How do you find the factorial of a number in a Bash script?

Question

In shell scripting how to find factorial of a number?

Answer 1

There are a number of instructive examples on Rosetta Code.

Here's one I found particularly useful:

function factorial {
  typeset n=$1
  (( n < 2 )) && echo 1 && return
  echo $(( n * $(factorial $((n-1))) ))
}