script to only run if it cant ping a host

[RabbieBurns]

Ive got a server that runs a runs a script on the hour. Trouble is said server is a bit prone to the occasional lockup or crash etc and sometimes the script wont run untill I can get someone to reboot the server..

Got a backup server that runs, that isnt really capable of running the script regularly but could cope with it for a couple of days.. I was wondernig if there was a wayh of running a script on the backup server to do the following

Check main server is replying to ping
if OK do nothing
if no ping, run the script locally

Both machines are gentoo linux so a perl / bash / python or whatever would be fine to run

Any ideas would be appreciated.. cheers..

[SYSMAN_MK]

Have something in VB but don't think that will help you.

[morganw]

This looks like a BASH script that would do it.

#!/bin/bash
# Simple SHELL script for Linux and UNIX system monitoring with
# ping command
# -------------------------------------------------------------------------
# Copyright (c) 2006 nixCraft project <http://www.cyberciti.biz/fb/>
# This script is licensed under GNU GPL version 2.0 or above
# -------------------------------------------------------------------------
# This script is part of nixCraft shell script collection (NSSC)
# Visit http://bash.cyberciti.biz/ for more information.
# -------------------------------------------------------------------------
# Setup email ID below
# See URL for more info:
# http://www.cyberciti.biz/tips/simple-linux-and-unix-system-monitoring-with-ping-command-and-scripts.html
# -------------------------------------------------------------------------
 
# add ip / hostname separated by white space
HOSTS="cyberciti.biz theos.in router"
 
# no ping request
COUNT=1
 
# email report when
SUBJECT="Ping failed"
EMAILID="me@mydomain.com"
for myHost in $HOSTS
do
  count=$(ping -c $COUNT $myHost | grep 'received' | awk -F',' '{ print $2 }' | awk '{ print $1 }')
  if [ $count -eq 0 ]; then
    # 100% failed
    echo "Host : $myHost is down (ping failed) at $(date)" | mail -s "$SUBJECT" $EMAILID
  fi
done

Got it from here
UNIX / Linux Shell Script For Monitoring System network with ping command

[Gerry]

I Googled perl ping and got this:
Net::Ping - perldoc.perl.org
The example script shows how to use it.

Then, to launch a script if there's no ping, try:
exec - perldoc.perl.org

Then you could cron your "pinging" script to run it every minute, hour, day, specific time etc...

[box_l]

how about these?

#!/bin/bash

if ping -c 1 4.2.2.2
then
  : # colon is a null and is required
else
   **** your command here ****
fi

and found this

in an old script of mine, cant remember where it came from tho.

this one would detect if the link was dropping some of the packets

#!/bin/bash
while [ -n "$(ping -c 1 192.168.0.1|grep 100%)" ]
do
: # colon is a null and is required
else
**** your command here ****

BoX

[RabbieBurns]

how about these?

#!/bin/bash

if ping -c 1 4.2.2.2
then
  : # colon is a null and is required
else
   **** your command here ****
fi

Thats perfect. Simple and effective. I added a > /dev/null to the first line to supress the output of the ping to the screen. Thanks