shell程序,根据输入的参数n,计算得阶乘

#!/基郑bin/bash

multiply()

{

if [ $1 -gt 1 ]then

result=`expr $result \* $1`

next=`expr $1 - 1`

multiply $next

fi

}

if [ $# -ne 1 ]then

echo -e "Please input a parameter!\nUsage: $0 [n]"

exit 1

fi

result=1

if [ $1 -eq 1 ]then

:

elif [ $1 -gt 1 ]then

multiply $1

else

echo "Invalid input parameter! It MUST be a integer greater than 0."

exit 1

fi

echo "$1! = $result"

exit 0

echo "$*" | sed 's/ //g' | egrep "^[0-9]+$" >/dev/null 2>&1

if [[ $# -eq 0 || $? -gt 0 ]]then

echo "Usage:./test.sh 参搭颂数(只允许是整橡码数)"

exit 1

fi

sum1=0

sum2=1

until [ $# -eq 0 ]do

sum1=$(echo "$sum1+$1" | bc)

sum2=$(echo "$sum2*$1" | bc)

shift

done

echo "和 is: $sum1"

echo "乘积 is: $sum2"