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In multitasking computer operating systems, a daemon ( or ) is a computer program that runs as a background process, rather than being under the direct control of an interactive user. Traditionally daemon names end with the letter ''d''. For example, syslogd is the daemon that implements the system logging facility, and sshd is a daemon that services incoming SSH connections. In a Unix environment, the parent process of a daemon is often, but not always, the init process. A daemon is usually either created by a process forking a child process and then immediately exiting, thus causing init to adopt the child process, or by the init process directly launching the daemon. In addition, a daemon launched by forking and exiting typically must perform other operations, such as dissociating the process from any controlling terminal (tty). Such procedures are often implemented in various convenience routines such as ''daemon(3)'' in Unix. Systems often start daemons at boot time and serve the function of responding to network requests, hardware activity, or other programs by performing some task. Daemons can also configure hardware (like udevd on some Linux systems), run scheduled tasks (like cron), and perform a variety of other tasks. ==Terminology== The term was coined by the programmers of MIT's Project MAC. They took the name from Maxwell's demon, an imaginary being from a thought experiment that constantly works in the background, sorting molecules. Unix systems inherited this terminology. Maxwell's Demon is consistent with Greek mythology's interpretation of a daemon as a supernatural being working in the background, with no particular bias towards good or evil. However, BSD and some of its derivatives have adopted a Christian demon as their mascot rather than a Greek daemon. The word ''daemon'' is an alternative spelling of ''demon,'' and is pronounced . In the context of computer software, the original pronunciation has drifted to for some speakers.〔 Alternate terms for ''daemon'' are ''service'' (Microsoft Windows NT), ''started task'' (IBM z/OS),〔(【引用サイトリンク】title=IBM Knowledge Center - Glossary of z/OS terms and abbreviations )〕 and ''ghost job'' (XDS UTS). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Daemon (computing)」の詳細全文を読む スポンサード リンク
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