A script to parse IP address and check it validity

A script to parse IP address and check it validity
[Chinese]一个解析IP地址并检查其合法性的脚本（使用awk）

For example, ip address is that 192.168.0.1
This script would do 2 checks,
one is to check each section is a 3 integer.
the others is to check they could not larger than 255.

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#!/bin/sh
CheckIPAddress()
{
        echo $1 > /tmp/tmpserverip
        echo $1 |grep "^[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}$" > /dev/null
        if [ $? = 1 ];  then
                return 1
        else
        a=$(cut -d. -f1 /tmp/tmpserverip)
        b=$(cut -d. -f2 /tmp/tmpserverip)
        c=$(cut -d. -f3 /tmp/tmpserverip)
        d=$(cut -d. -f4 /tmp/tmpserverip)

        for loop in $a $b $c $d
        do
                if [ $loop -ge 255 ] || [ $loop -le 0 ]; then
                        return 2
                fi
                done
        fi

        return 0
}

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This one is the one which using 'awk'.

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CheckIPAddress1()
{
        echo $1 | awk -F. '{if($1~/[0-9]/) print $0}'
        a=`echo $1 | awk -F. '{print $1}'`
        b=`echo $1 | awk -F. '{print $2}'`
        c=`echo $1 | awk -F. '{print $3}'`
        d=`echo $1 | awk -F. '{print $4}'`
        echo $a $b $c $d

        for loop in $a $b $c $d
        do
                if [ $loop -ge 255 ] || [ $loop -le 0 ]; then
                        return 2
                fi
        done

}

if      CheckIPAddress1 $1; then
        echo "error"
else
        echo "success"
fi

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