Bash If-Else Statement

Bash If-Else Statement

In Bash scripting, the if-else statement allows you to make decisions based on conditions and provide an alternative path if the condition is false.

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Syntax

if [ condition ]; then
    # commands if condition is true
else
    # commands if condition is false
fi

The basic syntax involves using if followed by the condition in square brackets, the commands to execute if the condition is true, and the else statement followed by the commands to execute if the condition is false.

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Example Bash If-Else Statements

Let's look at some examples of how to use if-else statements in Bash:

1. If-Else Statement to Compare Numbers

This script checks if the variable number is equal to 5 and prints a message if it is, otherwise, it prints a different message.

#!/bin/bash

number=5

if [ $number -eq 5 ]; then
    echo "The number is equal to 5."
else
    echo "The number is not equal to 5."
fi

In this script, the variable number is assigned the value 5. The if statement checks if number is equal to 5 using the -eq operator, and if true, prints a message. If the condition is false, the else statement prints a different message.

2. If-Else Statement to Compare Strings

This script checks if the variable string is equal to 'hello' and prints a message if it is, otherwise, it prints a different message.

#!/bin/bash

string="hello"

if [ "$string" = "hello" ]; then
    echo "The string is 'hello'."
else
    echo "The string is not 'hello'."
fi

In this script, the variable string is assigned the value 'hello'. The if statement checks if string is equal to 'hello' using the = operator, and if true, prints a message. If the condition is false, the else statement prints a different message.

3. If-Else Statement to Check if a Number is Greater

This script checks if the variable number is greater than 5 and prints a message if it is, otherwise, it prints a different message.

#!/bin/bash

number=10

if [ $number -gt 5 ]; then
    echo "The number is greater than 5."
else
    echo "The number is not greater than 5."
fi

In this script, the variable number is assigned the value 10. The if statement checks if number is greater than 5 using the -gt operator, and if true, prints a message. If the condition is false, the else statement prints a different message.

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Conclusion

The Bash if-else statement is a crucial tool for conditional operations in shell scripting. Understanding how to use if-else statements can help you create more dynamic and responsive scripts.