Math

• https://www.gnu.org/software/bash/manual/bash.html#Arithmetic-Expansion
• https://www.gnu.org/software/bash/manual/bash.html#Shell-Arithmetic

Simple calculation with integers

$ echo "$(( 4 / 2 ))"
2

But:

Evaluation is done in fixed-width integers

$ echo "$(( 2 / 3 ))"
0

Working with Floats means moving to another language such as awk or perl, or, more traditionally, bc.

$ echo $(perl -e '{printf "%.2f", 2/3}')
0.67
$ printf  "%.2f\n" $(bc --mathlib <<< '2/3')
0.67