尝试了所有的命令行，还是不行。我要做的事情有:

mv /usr/local/Cellar/mysql/5.7.16/bin/mysqld /usr/local/Cellar/mysql/5.7.16/bin/mysqld.bak
mysql.server stop

这种方法有效，mysqld进程消失了。但是/var/log/system.log有很多垃圾:

Jul  9 14:10:54 xxx com.apple.xpc.launchd[1] (homebrew.mxcl.mysql[78049]): Service exited with abnormal code: 1
Jul  9 14:10:54 xxx com.apple.xpc.launchd[1] (homebrew.mxcl.mysql): Service only ran for 0 seconds. Pushing respawn out by 10 seconds.

获取实例名:

ls /Library/LaunchDaemons | grep mysql

停止MySQL实例(适用于MacOS Catalina, MySQL 8):

sudo launchctl unload /Library/LaunchDaemons/com.oracle.oss.mysql.mysqld.plist

或者，您可以停止MySQL实例

MacOS Settings > MySQL > Stop MySQL Server 

此外，查看这里更多的方法: https://tableplus.com/blog/2018/10/how-to-start-stop-restart-mysql-server.html

Try

sudo <path to mysql>/support-files/mysql.server start
sudo <path to mysql>/support-files/mysql.server stop

其他的尝试:

sudo /Library/StartupItems/MySQLCOM/MySQLCOM start
sudo /Library/StartupItems/MySQLCOM/MySQLCOM stop<br>
sudo /Library/StartupItems/MySQLCOM/MySQLCOM restart

然而，我发现第二个选项只有在.plist已经加载了以下内容时才能工作(OS X 10.6, MySQL 5.1.50):

sudo launchctl load -w /Library/LaunchDaemons/com.mysql.mysqld.plist

PS:我还发现我需要卸载.plist来获得一个不相关的MAMP-MySQL安装，以正确启动/停止。运行之后，MAMP-MySQL启动正常:

sudo launchctl unload -w /Library/LaunchDaemons/com.mysql.mysqld.plist

在OSX雪豹

launchctl unload /System/Library/LaunchDaemons/org.mysql.mysqld.plist

在我的例子中，只要我使用PID杀死进程，它就会重新启动。此外，brew stop命令不工作，因为我没有使用自制程序安装。然后我打开了mac系统首选项，那里已经安装了MySQL。只要打开它并停止MySQL服务器，你就完成了。在这里的截图中，你可以在系统首选项的底部找到MySQL。

对我来说，它与mysql5一起工作

sudo launchctl unload -w /Library/LaunchDaemons/org.macports.mysql5.plist
sudo launchctl load -w /Library/LaunchDaemons/org.macports.mysql5.plist