在Ubuntu 16.04服务器上，MySQL启动和重启问题

Question

我安装了MySQL 5.7，但后来发现需要MySQL 5.6，因此我使用以下命令删除了所有与MySQL相关的包：

apt-get remove --purge mysql*

所以它被移除了。然后我发布了以下命令：

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

所提到的包已安装。 但无论是使用systemctl start mysql、service mysql start还是重新启动，都无法启动。结果如下：

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

返回：

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

但是

systemctl status mysql

返回

 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'.

什么是 Failed to start LSB: Start and stop the mysql database server daemon. 在安装5.6版本之前，5.7版本运行良好，但现在出现了这种情况。

/var/log/mysql/errors.log 是空的，这些是 /var/log/syslog 的最后几行。

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'.

mysqld_safe 的输出结果

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

这是我的 /etc/mysql/my.cnf，但没有 /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/

- mohammad fallah.rasoulnejad

---

你能检查一下MySQL进程服务器日志吗？可能在/var/log/mysql/目录下。 - Matt Clark

/var/log/mysql/errors.log是空的。我更新了问题，请再看一下。谢谢。 - mohammad fallah.rasoulnejad

你能检查一下手动启动进程的输出吗？只需运行 mysqld_safe。 - Matt Clark

170410 13:33:28 mysqld_safe 正在记录到系统日志。 170410 13:33:28 mysqld_safe 从 /var/lib/mysql 数据库启动 mysqld 守护进程。 170410 13:33:28 mysqld_safe 根据 pid 文件 /var/lib/mysql/server.pid，mysqld 进程已结束。 - mohammad fallah.rasoulnejad

我认为您仍然在/etc/my.cnf中有一个配置文件，其中包含特定于5.7的参数，现在尝试将其加载到5.6中会导致错误。尝试使用默认配置文件启动。另外，您提出问题才15分钟，放松一下，等待适当的答案。 - Matt Clark

实际上没有 /etc/my.cnf 文件，但我有一个 /etc/mysql/my.cnf 文件。它是一样的吗？ - mohammad fallah.rasoulnejad

Answer 1

当你的/etc/mysql/mysql.conf.d/mysqld.cnf文件设置错误时，就会出现这个问题。如果你最近对这个文件进行了更改，请恢复到以前的版本或将默认版本复制到这里。

    #
# 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

[mysqld_safe]
socket      = /var/run/mysqld/mysqld.sock
nice        = 0

[mysqld]
#
# * Basic Settings
#
user        = mysql
pid-file    = /var/run/mysqld/mysqld.pid
socket      = /var/run/mysqld/mysqld.sock
port        = 3306
basedir     = /usr
datadir     = /var/lib/mysql
tmpdir      = /tmp
lc-messages-dir = /usr/share/mysql
skip-external-locking
#
# Instead of skip-networking the default is now to listen only on
# localhost which is more compatible and is not less secure.
bind-address        = 0.0.0.0
#
# * Fine Tuning
#
key_buffer_size     = 16M
max_allowed_packet  = 16M
thread_stack        = 192K
thread_cache_size       = 8
# This replaces the startup script and checks MyISAM tables if needed
# the first time they are touched
myisam-recover-options  = BACKUP
#max_connections        = 100
#table_open_cache       = 64
#thread_concurrency     = 10
#
# * Query Cache Configuration
#
query_cache_limit   = 1M
query_cache_size        = 16M
#
# * Logging and Replication
#
# Both location gets rotated by the cronjob.
# Be aware that this log type is a performance killer.
# As of 5.1 you can enable the log at runtime!
#general_log_file        = /var/log/mysql/mysql.log
#general_log             = 1
#
# Error log - should be very few entries.
#
log_error = /var/log/mysql/error.log
#
# Here you can see queries with especially long duration
#slow_query_log     = 1
#slow_query_log_file    = /var/log/mysql/mysql-slow.log
#long_query_time = 2
#log-queries-not-using-indexes
#
# The following can be used as easy to replay backup logs or for replication.
# note: if you are setting up a replication slave, see README.Debian about
#       other settings you may need to change.
#server-id      = 1
#log_bin            = /var/log/mysql/mysql-bin.log
#expire_logs_days   = 10
max_binlog_size   = 100M
#binlog_do_db       = include_database_name
#binlog_ignore_db   = include_database_name
#
# * InnoDB
#
# InnoDB is enabled by default with a 10MB datafile in /var/lib/mysql/.
# Read the manual for more InnoDB related options. There are many!
#
# * Security Features
#
# Read the manual, too, if you want chroot!
# chroot = /var/lib/mysql/
#
# For generating SSL certificates I recommend the OpenSSL GUI "tinyca".
#
# ssl-ca=/etc/mysql/cacert.pem
# ssl-cert=/etc/mysql/server-cert.pem
# ssl-key=/etc/mysql/server-key.pem

- Nafiu Lawal

Answer 2

停止mysql服务：

sudo service mysql stop

移除mysql：

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

然后在终端中发出whereis mysql命令，并使用rm -rf命令删除该命令列出的所有位置。例如：rm -rf /etc/mysql。

然后重新安装所需版本的mysql。一切应该正常工作。

- coderodour

---

我按照你说的做了，但是apt-get remove mysql给我报错，所以我使用了apt-get remove mysql*和sudo apt-get purge mysql*。然后在上述命令中找到的目录被删除了，所以我重新安装了它，但是还是一样的。没有改变，也没有启动。 - mohammad fallah.rasoulnejad

执行以下命令，然后尝试启动MySQL：rm -rf /var/run/mysqld/*。 - coderodour

我按照你说的做了，但是又出现了这个问题：mysql.service任务失败，因为控制进程以错误代码退出。请参阅“systemctl status mysql.service”和“journalctl -xe”获取详细信息。 - mohammad fallah.rasoulnejad

我开始思考，在Ubuntu 16.04上安装MySQL 5.6是否可能？ - mohammad fallah.rasoulnejad

让我们在聊天中继续这个讨论。 - coderodour

Answer 3

只需检查您的数据库是否已被授予写日志的权限，授予它写日志的权限，问题就会得到解决。

- Venky

Answer 4

1)首先使用以下命令删除已安装的mysql-server-- sudo apt-get remove --purge mysql-server mysql-client mysql-common

2)然后清理所有文件 sudo apt-get autoremove

3)接着安装mysql-server -- sudo apt-get remove -f mysql-server

4)启动mysql服务器-- sudo systemctl start mysql

5)检查mysql-server状态-- systemctl status mysql

- Arpan Saha Mondal