Conditional statements in shell script

Continuation of “https://samhith1053.medium.com/operators-in-shell-script-fd47b77be80f”

If statement:

Structure

if [ condition ]; then

Statements to be done if the condition evaluated is true

fi

One practical example for simple if statement is

Printing the maximum of 2 numbers:

The code snippet is attached below:

Output:

If -else statement:

The above program we can modify a bit

We are checking num1 is greater than num2 if the condition is evaluated false 1st if block will not get executed and checking 2nd if block so instead of that if the condition of 1st if block is false we can tell directly that second number is greater

Output:

If else if statement:

The structure of if and else if statement is :

if [ condition ]

then

statements

elif [condition1]

then

Statements in elif

elif [ condition2 ]

then

Statements in elif

else

Statements in else

fi

There can be any number of elif statements

Consider the below example checking if the number is divisible by 10 or divisible by 2 or divisible by 5 or neither of 2 nor 5

Output:

Nested -if statements:

Structure of nested if

if [ condition 1 ]; then

Statements

if [ condition 2 ]; then

Statements in the nested if block — — condition1 and condition2 both are true

else

If the condition 2 is false innermost else statement executed — condition 1 is true but condition 2 is false

fi

else

Statements if the condition 1 is false

Let’s consider a task maximum of 2 numbers from the command line arguments

Snippet is given below:

Output: