How to finally set utf8mb4 properly on MySQL?

Question

I'm losing my mind on this issue since yesterday.

I'm trying to convert my MySQL database from utf8 to utf8mb4. To do so, I followed those sites/threads : https://mathiasbynens.be/notes/mysql-utf8mb4#utf8-to-utf8mb4 , Cannot store emoji in database , Change MySQL default character set to UTF-8 in my.cnf? , etc.

My database seems to have a utf8mb4_unicode_ci collation as expected, and all her tables too.

Nevertheless, when I proceed SHOW VARIABLES WHERE Variable_name LIKE 'character\_set\_%' OR Variable_name LIKE 'collation%'; I obtain :

#With a Root access
Variable_name              Value
character_set_client        utf8                #expecting utf8mb4
character_set_connection    utf8                #expecting utf8mb4
character_set_database      utf8mb4             #good
character_set_filesystem    binary              #good
character_set_results       utf8                #expecting utf8mb4
character_set_server        utf8mb4             #good
character_set_system        utf8                #expecting utf8mb4
collation_connection        utf8_general_ci     #expecting utf8mb4_unicode_ci
collation_database          utf8mb4_unicode_ci  #good
collation_server            utf8mb4_unicode_ci  #good

#With a standard user access
Variable_name               Value
character_set_client        utf8                #expecting utf8mb4
character_set_connection    utf8mb4             #good 
character_set_database      utf8mb4             #good
character_set_filesystem    binary              #good
character_set_results       utf8                #expecting utf8mb4
character_set_server        utf8mb4             #good
character_set_system        utf8                #expecting utf8mb4
collation_connection        utf8mb4_unicode_ci  #good
collation_database          utf8mb4_unicode_ci  #good
collation_server            utf8mb4_unicode_ci  #good

I set a /etc/mysql/conf.d/90-my.cnf file like this :

[client]
default-character-set = utf8mb4

[mysql]
default-character-set = utf8mb4

[mysqld]
character-set-client-handshake = FALSE
character-set-server = utf8mb4
collation-server = utf8mb4_unicode_ci
init-connect = 'SET collation_connection = utf8mb4_unicode_ci'
init-connect = 'SET NAMES utf8mb4'

My MySQL version is 5.5.54, all set in a debian 7.

Does anyone have a clue to help me ?

Thx for your help, and sorry for my bad english...

EDIT

Fun fact : when I check variables in the in-line command, I got this :

mysql> show variables like "%character%";
+--------------------------+----------------------------+
| Variable_name            | Value                      |
+--------------------------+----------------------------+
| character_set_client     | utf8mb4                    |
| character_set_connection | utf8mb4                    |
| character_set_database   | utf8mb4                    |
| character_set_filesystem | binary                     |
| character_set_results    | utf8mb4                    |
| character_set_server     | utf8mb4                    |
| character_set_system     | utf8                       |
| character_sets_dir       | /usr/share/mysql/charsets/ |
+--------------------------+----------------------------+

While I still have utf8 for character_set_client and character_set_results when I check with phpmyadmin (with a non-superuser access)

Answer 1

When connecting as user root, init-connect is ignored.

Give your application its own login without SUPER privilege.

Then, to make extra sure, whenever establishing a connection from your app, do the language-specific method of providing the character set. (Or execute SET NAMES utf8mb4.) What app language are you using?

In case something else is going wrong, see "Best Practice" in Trouble with utf8 characters; what I see is not what I stored