The simplest form of the RESTORE DATABASE command requires only that you specify the alias name of the database that you want to restore.
db2 restore db sample
This will restore the image from the path the restore command is run from.
In this example, because the SAMPLE database exists, the following message is returned:
SQL2539W Warning! Restoring to an existing database that is the same as the backup image database. The database files will be deleted. Do you want to continue ? (y/n)
If you enter Y, and a backup image for the SAMPLE database exists in the directory, the restore operation will be performed. ...