The following shell script is used to check if the input IP address is invalid o

Question

The following shell script is used to check if the input IP address is invalid or not. Rs = 1 while [$rs -gt 0]; do clear echo -n Please input the ip read ip #use expr to check if the input IP address follows the IP address pattern is IP = if; then replace each dot by a space in string ip ip = isvalid = 0; #loop over the words in string ip for n in; do if [-0 $n -1t 0]; then echo "ERROR: The number of the IP should not be greater less than 255 and less than 0" break; done if; then echo'----- This is a valid IP-'. Fi else echo "ERROR: The IP format you in is wrong, the format should be like 192.168.100.1 fi echo echo -n Press 0 to exit and other numbers to continue....." read rs done

Explanation / Answer

Sample Output:

Please input the ip: 192.145.23.12
-----This is a valid IP-----
Press 0 to exit and other numbers to continue....6

Please input the ip: 192.156.34.432
ERROR: The number of the IP should not be greater than 255 and less than 0
Press 0 to exit and other numbers to continue....4

Please input the ip: 192.15.45.34.32
ERROR: The IP format you input is wrong, the format should be like 192.168.100.1
Press 0 to exit and other numbers to continue....0

script:

rs=1
while [ $rs -gt 0 ]; do
        clear
        echo -n "Please input the ip: "
        read ip
        isIp=${#ip}
        if [[ $ip =~ ^[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}$ ]]; then
                ip="${ip//./ }"
                isValid=0;
                for n in $ip; do
                        if [ $n -gt 255 -o $n -lt 0 ]; then
                                echo "ERROR: The number of the IP should not be greater than 255 and less than 0"
                                isValid=1;
                                break;
                        fi
                        done
                if [ $isValid = 0 ];then
                        echo "-----This is a valid IP-----"
                fi
        else
                echo "ERROR: The IP format you input is wrong, the format should be like 192.168.100.1"
        fi
        echo -n "Press 0 to exit and other numbers to continue...."
        read rs
done

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