edit9：是否有可能我只是缺少文件夹的一些权限？我真的非常非常感谢更多的建议..
edit3：由于这篇文章没有得到足够的回复，而且这绝对是至关重要的，我尽快完成这件事，我重建了我的帖子以显示我认为到目前为止我已经扣除的内容。
注意：通过许多不同的命令正常登录根本不起作用。
我的过程：
- 删除了运行以下命令的 mysql（我忘记了什么吗？）：
sudo rm /usr/local/mysql
sudo rm -rf /usr/local/mysql*
sudo rm -rf /Library/StartupItems/MySQLCOM
sudo rm -rf /Library/PreferencePanes/MySQL*
rm -rf ~/Library/PreferencePanes/MySQL*
sudo rm -rf /Library/Receipts/mysql*
sudo rm -rf /Library/Receipts/MySQL*
sudo rm -rf /var/db/receipts/com.mysql.*
已下载mysql-5.7.9-osx10.10-x86_64.dmg from http://dev.mysql.com/downloads/mysql/ http://dev.mysql.com/downloads/mysql/
已安装mysql-5.7.9-osx10.9-x86_64.pkg在标准位置使用标准安装。 （为什么我下载的是 10.10 时 pkg 是 10.9？我的 OS X 版本是 10.10 yosemite）
我收到一条通知，表明 root@localhost 的临时密码已创建。我完美地写下了这一点。
这就是问题开始的地方。
尝试通过终端启动 mysql 服务器：
sudo /usr/local/mysql/support-files/mysql.server start返回：
Starting MySQL
.. ERROR! The server quit without updating PID file (/var/run/mysqld/mysqld.pid).
经过对这个 pid 文件的一些研究，我意识到我需要在 /etc 中创建 my.cnf，所以我这样做了..
cd /usr/local/mysql/support-files/
sudo cp my-default.cnf /etc/my.cnf
编辑并保存my.cnf..
cd /etc
sudo nano my.cnf, 进入该行
pid-file = /var/run/mysqld/mysqld.pid
-
创建目录..
须藤 mkdir /var/run/mysqld
sudo touch /var/run/mysqld/mysqld.pid
sudo chown -R mysql:mysql /var/run/mysqld
假设 my.cnf 现在应该已全部设置，包括 pid 文件。我尝试再次启动服务器。然而一切都没有改变。
好吧，所以我决定好吧，我会尝试更改安装时临时设置的密码。
我停止 mysql 服务器（它不应该运行，但以防万一）。sudo /usr/local/mysql/support-files/mysql.server stop。这可能很有趣，因为我最终处于某种外壳形式，在其中我无法做任何事情。我必须从这里重新启动终端。
-
尝试以安全模式启动 mysqlsudo mysql_safe --skip-grant-tables返回：
151110 10:28:10 mysqld_safe 记录到“/usr/local/var/mysql/Robs-MacBook-Pro.local.err”。
151110 10:28:10 mysqld_safe 使用 /usr/local/var/mysql 中的数据库启动 mysqld 守护进程
151110 10:28:10 mysqld_safe mysqld 来自 pid 文件 /usr/local/var/mysql/Robs-MacBook-Pro.local.pid 结束
所以这又是关于这个 pid 文件的。我在这里没有为 basedir/datadir/port/server_id/socket 设置值。也许就是这样？如果是这样我应该在这里设置什么值？
当我在互联网上摆弄不同的建议时，经常出现的其他错误包括：
Access denied for user root@localhost using password: yes/no or
Cant connect to mysql server through socket ..
/usr/local/var/mysql/data/mysqld.local.err最后几行：
2015-11-17T08:13:55.755115Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2015-11-17T08:13:55.756291Z 0 [Warning] 'NO_ZERO_DATE', 'NO_ZERO_IN_DATE' and 'ERROR_FOR_DIVISION_BY_ZERO' sql modes should be used with strict mode. They will be merged with strict mode in a future release.
2015-11-17T08:13:55.756310Z 0 [Warning] 'NO_AUTO_CREATE_USER' sql mode was not set.
2015-11-17T08:13:55.780792Z 0 [Warning] Insecure configuration for --secure-file-priv: Current value does not restrict location of generated files. Consider setting it to a valid, non-empty path.
2015-11-17T08:13:55.781750Z 0 [Note] /usr/local/mysql/bin/mysqld (mysqld 5.7.9) starting as process 94 ...
