Cron is a way of scheduling tasks on linux based machines; most often used to run nightly, weekly or monthly batch processes to move data or restart services. Crontab is the tool on ubuntu to interact with the cron daemon and really simplifies the process. To start, we need to start editing our crontab file. If this is your first time using crontab, it should prompt you that it’s creating a new file and ask you for an editor. I typically use nano on Ubuntu and vi/vim on other distros. To do this, run the following command.
user@host> crontab -e
The format of the tasks is as follows. Keep in mind that for any of the time properties, an asterisk (*) may be used to signify “all.”
minute hour day_of_month month day_of_week command
Our command is pretty straight forward. We want to run a shell script and store the output in a log file (for debugging). The path is not specific to crontab or cron jobs in general and may be changed to suit your needs. I generally keep my work in
/var to align with the general use of the server (
0 23 * * * /var/scripts/nightly.sh > /var/scripts/cron.log
/var, create your
scripts directory and start editing
nightly.sh. We’ll break the file into three sections: MySQL backups, File backups, and Service restarts.
#!/bin/sh echo "Making backups of MySQL databases" mysqldump -u USERNAME -pPASSWORD DATABASE_NAME | gzip > "/var/backups/SITE_NAME.sql.gz" echo "Making file backups of the websites" tar -czf /var/backups/SITE_NAME.files.tar.gz /var/www/SITE_NAME echo "Restarting services" sudo service MySQL restart sudo service apache2 restart echo "Finished!"
Keep in mind that the specifics of each line are relative to your setup. In my case, I keep all my backups in
/var and all my sites organized by
To test this script, all you need to do is manually run it.
If all is well, you’ll be set! Happy cronning!