bash-hackers-wiki/docs/dict/interpreter_directive.md

Interpreter Directive

• shebang

The interpreter directive, usually called shebang, is the character sequence starting with #! (hash, exclamation-point) at the beginning of the very first line of an executable text file on unixoid operating systems.

The program loader of the operating system may use this line to load an interpreter for this file when executed. This makes it a self-executable script.

A shebang will typically look like

#!/bin/bash

Since the line starting with # is a comment for the shell (and some other scripting languages), it's ignored.

Regarding the shebang, there are various, differences between operating systems, including:

• may require a space after #! and before the pathname of the interpreter
• may be able to take arguments for the interpreter
• ...

POSIX(r) doesn't specify the shebang, though in general it's commonly supported by operating systems.

See also

• #!-magic - a nice overview of the differences between various operating systems