I published a my utility script for backing up a mariadb to GitHub:
https://gist.github.com/MaaxGr/b0ed9675a9d581518543bd70a6b514ac

It has the following features:

• Help with list of all available databases
• Standardized output directory: /root/backups/mariadb
• Standardized file name with datetime and db name
• Progressbar
• Success-Message with filename, size and first 10 rows of dumpfile