select @@global.socket;
@@global.socket
MYSQL_TMP_DIR/mysqld.1.sock
select @@session.socket;
ERROR HY000: Variable 'socket' is a GLOBAL variable
show global variables like 'socket';
Variable_name	Value
socket	MYSQL_TMP_DIR/mysqld.1.sock
show session variables like 'socket';
Variable_name	Value
socket	MYSQL_TMP_DIR/mysqld.1.sock
select * from information_schema.global_variables where variable_name='socket';
VARIABLE_NAME	VARIABLE_VALUE
SOCKET	MYSQL_TMP_DIR/mysqld.1.sock
select * from information_schema.session_variables where variable_name='socket';
VARIABLE_NAME	VARIABLE_VALUE
SOCKET	MYSQL_TMP_DIR/mysqld.1.sock
set global socket=1;
ERROR HY000: Variable 'socket' is a read only variable
set session socket=1;
ERROR HY000: Variable 'socket' is a read only variable
