I'm curious is there a way to find my.cnf in shared hosting or is this file can be configured just by DBAs and no one can set his/her own settings?
In a shared hosting environment, you cannot access my.cnf
You can see the variables see other ways:
You can also access the variables by means of the INFORMATION_SCHEMA database. The tables to access those values are
The same requests using these tables are
The reason INFORMATION_SCHEMA.SESSION_VARIABLES exists is to see the setting your session has, in the event you change a variable during the session to something different form the global setting.
Please keep in mind that not all settings can be dynamically changed. Some values, such as sort_buffer_size (session or global) and max_connections (global only [session is N/A]), such as innodb_buffer_pool_size and lower_case_table_names, can only be changed by setting it in my.cnf and restarting mysqld.