SET NOCOUNT ON;
DECLARE @n sysname, @s nvarchar(max);
DECLARE c CURSOR LOCAL FAST_FORWARD FOR
  SELECT name FROM sys.databases WHERE database_id > 4 AND state = 0 AND source_database_id IS NULL;
OPEN c;
FETCH NEXT FROM c INTO @n;
WHILE @@FETCH_STATUS = 0
BEGIN
  SET @s = N'BACKUP DATABASE ' + QUOTENAME(@n) + N' TO DISK = N''/var/opt/mssql/backup/' + REPLACE(@n, N'''', N'''''') + N'.bak'' WITH INIT, COPY_ONLY, CHECKSUM';
  EXEC (@s);
  FETCH NEXT FROM c INTO @n;
END
CLOSE c;
DEALLOCATE c;