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How can I ping a certain address and when found, stop pinging.

I want to use it in a bash script, so when the host is starting up, the script keeps on pinging and from the moment the host is available, the script continues...

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up vote 40 down vote accepted

A further simplification of Martynas' answer:

while ! ping -c1 &>/dev/null; do :; done

note that ping itself (negated by !) is used as the loop test; as soon as it succeeds, the loop ends. The loop body is empty, with the null command ":" used to prevent a syntax error.

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perfect! should be accepted answer – cmcginty Feb 16 '13 at 23:35
yes, you are right. I will correct it. – lepe Apr 11 '15 at 3:54
To add 'sleep' (e.g. each 5 secs): while ! ping -c1 &>/dev/null; do sleep 5; done – lepe Apr 11 '15 at 3:55
Perfect! Works on Mac OSX as well. – Bart Kummel Jun 22 '15 at 8:02

You can do a loop, send one ping and depending on the status break the loop, for example (bash):

while true; do ping -c1 > /dev/null && break; done

Putting this somewhere in your script will block, until is pingable.

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This while true and break is the cleaner solution, IMO. – Dan Carley Jul 17 '09 at 8:26
@DanCarley I'm going to disagree with you for the reason that in the accepted answer, the null command version, one could substitute a sleep/wait to give your CPU a break, and in which case I would call it the cleaner solution. The other problem with this answer, is that it requires the reader/user to understand how the && works, and how that if the first command fails, it won't be called. This is just an opinion, like your own. – Hamid Jan 11 '15 at 19:06
The main difference I see between this solution and the accepted one, is that this one will echo the error message "unknown host ..." until its found. To add sleep (e.g. each 5 secs): while true; do sleep 5; ping ... – lepe Apr 10 '15 at 2:23

Ping the target host once. Check if the ping succeeded (return value of ping is zero). If host is not alive, ping again.

The following code can be saved as a file and called with the hostname as argument, or stripped of the first and last line and used as function within an existing script (waitForHost hostname).

The code does not evaluate the cause for failure if the ping does not result in a response, thus looping forever if the host does not exist. My BSD manpage lists the meaning of each return value, while the linux one does not, so I guess this might not be portable, that's why I left it out.


PING=`which ping`

function waitForHost
    if [ -n "$1" ]; 
        waitForHost1 $1;
        echo "waitForHost: Hostname argument expected"

function waitForHost1
    while [ $reachable -eq 0 ];
    $PING -q -c 1 $1
    if [ "$?" -eq 0 ];
    sleep 5
waitForHost $1
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good solution, thanks! you just forgot a space between 'c' and '1'... – Sander Versluys Jul 17 '09 at 9:10
-c1 works fine for me on linux and bsd (and solaris, but on solaris -c has another effect) – Jan Jungnickel Jul 17 '09 at 9:26
cool, you've improved your answer, lovely! ;-) – Sander Versluys Jul 17 '09 at 11:07

I know the question is old... and specifically asks regarding ping, but I wanted to share my solution.

I use this when rebooting hosts to know when I can SSH back into them again. (Since ping will respond for several seconds before sshd is started.)

until nc -vzw 2 $host 22; do sleep 2; done
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That's exactly what I searched for, thanks! You can even interrupt the call with CTRL+C which is not the case for some other solutions in this thread. – Alex Jan 19 '14 at 8:58
Note this works for BSD versions of netcat. The version in Linux distros is implemented differently, so the -z option doesn't exist, and the -w option waits for a connection but doesn't close when successful. Works great in OSX, though. – Paul Jan 8 at 16:59
while [ $UNREACHEABLE -ne "0" ]; 
   do ping -q -c 1 HOST &> /dev/null; UNREACHEABLE=$?; sleep 1;

You may remove sleep 1, it's only here to prevent any flooding problem in case where the host would be reacheable but ping would not exit with code 0.

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Please see good options at stackoverflow. Here is a sample in bash, you will have to loop over the following code until it returns a successfull ping result.

ping -c 1 -t 1;
if [ $? -eq 0 ]; then
    echo " is up";
    echo "ip is down";

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wow, the answer on that SO link is great! txn – Sander Versluys Jul 17 '09 at 9:02

any of the above loops can also be used with fping rather than ping which, IMO, is better suited for use in scripts than ping itself. See fping(1) for details.

while ! fping -q $HOSTNAMES ; do :; done

also useful for testing if machines are up before doing something on them. A simple example:

for h in HOST1 HOST2 HOST3 ; do
  if fping -q $h ; then
     echo -n "$h : "
     ssh $h "uname -a"
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wow cool, i'm such a noob, didn't know that command... txn ;-) – Sander Versluys Jul 20 '09 at 9:31
impossible. how can you not know all of the millions of commands available? :) – cas Jul 20 '09 at 9:40

This will try a given number of times.

t=4; c=0; r=0; until ping -c 1 >/dev/null 2>&1 || ((++c >= t)); do r=$?; done; echo $r

Instead of echoing $r, you can test it and act according to its value:

if ((r)); then echo 'Failed to contact host'; else echo 'Continuing with script'; fi
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I've been using the following function. I like it because I can tell it to stop trying after a while:

#!/usr/bin/env bash

function networkup {
  # Initialize number of attempts
  while [ $reachable -ne 0 ]; do
    # Ping supplied host
    ping -q -c 1 -W 1 "$2" > /dev/null 2>&1
    # Check return code
    if [ $? -eq 0 ]; then
      # Success, we can exit with the right return code
      echo 0
    # Network down, decrement counter and try again
    let reachable-=1
    # Sleep for one second
    sleep 1
  # Network down, number of attempts exhausted, quiting
  echo 1

It can be used like this to launch something:

# Start-up a web browser, if network is up
if [ $(networkup 60 -eq 0 ]; then
  firefox &
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