MySQL service not running on CentOS 7 system

[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
# Settings user and group are ignored when systemd is used.
# If you need to run mysqld under a different user or group,
# customize your systemd unit file for mariadb according to the
# instructions in http://fedoraproject.org/wiki/Systemd

[mysqld_safe]
log-error=/var/log/mariadb/mariadb.log
pid-file=/var/run/mariadb/mariadb.pid

#
# include all files from the config directory
#
!includedir /etc/my.cnf.d

I checked for the existence of files and directories listed in that file. I saw the following results for the locations for datadir, socket, log-error, and pid-file:

# ls -ld /var/lib/mysql
drwxr-xr-x. 19 mysql mysql 4096 Oct 14 23:46 /var/lib/mysql
[root@localhost install]# ls -l /var/lib/mysql/mysql.sock
srwxrwxrwx. 1 mysql mysql 0 Sep 29 15:05 /var/lib/mysql/mysql.sock
# ls -l /var/log/mariadb/mariadb.log
-rw-r-----. 1 mysql mysql 0 Oct  5 20:49 /var/log/mariadb/mariadb.log
# ls -l /var/run/mariadb/mariadb.pid
ls: cannot access /var/run/mariadb/mariadb.pid: No such file or directory

I didn't see any mariadb.pid file, but I wouldn't expect it to be created until the mysqld service successfully started.

So I didn't know why I was getting the "Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock'" message when I issued the command mysql nor why my attempt to start the mySQL service failed with a "No such file or directory" message. Searching online, I found a posting by danneth at No mysqld or mysql.server after mariadb-server install to use systemctl start mariadb.service. When I used that command, I didn't see any error messages. I tried the

systemctl status mysqld
service

after issuing the command, but still saw a error message for it. But, when I then issued the mysql command I received an "access denied" message this time, which seemed reasonable, since I hadn't provided the password for the root account when I issued the command..

When I was using CentOS 5, I had MySQL rather than MariaDB and I didn't know I needed to start the MariaDB RDBMS service on the CentOS 7 system using a command referencing mariadb rather than mysqld. I assumed I could reference mysqld to start the service.

To have the MariaDB service start automatically each time the system boots, issue the command systemctl enable mariadb.service. After you have started the service, also issue the command mysql_secure_installation.

# mysql_secure_installation
/usr/bin/mysql_secure_installation: line 379: find_mysql_client: command not found

NOTE: RUNNING ALL PARTS OF THIS SCRIPT IS RECOMMENDED FOR ALL MariaDB
      SERVERS IN PRODUCTION USE!  PLEASE READ EACH STEP CAREFULLY!

In order to log into MariaDB to secure it, we'll need the current
password for the root user.  If you've just installed MariaDB, and
you haven't set the root password yet, the password will be blank,
so you should just press enter here.

Enter current password for root (enter for none):
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)
Enter current password for root (enter for none):
OK, successfully used password, moving on...

Setting the root password ensures that nobody can log into the MariaDB
root user without the proper authorisation.

You already have a root password set, so you can safely answer 'n'.

Change the root password? [Y/n] n
 ... skipping.

By default, a MariaDB installation has an anonymous user, allowing anyone
to log into MariaDB without having to have a user account created for
them.  This is intended only for testing, and to make the installation
go a bit smoother.  You should remove them before moving into a
production environment.

Remove anonymous users? [Y/n] y
 ... Success!

Normally, root should only be allowed to connect from 'localhost'.  This
ensures that someone cannot guess at the root password from the network.

Disallow root login remotely? [Y/n] Y
 ... Success!

By default, MariaDB comes with a database named 'test' that anyone can
access.  This is also intended only for testing, and should be removed
before moving into a production environment.

Remove test database and access to it? [Y/n] Y
 - Dropping test database...
 ... Success!
 - Removing privileges on test database...
 ... Success!

Reloading the privilege tables will ensure that all changes made so far
will take effect immediately.

Reload privilege tables now? [Y/n] Y
ERROR 1146 (42S02) at line 1: Table 'mysql.servers' doesn't exist
 ... Failed!

Cleaning up...

All done!  If you've completed all of the above steps, your MariaDB
installation should now be secure.

Thanks for using MariaDB!

I had it remove the anonymous account, since leaving it would be a security vulnerability. I also chose to disallow remote root login to MariaDB and the test database for the same reason.

I had copied the contents of the /var/lib/mysql directory from the hard drive of the prior CentOS 5 system to the new CentOS 7 system to have all of the databases from the old system available on the new system, so that appeared to be the reason that the mysql_secure_installation, which can be found in /usr/bin, did not accept my just hitting Enter for the password initially. When I entered the root password for MySQL on the old system, it was accepted. And I was able finally get a prompt where I could enter SQL commands using that password with

mysql -u root -p

So the 3 steps to enable and run MariaDB are as follows, assuming it was previously installed during the initial setup for the system or with yum install mariadb mariadb-server:


systemctl start mariadb.service

systemctl enable mariadb.service

mysql_secure_installation