Shell check string in Linux is not a valid IP

Example

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zj@zj:~/script/cushell/08.11.04$ Cat checkip.sh View Plainprint? #!/bin/bash Printerr () { echo "Incorrect IP format." Readip Chkip } Readip () { Read-p "Your IP:" IP } Chkip () { echo "$IP" | Grep-eq ' [^0-9.]| ^\.| \.$|^0*\.| \.\. ' && printerr [$ (echo-e "${ip//./\n}" | wc-l)-ne 4] && Printerr For i in ${ip//./}; Todo echo $i | Grep-eq "^0+[^0]" && printerr [$ ((10# $i/8))-GT] && Printerr Done } If ["$"]; Then Ip=$1 Else Readip Fi Chkip echo "$IP is good!"

Explained below:

Grep-eq ' [^0-9.]| ^\.| \.$|^0*\.| \.\.'
[^0-9.] Is there a character other than 0-9 and.
^\.| \.$ at the beginning of or at the end of.
^0*\.| \.\. With 0 opening or two consecutive.
All three of these things are wrong oh, so just Printerr

Echo-e "${ip//./\n}" | Wc-l, to be honest, I'm also first in the first place. Replace with line, 3 points is 4 line oh. It's not 3 points, it's printerr.

$ ((10# $i/8))-GT 31 This is the judgment is not <=255, of course, you can also modify the $I-GT 255

OK explain complete ^_^

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zj@zj:~/script/cushell/08.11.04$./checkip.sh 1.2.3.4 1.2.3.4 is zj@zj:~/script/cushell/08.11.04$./checkip.sh 01.2.3.4 Incorrect IP format. Your IP:A.B.A.D Incorrect IP format. Your ip:266.1.1.1 Incorrect IP format. Your ip:244.255.255.255 244.255.255.255 is

Example 2, using the shell to verify the legality of IP address

How to use:

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[Root@yang python]# bash check_ip.sh IP address

Execution Result: The return value of 0 checksum is valid, not 0 illegal.

Shell code:

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[Root@yang python]# VI check_ip.sh #!/usr/bin/sh CHECKIPADDR () { echo $1|grep "^[0-9]\{1,3\}\.\ ([0-9]\{1,3\}\.\) \{2\}[0-9]\{1,3\}$" >/dev/null; #IP地址必须为全数字 If [$?-ne 0] Then Return 1 Fi Ipaddr=$1 A= ' echo $ipaddr |awk-f. ' {print '} ' #以. ' Separate, remove the value of each column B= ' echo $ipaddr |awk-f. ' {print $} ' C= ' echo $ipaddr |awk-f. ' {print $} ' D= ' echo $ipaddr |awk-f. ' {print $} ' For num in $a $b $c $d Todo If [$num-gt 255] | | [$num-lt 0] #每个数值必须在0-255 Then Return 1 Fi Done return 0 } If [$#-ne 1];then #判断传参数量 echo "Usage: $ ipaddress." Exit Else CHECKIPADDR $ Fi