判断输入的IP是否正确

编写shell脚本，判断输入的IP是否正确（IP的规则是，n1.n2.n3.n4，其中1<n1<255, 0<n2<255, 0<n3<255, 0<n4<255）。

#!/bin/bash

check_ip(){

if echo $1 | egrep -q "^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$";then

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}‘`

if [ $a -le 1 -o $a -ge 255 ] || [ $b -le 0 -o $b -ge 255 ] || [ $c -le 0 -o $c -ge 255 ] || [ $d -le 0 -o $d -ge 255 ] ;then

echo "IP的规则是，n1.n2.n3.n4，其中1<n1<255, 0<n2<255, 0<n3<255, 0<n4<255 "

return 1

fi

else

echo "please enter an IP like "192.168.16.1""

return 2

fi

}

stat=1

while [ $stat -ne 0 ];do

read -p "please enter an IP:" ip

check_ip $ip

stat=`echo $?`

done

echo "The ip $ip is right!"