MariaDB startup failure on Ubuntu 18.04

Question

I have installed MariaDb hundreds of times on previous Ubuntu versions, but on Ubuntu 18.04 I'm struggling. After the installation finishes, once I restart the PC, MariaDB starts for around 2 minutes and then stops.

When I try to login to MySQL, I get the below error:

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2 "No such file or directory")

I was able to login before I restarted the PC with my username root and the root password. Why does everything change after the restart?

error log from /var/log/mysql/error.log

usr/sbin/mysqld: Too many arguments (first extra is 'start').

2018-09-02 17:35:48 139917209496704 [ERROR] Aborting

2018-09-02 17:38:00 140363564260480 [Note] InnoDB: innodb_empty_free_list_algorithm has been changed to legacy because of small buffer pool size. In order to use backoff, increase buffer pool at least up to 20MB.

2018-09-02 17:38:00 140363564260480 [Note] InnoDB: Using mutexes to ref count buffer pool pages
2018-09-02 17:38:00 140363564260480 [Note] InnoDB: The InnoDB memory heap is disabled
2018-09-02 17:38:00 140363564260480 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2018-09-02 17:38:00 140363564260480 [Note] InnoDB: GCC builtin __atomic_thread_fence() is used for memory barrier
2018-09-02 17:38:00 140363564260480 [Note] InnoDB: Compressed tables use zlib 1.2.11
2018-09-02 17:38:00 140363564260480 [Note] InnoDB: Using Linux native AIO
2018-09-02 17:38:00 140363564260480 [Note] InnoDB: Using SSE crc32 instructions
2018-09-02 17:38:00 140363564260480 [Note] InnoDB: Initializing buffer pool, size = 128.0M
2018-09-02 17:38:00 140363564260480 [Note] InnoDB: Completed initialization of buffer pool
2018-09-02 17:38:00 140363564260480 [Note] InnoDB: Highest supported file format is Barracuda.
2018-09-02 17:38:00 140363564260480 [Note] InnoDB: The log sequence number 1683676 in ibdata file do not match the log sequence number 1683686 in the ib_logfiles!
2018-09-02 17:38:00 140363564260480 [Note] InnoDB: Restoring possible half-written data pages from the doublewrite buffer...
2018-09-02 17:38:00 140363564260480 [Note] InnoDB: 128 rollback segment(s) are active.
2018-09-02 17:38:00 140363564260480 [Note] InnoDB: Waiting for purge to start
2018-09-02 17:38:00 140363564260480 [Note] InnoDB:  Percona XtraDB (http://www.percona.com) 5.6.39-83.1 started; log sequence number 1683686
2018-09-02 17:38:00 140362895062784 [Note] InnoDB: Dumping buffer pool(s) not yet started
2018-09-02 17:38:00 140363564260480 [Note] Plugin 'FEEDBACK' is disabled.
2018-09-02 17:38:00 140363564260480 [Note] Recovering after a crash using tc.log
2018-09-02 17:38:00 140363564260480 [Note] Starting crash recovery...
2018-09-02 17:38:00 140363564260480 [Note] Crash recovery finished.
2018-09-02 17:38:00 140363564260480 [Note] Server socket created on IP: '127.0.0.1'.
2018-09-02 17:38:00 140363564260480 [Note] /usr/sbin/mysqld: ready for connections.
Version: '10.1.34-MariaDB-0ubuntu0.18.04.1'  socket: '/var/run/mysqld/mysqld.sock'  port: 3306  Ubuntu 18.04
2018-09-02 17:39:30 140363563476736 [Note] /usr/sbin/mysqld: Normal shutdown
2018-09-02 17:39:30 140363563476736 [Note] Event Scheduler: Purging the queue. 0 events
2018-09-02 17:39:30 140362953770752 [Note] InnoDB: FTS optimize thread exiting.
2018-09-02 17:39:30 140363563476736 [Note] InnoDB: Starting shutdown...
2018-09-02 17:39:30 140363563476736 [Note] InnoDB: Waiting for page_cleaner to finish flushing of buffer pool
2018-09-02 17:39:32 140363563476736 [Note] InnoDB: Shutdown completed; log sequence number 1683696
2018-09-02 17:39:32 140363563476736 [Note] /usr/sbin/mysqld: Shutdown complete
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Answer 1

mysqld is the server. You don't log into it as a user.

mysql is the client. You do log into it as a user; it then connects to mysqld for you.