Lecture # 3 - Basic Shell Script

Shebang:

All the shell script files have the same extension that is .sh . There can be multiple shells installed in an operating system. The operating system will know which shell to use to execute the shell script using shebang.

• For sh:#!/bin/sh

• For bash:#!/bin/bash

Basics of a Shell Script:

• Shebang Line (The first line of a shell script should start with a shebang)

• Comments

• Commands

• Variables

• Control Structures

• Functions

• Exit Status

• File Permissions

• Executing the Script

Operators:

• Relational Operators:

  These operators works only for numeric values.

• String Operators:

  

Basic Shell Script:

#!/bin/bash
echo "This is my first Shell Script."

• Create a file with .sh extension.

• 

  Open the file in any editor and write the script.

• 

  Give execute permission to the file using sudo chmod +x [script-name].sh .

• 

  Execute your script using ./[script-name].sh .

  

Taking input from the user:

#!/bin/bash
echo "Please enter your name:"
read name
echo "Hi, $name!"