You may have gotten an error like, "Error: Must execute as <<username>>" . This means that you installed HarperDB as <<user>>. Because HarperDB stores files natively on the operating system, we only allow the HarperDB executable to be run by a single user. This prevents permissions issues on files.
For example if you installed as user_a, but later wanted to run as user_b. User_b may not have access to the hdb files HarperDB needs. This also keeps HarperDB more secure as it allows you to lock files down to a specific user and prevents other users from accessing your files.