我最近在 ubuntu-20.04 上安装了 mysql 5.7，但似乎缺少 debian-sys-maint 用户和配置。有人能解释一下如何恢复或设置它吗？据我了解，用户应该是用于启动、关闭和其他维护功能的用户。我试过重新安装：
# apt reinstall mysql-community-server=5.7* mysql-server=5.7*
Reading package lists... Done
Building dependency tree
Reading state information... Done
Selected version '5.7.39-1ubuntu18.04' (MySQL:repo.mysql.com [amd64]) for 'mysql-community-server'
Selected version '5.7.39-1ubuntu18.04' (MySQL:repo.mysql.com [amd64]) for 'mysql-server'
0 upgraded, 0 newly installed, 2 reinstalled, 0 to remove and 3 not upgraded.
Need to get 39.9 MB of archives.
After this operation, 0 B of additional disk space will be used.
Get:1 http://repo.mysql.com/apt/ubuntu bionic/mysql-5.7 amd64 mysql-community-server amd64 5.7.39-1ubuntu18.04 [39.8 MB]
Get:2 http://repo.mysql.com/apt/ubuntu bionic/mysql-5.7 amd64 mysql-server amd64 5.7.39-1ubuntu18.04 [69.5 kB]
Fetched 39.9 MB in 1s (35.9 MB/s)
Preconfiguring packages ...
(Reading database ... 102617 files and directories currently installed.)
Preparing to unpack .../mysql-community-server_5.7.39-1ubuntu18.04_amd64.deb ...
.
Unpacking mysql-community-server (5.7.39-1ubuntu18.04) over (5.7.39-1ubuntu18.04) ...
Preparing to unpack .../mysql-server_5.7.39-1ubuntu18.04_amd64.deb ...
Unpacking mysql-server (5.7.39-1ubuntu18.04) over (5.7.39-1ubuntu18.04) ...
Setting up mysql-community-server (5.7.39-1ubuntu18.04) ...
Setting up mysql-server (5.7.39-1ubuntu18.04) ...
Processing triggers for man-db (2.9.1-1) ...
Processing triggers for systemd (245.4-4ubuntu3.17) ...
root@xblgx-ops-4:~# ls /etc/mysql
conf.d my.cnf my.cnf.fallback mysql.cnf mysql.conf.d
注意没有 /etc/mysql/debian.cnf
我可以很容易地创建用户，但我担心安装任何脚本和配置设置可能需要让它做它应该做的任何事情。