How to solve ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (111)

Question

 ps ax | grep mysql
  38737 pts/4    R+     0:00 grep --color=auto mysql
[root@ ~]# chown mysql:mysql -R /var/lib/mysql/*
[root@ ~]# chmod 755 -R /var/lib/mysql/*
[root@ ~]# service mysql restart
Redirecting to /bin/systemctl restart mysql.service
Failed to restart mysql.service: Unit mysql.service not found.
[root@ ~]# mysql

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (111)

[root@ ~]# sudo pkill mysql
[root@ ~]# sudo pkill mysqld
[root@ ~]# sudo service mysql restart
Redirecting to /bin/systemctl restart mysql.service
Failed to restart mysql.service: Unit mysql.service not found.
[root@ ~]# sudo systemctl restart mysqld
Job for mysqld.service failed because the control process exited with error code.
See "systemctl status mysqld.service" and "journalctl -xe" for details.
[root@ ~]# sudo systemctl status mysqld
● mysqld.service - MySQL 8.0 database server
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
   Active: failed (Result: exit-code) since Tue 2022-12-27 19:02:07 UTC; 7s ago
  Process: 39028 ExecStopPost=/usr/libexec/mysql-wait-stop (code=exited, status=0/SUCCESS)
  Process: 39004 ExecStartPre=/usr/libexec/mysql-check-socket (code=exited, status=1/FAILURE)
 Main PID: 33163 (code=killed, signal=KILL)

Dec 27 19:02:07 j systemd[1]: mysqld.service: Failed with result 'exit-code'.
Dec 27 19:02:07 j systemd[1]: Failed to start MySQL 8.0 database server.
Dec 27 19:02:07 j systemd[1]: mysqld.service: Service RestartSec=100ms expired, scheduling restart.
Dec 27 19:02:07 j systemd[1]: mysqld.service: Scheduled restart job, restart counter is at 5.
Dec 27 19:02:07 j systemd[1]: Stopped MySQL 8.0 database server.
Dec 27 19:02:07 j systemd[1]: mysqld.service: Start request repeated too quickly.
Dec 27 19:02:07 j systemd[1]: mysqld.service: Failed with result 'exit-code'.
Dec 27 19:02:07 j systemd[1]: Failed to start MySQL 8.0 database server.
[root@ ~]# sudo systemctl start mysqld
Job for mysqld.service failed because the control process exited with error code.
See "systemctl status mysqld.service" and "journalctl -xe" for details.

Answer 1

Have you checked what is in the MySQL error log? Depends on the details but could be in the normal syslog output (e.g. /var/log/messages), or could be ${datadir}/${hostname}.err

Slow down, don't panic, and first of all make sure mysqld is stopped. Check if any mysqld/mariadbd processes exist:

ps -ef | grep mysqld
ps -ef | grep mariadbd

If mysqld/mariadbdb processes are running, stop the processes. Try stopping the nice way (systemctl stop mysql/mariadb) and if they fail, kill -9 <pid>.

Check the error log before you continue.

Then start mysql/mariadb again: (systemctl start mysql/mariadb)

Check the error log again.