无法让 MYSQL8 在 Ubuntu 20.04 上工作

Question

我已经清除并重新安装了 mysql-client 和服务器几次，我已经重新启动了我的系统，但我无法让 mysql 在我的计算机上工作。

我根据另一个 askubuntu 帖子运行了这些命令：

sudo apt-get --purge remove mysql-server mysql-common mysql-client.

sudo apt update && sudo apt dist-upgrade && sudo apt autoremove.

sudo apt-get install -y mysql-server mysql-client

然后我重新启动，什么也没发生。

命令输出：

mysql -V

mysql  Ver 8.0.20-0ubuntu0.20.04.1 for Linux on x86_64 ((Ubuntu))

须藤 systemctl 状态 mysql.service

Unit mysql.service could not be found.

须藤 systemctl 启动 mysql.service

Failed to start mysql.service: Unit mysql.service not found.

须藤 systemctl 启动 mysqld.service

Failed to start mysqld.service: Unit mysqld.service not found

我不知道从哪里开始，因为我已经删除并清除了 mysql 似乎已安装但无法正常工作。

mysql -h localhost -P 3306 -u root -p 或 mysql -h 127.0.0.1 -P 3306 -u root -p

相同的结果：

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)

cat mysql.cnf                                                           1 ?
#
# 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

#
# * IMPORTANT: Additional settings that can override those from this file!
#   The files must end with '.cnf', otherwise they'll be ignored.
#

!includedir /etc/mysql/conf.d/
!includedir /etc/mysql/mysql.conf.d/

任何帮助表示赞赏。谢谢你。

<------UPDATE------> 刚刚运行了评论中推荐的命令，这是输出：

sudo apt-get install --reinstall mysql-server-8.0

Reading package lists... Done
Building dependency tree       
Reading state information... Done
0 upgraded, 0 newly installed, 1 reinstalled, 0 to remove and 0 not upgraded.
Need to get 0 B/1,228 kB of archives.
After this operation, 0 B of additional disk space will be used.
Preconfiguring packages ...
(Reading database ... 326219 files and directories currently installed.)
Preparing to unpack .../mysql-server-8.0_8.0.20-0ubuntu0.20.04.1_amd64.deb ...
Failed to stop mysql.service: Unit mysql.service not loaded.
invoke-rc.d: initscript mysql, action "stop" failed.
dpkg: warning: old mysql-server-8.0 package pre-removal script subprocess returned error exit status 1
dpkg: trying script from the new package instead ...
Failed to stop mysql.service: Unit mysql.service not loaded.
invoke-rc.d: initscript mysql, action "stop" failed.
dpkg: error processing archive /var/cache/apt/archives/mysql-server-8.0_8.0.20-0ubuntu0.20.04.1_amd64.deb (--unpack):
 new mysql-server-8.0 package pre-removal script subprocess returned error exit status 1
Failed to stop mysql.service: Unit mysql.service not loaded.
invoke-rc.d: initscript mysql, action "stop" failed.
Failed to preset unit: File mysql.service: Link has been severed
/usr/bin/deb-systemd-helper: error: systemctl preset failed on mysql.service: No such file or directory
Failed to start mysql.service: Unit mysql.service not found.
invoke-rc.d: initscript mysql, action "start" failed.
Unit mysql.service could not be found.
dpkg: error while cleaning up:
 installed mysql-server-8.0 package post-installation script subprocess returned error exit status 1
Errors were encountered while processing:
 /var/cache/apt/archives/mysql-server-8.0_8.0.20-0ubuntu0.20.04.1_amd64.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)

ls -laF /lib/systemd/system/mysql.service

-rw-r--r-- 1 root root 524 Nov  6 11:34 /lib/systemd/system/mysql.service

得到这个错误:: sudo apt-get install -f

Reading package lists... Done
Building dependency tree       
Reading state information... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
1 not fully installed or removed.
Need to get 0 B/1,228 kB of archives.
After this operation, 0 B of additional disk space will be used.
dpkg: error processing package mysql-server-8.0 (--configure):
 package is in a very bad inconsistent state; you should
 reinstall it before attempting configuration
Errors were encountered while processing:
 mysql-server-8.0
E: Sub-process /usr/bin/dpkg returned an error code (1)

须藤 dpkg --configure -a

dpkg: error processing package mysql-server-8.0 (--configure):
 package is in a very bad inconsistent state; you should
 reinstall it before attempting configuration
Errors were encountered while processing:
 mysql-server-8.0

Answer 1

尝试

sudo apt-get install --reinstall mysql-server-8.0

并检查 mysql.service 是否存在

ls -laF /lib/systemd/system/mysql.service

修复损坏的包

sudo apt-get install -f
sudo dpkg --configure -a

修复旧安装遗留下来的 mysql.service

sudo killall mysqld
sudo systemctl disable mysql.service
sudo rm -rf /lib/systemd/system/mysql.service
sudo rm -rf /usr/lib/systemd/system/mysql.service
sudo rm -rf /etc/systemd/system/multi-user.target.wants/mysql.service
sudo rm -rf /var/lib/systemd/deb-systemd-helper-enabled/multi-user.target.wants/mysql.service
sudo rm -rf /var/cache/apt/archives/mysql-server-*.deb

sudo apt-get install -f
sudo dpkg --configure -a

sudo apt-get install --reinstall mysql-server-8.0

Answer 2

关于这个特定的错误：

Unit mysql.service could not be found.

[我正在运行 Ubuntu 20.04]

我花了几个小时才发现这个：几个月前我玩过 MariaDB 并卸载了它，但显然它没有完全/干净地卸载。它留下了两个符号链接

ls /etc/systemd/system
mysql.service -> /lib/systemd/system/mariadb.service
mysqld.service -> /lib/systemd/system/mariadb.service

链接的文件不是由链接本身删除的。我在两个链接上都运行了“取消链接”，卸载了所有 mysql 包dpkg -P并重新安装，结果很好。

[我正在运行 Ubuntu 20.04] 祝你好运。