mjhjmtu

I have several Raspberry Pi's named numerically (pi0, pi1, etc). They have static IP addresses, but I wanted a simple tool to check on them and make sure they were online even if they got the wrong IP (I've had some trouble in the past. Nothing recently, but it seemed like a good idea to make it foolproof regardless). Instead of using IPs, this tool uses MDNS hostnames that are already in a nice format. The script I wrote is:

#!/bin/bash

report+="Device Name Status Locationn"
report+="----------- ------ --------n"

for i in 0..3
do
 report+="Pi$i "
 ping -c1 pi$i.local > /dev/null
 if [ $? == 0 ]
 then
 report+="Online "
 report+=$(ping -c1 pi$i.local | grep -o "w*192.168.1.w*" | head -1)
 else
 report+="Unreachable"
 fi
 report+="n"
done
echo -e "$report"

It works wonderfully when devices are online, returning

Device Name Status Location
----------- ------ --------
Pi0 Online 192.168.1.3
Pi1 Online 192.168.1.4
Pi2 Online 192.168.1.5
Pi3 Online 192.168.1.6

However, when they are offline the output looks like this

ping: pi0.local: Name or service not known
ping: pi1.local: Name or service not known
ping: pi2.local: Name or service not known
ping: pi3.local: Name or service not known
Device Name Status Location
----------- ------ --------
Pi0 Unreachable
Pi1 Unreachable
Pi2 Unreachable 
Pi3 Unreachable

Is there a way to suppress the "Name or service not known" for the MDNS lookup on the ping? I already direct output to /dev/null, so I don't see how it is still giving output.

Alternatively, if you have a better/faster/easier/prettier way to do this checking, I'd love to hear it.

As was briefly pointed out in the comments, ping is displaying that message to stderr, which you had not redirected. Do so with:

...
ping -c1 pi$i.local > /dev/null 2>&1
...