003_Shebang.md

Shebang (#!)

BASH STARTUP SCRIPT --- HOME --- WRITING FIRST SCRIPT

#! syntax is used in scripts to indicate an interpreter for execution under UNIX/Linux Operating System.

#!/bin/bash

#!/usr/bin/env bash

Starting script with #!

1. #! is called Shebang or bang line.
2. It is nothing but absolute path of BASH.
3. It conists of #! followed by interpreter's path.
4. All script run on the specific interpretor.
5. Almost all scripts begin with #!/bin/bash.
6. Shebang was introduced Dennis Ritchie.

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#!/bin/sh -> Used for system boot script.

#!/bin/bash -> Used for typical scripts.

#!/usr/bin/env bash -> Run bash in modified environment. Makes BASH script portable. Uses whichever bash executable appear first in user's PATH.