How the shell script determines whether the IP address is legitimate _linux shell

Verifying IP address legality using the shell

How to use:

Copy Code code as follows:

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

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

Copy Code code as follows:

[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