In this tutorial, we will discuss a few methods to calculate the sum of the two numbers in a bash script.

Bash – Adding Two Numbers

The expr is the command-line utility used for evaluating mathematical expressions. Bash shell also supports evaluating the mathematical expressions directly. Use the following syntax to calculate the sum of two integers in a shell script:

Using expr command with quotessum=expr $num1 + $num2 Use expr command inclosed with brackets and start with dollar symbol.sum=$(expr $num1 + $num2) This is my preferred way to directly with the shell.sum=$(($num1 + $num2))

In the next few examples, we will discuss calculating the sum of numbers directly with a shell. You can also choose expr command to give the syntax above.

Calculate Sum in Shell Script

Bash shell also evaluates the mathematical expressions directly. You just need to write the expressions enclosed in double brackets with a dollar like $((…)). Write an example shell script to initialize two numeric variables. Then perform an addition operation on both values and store results in the third variable.


Calculate Sum with Command Line Arguments

In this second example, the shell script reads two numbers as command line parameters and performs the addition operation.

Let’s execute this script is a shell

Calculate Sum with Run Time Input

Here is another example of a shell script, which takes input from the user at run time. Then calculate the sum of given numbers and store to a variable and show the results.



In this tutorial, you have learned few methods to add two numbers in a shell script.