2015-11-17T08:13:55.796438Z 0 [Warning] Setting lower_case_table_names=2 because file system for /usr/local/mysql/data/ is case insensitive
2015-11-17T08:13:55.802783Z 0 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2015-11-17T08:13:55.802816Z 0 [Note] InnoDB: Uses event mutexes
2015-11-17T08:13:55.802826Z 0 [Note] InnoDB: GCC builtin __atomic_thread_fence() is used for memory barrier
2015-11-17T08:13:55.802834Z 0 [Note] InnoDB: Compressed tables use zlib 1.2.3
2015-11-17T08:13:55.804723Z 0 [Note] InnoDB: Number of pools: 1
2015-11-17T08:13:55.808009Z 0 [Note] InnoDB: Using CPU crc32 instructions
2015-11-17T08:13:55.821713Z 0 [Note] InnoDB: Initializing buffer pool, total size = 128M, instances = 1, chunk size = 128M
2015-11-17T08:13:55.843514Z 0 [Note] InnoDB: Completed initialization of buffer pool
2015-11-17T08:13:55.898365Z 0 [Note] InnoDB: Highest supported file format is Barracuda.
2015-11-17T08:13:55.935027Z 0 [Note] InnoDB: Creating shared tablespace for temporary tables
2015-11-17T08:13:55.935222Z 0 [Note] InnoDB: Setting file './ibtmp1' size to 12 MB. Physically writing the file full; Please wait ...
2015-11-17T08:13:55.950640Z 0 [Note] InnoDB: File './ibtmp1' size is now 12 MB.
2015-11-17T08:13:55.952035Z 0 [Note] InnoDB: 96 redo rollback segment(s) found. 96 redo rollback segment(s) are active.
2015-11-17T08:13:55.952061Z 0 [Note] InnoDB: 32 non-redo rollback segment(s) are active.
2015-11-17T08:13:55.952538Z 0 [Note] InnoDB: Waiting for purge to start
2015-11-17T08:13:56.070486Z 0 [Note] InnoDB: 5.7.9 started; log sequence number 2471474
2015-11-17T08:13:56.070792Z 0 [Note] InnoDB: Loading buffer pool(s) from /usr/local/mysql-5.7.9-osx10.9-x86_64/data/ib_buffer_pool
2015-11-17T08:13:56.071268Z 0 [Note] InnoDB: not started
2015-11-17T08:13:56.072953Z 0 [Note] Plugin 'FEDERATED' is disabled.
2015-11-17T08:13:56.075825Z 0 [Note] InnoDB: Buffer pool(s) load completed at 151117 9:13:56
2015-11-17T08:13:56.086709Z 0 [Warning] Failed to set up SSL because of the following SSL library error: SSL context is not usable without certificate and private key
2015-11-17T08:13:56.112666Z 0 [Note] Server hostname (bind-address): '*'; port: 3306
2015-11-17T08:13:56.112759Z 0 [Note] IPv6 is available.
2015-11-17T08:13:56.112804Z 0 [Note] - '::' resolves to '::';
2015-11-17T08:13:56.113081Z 0 [Note] Server socket created on IP: '::'.
2015-11-17T08:13:56.180223Z 0 [Note] Event Scheduler: Loaded 0 events
2015-11-17T08:13:56.180406Z 0 [Note] /usr/local/mysql/bin/mysqld: ready for connections.
Version: '5.7.9' socket: '/tmp/mysql.sock' port: 3306 MySQL Community Server (GPL)
Vasfed 提出的好建议的结果：然后，按照所述创建 txt 文件。使用我使用的目录和文件名输入命令：mysqld_safe --init-file=/home/mysql-init &返回：Robs-MacBook-Pro:home leroyklotz$ 151118 09:25:23 mysqld_safe Logging to '/usr/local/var/mysql/Robs-MacBook-Pro.local.err'.
151118 09:25:23 mysqld_safe Starting mysqld daemon with databases from /usr/local/var/mysql
/usr/local/bin/mysqld_safe: line 129: /usr/local/var/mysql/Robs-MacBook-Pro.local.err: Permission denied
rm: /tmp/mysql.sock: Permission denied
/usr/local/bin/mysqld_safe: line 166: /usr/local/var/mysql/Robs-MacBook-Pro.local.err: Permission denied
151118 09:25:23 mysqld_safe mysqld from pid file /usr/local/var/mysql/Robs-MacBook-Pro.local.pid ended
/usr/local/bin/mysqld_safe: line 129: /usr/local/var/mysql/Robs-MacBook-Pro.local.err: Permission denied
授予 Robs-MacBook-Pro.local.err 和 mysql.sock（仍然称为 mysql.sock.lock，这有关系吗？）的权限并不能完全解决问题，错误消息现在显示：
Robs-MacBook-Pro:~ leroyklotz$ mysqld_safe --init-file=/home/mysql-init &
[1] 747
Robs-MacBook-Pro:~ leroyklotz$ 151119 09:13:51 mysqld_safe Logging to '/usr/local/var/mysql/Robs-MacBook-Pro.local.err'.
151119 09:13:51 mysqld_safe Starting mysqld daemon with databases from /usr/local/var/mysql
rm: /tmp/mysql.sock: Permission denied
151119 09:13:53 mysqld_safe mysqld from pid file /usr/local/var/mysql/Robs-MacBook-Pro.local.pid ended
