The MySQL server, mysqld, has many command options and system variables that can be set at startup to configure its operation. To determine the command option and system variable values used by the server, execute this command:
shell> mysqld --verbose --help
The command produces a list of all mysqld options and configurable system variables. Its output includes the default option and variable values and looks something like this:
abort-slave-event-count 0 allow-suspicious-udfs FALSE archive ON auto-increment-increment 1 auto-increment-offset 1 autocommit TRUE automatic-sp-privileges TRUE avoid-temporal-upgrade FALSE back-log 80 basedir /home/jon/bin/mysql-8.0/ ... tmpdir /tmp transaction-alloc-block-size 8192 transaction-isolation REPEATABLE-READ transaction-prealloc-size 4096 transaction-read-only FALSE transaction-write-set-extraction OFF updatable-views-with-limit YES validate-user-plugins TRUE verbose TRUE wait-timeout 28800
To see the current system variable values used by the server as it runs, connect to it and execute this statement:
mysql> SHOW VARIABLES;
To see some statistical and status indicators for a running server, execute this statement:
mysql> SHOW STATUS;
System variable and status information also is available using the mysqladmin command:
shell> mysqladmin variables shell> mysqladmin extended-status
For a full description of all command options, system variables, and status variables, see these sections:
More detailed monitoring information is available from the Performance Schema; see Chapter 25, MySQL Performance Schema.
If you specify an option on the command line for mysqld or mysqld_safe, it remains in effect only for that invocation of the server. To use the option every time the server runs, put it in an option file. See Section 4.2.6, “Using Option Files”.