Bash Script to Find Out If MySQL Is Running Or Not

Overview

This is a simple solution to monitor the MySQL daemon, if it detects that the daemon is not running, it starts it and send a notification email.

It is a simpler solution than using other more complete software like supervisord or MonIT.

Creating the script

Create the script /root/scripts/monitor_mysql.sh with the following content:

#!/bin/bash

##########
# Config #
##########
mysql_daemon='mysqld'
pgrep='/usr/bin/pgrep'
mysql_start='sudo service mysql start'
fail_msg="MySQL is down in $(hostname)."

##########
# Script #
##########

#look up process
$pgrep $mysql_daemon > /dev/null
if [ $? -ne 0 ]; then
    echo $fail_msg
    $mysql_start
fi

And make it executable:

# chmod +x /root/scripts/monitor_mysql.sh

Cronjob

Specify through crontab to run it every 10 minutes. Running

# crontab -e

Add the following lines:

MAILTO=mail@example.com
*/10 * * * * /root/scripts/monitor_mysql.sh

Every time the script starts the daemon, an email will be sent with its output.

cron(8) looks at the MAILTO variable if a mail needs to be send as a result of running any commands in that particular crontab. If MAILTO is defined (and non-empty), mail is sent to the specified address. If MAILTO is defined but empty (MAILTO=""), no mail is sent. Otherwise, mail is sent to the owner of the crontab.

Reference

• Crontab http://man7.org/linux/man-pages/man5/crontab.5.html
• Simple bash script to check whether MySQL is running