Can't start MySQL server because of wrong file permissions?

I'm trying to start the server and then fix the root user by

$ mysql -u root mysql
$mysql> UPDATE user SET Password=PASSWORD('my_password') where USER='root';
$mysql> FLUSH PRIVILEGES;

But the server can't be started:

```
$ mysqld --skip-grant-tables
2014-10-21 07:18:24 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2014-10-21 07:18:24 1967 [Warning] Can't create test file /usr/local/mysql-5.6.21-osx10.8-x86_64/data/x4430.lower-test
2014-10-21 07:18:24 1967 [Warning] Can't create test file /usr/local/mysql-5.6.21-osx10.8-x86_64/data/x4430.lower-test
2014-10-21 07:18:24 1967 [Note] Plugin 'FEDERATED' is disabled.
2014-10-21 07:18:24 1967 [Note] InnoDB: Using atomics to ref count buffer pool pages
2014-10-21 07:18:24 1967 [Note] InnoDB: The InnoDB memory heap is disabled
2014-10-21 07:18:24 1967 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2014-10-21 07:18:24 1967 [Note] InnoDB: Memory barrier is not used
2014-10-21 07:18:24 1967 [Note] InnoDB: Compressed tables use zlib 1.2.3
2014-10-21 07:18:24 1967 [Note] InnoDB: Using CPU crc32 instructions
2014-10-21 07:18:24 1967 [Note] InnoDB: Initializing buffer pool, size = 128.0M
2014-10-21 07:18:24 1967 [Note] InnoDB: Completed initialization of buffer pool
2014-10-21 07:18:24 1967 [ERROR] InnoDB: ./ibdata1 can't be opened in read-write mode
2014-10-21 07:18:24 1967 [ERROR] InnoDB: The system tablespace must be writable!
2014-10-21 07:18:24 1967 [ERROR] Plugin 'InnoDB' init function returned error.
2014-10-21 07:18:24 1967 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
2014-10-21 07:18:24 1967 [ERROR] Unknown/unsupported storage engine: InnoDB
2014-10-21 07:18:24 1967 [ERROR] Aborting

2014-10-21 07:18:24 1967 [Note] Binlog end
2014-10-21 07:18:24 1967 [Note] Shutting down plugin 'partition'
2014-10-21 07:18:24 1967 [Note] Shutting down plugin 'PERFORMANCE_SCHEMA'
201

The entire folder should be owned by mysql

cd /usr/local/mysql-5.6.21-osx10.8-x86_64/data/
chown -R mysql:mysql *

Then go restart mysql

Give it a Try !!!

StackExchange Database Administrators Q#80742, answer score: 17