An error occurred while configuring multiple instances in mysqld_multi and mysql_install_db.

Ubuntu8.04 ~ 8.10 install the default MySQL instance. You cannot run mysql_install_db. You cannot use mysqld_multi to configure apparmor and apparmor ), an error occurs because apparmor controls the permission to access the data directory of the multi instance.
Error code:

> Sudo mysql_install_db -- datadir =/var/lib/mysql1 -- no-defaults -- user = MySQL
Installing MySQL system tables...
100304 22:34:18 [Warning] can't create test file/var/lib/mysql1/PB. Lower-test
100304 22:34:18 [Warning] can't create test file/var/lib/mysql1/PB. Lower-test
Error: 1005 can't create table 'db' (errno: 13)
100304 22:34:18 [Error] aborting

Solution:
Edit/etc/apparmor. d/usr. sbin. in the mysqld file, you can see that the data directory, logs, and Socket of MySQL installed with APT-Get by default exist. the permissions of the PID file are as follows:

/Etc/MySQL/*. pem R,
/Etc/MySQL/CONF. d/R,
/Etc/MySQL/CONF. d/* r,
/Etc/MySQL/My. cnf r,
/Usr/sbin/mysqld Mr,
/Usr/share/MySQL/** R,
/Var/log/MySQL. Log RW,
/Var/log/MySQL. Err RW,
/Var/lib/MySQL/R,
/Var/lib/MySQL/** rwk,
/Var/log/MySQL/R,
/Var/log/MySQL/* RW,
/Var/run/mysqld. pid w,
/Var/run/mysqld. Sock W,

/Var/log/mysql1.log RW,
/Var/log/mysql1.err RW,
/Var/lib/mysql1/R,
/Var/lib/mysql1/** rwk,
/Var/log/mysql1/R,
/Var/log/mysql1/* RW,
/Var/run/mysqld/mysqld1.pid W,
/Var/run/mysqld/mysqld1.sock W,

/Var/log/mysql2.log RW,
/Var/log/mysql2.err RW,
/Var/lib/mysql2/R,
/Var/lib/mysql2/** rwk,
/Var/log/mysql2/R,
/Var/log/mysql2/* RW,
/Var/run/mysqld/mysqld2.pid W,
/Var/run/mysqld/mysqld2.sock W,

After this file is modified, sudo/etc/init. d/apparmor restart and restart apparmor.

Continue to run sudo mysql_install_db-datadir =/var/lib/mysql1-no-defaults-user = MySQL
In this way, the MySQL System data file can be installed under/var/lib/mysql1.

It is easy to configure multiple instances: edit/etc/MySQL/My. CNF

[Mysqld_multi]
Mysqld =/usr/bin/mysqld_safe
Mysqladmin =/usr/bin/mysqladmin
User = root
Password = 123

[Mysqld1]
PID-file =/var/run/mysqld/mysqld1.pid
Socket =/var/run/mysqld/mysqld1.sock
Port = 3306
Datadir =/var/lib/mysql1
User = MySQL
Log =/var/log/mysql1.log

[Mysqld2]
PID-file =/var/run/mysqld/mysqld2.pid
Socket =/var/run/mysqld/mysqld2.sock
Port = 3307
Datadir =/var/lib/mysql2
User = MySQL
Log =/var/log/mysql2.log

Run sudo mysqld_multi start 1, 2-no-log to view the terminal's output of the correct startup information.

~ /Home/Pb $ netstat-lt | grep 33
TCP 0 0 *: 3307 *: * listen
TCP 0 0 *: 3308 *: * Listen http://www.neocanable.com/error-for-mysql-multi-and-mysql-install-db/