Shell script realizes IP address legality judgment _linux shell

Do unix/linux under the development, scripting skill is indispensable, as Shell programming, is also a profound technical field, here in order to learn, write a simple IP address is the legal micro-script program, this small program is also very useful.

The IP address is 32-bit, and can be represented by 4 decimal digits, each of which ranges from a 0~255 value.

Copy Code code as follows:

#!/bin/bash

# Test an IP addresses for validity:
# Usage:
# valid_ip IP_Address
# if [[$]-eq 0]]; then echo good; else echo bad; Fi
# OR
# if VALID_IP ip_address; then echo good; else echo bad; Fi
#
function Valid_ip ()
{
Local ip=$1
Local Stat=1

    if [[$ip =~ ^[0-9]{1,3}/.[ 0-9]{1,3}/. [0-9] {1,3}/. [0-9] {1,3}$]]; Then
        oifs= $IFS
        ifs= ' .'
        ip= ($ip)
        ifs= $OIFS
        [[${ip[0]}-le 255 && ${ip[1]}-le 255/
   & nbsp;        && ${ip[2]}-le 255 && ${ip[3]}-le 255]]
 & nbsp;      stat=$?
    fi
    return $stat
}

# If run directly, execute some tests.
If [[$ (basename $ sh) "= = ' valid_ip ']]; then
    ips= '
     &nbs p;  4.2.2.2
        a.b.c.d
         192.168.1.1
        0.0.0.0
         255.255.255.255
        255.255.255.256
         192.168.0.1
        192.168.0
         1234.123.123.123
       
    For IP in $ips
    do
        if valid_ip $ip then stat= ' good ' ; else stat= ' bad '; Fi
        printf "%-20s:%s/n" "$ip" "$stat"
    done
Fi

If you store it as a valid_ip.sh direct run you can get the following results

Copy Code code as follows:

# sh valid_ip.sh
4.2.2.2:good
A.b.c.d:bad
192.168.1.1:good
0.0.0.0:good
255.255.255.255:good
255.255.255.256:bad
192.168.0.1:good
192.168.0:bad
1234.123.123.123:bad