1select @@global.plugin_dir;
2@@global.plugin_dir
3MYSQL_TMP_DIR/
4select @@session.plugin_dir;
5ERROR HY000: Variable 'plugin_dir' is a GLOBAL variable
6show global variables like 'plugin_dir';
7Variable_name	Value
8plugin_dir	MYSQL_TMP_DIR/
9show session variables like 'plugin_dir';
10Variable_name	Value
11plugin_dir	MYSQL_TMP_DIR/
12select * from information_schema.global_variables where variable_name='plugin_dir';
13VARIABLE_NAME	VARIABLE_VALUE
14PLUGIN_DIR	MYSQL_TMP_DIR/
15select * from information_schema.session_variables where variable_name='plugin_dir';
16VARIABLE_NAME	VARIABLE_VALUE
17PLUGIN_DIR	MYSQL_TMP_DIR/
18set global plugin_dir=1;
19ERROR HY000: Variable 'plugin_dir' is a read only variable
20set session plugin_dir=1;
21ERROR HY000: Variable 'plugin_dir' is a read only variable
22