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
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:
#!and before the pathname of the interpreter
POSIX® doesn't specify the shebang, though in general it's commonly supported by operating systems.