This sequence of characters (#!) is called shebang and is used to tell the operating system which interpreter to use to parse the rest of the file.
How to Check if a String Contains a Substring in Bash
One of the most common operations when working with strings in Bash is to determine whether or not a string contains another string. In this article, we will show you several ways to check if a string contains a substring.
Bash Source Command
The source command reads and executes commands from the file specified as its argument in the current shell environment. Source is a shell builtin in Bash and other popular shells used in Linux and UNIX operating systems.
Bash if..else Statement
Decision making is one of the most fundamental concepts of computer programming. Like in any other programming language, if, if..else, if..elif..else and nested if statements in Bash can be used to execute code based on a certain condition.