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..

[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 
# 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="[email protected]"
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

Edited January 21, 2010 by box_l

[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

[Rokixz]

Hello,

I'm trying to make script with bash so I want to gain more experience with this super tool.

 

I've trying to make a host script to make job more effective and faster.

 

#!/bin/bash

#By Rokas Klyvis

echo "Iveskite adresa arba IP"

read hostname

host $hostname

host www.$hostname

host mail.$hostname

whois $hostname | grep -E 'Domain:|Nameserver:|Status:|Registrar:'

 

 

 

 

PACKETS=1

 

 

for myHost in $hostname

do

check=$(ping -c $PACKETS $myHost | grep 'received' | awk -F',' '{ print $2 }' | awk '{ print $1 }')

if [ $check -eq 0 ]; then

echo "Hostname : $myHost nepingina"

 

else

echo "Hostas pingina OK"

fi

done

 

 

So for example, if I put domain, that doesn't exist, this script gives error ./host.sh: line 16: [: -eq: unary operator expected

 

I understand, that awk cutting doesn't help anymore, tried to make if statements with != ping: unknown host $myHost but still no luck, I just need to make, if host doesn't exists, just to show single line "Host doesn't exist" and that's it. It should be useful for many sysadmins so would be lovely to get your pros help for such newbies like me

 

Regards.

[Steve21]

It's been a while since I've done bash, but can't you ignore most of that and just use the return value from ping?

 

ping -c 1 $myHost > /dev/null
if [ $? -eq 0 ]; then 
echo "Ping Failed"
else
echo "Ping Ok"
fi

 

Every command in bash will always return a return code to $? so just use that to get your answer from. No need to populate/copy from output (or shouldn't be if i remember correctly)

 

Should work anyway.

 

- Edit: Might have my "failed" and "ok" wrong way round. But can't really test it on windows machine If it's doing it back to front, just change echos etc

 

Steve

Edited November 3, 2012 by Steve21

[Rokixz]

Thanks for quick reply, will try to make advanced sheet and than share, or maybe there are some good admin scripts? Will check later on

[costis]

heh, sorry for opening this again, I did this:

 

while true; do
ping -c 3 8.8.8.8 | grep "0 received" && mplayer -volume 150 -loop 0 ~/Music/siren_alert.mp3 || echo Ping OK : $(date)
done

This way only when it does not receive 3 consecutive pings (with "-c 3") it alerts me. If it misses only one or two everything is fine.