计算小于12的阶乘

#!/bin/sh
if test $1 -gt 12 then
  echo "参数大于12!"
  exit
else
  i=$1
  j=1
  while test $i -ne 0
  do
    j=`expr $j \* $i`
    i=`expr $i -1`
  done
  echo $j
fi

注：bash整数测试
测试                      真值
vall -eq val2          val1等于val2
val1 -ge val2          val1大于等于val2 
val1 -gt val2          val1大于val2
val1 -le val2          val1小于等于val2
val1 -lt val2          val1小于val2
val1 -ne val2          val1不等于val2