CODEWITHSUNDEEP
bashping
Lurch
Lurch

Reputation: 875

Ping servers and execute command when all respond

I have the following script:

#!/bin/bash

servers=( "10.10.10.1" "10.10.10.2" "10.10.10.3" "10.10.10.4" )

for i in "${servers[@]}";
do
ping -c 4 "$i" >/dev/null 2>&1 &&
echo "Ping Status of $i : Success" ||
echo "Ping Status of $i : Failed"
done

which outputs 

Ping Status of 10.10.10.1 : Success
Ping Status of 10.10.10.2 : Success
Ping Status of 10.10.10.3 : Failed
Ping Status of 10.10.10.4 : Failed

I need to constantly ping those addresses until they all succeed then, execute a command. I don't need the success/failed output, I just want to ping all IPs and then echo "All Hosts Online", for example.

Upvotes: 0

Views: 521

Answers (1)

Martin Tournoij
Martin Tournoij

Reputation: 27822

I hope the comments in the code make it clear what this does. Basically, the trick is to wrap the entire thing in an infinite while loop, and use a variable to signal whether one of the commands failed.

#!/bin/bash

servers=( "10.10.10.1" "10.10.10.2" "10.10.10.3" "10.10.10.4" )

# Keep looping forever : is a special builtin command that does
# nothing and always exits with code 0
while :; do
    # Assume success
    failed=0

    # Loop over all the servers
    for i in "${servers[@]}"; do
        # We failed one!
        if ! ping -c 4 "$i" >/dev/null 2>&1; then
            # Set failed to 1 to signal the code after the for loop that
            # a ping failed
            failed=1

             # We don't need to ping the others, so we can break from this for
             # loop
             break
        fi
    done

    # If none of the ping commands failed, the $failed variable is still 0
    if [ $failed -eq 0 ]; then
        # Yes! We can now run our command
        echo "All hosts online"

        # And break the infinite while loop
        break
    else
        # Nope, wait a while and start the loop from the top
        sleep 5
    fi
done

I also fixed a typo; you used /dev/nul, but that should be /dev/null, with two l.

Upvotes: 1

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