You grant the user privileges. The user must have a valid unix account on the server.
To allow a user to connect to database. As owner of the database or user who has permission currently issue:
Where <databasename> is the name of the database. <username> is the user who requires ability to connect.
To allow user to run queries on specific tables:
Where <table> is the table. <username> is the user who requires select ability. <owneroftable> is the owner of the table. <databasename> is the name of the database
NOTE: If the table has PUBLIC privileges, the second step is not necessary. (dbschema will show)
NOTE: Other abilities such as insert, delete, update can be added in the same manner as the second step. Substitute "select" with desired action.
dbschema -d <databasename> -t <tablename> -ss