mysql参数处理顺序

1. MySQL programs determine which options are given first by examining environment variables, then option files, and then the command line. If an option is specified multiple times, the last occurrence takes precedence. This means that environment variables have the lowest precedence and command-line options the highest.

2. On Unix, MySQL programs read startup options from the following files:

Filename	Purpose
/etc/my.cnf	Global options
DATADIR/my.cnf	Server-specific options
defaults-extra-file	The file specified with --defaults-extra-file=path, if any
~/.my.cnf	User-specific options

3. All MySQL programs that support option files handle the following command-line options:

• --no-defaults

  Don't read any option files.

• --print-defaults

  Print the program name and all options that it will get from option files.

• --defaults-file=path_name

  Use only the given option file. path_name is the full pathname to the file.

• --defaults-extra-file=path_name

  Read this option file after the global option file but before the user option file. path_name is the full pathname to the file.