5 Useful Ways to Do Arithmetic in Linux Terminal

In this article, we will show you various useful ways of doing arithmetic’s in the Linux terminal. By the end of this article, you will learn basic different practical ways of doing mathematical calculations in the command line.

Let’s get started!

1. Using Bash Shell

The first and easiest way do basic math on the Linux CLI is a using double parenthesis. Here are some examples where we use values stored in variables:

$ ADD=$(( 1 + 2 ))
$ echo $ADD
$ MUL=$(( $ADD * 5 ))
$ echo $MUL
$ SUB=$(( $MUL - 5 ))
$ echo $SUB
$ DIV=$(( $SUB / 2 ))
$ echo $DIV
$ MOD=$(( $DIV % 2 ))
$ echo $MOD
Arithmetic in Linux Bash Shell

Arithmetic in Linux Bash Shell

2. Using expr Command

The expr command evaluates expressions and prints the value of provided expression to standard output. We will look at different ways of using expr for doing simple math, making comparison, incrementing the value of a variable and finding the length of a string.

The following are some examples of doing simple calculations using the expr command. Note that many operators need to be escaped or quoted for shells, for instance the * operator (we will look at more under comparison of expressions).

$ expr 3 + 5
$ expr 15 % 3
$ expr 5 \* 3
$ expr 5 – 3
$ expr 20 / 4
Basic Arithmetic Using expr Command in Linux

Basic Arithmetic Using expr Command in Linux

Next, we will cover how to make comparisons. When an expression evaluates to false, expr will print a value of 0, otherwise it prints 1.

Let’s look at some examples:

$ expr 5 = 3
$ expr 5 = 5
$ expr 8 != 5
$ expr 8 \> 5
$ expr 8 \< 5
$ expr 8 \<= 5
Comparing Arithmetic Expressions in Linux

Comparing Arithmetic Expressions in Linux

You can also use the expr command to increment the value of a variable. Take a look at the following example (in the same way, you can also decrease the value of a variable).

$ NUM=$(( 1 + 2))
$ echo $NUM
$ NUM=$(expr $NUM + 2)
$ echo $NUM
Increment Value of a Variable

Increment Value of a Variable

Let’s also look at how to find the length of a string using:

$ expr length "This is Tecmint.com"
Find Length of a String

Find Length of a String

For more information especially on the meaning of the above operators, see the expr man page:

$ man expr

3. Using bc Command

bc (Basic Calculator) is a command-line utility that provides all features you expect from a simple scientific or financial calculator. It is specifically useful for doing floating point math.

If bc command not installed, you can install it using:

$ sudo apt install bc   #Debian/Ubuntu
$ sudo yum install bc   #RHEL/CentOS
$ sudo dnf install bc   #Fedora 22+

Once installed, you can run it in interactive mode or non-interactively by passing arguments to it – we will look at both case. To run it interactively, type the command bc on command prompt and start doing some math, as shown.

$ bc 
Start bc in Non-Interactive Mode

Start bc in Non-Interactive Mode

The following examples show how to use bc non-interactively on the command-line.

$ echo '3+5' | bc
$ echo '15 % 2' | bc
$ echo '15 / 2' | bc
$ echo '(6 * 2) - 5' | bc
Do Math Using bc in Linux

Do Math Using bc in Linux

The -l flag is used to the default scale (digits after the decimal point) to 20, for example:

$ echo '12/5 | bc'
$ echo '12/5 | bc -l'
Do Math with Floating Numbers

Do Math with Floating Numbers

4. Using Awk Command

Awk is one of the most prominent text-processing programs in GNU/Linux. It supports the addition, subtraction, multiplication, division, and modulus arithmetic operators. It is also useful for doing floating point math.

You can use it to do basic math as shown.

$ awk 'BEGIN { a = 6; b = 2; print "(a + b) = ", (a + b) }'
$ awk 'BEGIN { a = 6; b = 2; print "(a - b) = ", (a - b) }'
$ awk 'BEGIN { a = 6; b = 2; print "(a *  b) = ", (a * b) }'
$ awk 'BEGIN { a = 6; b = 2; print "(a / b) = ", (a / b) }'
$ awk 'BEGIN { a = 6; b = 2; print "(a % b) = ", (a % b) }'
Do Basic Math Using Awk Command

Do Basic Math Using Awk Command

If you are new to Awk, we have a complete series of guides to get you started with learning it: Learn Awk Text Processing Tool.

5. Using factor Command

The factor command is use to decompose an integer into prime factors. For example:

$ factor 10
$ factor 127
$ factor 222
$ factor 110  
Factor a Number in Linux

Factor a Number in Linux

That’s all! In this article, we have explained various useful ways of doing arithmetic’s in the Linux terminal. Feel free to ask any questions or share any thoughts about this article via the feedback form below.

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Aaron Kili

Aaron Kili is a Linux and F.O.S.S enthusiast, an upcoming Linux SysAdmin, web developer, and currently a content creator for TecMint who loves working with computers and strongly believes in sharing knowledge.

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18 Responses

  1. genek says:

    Sorry last example works for pyton3, not python.

    therefore

    python3
    27**(1/3)
    ^d
    

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