MySQL 5.7 Release Notes
On Unix and Unix-like systems, mysqld uses
the --log-error option to
determine whether mysqld writes the error log
to the console or a file, and, if to a file, the file name:
If
--log-erroris not given, mysqld writes the error log to the console.If
--log-erroris given without naming a file, mysqld writes the error log to a file namedhost_name.errIf
--log-erroris given to name a file, mysqld writes the error log to that file (with an.errsuffix added if the name has no suffix). The file ___location is under the data directory unless an absolute path name is given to specify a different ___location.If
--log-erroris given in an option file in a[mysqld],[server], or[mysqld_safe]section, on systems that use mysqld_safe to start the server, mysqld_safe finds and uses the option, and passes it to mysqld.
Note
It is common for Yum or APT package installations to configure
an error log file ___location under /var/log
with an option like
log-error=/var/log/mysqld.log in a server
configuration file. Removing the path name from the option
causes the
host_name.err
If the server writes the error log to the console, it sets the
log_error system variable to
stderr. Otherwise, the server writes the
error log to a file and sets
log_error to the file name.