Note: This will work on other systems as well and also on MySQL Databases not only MariaDB.
Find the databases that are present on the server
mysql -u root -p
show databases; exit
Make a note of the database you which to backup. Them make sure nothing writes to the database before you continue. If you are not sure whether stuff is still getting written to the database. You can lock the tables like this.
mysql -u root -p
FLUSH TABLES WITH READ LOCK; exit
Now we can backup the database in this example we are backing up the a database called pineapple.
mysqldump -u root -p pineapple > pineapple.dd.mm.yyyy.sql
Now we can unlock the tables again.
mysql -u root -p
UNLOCK TABLES; exit
Tip: On large databases or systems with low disk space you can choose to compress it during the dump.
mysqldump -u root -p pineapple | gzip > pineapple.dd.mm.yyyy.sql.gz
gunzip < pineapple.dd.mm.yyyy.sql.gz | mysql -u root -p pineapple
Or
zcat pineapple.dd.mm.yyyy.sql.gz | mysql -u root -p pineapple