的ubuntu - Ubuntu的16.04服务器

Question

mysql的启动和重新启动的问题，我mysql安装5.7但后来发现我需要的mysql 5.6，所以我删除了所有MySQL相关的软件包与

apt-get remove --purge mysql* 

所以它得到了清除。然后我发出：

apt-get install mysql-server-5.6 mysql-client-5.6 

所以提到的软件包得到安装。 但它并未使用systemctl start mysql或service mysql start甚至重新启动。结果是这样的：

service mysql restart 
or 
service mysql start 
or 
systemctl restart mysql 
or 
systemctl start mysql 

回报：

Job for mysql.service failed because the control process exited with error code. See "systemctl status mysql.service" and "journalctl -xe" for details. 

但

systemctl status mysql 

回报

mysql.service - LSB: Start and stop the mysql database server daemon 
    Loaded: loaded (/etc/init.d/mysql; bad; vendor preset: enabled) 
    Active: failed (Result: exit-code) since Mon 2017-04-10 13:24:00 EDT; 29s ago 
    Docs: man:systemd-sysv-generator(8) 
    Process: 15820 ExecStart=/etc/init.d/mysql start (code=exited, status=1/FAILURE) 
Main PID: 1323 (code=exited, status=0/SUCCESS) 

Apr 10 13:23:30 server mysqld[15926]: 2017-04-10 13:23:30 15925 [Note] InnoDB: Compressed tables use zlib 1.2.8 
Apr 10 13:23:30 server mysqld[15926]: 2017-04-10 13:23:30 15925 [Note] InnoDB: Using Linux native AIO 
Apr 10 13:23:30 server mysqld[15926]: 2017-04-10 13:23:30 15925 [Note] InnoDB: Using CPU crc32 instructions 
Apr 10 13:23:30 server mysqld[15926]: 2017-04-10 13:23:30 15925 [Note] InnoDB: Initializing buffer pool, size = 128.0M 
Apr 10 13:23:30 server mysqld[15926]: 2017-04-10 13:23:30 15925 [Note] InnoDB: Completed initialization of buffer pool 
Apr 10 13:24:00 server mysql[15820]: ...fail! 
Apr 10 13:24:00 server systemd[1]: mysql.service: Control process exited, code=exited status=1 
Apr 10 13:24:00 server systemd[1]: Failed to start LSB: Start and stop the mysql database server daemon. 
Apr 10 13:24:00 server systemd[1]: mysql.service: Unit entered failed state. 
Apr 10 13:24:00 server systemd[1]: mysql.service: Failed with result 'exit-code'. 

是什么Failed to start LSB: Start and stop the mysql database server daemon. 安装5.6 5.7 versio前n工作正常，但现在它是这样的。

的/var/log/mysql/errors.log是空的，这些都是/var/log/syslog最后几行

输出 mysqld_safe

170410 13:33:28 mysqld_safe Logging to syslog. 
170410 13:33:28 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql 
170410 13:33:28 mysqld_safe mysqld from pid file /var/lib/mysql/server.pid ended 

Apr 10 13:23:30 server mysqld: 2017-04-10 13:23:30 15925 [Note] InnoDB: Completed initialization of buffer pool 
Apr 10 13:23:30 server mysqld_safe: mysqld from pid file /var/lib/mysql/server.pid ended 
Apr 10 13:24:00 server /etc/init.d/mysql[16277]: 0 processes alive and '/usr/bin/mysqladmin --defaults-file=/etc/mysql/debian.cnf ping' resulted in 
Apr 10 13:24:00 server /etc/init.d/mysql[16277]: #007/usr/bin/mysqladmin: connect to server at 'localhost' failed 
Apr 10 13:24:00 server /etc/init.d/mysql[16277]: error: 'Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)' 
Apr 10 13:24:00 server /etc/init.d/mysql[16277]: Check that mysqld is running and that the socket: '/var/run/mysqld/mysqld.sock' exists! 
Apr 10 13:24:00 server /etc/init.d/mysql[16277]: 
Apr 10 13:24:00 server mysql[15820]: ...fail! 
Apr 10 13:24:00 server systemd[1]: mysql.service: Control process exited, code=exited status=1 
Apr 10 13:24:00 server systemd[1]: Failed to start LSB: Start and stop the mysql database server daemon. 
Apr 10 13:24:00 server systemd[1]: mysql.service: Unit entered failed state. 
Apr 10 13:24:00 server systemd[1]: mysql.service: Failed with result 'exit-code'. 

，这是我/etc/mysql/my.cnf并没有/etc/my.cnf

# 
# The MySQL database server configuration file. 
# 
# You can copy this to one of: 
# - "/etc/mysql/my.cnf" to set global options, 
# - "~/.my.cnf" to set user-specific options. 
# 
# One can use all long options that the program supports. 
# Run program with --help to get a list of available options and with 
# --print-defaults to see which it would actually understand and use. 
# 
# For explanations see 
# http://dev.mysql.com/doc/mysql/en/server-system-variables.html 

# This will be passed to all mysql clients 
# It has been reported that passwords should be enclosed with ticks/quotes 
# escpecially if they contain "#" chars... 
# Remember to edit /etc/mysql/debian.cnf when changing the socket location. 

# Here is entries for some specific programs 
# The following values assume you have at least 32M ram 

!includedir /etc/mysql/conf.d/ 

Answer 1

停止MySQL服务CE：

sudo service mysql stop 

删除的mysql：

sudo apt-get remove mysql 
sudo apt-get purge mysql 

然后发出在终端whereis mysql命令，并删除所有该命令使用rm -rf命令列出的位置。例如rm -rf /etc/mysql。

然后重新安装你想要的mysql版本。所有应该按预期工作。