Importing a database from a shell:
If you already have a dump of the database you wish to import on a server, then run from your terminal window command to import it:
mysql -u username -ppassword database_name < dump.sql
Backup all available databases:
Run from your terminal window to get dump of all databases:
mysqldump -u username -ppassword -all-databases > dump.sql
Please note, that all databases in the example above will be dumped as a single file.