Question

Automatically restart MySQL on Ubuntu 16.04.x - If statement may be wrong?

Posted on September 16, 2016
MySQL Ubuntu 16.04
Asked by Zonax7100

Hey guys!

I have a Ubuntu 16.04.x server, where I installed MySQL. Works great and everything, but I would like MySQL to be restarted if it, for any reason stops. First of all, i know this isn’t a very good solution, because there is a reason that the MySQL proccess stops. But I also have a Ubuntu 14.04.x server which has been running for over a year, where it happend 2 times. In these cases it would be really nice to get it up and running again. I have my logs to see why it went down.

So to the actual thing I need help with:

I found this script, that claims to be able to restart MySQL if it stops:

I have made a file called mysqlfix.sh in /root/

#!/bin/bash
PATH=/usr/sbin:/usr/bin:/sbin:/bin
if [[ ! "$(/usr/sbin/service mysql status)" =~ "start/running" ]]
then
    echo " The MySQL service on the server has been stopped. It has now been restarted." | mail -s " MySQL has been restarted" my@email.com
    sudo service mysql start
fi

Then made sure that it can run:

chmod +x mysqlfix.sh

Then added a cron job(crontab -e) that checks it every minute:

chmod +x mysqlfix.sh

This seems to be working on Ubuntu 14.04.x. But not on my new Ubuntu 16.04 server. It sends me an E-mail every minute with the “The MySQL has been restarted” message. This makes me think that the if statement is wrong. But I haven’t been able to find what is wrong with it.

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Marko Mudrinić • September 16, 2016

Accepted Answer

Reason could be that Ubuntu 16.04.x is now using systemd instead of Upstart. This results in changed output of service status command. When you run /usr/sbin/service mysql status in terminal you will notice this:

● mysql.service - MySQL Community Server
   Loaded: loaded (/lib/systemd/system/mysql.service; enabled; vendor preset: enabled)
   Active: active (running) since Fri 2016-09-16 17:46:40 CEST; 1min 30s ago
  Process: 25747 ExecStartPost=/usr/share/mysql/mysql-systemd-start post (code=exited, status=0/SUCCESS)
  Process: 25744 ExecStartPre=/usr/share/mysql/mysql-systemd-start pre (code=exited, status=0/SUCCESS)
 Main PID: 25746 (mysqld)
    Tasks: 28
   Memory: 128.4M
      CPU: 265ms
   CGroup: /system.slice/mysql.service
           └─25746 /usr/sbin/mysqld

As far as you see, output is changed. Most important change is this: Active: active (running).

So, if you change your if to: if [[ ! "$(/usr/sbin/service mysql status)" =~ "active (running)" ]], your script should be working fine.

Whole script for reference will be:

#!/bin/bash
PATH=/usr/sbin:/usr/bin:/sbin:/bin
if [[ ! "$(/usr/sbin/service mysql status)" =~ "active (running)" ]]
then
    echo " The MySQL service on the server has been stopped. It has now been restarted." | mail -s " MySQL has been restarted" my@email.com
    sudo service mysql start
fi

Adam Robertson • September 16, 2016

I have a similar script, but it can check other services as well. I recently updated it to work with 16.04:

https://github.com/sierracircle/services-checker

alexdo

Site Moderator

• May 30, 2022

You can create a simple bash script to check if MySQL is running and if not to restart it.

#!/bin/bash

# Check if MySQL is running
sudo service mysql status > /dev/null 2>&1

# Restart the MySQL service if it's not running.
if [ $? != 0 ]; then
    sudo service mysql restart
fi

Run this script every 5 minutes using a cron job like this one:

 */5 * * * * /home/user/scripts/monitor.sh > /dev/null 2>&1

Hope that this helps!

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