Shell Script--Determine if the IP entered is correct

#!/bin/bash

#It ' s written by Caibingsen

#!/bin/bash

#It ' s written by Caibingsen

#date: 2016-03-15

#while设置成死循环, re-enter when the IP entered does not meet the criteria

While:

Do

Read-p "Please enter the IP address to be judged:" IP

#判断输入的ip地址是否仅由数字和点组成, and assigns the value to M.

#判断输入的ip地址的小数点的个数, copy to n

M= ' echo $ip |sed ' s/[0-9. G '

N= ' echo $ip |sed ' s/[0-9]//g ' |wc-c '

#截取ip地址的四个数字的部分, and copy them separately.

N1= ' echo $ip |cut-d '. '-f1 '

N2= ' echo $ip |cut-d '. '-f2 '

N3= ' echo $ip |cut-d '. '-f3 '

N4= ' echo $ip |cut-d '. '-f4 '

#第一个if通过m和n来判断输入的ip是否符合要求

If [-Z $m] && [$n-eq 4] && [-n $n 1] && [-n $n 2] && [-n $n 3] && [-N $n 4 ];then

#第二个if通过n1到n4来判断输入的范围是否符合要求.

If [$n 1-ge 0] && [$n 1-le 255] && [$n 2-ge 0] && [$n 2-le 255] && [$n 3-ge 0] & amp;& [$n 3-le 255] && [$n 4-ge 0] && [$n 4-le 255]

Then

echo "IP Right"

Exit

Else

echo "The IP error you entered, please re-enter"

Fi

Else

echo "The IP error you entered, please re-enter"

Fi

Done

Shell Script--Determine if the IP entered is correct