In this case, the upgrade changed a line in the service init script /etc/init.d/mysql
from if ! mysqladmin ping &>/dev/null;then
to if ! $(mysqladmin --no-defaults --socket="$socket" --user=UNKNOWN_MYSQL_USER ping &>/dev/null) ;then
.
Printing out $socket
revealed it was empty. That value was coming from /usr/sbin/mysqld --print-defaults
, which prints out the the configuration defined in the config file. I had not defined socket
in my config file (instead just using mysql default socket location), so adding the line socket=/var/run/mysqld/mysqld.sock
to /etc/mysql/my.cnf
solved the problem.