Installation Problem - mySQL 5.6.34 on macOS X Server 10.11.6

[Rick Aurbach]

I am trying to install mySQL 5.6.34 on my MacMini server (running 10.11.6). I chose 5.6.34 because the server is too old to update to Sierra. [The purpose of this installation is to install and use Mantis BugTracker.]

The installation appeared to succeed, but the suggested testing didn't work out.

In particular, mysqlshow did not include mysql in the list of databases, and

Prospero:mysql server$ bin/mysqlshow mysql
bin/mysqlshow: Access denied for user ''@'localhost' to database 'mysql'

although I am logged in and running this query as root (connected via ScreenSharing).

The listing of the data directory doesn't show up anything that I'm smart enough to recognize as a problem.

Prospero:mysql server$ ls -l data
total 221216
-rw-rw---- 1 _mysql _mysql 56 Apr 17 14:33 auto.cnf
-rw-rw---- 1 _mysql _mysql 50331648 Apr 17 17:29 ib_logfile0
-rw-rw---- 1 _mysql _mysql 50331648 Apr 17 14:22 ib_logfile1
-rw-rw---- 1 _mysql _mysql 12582912 Apr 17 17:29 ibdata1
drwx---rwx 81 _mysql _mysql 2754 Apr 17 14:22 mysql
-rw-rw---- 1 _mysql _mysql 6864 Apr 17 17:29 mysqld.local.err
-rw-rw---- 1 _mysql _mysql 6 Apr 17 17:29 mysqld.local.pid
drwx---rwx 55 _mysql _mysql 1870 Apr 17 14:22 performance_schema
drwxr-xr-x 3 _mysql _mysql 102 Sep 30 2016 test

Can anyone offer me help with this problem??