启动mysql：

方式一：sudo /etc/init.d/mysql start 
方式二：sudo start mysql
方式三：sudo service mysql start
sudo ./mysqld_safe
 
停止mysql：
方式一：sudo /etc/init.d/mysql stop 
方式二：sudo stop mysql
方式三：sudo service mysql stop
 
重启mysql：
方式一：sudo/etc/init.d/mysql restart
方式二：sudo restart mysql
方式三：sudo service mysql restart
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ubuntu下的操作

sue@suepc:/$ whereis mysql
mysql: /usr/bin/mysql /etc/mysql /usr/lib/mysql /usr/bin/X11/mysql /usr/include/mysql /usr/local/mysql /usr/share/mysql /usr/share/man/man1/mysql.1.gz

1.

sue@suepc:/$ sudo /usr/bin/service mysql start

..
* MySQL Community Server 5.7.19 is started
sue@suepc:/$ sudo /etc/init.d/mysql stop
...
* MySQL Community Server 5.7.19 is stopped

2.
sue@suepc:/$ sudo /etc/init.d/mysql start
..
* MySQL Community Server 5.7.19 is started
sue@suepc:/$