Shebang (Unix)

Shebang (Unix)

In computing, a shebang (also called a sha-bang, hashbang, pound-bang, hash-exclam, or hash-pling), when it occurs as the initial two characters on the initial line of a script, is the character sequence consisting of the characters number sign and exclamation mark (that is, "#!").

Under Unix-like operating systems, when a script with a shebang is run as a program, the program loader parses the rest of the script's initial line as an interpreter directive; the specified interpreter program is run instead, passing to it as an argument the path that was initially used when attempting to run the script. For example, if a script is named with the path "path/to/script", and it starts with the following line:

#!/bin/sh

then the program loader is instructed to run the program "/bin/sh" instead (usually this is the Bourne shell or a compatible shell), passing "path/to/script" as the first argument.

The shebang line is usually ignored by the interpreter because the "#" character is a comment marker in many scripting languages; some language interpreters that do not use the hash mark to begin comments (such as Scheme) still may ignore the shebang line in recognition of its purpose.