问题：

[root@base tmp]# cat ent.txt

1

2

3

4

5

6

7

8

9

10

要求输出结果：1+2+3+4+5+6+7+8+9+10+=55

最好使用tr命令打印出

分析题后，想到最简单的解法就是循环拼接打印结果：

#!/bin/sh

NumArray=($(cat /tmp/ent.txt | awk '{print $1}'))

result="1"

all=1

for((i=1;i<${#NumArray[*]};i++))

do

result="$result+${NumArray[$i]}"

all=$((${NumArray[$i]}+$all))

done

echo $result=$all

看过老男孩老师的答案，才叫拜服，很是简单：

cat ent.txt | tr "\n" "+" | sed 's/\+$/\n/' 直接用tr将"\n"替换为"+"，然后sed替换最后一个"+"

cat ent.txt |tr "\n" "+"|sed 's/\+$/\n/'|bc 一个|bc就可以将字符串表达式，转换成算术表达式

python实现：

# coding: utf-8
import sys
from itertools import groupby

def demo(ListFile):
reList = []
files = file(ListFile,'r')
lines = files.readlines()
str_list = "1"
result=0
for item in lines:
rLIst = item.replace("\n","")
reList.append(rLIst)
if int(rLIst) > 1:
str_list = str(str_list)+"+"+str(rLIst)
result = result + int(rLIst)

return "%s=%d" %(str_list,result)
if __name__ == "__main__":
print demo("/tmp/ent.txt")