# Linux Shell Scripting : Functions &Cases

These were the topics that are covered during this session.

### **Functions**

* Functions refer to **blocks of code** that can be **defined** and **executed** within **scripts** or the **command line.**
    
* These functions allow you to **modularize** your **code**, making it **easier to manage**, **reuse**, and **understand**.
    
* Functions can **accept parameters** and **return** values, just like in programming languages.
    

```bash
#Syntax:
Function_Name () {
    #Statements
}
```

```bash
#Example:
#A function to print "Hello Linux" on terminal
   
#!/bin/bash
#Function Defination
print_Hello () {
    echo "Hello Linux"
}    

#Function Call
print_Hello 
```

---

**Function To Add Two Numbers**

```bash
#!/bin/bash
#Function Defn
addTwoNumbers () {
    echo "Enter the first number:"
    read num1

    echo "Enter the second number:"
    read num2
        
    sum=$(expr $num1 + $num2)
    echo "The addition of ${num1} + ${num2} is : ${sum}"
} 

#Function Call
addTwoNumbers

#Output:
Enter the first number:
10
Enter the second number:
20
The addition of 10 + 20 is : 30
```

---

### **Case**

* In **Linux Shell Scripting**, "**cases**" refer to **switch/case** statements.
    
* These are **control structures** that allow you to perform different actions based on the value of a **variable** or **expression**.
    

```bash
#Syntax:
case ${variable} in
val1)
    #Statement1
;;
val2)
    #Statement2
;;
*)
    #Default Statement
;;
esac
```

```bash
#Example:
#Write a case which when executes, perform some commands in Linux

#!/bin/bash
echo "1 : File Create"
echo "2 : Display IP Address"
echo "3 : Current Directory"
echo "4 : Make Directory"

echo "Enter the input : "
read input

case ${input} in
1)
    echo "Enter the file name : "
    read fileName
    touch /tmp/${filename}
;;
2)
    ifconfig
;;
3)
    pwd
;;
4)
    echo "Enter the directory name : "
    read dirName
    mkdir /tmp/${dirname}
;;
*)
    echo "I can't do it !!"
;;
esac

#Executing the Script...
1 : File Create
2 : Display IP Address
3 : Current Directory
4 : Make Directory
Enter the input :
3
/home/viraj
```

---

This was our last lecture at the **Linux Workshop**. @[Pranav Jambare](@AutomateMaster) (**DevOps @TCS**), delivered an exceptional amount of lectures. His guidance led us through intricate Linux landscapes, **mastering commands** and **scripting**. His **passion** and **support** created a vibrant learning environment, igniting our love for Linux.

**A big thank you to Pranav Sir for an amazing workshop.**

---