much confusion with config files for server

[fugee ohu]

there's
/etc/mysql/my.cnf
/etc/mysql/mysql.cnf
/etc/mysql/conf.d/mysql.cnf
/etc/mysql/mysql.conf.d/mysqld.cnf

so can we make sense of all this or should we just say mysql is somewhat messed up/borked as is starting to look like a lot of people would say

i'm trying to change my data store directory to another partition and i have seen threads in which people ended up believing it couldn't be done, that mysql wants it's data files where it wants them, in my case /var/lib/mysql (linux), and won't start with changes made to the data paths in mysqld.cnf which is where i settled on putting my changes because other cnf files had no datadir, socket, tempdir, basedir entries The only file i found those entries in was msyqld.conf