or tool to use for a particular component in a blueprint, the shebang specifies which tool (interpreter) should be used to execute the script. It ensures that the script is run with the correct settings right from the start, avoiding errors or unexpected behaviors.