How to "safely" terminate mysqld? - mysql

Question

I am following mysql on Cygwin.
# To begin MySQL setup run the following:
mysql_install_db
# Run mysql - you'll get a firewall alert from windows if you have it active.
mysqld_safe &
# Immediately following that, it would be wise to run the following:
mysql_secure_installation
During the mysql_install_db, I was asked who the database (DB) would be for. I specified a non-administrator account nonadmin.
For the mysql_secure_installation process, I followed the similarly named MariaDB page. In contrast to the description, I was told that I had no root password, so I set it to the same as my cygwin and windows administrator account.
I lost track of whether which account was used for each of the three commands above, but here is what I remember:
mysql_install_db: Ran as nonadmin, but prompted for admin password
mysqld_safe: Run as nonadmin
mysql_secure_installation: Attempted as nonadmin, abandoned, and
completed as administrator account admin
It seems that I should restart the server after the final step. Using ps -ef, I noted that process mysqld belongs to nonadmin. Using nonadmin, I attempted the mysqladmin shutdown command at mysql on Cygwin. I get:
mysqladmin: connect to server at 'localhost' failed
error: 'Access denied for user 'nonadmin'#'localhost' (using password: NO)'
I tried the variation of the command that prompts the user for a password: mysqladmin -p shutdown. I did this twice, entering the cygwin/windows passwords for nonadmin and admin. Both times, I get:
mysqladmin: connect to server at 'localhost' failed
error: 'Access denied for user 'nonadmin'#'localhost' (using password: YES)'
This totalled 3 attempts. I then switched to the admin account and retried all 3 attempts. I got the above messages, but with the username admin:
mysqladmin: connect to server at 'localhost' failed
error: 'Access denied for user 'admin'#'localhost' (using password: NO)'
mysqladmin: connect to server at 'localhost' failed
error: 'Access denied for user 'admin'#'localhost' (using password: YES)'
So no joy connecting to the daemon to shut it down. As an alternative, I want to avoid clobbering mysqld with kill -9 because I like things to terminate cleanly (though I will probably do so soon).
As another alternative, I've come across references to /etc/init.d, but I have no such file.
Can anyone please explain why I can't connect to the daemon to shut it down?
Also, I'm new to MySQL, so if possible, it'd be nice to find a way back to the process at mysql on Cygwin rather than deviating from it too much.
Thanks.

Answer 1

What I ended up doing was kill -9 on all mysql looking processes shown by ps -ef. I then deleted /var/lib/mysql -- and accidentally deleted all of /var/lib/*. Subsequently, therefore, I reinstalled all of my Cygwin packages, thus starting from a clean slate.
I also found the following more detailed process at this alaya page for installing a MySQL/MariaDB database on Cygwin, after which I was able to shut down the MySQL server.
from the Administrator terminal run:
mysql_install_db
Start the mysql server:
mysqld_safe &
then run:
mysql_secure_installation
You should then be able to log in to MariaDB from a non-administrative shell with:
mysql -u root -p
The initial mysql_install_db step generates the following useful looking information, which I'm capturing here because I'm not sure if there is a way to get it again.
Installing MariaDB/MySQL system tables in '/var/lib/mysql' ...
2019-05-01 23:00:06 0 [Warning] InnoDB: innodb_open_files 300 should not be greaterthan the open_files_limit 256
OK
To start mysqld at boot time you have to copy
support-files/mysql.server to the right place for your system
PLEASE REMEMBER TO SET A PASSWORD FOR THE MariaDB root USER !
To do so, start the server, then issue the following commands:
'/usr/bin/mysqladmin' -u root password 'new-password'
'/usr/bin/mysqladmin' -u root -h fmaPC password 'new-password'
Alternatively you can run:
'/usr/bin/mysql_secure_installation'
which will also give you the option of removing the test
databases and anonymous user created by default. This is
strongly recommended for production servers.
See the MariaDB Knowledgebase at http://mariadb.com/kb or the
MySQL manual for more instructions.
You can start the MariaDB daemon with:
cd '/usr' ; /usr/bin/mysqld_safe --datadir='/var/lib/mysql'
You can test the MariaDB daemon with mysql-test-run.pl
cd '/usr/mysql-test' ; perl mysql-test-run.pl
Please report any problems at http://mariadb.org/jira
The latest information about MariaDB is available at http://mariadb.org/.
You can find additional information about the MySQL part at:
http://dev.mysql.com
Consider joining MariaDB's strong and vibrant community:
https://mariadb.org/get-involved/
During the mysql_secure_installation step, I followed the recommendation to set a root password. Instead of the mysql -u root -p step, then, I could instead issue the following to stop the MySQL server:
mysqladmin -u root -p shutdown
I made an important discovery made about this process from the point of view of a user without administrator rights. Contrary to what is suggested on the alaya page cited above, the above process does not have to be done from an administrator account. Importantly, the user accounts with which one can connect to the MySQL server has nothing to do with the user accounts on the host system (Windows or *nix) (a fact that I got from perusing MariaDB knowledgebase). I suspect that any user on the host system can connect to any user account on the server via the socket that it presents [1], with the right password.
I also found that the above process works on a machine that has very restrictive Windows firewall policies. Even if the server (the mysqld_safe & step) and client (the mysql -u root -p step) are started from the same non-administrative account, the Windows firewall will issue a warning about curtailing some features. I suspect that the trigger is the creation of a socket for connecting to the server. Despite the warning, however, ps -ef shows the server to be running. Therefore, I suspect that the firewall restriction consists of allowing only loop-back connections. The mysql_secure_installation step apparently disallows external connections, and I found that after this step, stopping and relaunching the server no longer triggers the firewall warning. So the effect of mysql_secure_installation seems to persist into subsequent sqld launches, at least when they are started via mysqld_safe.
[1] "Present" might not be the right terminology here, as I'm more of an analyst rather than a developer or administrator.