Disk and Execution Monitor

Why Trust Techopedia

What Does Disk and Execution Monitor Mean?

A disk and execution monitor (daemon) is a background process run in computer multitasking operating systems, usually at bootstrap time, to perform administrative changes or monitor services.


Common daemon processes include email handlers, print spoolers and other programs that perform OS administrative tasks. Daemons also perform specified operations at predefined times in response to events.

Techopedia Explains Disk and Execution Monitor

Unix daemon files generally have a “d” suffix. For example, “identd” refers to a daemon that provides the identity of a TCP connection. Microsoft OS daemons are referred to as terminate and stay resident (TSR) programs and are called “system agents” or “services” within the context of OS administration.

Mac OS X, a Unix-based system, also uses daemons, but it does not provide the same services as in the Microsoft OS.

Daemon parent processes are often the initialization process. A process becomes a daemon by forking a child process and exiting the parent process, causing initialization to adopt the child process.

Systems often start daemons at boot time, which to respond to network requests, hardware activity or programs that perform specified tasks. Daemons are also able to configure hardware and run scheduled tasks.

The common methods by which a process becomes a daemon include:

  • Dissociating from the controlling tty
  • Forming a session leader
  • Forming a process group leader
  • Staying in the background by forking and exiting
  • Setting the root directory as the current working directory
  • Setting the unmask to zero to allow open () and create () calls to provide their own permission masks
  • Closing inherited files left open by the parent process at the time of execution
  • Using the console, a log file or/dev/null as standard input, standard output and standard error

Related Terms

Margaret Rouse
Technology Expert
Margaret Rouse
Technology Expert

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.