编写一个判断IP地址合法性的bash脚本

#!/bin/bash

# Test an IP address 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 /
&& ${ip[2]} -le 255 && ${ip[3]} -le 255 ]]
stat=$?
fi
return $stat
}

# If run directly, execute some tests.
if [[ "$(basename $0 .sh)" == 'valid_ip' ]]; then
ips='
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

如果你存储成valid_ip.sh直接运行就可以得到如下结果

# 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