shell script 实现累加计算

使用循环实现累加计算，并对输入进行判断

1、while do … done

#!/bin/bash
#Program:
#       this is a while demo script
#History:
#       2017-11-14 16:34:58
#
echo  -------------^_^ hello world ^_^---------------
echo  Contact Me: flist_liu@163.com------------------
echo  current time :  $(date '+%Y年%m月%d日 %H:%M:%S')
echo  -----------------------------------------------
#set environment variable
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games
export PATH

function fun(){
echo "please input a int Number or 'q' to exit : "
read num
}

fun;

while [ "$num" != "q" ]
do
if echo $num | [ -n "`sed -n '/^[0-9][0-9]*$/p'`" ];then #判断输入是否为数字
echo "$num is a number"
i=0
sum=0
while [ $i -le $num ]
do
sum=$(($sum + $i))
i=$(($i + 1))
done
echo "The sum 0 + 1 + ... + $num is $sum"
fun;
else
fun;
fi
done

echo  ---------------- ^_^ END ^_^ ------------------
exit 0

2、until do … done

#!/bin/bash
#Program:
#       this is a while demo script
#History:
#       2017-11-14 16:34:58
#
echo  -------------^_^ hello world ^_^---------------
echo  Contact Me: flist_liu@163.com------------------
echo  current time :  $(date '+%Y年%m月%d日 %H:%M:%S')
echo  -----------------------------------------------
#set environment variable
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games
export PATH

function fun(){
echo "please input a int Number or 'q' to exit : "
read num
}

num=hello

until [ "$num" == "q" ]
do
fun
if echo $num | [ -n "`sed -n '/^[0-9][0-9]*$/p'`" ];then #判断输入是否为数字
echo "$num is a number"
i=0
sum=0
while [ $i -le $num ]
do
sum=$(($sum + $i))
i=$(($i + 1))
done
echo "The sum 0 + 1 + ... + $num is $sum"
fi
done

echo  ---------------- ^_^ END ^_^ ------------------
exit 0

3、for … in … do … done

#!/bin/bash
#Program:
#       this is a while demo script
#History:
#       2017-11-14 16:34:58
#
echo  -------------^_^ hello world ^_^---------------
echo  Contact Me: flist_liu@163.com------------------
echo  current time :  $(date '+%Y年%m月%d日 %H:%M:%S')
echo  -----------------------------------------------
#set environment variable
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games
export PATH

function fun(){
echo "please input a int Number or 'q' to exit : "
read num
}

num=hello

until [ "$num" == "q" ]
do
fun
if echo $num | [ -n "`sed -n '/^[0-9][0-9]*$/p'`" ];then #判断输入是否为数字
echo "$num is a number"
i=0
sum=0
#               while [ $i -le $num ]
for i in $(seq 0 $num) #seq表示连续
do
sum=$(($sum + $i))
i=$(($i + 1))
done
echo "The sum 0 + 1 + ... + $num is $sum"
fi
done

echo  ---------------- ^_^ END ^_^ ------------------
exit 0

#!/bin/bash
#Program:
#       this is a while demo script
#History:
#       2017-11-14 16:34:58
#
echo  -------------^_^ hello world ^_^---------------
echo  Contact Me: flist_liu@163.com------------------
echo  current time :  $(date '+%Y年%m月%d日 %H:%M:%S')
echo  -----------------------------------------------
#set environment variable
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games
export PATH

function fun(){
echo "please input a int Number or 'q' to exit : "
read num
}

num=hello

until [ "$num" == "q" ]
do
fun
if echo $num | [ -n "`sed -n '/^[0-9][0-9]*$/p'`" ];then #判断输入是否为数字
echo "$num is a number"
sum=0
for ((i=0;i <= $num ; i++))
do
sum=$(($sum + $i))
done
echo "The sum 0 + 1 + ... + $num is $sum"
fi
done

echo  ---------------- ^_^ END ^_^ ------------------
exit 0