分析:IP由四位数字组成,以点【.】分割,最一组最长为3位并且每个字段不能大于255 #!/bin/bash function checkip() {
if echo $IP|egrep"^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$" >/dev/null; then
if [ $VALID_CHECK == "yes" ]; then
echo "IP $IP available!"
return 0
else
echo "IP $IP not available!"
return 1
fi
else
echo "IP format error!"
return 1
fi
} while true; do read -p "Please enter IP: " IP checkip $IP [ $? -eq 0 ] && break done