Import database from MSSQL export dump on Ubuntu localhost
The problem was that the export dump file didn't have any extension and the SQLCMD couldn't recognize the file and didn't accept it.  

I added the a .bak extension to the file and the SQL Server Management Tool restored the database from this modified file. It's still doesn't work on Ubuntu but that's a permissions problem. I'll maybe ask a separate question or look for it if it's already asked.