как исправить ошибку при установке mysql?

знаю, что есть уже несколько таких вопросов, но решения оттуда мне не помогли.

ставлю LEMP на linux kubuntu 18.04, во время установки mysql-server не запрашивает root-пароль. пишу sudo mysql_secure_installation, ошибка:

some@user-All-Series:~$ sudo mysql_secure_installation
Securing the MySQL server deployment.
Enter password for user root: 
Error: Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)

при попытке запустить сервис:

some@user-All-Series:~$ sudo service mysql start
Failed to start mysql.service: Unit mysql.service is masked.

как править?

upd: some@user-All-Series:~$ sudo systemctl status mysql

● mysql.service
   Loaded: masked (/dev/null; bad)
   Active: inactive (dead)
авг 14 10:57:16 user-All-Series mysqld[7100]: 2018-08-14T07:57:16.512821Z 0 [Note] InnoDB: Buffer pool(s) dump completed at 180814 10:57:16
авг 14 10:57:18 user-All-Series mysqld[7100]: 2018-08-14T07:57:18.179893Z 0 [Note] InnoDB: Shutdown completed; log sequence number 1619804
авг 14 10:57:18 user-All-Series mysqld[7100]: 2018-08-14T07:57:18.181836Z 0 [Note] InnoDB: Removed temporary tablespace data file: "ibtmp1"
авг 14 10:57:18 user-All-Series mysqld[7100]: 2018-08-14T07:57:18.181853Z 0 [Note] Shutting down plugin 'MEMORY'
авг 14 10:57:18 user-All-Series mysqld[7100]: 2018-08-14T07:57:18.181859Z 0 [Note] Shutting down plugin 'CSV'
авг 14 10:57:18 user-All-Series mysqld[7100]: 2018-08-14T07:57:18.181864Z 0 [Note] Shutting down plugin 'sha256_password'
авг 14 10:57:18 user-All-Series mysqld[7100]: 2018-08-14T07:57:18.181867Z 0 [Note] Shutting down plugin 'mysql_native_password'
авг 14 10:57:18 user-All-Series mysqld[7100]: 2018-08-14T07:57:18.182034Z 0 [Note] Shutting down plugin 'binlog'
авг 14 10:57:18 user-All-Series mysqld[7100]: 2018-08-14T07:57:18.182268Z 0 [Note] /usr/sbin/mysqld: Shutdown complete
авг 14 10:57:18 user-All-Series systemd[1]: Stopped MySQL Community Server.

если сделать unmask:

some@user-All-Series:~$ sudo systemctl unmask mysql
Removed /etc/systemd/system/mysql.service.
some@user-All-Series:~$ sudo systemctl start mysql 
Job for mysql.service failed because the control process exited with error code.
See "systemctl status mysql.service" and "journalctl -xe" for details.

содержимое файлов mysql.service # MySQL systemd service file

[Unit]
Description=MySQL Community Server
After=network.target
[Install]
WantedBy=multi-user.target
[Service]
Type=forking
User=mysql
Group=mysql
PIDFile=/run/mysqld/mysqld.pid
PermissionsStartOnly=true
ExecStartPre=/usr/share/mysql/mysql-systemd-start pre
ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/run/mysqld/mysqld.pid
TimeoutSec=600
Restart=on-failure
RuntimeDirectory=mysqld
RuntimeDirectoryMode=755
LimitNOFILE=5000
cat: /etc/systemd/system/mysql.service: Нет такого файла или каталога

upd: systemctl status mysql

● mysql.service - MySQL Community Server
   Loaded: loaded (/lib/systemd/system/mysql.service; disabled; vendor preset: enabled)
   Active: failed (Result: exit-code) since Tue 2018-08-14 12:15:57 MSK; 2min 20s ago
  Process: 18752 ExecStartPre=/usr/share/mysql/mysql-systemd-start pre (code=exited, status=1/FAILURE)
авг 14 12:15:57 user-All-Series systemd[1]: Stopped MySQL Community Server.
авг 14 12:15:57 user-All-Series systemd[1]: mysql.service: Start request repeated too quickly.
авг 14 12:15:57 user-All-Series systemd[1]: mysql.service: Failed with result 'exit-code'.
авг 14 12:15:57 user-All-Series systemd[1]: Failed to start MySQL Community Server.
авг 14 12:15:59 user-All-Series systemd[1]: mysql.service: Start request repeated too quickly.
авг 14 12:15:59 user-All-Series systemd[1]: mysql.service: Failed with result 'exit-code'.
авг 14 12:15:59 user-All-Series systemd[1]: Failed to start MySQL Community Server.
авг 14 12:16:01 user-All-Series systemd[1]: mysql.service: Start request repeated too quickly.
авг 14 12:16:01 user-All-Series systemd[1]: mysql.service: Failed with result 'exit-code'.
авг 14 12:16:01 user-All-Series systemd[1]: Failed to start MySQL Community Server.