Manual page and help for the mysql_install_db linux command. Mysql_install_db initializes the MariaDB data directory and creates the system tables in it if they do not exist. Because the MariaDB server, mysqld, must have access to the data directory when it is run later, the mysql_install_db command must be run with the same user that mysqld is running with, or run as root with the --user option to specify username on whose behalf it will run. You may also need to specify other options, such as --basedir or --datadir, if mysql_install_db does not use the correct paths to access the installation directory or data directory.