一、

#!/bin/sh
factorial()
{
  if [ "$1" -gt "1" ]; then
    i=`expr $1 - 1`
    j=`factorial $i`
    k=`expr $1 \* $j`
    echo $k
  else
    echo 1
  fi
}


while :
do
  echo "Enter a number:"
  read x
  factorial $x
done

二、

效果:shell實現階乘計算

? ? bash test.sh
Enter a number:
3
6
Enter a number:
4
24
Enter a number:
5
120
Enter a number:

Reference:https://www.shellscript.sh/ #Shell Scripting Tutorial

028_shell腳本遞歸求值