MySQL service : Unable to setup unix socket lock file.

How to solve mysqld service restart problem for above error?

Problem :
I was adding shell and home directory for mysql user,executed following cmd,

shell> usermod -m -d /home/mysql -s /bin/bash mysql

If mysql is running and process running with mysql , we need to stop mysql otherwise it will throw an error like usermod: user mysql is currently used by process 27768

After stopping MySQL service and adding shell and homedir for mysql user, at the time mysqld service startup it started throwing error.

shell> service mysqld restart
Redirecting to /bin/systemctl restart mysqld.service
Job for mysqld.service failed because the control process exited with error code. See "systemctl status mysqld.service" and "journalctl -xe" for details.
Shell> systemctl status mysqld.service

● mysqld.service - MySQL Server
Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
Active: deactivating (final-sigterm) (Result: exit-code) since Wed 2016-12-14 22:16:42 MST; 7min ago
Docs: man:mysqld(8)
Process: 35222 ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/ $MYSQLD_OPTS (code=exited, status=1/FAILURE)
Process: 35204 ExecStartPre=/usr/bin/mysqld_pre_systemd (code=exited, status=0/SUCCESS)
Main PID: 27768 (code=exited, status=0/SUCCESS)
CGroup: /system.slice/mysqld.service
└─35226 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/

mysqld error logs:

[ERROR] Could not create unix socket lock file /var/lib/mysql/mysql.sock.lock.
[ERROR] Unable to setup unix socket lock file.
[ERROR] Aborting

Tried to stop, kill mysqld service but still it’s not going out from process list.

Root cause : Suspecting change in process id after modifying mysql user properties.


Just Move/Rename your my.cnf and start mysqld service with default configuration.You will see no more error at the time for service startup.
Move backuped up /renamed original my.cnf and restart mysqld service again.

service mysqld restart

And should start working fine, as it is.

ALl set!!