What is the difference between a daemon and a server process?

last updated in Categories Howto, Linux, UNIX

Asked by Pari Kulkarni


Q.What is the difference between a daemon and a server process?

A. A ‘daemon’ is a software process that runs in the background (continuously) and provides the service to client upon request. For example named is a daemon. When requested it will provide DNS service. Other examples are:

  • xinetd (it is a super-daemon, it is responsible for invoking other Internet servers when they are needed)
  • inetd (same as xinetd, but with limited configuration options)
  • sendmail/postfix (to send/route email)
  • Apache/httpd (web server)

Following simple example illustrate relationship between client and daemon.

CLIENT  -> Daemon

Browser Running one daemon for each of the services could significantly increase the load. However if you are running big site (with many user) it is advisable to use dedicated daemon. For example web server or MySQL database server.

A ‘server process’ run runs one time, when called by a daemon. Once done it will stop. For example telnetd (in.telnetd) or ftpd called from xinetd/inetd daemon . By calling server process from daemon you can save the load and memory. Use a server process for small services such as ftpd, telnetd

CLIENT -> Daemon   -> Calls server process
ftp    -> xinetd   -> Calls ftpd
ftp     xinetd stops ftpd


Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin, DevOps engineer, and a trainer for the Linux operating system/Unix shell scripting. Get the latest tutorials on SysAdmin, Linux/Unix and open source topics via RSS/XML feed or weekly email newsletter.

4 comment

  1. it is good

    if i want to restart a service can i directly restart the service

    or i want to restart pariticular daemon

    what is difference

    can u clear this

    thanks in advance.

    1. hi u can restart any one or both (service or daemon) and if u install daemon newly u must & shod restart the daemon

  2. If you have made new chenges in the configuration file you can simply run below:
    # service refresh
    # service reload

    If you want to disable/enable one of the specific service which are under xinetd/inetd daemon you can simply comment out that particular filel in xinetd conf file.

    Have a question? Post it on our forum!