Shell script to read an IP address from user\'s input and check if the input IP

Question

Shell script to read an IP address from user's input and check if the input IP address is valid or not.

Fill in the Blank to complete the task!

#!/bin/bash
echo -n "Please enter the ip:"
_______A._______
echo $ip|grep _______B.______________
if [_______C._______]
then
echo "Please enter IP address following the
IP address pattern"
exit
fi

#replace the dots in ip with spaces
ip=`echo $ip | sed _______D._______
valid=1
n=1
for num in $ip
do
if [ _______E._______ ]
then
echo "INVALID: Please enter a number
between 0-255 in field $n (index starts
from 1 from left)"
valid=0
exit
fi
n=`expr $n + 1`
done
if [ $valid -eq 1 ];then
echo "The ip you entered is valid"

fi

Explanation / Answer

#!/bin/bash
echo -n "Please enter the ip: "
read ip
# check if IP follows the correct pattern
echo $ip | grep '^[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}$'
if [ $ip -ne ]
then
echo "Please enter IP address following the
IP address pattern"
exit
fi

#replace the dots in ip with spaces
ip=`echo $ip | sed "s/./ /g"`
valid=1
n=1
for num in $ip
do
if [ $num > 255 -o $num < 0 ]
then
echo "INVALID: Please enter a number
between 0-255 in field $n (index starts
from 1 from left)"
valid=0
exit
fi
n=`expr $n + 1`
done
if [ $valid -eq 1 ];then
echo "The ip you entered is valid"

fi

Related Questions

Navigate

• Browse (All)
• Browse S
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.