Difference between [mysql] and [mysqld] in MySQL configuration file There are multiple sections in MySQL configuration file:


[mysql] 
[mysqld]
[myisamchk]
[mysqld_safe] 
[mysqlhotcopy]
[mysqldump] 
[client]


I found that same variables with different values have been defined under these sections. 


What are the specific purpose behind defining these sections?  
Is it necessary to define all? 
How MySQL interprets these variables?
MySQL calls these section "Groups". The [mysqld] group contains the variables apply to the MySQL Server (the mysqld process). The [mysql] group contains the variables for the client program (mysql).

The [client] option group is read by all client programs (but not by mysqld), so "mysql", "mysqldump" etc...

None of these groups are mandatory but usually we set at least the [mysqld] because it's where we configure the server.

About how MySQL interprets these variables, MySQL Documentation says:


  If an option group name is the same as a program name, options in the
  group apply specifically to that program.


Max