MySQL ignoring the options I set in ~/.my.conf - mysql

Question

I am trying to turn off ONLY_FULL_GROUP_BY in my local ~.my.cnf options file.
Here are my system details:
$ sudo service mysql status
* /usr/bin/mysqladmin Ver 8.42 Distrib 5.7.25, for Linux on x86_64
Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Server version 5.7.25-0ubuntu0.18.04.2
Protocol version 10
Connection Localhost via UNIX socket
UNIX socket /var/run/mysqld/mysqld.sock
Uptime: 19 min 35 sec
Threads: 1 Questions: 14 Slow queries: 0 Opens: 108 Flush tables: 1
Open tables: 27 Queries per second avg: 0.011`
~.my.cnf has the following content:
[mysqld]
key_buffer_size=32M
max_allowed_packet=512M
sql_mode=STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,
ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
When I use "mysqld --help --verbose" this is what I see:
$ sudo mysqld --help --verbose
mysqld Ver 5.7.25-0ubuntu0.18.04.2 for Linux on x86_64 ((Ubuntu))
Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Starts the MySQL database server.
Usage: mysqld [OPTIONS]
Default options are read from the following files in the given order:
/etc/my.cnf /etc/mysql/my.cnf ~/.my.cnf
So my ~/.my.cnf is being read last meaning that it should override any settings made in previous files.
When I use "mysqld --print-defaults" to see what is being set, here's what I get:
$ sudo mysqld --print-defaults
mysqld would have been started with the following arguments:
--user=mysql --pid-file=/var/run/mysqld/mysqld.pid
-- socket=/var/run/mysqld/mysqld.sock --port=3306 --basedir=/usr
--datadir=/var/lib/mysql --tmpdir=/tmp --lc-messages-dir=/usr/share/mysql
--skip-external-locking
--bind-address=127.0.0.1 --key_buffer_size=16M --max_allowed_packet=16M
--thread_stack=192K --thread_cache_size=8
--myisam-recover-options=BACKUP --query_cache_limit=1M
--query_cache_size=16M --log_error=/var/log/mysql/error.log
--expire_logs_days=10 --max_binlog_size=100M --key_buffer_size=32M
--max_allowed_packet=512M
--sql_mode=STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,
ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
It would appear my settings have been actioned.
Using another method shows the same:
$ sudo mysqladmin variables | grep sql_mode
| sql_mode
ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,
ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
$ sudo mysqladmin variables | grep max_allowed_packet
| max_allowed_packet| 16777216
However, when I look at the settings of sql_mode and max_allowed_packet in mysql itself I see they still have their system default values:
$ mysql
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 5
Server version: 5.7.25-0ubuntu0.18.04.2 (Ubuntu)
Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> select ##global.sql_mode;
+--------------------------------------------------------------------------+
| ##global.sql_mode |
+--------------------------------------------------------------------------+
| ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE, |
| NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER, |
| NO_ENGINE_SUBSTITUTION |
+--------------------------------------------------------------------------+
mysql> select ##global.max_allowed_packet;
+-----------------------------+
| ##global.max_allowed_packet |
+-----------------------------+
| 16777216 |
+-----------------------------+
What am I'm doing wrong?

Answer 1

Your personal ~/.my.cnf can only affect programs run by you, for example mysql client or mysqldump, etc.
It does no good to write a section for [mysqld] in your personal ~/.my.cnf file, because your user is probably not the one who launches mysqld.
You could declare your preferred sql_mode for your own sessions in the MySQL client by writing the option into a [client] section:
[client]
max_allowed_packet=512M
sql_mode=STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,
ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
But [client] only applies to MySQL tools like mysql and mysqldump. It doesn't affect any of your own apps, like if you code something in Java, Python, Ruby, or PHP, etc.
If you want an option to affect all clients, including your apps, you must apply the option in the global MySQL Server config, which is probably /etc/my.cnf as described in the other answer.
You can also change many global options dynamically without restarting mysqld. I often do this right after I edit the /etc/my.cnf file, so I can get the change without interrupting service.
mysql> SET GLOBAL sql_mode='...whatever...';
Final note: I recommend NOT disabling ONLY_FULL_GROUP_BY. That sql_mode is a useful way to prevent bogus query results. It's much better to keep that sql_mode enabled, and fix your SQL queries so they don't cause errors.

Answer 2

mysqld usually runs as its own user mysql, so ~/.my.cnf is meaningless unless it is in the home directory of the mysql user. For server configurations, you typically put settings in the /etc/my.cnf file or /etc/my.cnf.d depending on your mysql version.