Detect if any ping succeeds

I don't think I've ever seen a ping tool that allows multiple targets on the command line, and it's mostly aimed for interactive use anyway.

On the other hand, fping is pretty much made for scripting and allows pinging multiple targets in parallel. Of course, it also exits with a falsy status if any of the targets fail to answer, but it can also give you a list of the ones that did answer as output. If there's any output, someone answered.

So, e.g.

ping_any() {
    # truthy if the output is not empty
    [ "$(fping -a -r1 "$@")" ]
}
if ping_any somehost otherhost...; then
    echo someone answered
fi

(adjust the retries and time limits with -t, -r and -B to taste)

If you're doing network analysis on that machine, you might as well use a bit more network-analystic tools. Install mtr-packet (often in the mtr software package). You need to resolve your hostnames first, but that's a good idea anyways, because if you want to check whether any host succeeds, and a single hostname has multiple A records, then ping only tries one, and not the others, too, even if the first fails.

So, here goes:

#!/bin/bash
# let's assume we have all the hostnames we care about in
# a file called names.hosts
parallel -j1 -m dig +short :::: names.hosts > addresses.hosts

counter=1
while IFS=$'\n' read -r addr; do
  printf '%d send-probe ip-4 %s timeout 2\n' ${counter} "${addr}"
  counter=$((counter + 1))
done < addresses.hosts \
  | mtr-packet \
  | grep '^[0-9]* reply'

You'll really to read mtr-packet's man page, as aside from icmp (which is what ping does), it also supports other probe protocols, and can set quite some other options.

For compactness, the whole while… thing could be replaced with awk or sed = | sed 'N;s/\n/ /' rather straightforwardly. I just didn't feel like discussing the more obscure sed commands.

parallel -j1 -m dig +short :::: names.hosts \
  | sed = \
  | sed 'N;s/\n/ send-probe timeout 2 ip-4 /' \
  | mtr-packet

My problem is that ping will return zero if the ping succeeds and non-zero (actually 1) if the ping fails.

That's usual UNIX shell command behaviour! a return value of 0 signals success, anything else failure. So, that seems right?

This means, that the overall command returns 123 if any of the pings fail, and 0 if all pings succeed, which isn't what I want.

You could instead of xargs use parallel (thanks @OleTange!), it supports cancelling on a count of failed or successful tasks with the --halt (short version of --halt-on-error) option:

echo host1 host2 host… | parallel -P 0 -n 1 --halt now,success=1 --joblog=jobs.log ping -c1 -w2
# or, simpler without the echo & pipe
parallel -P 0 -n 1 --halt now,success=1 --joblog=jobs.log ping -c1 -w2 ::: host1 host2 host…

now means that when the condition (after the comma) is achieved to stop all other processes immediately (alternative is soon, which lets them finish but doesn't spawn new ones). success=1 means the condition is the successful completion of at least 1 started process.

Now you have a joblog, which is a tab-separated file. So,

# strip off first line and get seventh, ninth column
# then look for columns that start with 0 and 
<jobs.log tail -n+2 \
  | cut -f7,9 \
  | grep -q '^0'

This returns success if there's any line with a 0 exit status, and failure if there isn't. You could of course also do more fancy stuff with the joblog and see which hosts actually responded.

How about a simple for loop (I'm assuming bash, I am unfamiliar with other shells):

for x in host1 host2 host3
do
    ping -c1 -w2 -q $x && echo $x OK || echo $x Failed
done

Which pings each host and reports success or failure.

This answer shows how to embed the loop in an xargs command.

Sequential testing rather than parallel

#!/bin/bash
#
hosts=( 192.0.2.1  198.51.100.2  1.1.1.1  203.0.113.3 )

for host in "${hosts[@]}"
do
    ping -c1 -i0.3 -w1 "$host" && break
done

if [ "$?" -eq 0 ]
then
    echo "One of the hosts ($host) successfully responded" >&2
fi

You can encapsulate this in a function, and it wouldn't be too hard to write the first responding host name to stdout if required.

pingAny()
{
    local host
    for host in "$@"
    do
        ping -q -c1 -i0.3 -w1 "$host" >/dev/null 2>&1 && break
    done
}

if pingAny 192.0.2.1 198.51.100.2 1.1.1.1 203.0.113.3
then
    echo "One of the hosts successfully responded" >&2
fi