How to Write the Bash If-Else Statement in One Line


The Bash if-else statement is a fundamental construct that allows programmers to make decisions based on conditions. While the traditional if-else syntax spans multiple lines, there are cases where writing it in a single line can be more convenient and concise. In this article, we will explore how to write the Bash if-else statement in one line, providing a compact alternative for simple conditional expressions, for illustration I will be using Ubuntu 22.04

How to Write the Bash If-Else Statement in One Line

To write the Bash if-else statement in one line, we can utilize the inline command substitution syntax with the && and || operators. Here’s the general structure of the one-line if-else statement:

[ condition ] && command1 || command2

Explanation

1. Start by enclosing the condition in square brackets []. The condition can be any valid Bash expression that evaluates to either true or false.

2. After the condition, use the && operator, which acts as a logical “AND” operator. It ensures that if the condition is true, the subsequent command (command1) is executed.

3. Following the && operator, use the || operator, which acts as a logical “OR” operator. It executes the alternative command (command2) only if the condition is false.

By using this syntax, we can execute different commands based on the evaluation of a single condition, all in one line.

Example

Let’s consider a simple example to demonstrate the one-line if-else statement. Suppose we want to check if a number is greater than 10 and display a message accordingly:

#!/bin/bash

num=15

[ $num -gt 10 ] && echo "The number is greater than 10" || echo "The number is not greater than 10"

In this example, $num represents the variable containing the number we want to check. If the number is greater than 10, the first command ( echo “The number is greater than 10”) will be executed. Otherwise, if the number is not greater than 10, the second command (echo “The number is not greater than 10”) will be executed.

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Conclusion

Writing the Bash if-else statement in one line using the inline command substitution syntax with && and || operators offer a concise and convenient way to express simple conditional expressions. While it may not be suitable for complex or multi-line conditions, it can be a useful technique for certain scenarios where brevity is valued.

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