ip.bash

#!/usr/bin/env bash
: <<'!COMMENT'

GGCOM - Bash - Library - Internet Protocol v201504162001
Louis T. Getterman IV (@LTGIV)
www.GotGetLLC.com | www.opensour.cc/ggcom/bash/lib/ip

Example usage:
source "ip.bash"
if valid_ipv4 '192.168.1.1' == true; then echo 'Valid IP'; else echo 'Invalid IP'; fi

!COMMENT

# http://www.linuxjournal.com/content/validating-ip-address-bash-script
# 
# 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_ipv4()
{
    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
}