Master Linux Command‑Line Calculators: bc, calc, expr, gcalccmd & qalc

Linux users often need to perform calculations directly from the terminal. This article presents five command‑line calculators— bc, calc, expr, gcalccmd, and qalc —covering their installation on major distributions and basic usage examples.

1. Using bc

bc

is an arbitrary‑precision calculator with a C‑like syntax. It is pre‑installed on most Linux systems; otherwise install it with:

Fedora: $ sudo dnf install bc Debian/Ubuntu: $ sudo apt install bc Arch: $ sudo pacman -S bc RHEL/CentOS: $ sudo yum install bc openSUSE Leap: $ sudo zypper install bc Basic arithmetic works directly:

<code>$ bc bc 1.07.1 1+2 3 10-5 5 2*5 10 10/2 5 13/5 2 (2+4)*5-5 25 2^3 8 8%3 2 quit</code>

Use the -l option to load the standard math library for floating‑point results, e.g., $ bc -l yields 3/5 → .60000000000000000000.

2. Using calc

calc

provides arbitrary‑precision calculations with a simple interactive prompt. Install it using the same commands as bc. Example session:

<code>$ calc C-style arbitrary precision calculator (version 2.12.7.1) ; 5+1 6 ; 5-1 4 ; 5*2 10 ; 10/2 5 ; 13/5 2.6 ; 13%5 3 ; 2^4 16 ; 9^0.5 3 ; quit</code>

Non‑interactive use: $ calc 3/5 → 0.6.

3. Using expr

expr

is part of the coreutils package, so no installation is required. It evaluates integer expressions; spaces are required between operands and operators.

$ expr 2 + 3
5
$ expr 6 - 2
4
$ expr 3 \* 4
12
$ expr 15 / 3
5

Incorrect spacing (e.g., expr 2+3) results in the literal string being echoed.

4. Using gcalccmd

gcalccmd

is the console version of GNOME Calculator, typically pre‑installed on GNOME desktops. It supports standard arithmetic and functions like sqrt():

<code>$ gcalccmd > 5+1 6 > sqrt(16) 4 > 3/5 0.6 > quit</code>

5. Using qalc (Qalculate)

Qalculate is a powerful cross‑platform calculator offering unit conversion, currency conversion, arbitrary precision, and symbolic math. Install the library package:

Fedora: $ sudo dnf install libqalculate Debian/Ubuntu: $ sudo apt install libqalculate Arch: $ sudo pacman -S libqalculate RHEL/CentOS: $ sudo yum install libqalculate openSUSE Leap: $ sudo zypper install libqalculate Example interactive session:

<code>$ qalc > 5+1 5 + 1 = 6 > ans*2 ans * 2 = 12 > 1 USD to INR 1 * dollar = approx. INR 69.638581 > quit</code>

6. Shell built‑ins for simple calculations

For quick arithmetic, Bash arithmetic expansion can be used:

$ echo $((5+5))
10

Data processing can be done with awk:

$ cat data | awk '{sum+=$1} END {print "Sum = ", sum}'

This collection equips Linux users with a range of tools—from basic integer math to advanced scientific and unit calculations—usable directly from the command line.