Jump into the Linux world

Hi guys! I hope you all read my previous blog.

So, today we covered the above topics.

Pranav Jambare.

#learnwithpra9

Functions

• In Linux shell scripting, a function is a self-contained block of code that performs a specific task or set of tasks.

• Its main goal is to break down a complicated procedure into simpler subroutines that can subsequently be used to accomplish the more complex routine.

• Syntax:

    function-name()
    {
        statement
    }
  

• Example:

    #!/bin/bash
  
    create_user ()
    {
        echo "Enter user name:"
        read username
        useradd ${username}
        echo "User is created: ${uesrname}"
    }
  
    crete_uesr
  

• Output:

    Enter uesr name:
    SoulTroy
    User is created: SoulTroy
  

Case Statement

• A case statement in bash scripts is used when a decision has to be made against multiple choices. In other words, it is useful when an expression can have multiple values.

• It allows you to perform different actions depending on the value of a single variable, reducing the need for multiple if-else statements.

• In simple words, they don’t require any break statement that is mandatory to be used in C to stop searching for a pattern further.

• Syntax:

    case {expression} in
    Pattern_Case_1)
        #Statements to be executed
    ;;
    Pattern_Case_2)
        #Statements to be executed
    ;;
    Pattern_Case_N)
        #Statements to be executed
    ;;
    *)
        #Statements to be executed
    ;;
    esac
  

• Example:

    #!/bim/bash
  
     echo "Choose the color: "
     echo "1) Red"
     echo "2) Green"
     echo "3) Blue"
     read colour
  
    case {colour} in
    Black)
        echo "You have choosen the Black colour..!!"
    ;;
    Red)
        echo "You have choosen the Red colour..!!"
    ;;
    Blue)
        echo "You have choosen the Blue colour..!!"
    ;;
    *)
        echo "The colour you choose is unavailable.."
    ;;
    esac
  

• Output:

    Choose the color:
    1)Black
    2)Red
    3)Blue
    Black
    You have choosen the Black colour..!!