Small bash script to notify server user

makowka · 02-14-2010, 02:24 PM

Hi

I want to share a small script, which checks, whether a server (e.g. FTP-server) is working and sends to the server user(s) a notification email ("Server is UP"). After the server has been shut down, the script sends another message to the user(s): "Server is DOWN".

Code:

#!/bin/sh

CHECKINGPERIOD=10                  # in sec

if [ -n "$(pidof proftpd)" ]
   then
   /usr/bin/mail -s 'FTP is UP' user@isp.com -- -r me@isp.com
   else
   exit 0
fi

while [ 1=1 ];

do
    if [ -z "$(pidof proftpd)" ]
       then
       /usr/bin/mail -s 'FTP is DOWN' user@isp.com -- -r me@isp.com
       exit
    fi

sleep $CHECKINGPERIOD

done

This script needs the exim/postfix smtp server (configured as smarthost), in order to work. It can be started after the ftp server has been started MANUALLY with the command "nohup /usr/local/bin/ftpcheck > /dev/null 2>&1". The scripts ends, as soon as it discovers, that the server isn't up anymore. That's all, I know, that this is not very complicated code, but it took me some time to write it in a clean way. I hope, it will be of use for someone. All suggestions are welcome.

carltm · 02-14-2010, 03:16 PM

As I understand your script, it will check once to see if the server is up.
If so it sends email and then continues running, only to send you email every
10 seconds when the server is down.

That means if the ftp server goes down in the middle of the night, you'll be
bombarded with email in the morning. Also you'll never be notified when it
comes back up.

catkin · 02-15-2010, 02:17 AM

Quote:

Originally Posted by makowka

Code:

while [ 1=1 ];

Thanks for sharing

The above snippet is not a test because the "=" test operator must have whitespace around it. The cleanest way to set up an infinite loop is

Code:

while true

or, less legibly

Code:

while :