Daemons are the invisible workhorses of the Linux world. A daemon is a program run in the background (i.e., not attached to any particular terminal) that performs some system task. Typically, that system task is to service a request by some user program for a piece of information (e.g., rwhod), access to some system resource (e.g., lpd), or to facilitate communication between two systems or two parts of the same system (e.g., telnetd, talkd).

The word “daemon” should be pronounced the same as “demon,” but lots of people say “day-mon” or “die-mon” and no one laughs. In general, I try to stick with whichever pronunciation my boss prefers. The word originates in Greek mythology and refers to a supernatural agent somewhere above a human, ...

Get Linux® Desk Reference, Second Edition now with the O’Reilly learning platform.

O’Reilly members experience live online training, plus books, videos, and digital content from nearly 200 publishers.