I would like a script to look for an IP address among others.

I use the following command to generate the list:

ip -4 neighbor show

But I don't know how to look.

command | awk ...


for i in command ; do ... done

Finally this seems to be correct:

LIST=$(the regex of Reda Salih)  
for i in $LIST
  if [ "${i}" == $my_ip]
    echo found
    exit 0
echo not found

But is there a more elegant solution?

  • It would be easier if you show us the output of the command and an example of the desired output of the script. Please edit your question. – BANJOSA Nov 17 '20 at 14:41
  • The command "ip -4 neighbor show" provides a list of IP. My desired output is True or false according to the presence or not of a specific IP. – jpc Nov 17 '20 at 16:04

You can use grep with following regex :

ip -4 neighbor show | grep -E -o "(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)" | grep -oh <ip_addr>

Just replace <ip_addr> with your IP..

  • Ok but how to find a specific IP is present in this list ? – jpc Nov 17 '20 at 16:06
  • I have updated the post. Don't forgot to make it as resolved / answered. Thanks – Reda Salih Nov 17 '20 at 16:50
  • if <ip_addr> is your solution find and – jpc Nov 17 '20 at 17:04
  • I have added '-oh' flags to the last grep, so it will show only the matched word. It will be fine now ! – Reda Salih Nov 17 '20 at 18:17
  • OK Thank you for your solution – jpc Nov 17 '20 at 21:56

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