Mostra la font per a Instal·lació MariaDB. Curs 2025-2026

= Instal·lació =
Actualitzeu els repositoris i instal·leu '''mariadb-server'''
 jordi@iot-clot:~$ '''sudo apt update'''
 jordi@iot-clot:~$ '''sudo apt install mariadb-server'''
Protegiu l'accés a la base de dades MariaDB. (Proposta de contrasenya per a l'usuari ''root'': '''fjeclot''')
 jordi@iot-clot:~$ '''sudo mysql_secure_installation'''
 [sudo] contrasenya per a jordi:  
 
 NOTE: RUNNING ALL PARTS OF THIS SCRIPT IS RECOMMENDED FOR ALL MariaDB
      SERVERS IN PRODUCTION USE!  PLEASE READ EACH STEP CAREFULLY!
 
 In order to log into MariaDB to secure it, we'll need the current
 password for the root user. If you've just installed MariaDB, and
 haven't set the root password yet, you should just press enter here.
 
 '''Enter current password for root (enter for none): '''
 OK, successfully used password, moving on... 
 
 Setting the root password or using the unix_socket ensures that nobody
 can log into the MariaDB root user without the proper authorisation.
 
 You already have your root account protected, so you can safely answer 'n'.
 
 '''Switch to unix_socket authentication [Y/n] n'''
 ... skipping.
 
 You already have your root account protected, so you can safely answer 'n'.
 
 '''Change the root password? [Y/n] n'''
 ... skipping.
 
 By default, a MariaDB installation has an anonymous user, allowing anyone
 to log into MariaDB without having to have a user account created for
 them.  This is intended only for testing, and to make the installation
 go a bit smoother.  You should remove them before moving into a
 production environment.
 
 '''Remove anonymous users? [Y/n] '''
 ... Success!
 
 Normally, root should only be allowed to connect from 'localhost'.  This
 ensures that someone cannot guess at the root password from the network.
 
 '''Disallow root login remotely? [Y/n] '''
 ... Success!
 
 By default, MariaDB comes with a database named 'test' that anyone can
 access.  This is also intended only for testing, and should be removed
 before moving into a production environment.
 
 '''Remove test database and access to it? [Y/n] '''
 - Dropping test database...
 ... Success!
 - Removing privileges on test database...
 ... Success!
 
 Reloading the privilege tables will ensure that all changes made so far
 will take effect immediately.
 
 '''Reload privilege tables now? [Y/n] '''
 ... Success!
 
 Cleaning up...
 
 All done!  If you've completed all of the above steps, your MariaDB
 installation should now be secure.
 
 Thanks for using MariaDB!
[https://www.digitalocean.com/community/tutorials/how-to-reset-your-mysql-or-mariadb-root-password Si necessiteu sobreescriure la contrasenya de ''root'' que no recordeu d'una instal·ació anterior]

= Creació d'usuaris =
[https://www.digitalocean.com/community/tutorials/how-to-create-a-new-user-and-grant-permissions-in-mysql Un tutorial de creació d'usuaris amb diferentes permisos (''privilegis'')]

Des del terminal del sistema operatiu es demana entrar al terminal de MariaDB. El primer cop com a usuari ''root'':
 mysql -u root -p
 ''(el sistema demana la contrasenya de l'usuari root)''
Un cop a dins del terminal de MariaDB es creen els usuarios ''iot'' i ''convidat'' amb les seves respectives contrasenyes. Es crea la base de dades ''aula311'', es donen tots els permisos al usuario ''iot'' i tan sols la lectura a l'usuario ''convidat'':
 CREATE USER 'iot'@'localhost' IDENTIFIED BY 'iot';
 CREATE USER 'convidat'@'localhost' IDENTIFIED BY 'benvingut';
 
 CREATE DATABASE aula311;
 SHOW DATABASES;
 USE aula311;
 
 GRANT ALL PRIVILEGES ON aula311.* TO 'iot'@'localhost';
 GRANT SELECT ON aula311.* TO 'convidat'@'localhost';
 FLUSH PRIVILEGES;
Per a visualitzar els vostres usuaris a MariaDB:
 SELECT User FROM mysql.user;
= Accés a la base de dades des del terminal =
Per a accedir a la base de dades hi ha tres usuaris amb permisos diferents:

- '''root''': Té tots els permisos. Pot crear usuaris i bases de dades.

- '''iot''': Té permisos de '''lectura i escriptura''' sobre la base de dades '''aula311'''.

- '''convidat''': Té permisos de '''lectura''' sobre la base de dades '''aula311'''.

Per a accedir al terminal de MariaDB com usuario '''iot''':
 mysql -u '''iot''' -p
 (el sistema pregunta per la contrasenya d'aquest usuari. És la que surt a l'apartat anterior després de ''IDENTIFIED BY'')

Per a accedir al terminal de MariaDB com usuario '''convidat''':
 mysql -u '''convidat''' -p
 (el sistema pregunta per la contrasenya d'aquest usuari. És la que surt a l'apartat anterior després de ''IDENTIFIED BY'')