daemon
What is a daemon? In computing, a daemon (pronounced DEE-muhn) is a program that runs continuously as a background process and wakes up to handle periodic service requests, which often come from remote processes. The daemon program is alerted to the request by the operating system (OS), and it either responds to the request itself or forwards the request to another program or process as appropriate. Common daemon processes include print spoolers, email handlers and other programs that manage administrative tasks. Many Unix or Linux utility programs run as daemons. For example, on Linux, the Network Time Protocol ( NTP ) daemon is used to measure time differences between the clock on the computer it runs on and those of all other computers on the network. A time daemon runs on each of the host computers, with one being designated as primary and all others as secondary. Secondary daemons reset the network time on their host computer by first sending a request to the primary time da...