Bash Decrement

In Bash scripting, decrementing a variable is a common operation used when working with loops, counters, or iterative tasks. The decrement operation reduces the value of a variable by one. Bash offers several ways to perform this operation using arithmetic expansion, the let command, and the expr command.

In this tutorial, we will explore different methods of decrementing a variable in Bash with detailed examples and best practices.

Bash Decrement is one of the basic Arithmetic Operations in Bash scripting.

Syntax for Decrement in Bash

There are several ways to decrement a variable in Bash. Here are the common approaches:

Decrement using Arithmetic Expansion:

</>
Copy
variable=$((variable - 1))

Decrement using let:

</>
Copy
let variable-=1

Decrement using expr:

</>
Copy
variable=$(expr $variable - 1)

Examples of Decrement in Bash

Let’s go through different examples to see how decrementing a variable can be done using these methods.

1 Bash Decrement Using Arithmetic Expansion

Arithmetic expansion is the most efficient way to decrement a variable in Bash. It uses the $((...)) syntax to perform the arithmetic operation.

example.sh

</>
Copy
#!/bin/bash

# Initialize a variable
count=10

# Decrement the variable
count=$((count - 1))

# Display the result
echo "The value of count after decrementing is $count."

Output