Bash if..else Statement

In this tutorial, we will walk you through the basics of the Bash if statement and show you how to use it in your shell scripts.

Decision making is one of the most fundamental concepts of computer programming. Like in any other programming language, if, if..else, if..elif..else and nested if statements in Bash can be used to execute code based on a certain condition.

if Statement

Bash if conditionals can have different forms. The most basic if statement takes the following form:

if TEST-COMMAND
then
  STATEMENTS
fi

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The if statement starts with the if keyword followed by the conditional expression and the then keyword. The statement ends with the fi keyword.

If the TEST-COMMAND evaluates to True, the STATEMENTS gets executed. If TEST-COMMAND returns False, nothing happens, the STATEMENTS gets ignored.

In general, it is a good practice to always indent your code and separate code blocks with blank lines. Most people choose to use either 4-space or 2-space indentation. Indentations and blank lines make your code more readable and organized.

Let’s look at the following example script that checks whether a given number is greater than 10:

#!/bin/bash

echo -n "Enter a number: "
read VAR

if [[ $VAR -gt 10 ]]
then
  echo "The variable is greater than 10."
fi

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Save the code in a file and run it from the command line:

bash test.sh

#bash #statement