bash: ip address

twantrd · 04-20-2005, 01:08 PM

Don't know if you can do this in the way that I presented. My script is pretty simple. It asks you for an ip address and it makes sure you entered the ip address syntactically correct.

#!/bin/bash

echo "What ip address would you like to enter?"
read ip
if [ $ip -ne [0-9][0-9][0-9].[0-9][0-9][0-9].[0-9][0-9][0-9].[0-9][0-9][0-9] ]; then
echo "Incorrect input. Must be in XXX.XXX.XXX.XXX. Exitting...."
exit 0
fi

As you can see, the user must type in something like 111.111.111.111. However, I get an error. How do you check for this in an if statement for bash? Can anyone help me? Thanks!

-twantrd

rose_bud4201 · 04-20-2005, 02:14 PM

From http://www.codecomments.com/Unix_She...ge453842.html:

Code:

#!/bin/bash

IP=$1

ONE=$(echo $1 | cut -f 1 -d '.')
TWO=$(echo $1 | cut -f 2 -d '.')
THREE=$(echo $1 | cut -f 3 -d '.')
FOUR=$(echo $1 | cut -f 4 -d '.')

if ! echo $IP | egrep '^[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+$'; then
   exit 10
fi

for i in $ONE $TWO $THREE $FOUR; do
   if [ ! $i -ge 0 -o ! $i -le 255 ]; then 
      echo "IP Address: $IP does not conform."
      exit 20
   fi
done

echo "IP Address: $IP conforms. Have a nice day."

Ivoke it like "./script 1.2.3.4".

You could just use

Code:

if ! echo $IP | egrep '^[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+$'; then
  echo "Yep!"
else 
  echo "Nope"
fi

If you wanted a really simple check. However, that simple regex won't bounds check, and octets of 0-999 will signal a "Yep!" printout.

twantrd · 04-20-2005, 05:48 PM

Hey, thanks for the help rose! I actually got it figured out with 'case' instead. Thanks!

-twantrd

rose_bud4201 · 04-21-2005, 08:40 AM

w00t :-) Congrats!