How to do exponentiation in bash

Question

I try

echo 10**2 

it prints 10**2. How to make it work?

Answer 1

You can do:

let var=10**2   # sets var to 100.

or even better and recommended way:

var=$((10**2))  # sets var to 100.

If you just want to print the expression result you can do:

echo $((10**2)) # prints 100.

For large numbers you might want to use the exponentiation operator of bc as:

bash:$ echo 2^100 | bc
1267650600228229401496703205376

If you want to store the above result in a variable you can again use the $(()) syntax as:

 var=$((echo 2^100 | bc))  

Answer 2

various ways

Bash

x=2
echo $((x**2))

Awk

awk 'BEGIN{print 2**2}'

bc

echo "2 ^ 2" |bc

dc

dc -e '2 2 ^ p'