Executables in Linux
If you are familiar with Windows, then you know that there is a type of file that we call Executable. It uses .exe as the file format, and you can run such a file by double-clicking on it. You can also run such a file by typing its name inside the command line and hitting Enter.
When you enter the world of Linux, you may realize that there is no fixed executable format. Long-time Linux users know that in Linux, you can run any kind of file as an executable so long as its executable flag has been set. When you run the ls command in a folder, the files which can be executed appear green, and you can type dot, slash, and then the name of that file and hit Enter to run that file, as seen in this picture:
When the green file ‘greet ‘ in the above picture was run, it executed some Linux shell commands. In fact, the file greet is a text file containing one line of code:
echo Hello, World!
By default, any text file with lines of Linux shell commands inside it can be turned into an executable file by setting its Executable Flag, which is done with the command:
chmod +x <filename>
But sometimes, you want to run a text file which has commands in Python, Perl, Ruby, Javascript, etc. languages instead of Linux Shellscript. That is where the Shebang comes into the picture.
Using Shebang in Linux
Imagine you’re working on a Linux computer and have a recipe with instructions written in different languages. But your computer only understands English! That’s where the shebang comes in. It’s like a tiny label at the beginning of the recipe that tells your computer which “translator” to use for each language. This magic symbol, #!, followed by the interpreter’s path, is the key to understanding and running all sorts of scripts on your system.