Options (DBMGUI) 

When you call the Database Manager GUI at command line level, you can specify options (Database Manager GUI: SAP DB 7.4 ® Starting the DBMGUI). If you do not enter any options, you can make the entries needed for logging on to the database instance on the logon screen.

You want to specify the following user data as options: the DBM operator and the name of the database instance

dbmgui -u dbmmann,secret -d MK1

The Database Manager is called and a database session is created for the DBM operator dbmmann, password secret with the registered database instance MK1.