What led to the design of having multiple option file locations?

Hi MySQL,

Good evening!

One special thing for MySQL configuration is that there're multiple
locations for the option files (there're 5 locations both on Windows
and Unix-like platforms),
http://dev.mysql.com/doc/refman/5.5/en/option-files.html

This actually does not make much sense to me. I'm constantly falling
into the mess caused by the multiple configuration files in different
places, especially on the machines shared with other users.
Oftentimes, someone's carelessly putting a file on the parent
locations impacts my own settings (I usually put only a few necessary
settings in my option files so it naturally inherit the parent
settings).

Although I can always printout the values of the options using
--verbose --help, it's really not very convenient. Especially given my
limited experience, not many software projects has such design for
configuration settings.

Could anyone tell me the design idea of having multiple option file
locations? Just of my own curiosity.

Thank you very much!
Tianyin

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