Let us understand how option files can be used with MySQL programs −
Most MySQL programs can read the startup options from option files, which is also known as the configuration files.
Option files provide an easy way to specify commonly used options so that they need not be entered on the command line every time the user runs a program.
To know whether a program reads option files or not, it can be invoked with the help of the −−help option.
For mysqld, the −−verbose and –help can be used.
If the program reads option files, the help message indicates the files that it needs to look for and which option groups it will recognize.
A MySQL program that is started with the −−no−defaults option reads no option files apart from the .mylogin.cnf. A server that is started with the persisted_globals_load system variable disabled doesn’t read mysqld−auto.cnf.
Option Files
Many option files are plain text files which are created using any text editor. The exceptions are discussed below −
The .mylogin.cnf file which contains login path options.
This is an encrypted file which is created by the mysql_config_editor utility.
A “login path” is an option group that allows only certain options: host, user, password, port and socket.
Client programs specify which login path to read from .mylogin.cnf with the help of the −−login−path option.
To specify an alternative login path file name, the MYSQL_TEST_LOGIN_FILE environment variable has to be set.
This variable is used by the mysql−test−run.pl testing utility, but is also recognized by mysql_config_editor and by MySQL clients like mysql, mysqladmin, and so forth.
The mysqld−auto.cnf file in the data directory is a JSON−format file that contains persisted system variable settings.
It is created by the server after execution of SET PERSIST or SET PERSIST_ONLY statements.
Management of mysqld−auto.cnf should be done by the server and not performed manually.