1.1. UIs and Daemons
Assuming that our Linux appliance will have multiple, simultaneous UIs, when we look at the appliance from the point of view of running processes we get an architecture something like that shown in Figure 1-2. The UI programs interact with the users to accept commands and configuration and to display status and statistics. Daemons, on the other hand, interact with the hardware, other daemons, and the UIs to provide the appliance's defining service as well as status and statistics.
Figure 1-2. A common appliance architecture
Daemons are background programs that are most often started just after booting Linux. Daemons ...