Shebang / Hashbang
What is Shebang or Hashbang?
In computing, a shebang aka hashbang is a special character sequence consisting of a hash sign (#) and an exclamation mark (!) at the beginning of a script like this: #!.
In UNIX / Linux operating systems, #! syntax used at the beginning of the script is to indicate an interpreter for execution. The shebang i.e. #! takes an argument which is always the path to the interpreter that will be used to interpret the script itself.
Thus, the syntax is as follows #! interpreter [argument] in which interpreter is an absolute path to an executable program/interpreter followed by the “optional” argument in case the interpreter requires it. For instance, #!/bin/sh where the program loader is instructed to run the program /bin/sh.
Note: Many scripting languages use the # character to indicate the beginning of a comment line that should be ignored by the interpreter. However, the shebang is a special exception to this rule.
Examples
#!/bin/sh– Execute the file using the Bourne shell, or a compatible shell, with path /bin/sh.#!/bin/bash– Execute the file using the Bash shell.#!/usr/bin/python– Execute using Python by looking up the path to the Python interpreter.#!/bin/false– Do nothing, but return a non-zero exit status, indicating failure.
