Linux Shell Scripting Cookbook, Second Edition - Second Edition

Math with the shell

Arithmetic operations are an essential requirement for every programming language. In this recipe, we will explore various methods for performing arithmetic operations in shell.

Getting ready

The Bash shell environment can perform basic arithmetic operations using the commands let, (( )), and []. The two utilities expr and bc are also very helpful in performing advanced operations.

How to do it...

1. A numeric value can be assigned as a regular variable assignment, which is stored as a string. However, we use methods to manipulate as numbers:

   #!/bin/bash
   no1=4;
   no2=5;
   

2. The let command can be used to perform basic operations directly. While using let, we use variable names without the $ prefix, for example:

   let result=no1+no2
   echo $result ...