Question

I want to do a function that will return the factorial of a number in bash

Here’s the current code that doesn’t work, can anyone tell me what’s wrong and how to correct it? I just started learning bash and I don’t know that much.

#!/bash/bin
factorial()
{
  let n=$1
  if (( "$n" <= "1" ))
  then return 1
  else
  factorial n-1
  return $n*$?
  fi
  return 0
}
factorial 5
echo "factorial 5 = $?"

Answer 1

There are several syntax and a quite obvious logic one (return 0)

A working version is below:

#!/bin/bash

factorial()
{
    if (( $1 <= 1 )); then
        echo 1
    else
        last=$(factorial $(( $1 - 1 )))
        echo $(( $1 * last ))
    fi
}
factorial 5

You are missing:

1. return is bad (should use echo)

2. shbang line (is /bin/bash not /bash/bin)

3. Can’t do arithmetic outside of (( )) or $(( )) (or let, but (( )) is preferred)