MySQL未启动，systemctl状态为MySQL.service“；及；journalctl-xe“；

系统：Ubuntu 18.04.5 LTS MYSQL:5.7.31

尝试下列命令都显示相同的错误

systemctl启动mysql

/etc/init.d/mysql start

服务mysql启动

journalctl-xe显示了以下内容

Sep 19 05:38:32 www systemd[1]: Starting MySQL Community Server... 
Sep 19 05:38:32 www mysql-systemd-start[2938]: ERROR: Unable to start MySQL server:
**Sep 19 05:38:32 www mysql-systemd-start[2938]: /usr/share/mysql/mysql-systemd-start: line 44: mysqld: command not found** 
Sep 19 05:38:32 www mysql-systemd-start[2938]: Please take a look at  https://wiki.debian.org/Teams/MySQL/FAQ for tips on fixing common upgrade issues. 
Sep 19 05:38:32 www mysql-systemd-start[2938]: Once the problem is resolved, restart the service. 
Sep 19 05:38:32 www systemd[1]: mysql.service: Control process exited, code=exited status=1 Sep 19 05:38:32 www systemd[1]: mysql.service: Failed with result 'exit-code'. 
Sep 19 05:38:32 www systemd[1]: Failed to start MySQL Community Server. Sep 19 05:38:32 www systemd[1]: mysql.service: Service hold-off time over, scheduling restart. 
Sep 19 05:38:32 www systemd[1]: mysql.service: Scheduled restart job, restart counter is at 1. 
Sep 19 05:38:32 www systemd[1]: Stopped MySQL Community Server.

我强调了我认为造成问题的那一行

$PATH是 /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin

/与mysql相关的usrs/bin内容

-rwxr-xr-x 1 root root  4027496 Jul 20 10:50 myisamchk
-rwxr-xr-x 1 root root  3916200 Jul 20 10:50 myisam_ftdump
-rwxr-xr-x 1 root root  3894296 Jul 20 10:50 myisamlog
-rwxr-xr-x 1 root root  3945448 Jul 20 10:50 myisampack
-rwxr-xr-x 1 root root  3608840 Jul 20 10:50 my_print_defaults
-rwxr-xr-x 1 root root  3908456 Jul 20 10:50 mysql
-rwxr-xr-x 1 root root  3799752 Jul 20 10:50 mysqladmin
lrwxrwxrwx 1 root root       10 Jul 20 10:50 mysqlanalyze -> mysqlcheck
-rwxr-xr-x 1 root root  4068280 Jul 20 10:50 mysqlbinlog
-rwxr-xr-x 1 root root  3825320 Jul 20 10:50 mysqlcheck
-rwxr-xr-x 1 root root     5350 Jul 20 10:50 mysql_config
-rwxr-xr-x 1 root root  3627200 Jul 20 10:50 mysql_config_editor
-rwxr-xr-x 1 root root    26952 Jul 20 10:50 mysqld_multi
-rwxr-xr-x 1 root root    27790 Jul 20 10:50 mysqld_safe
-rwxr-xr-x 1 root root  3875176 Jul 20 10:50 mysqldump
-rwxr-xr-x 1 root root     7865 Jul 20 10:50 mysqldumpslow
-rwxr-xr-x 1 root root 22627736 Jul 20 10:50 mysql_embedded
-rwxr-xr-x 1 root root  3791912 Jul 20 10:50 mysqlimport
-rwxr-xr-x 1 root root  5224224 Jul 20 10:50 mysql_install_db
lrwxrwxrwx 1 root root       10 Jul 20 10:50 mysqloptimize -> mysqlcheck
-rwxr-xr-x 1 root root  3616952 Jul 20 10:50 mysql_plugin
-rwxr-xr-x 1 root root  4286152 Jul 20 10:50 mysqlpump
lrwxrwxrwx 1 root root       10 Jul 20 10:50 mysqlrepair -> mysqlcheck
-rwxr-xr-x 1 root root    39016 Jan 12  2018 mysqlreport
-rwxr-xr-x 1 root root  3788520 Jul 20 10:50 mysql_secure_installation
-rwxr-xr-x 1 root root  3790504 Jul 20 10:50 mysqlshow
-rwxr-xr-x 1 root root  3809512 Jul 20 10:50 mysqlslap
-rwxr-xr-x 1 root root  3653288 Jul 20 10:50 mysql_ssl_rsa_setup
-rwxr-xr-x 1 root root  3569976 Jul 20 10:50 mysql_tzinfo_to_sql
-rwxr-xr-x 1 root root  4446416 Jul 20 10:50 mysql_upgrade

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知道怎么了吗？怎么办？

我用apt get remove逐个卸载了所有mysql软件包，然后重新安装。我没有删除所有数据所在的/var/lib/mysql目录。重新安装后，一切正常，数据也安全。所有表格和站点都在工作。我不确定，但我认为上一次软件包升级导致了这种情况。

尝试强制重新安装mysql服务器软件包。显然，

/usr/sbin/mysqld

丢失了，很难猜出可能是什么错误。描述一下你的场景，哪里出了问题。你做了什么导致了这一切？你安装了什么东西吗？