Server Administration - MySQL - page 764

Examples:
• Write the error log to the err.log file in the data directory:
[mysqld]
log_error=err.log
• As of MySQL 5.7.2, you can influence the amount of error log output by setting the
log_error_verbosity system variable. Permitted values range from 1 (errors only)
to 3 (errors, warnings, notes; the default). To see errors only, do this:
[mysqld]
log_error=err.log
log_error_verbosity=1
• On Unix, if you start the server using mysqld_safe , it's possible to redirect the error
log to the syslog facility:
[mysqld_safe]
syslog
The general query and slow query logs
Several system variables control the general query and slow query logs. Each variable
can be set at server startup or changed at runtime:
• log_output controls the log destinations. The value is FILE (log to files, the default),
TABLE (log to tables), NONE (disable logging), or a comma-separated combination
of values, in any order. NONE overrides any other value. If the value is NONE , other
settings for these logs have no effect. Destination control applies to the general query
and slow query logs together; you cannot write one to a file and the other to a table.
• general_log and slow_query_log enable or disable the respective logs. By default,
each log is disabled. If you enable either of them, the server writes the log to the
destinations specified by log_output , unless that variable is NONE .
• general_log_file and slow_query_log_file specify log filenames. The default
names are host_name .log and host_name -slow.log ; however, these settings have no
effect unless log_output specifies FILE logging.
Examples:
• Write the general query log to the query.log file in the data directory:
[mysqld]
log_output=FILE
general_log=1
general_log_file=query.log