Answer to Question #176627 in C++ for Joseph Owusu

Question

apart from init, identify any three system processes or daemons and outline their function

Answer 1

Daemons process:- A daemon is a long-running background process that answers requests for services. The term originated with Unix, but most operating systems use daemons in some form or another. In Unix, the names of daemons conventionally end in "d". Some examples include inetd, httpd, nfsd, sshd, named, and lpd.

1. inetd daemon:- It is a superserver that standardizes network port access and interfaces between regular programs and network ports. After you start inetd, it reads the inetd.conf file and then listens on the network ports defined in that file, attaching a newly started process to every new incoming connection.
2. httpd:- It is the Apache HyperText Transfer Protocol (HTTP) server program. It is designed to be run as a standalone daemon process. When used like this it will create a pool of child processes or threads to handle requests.
3. nfsd: nfsd handles client requests from remote systems. Multiple copies of this daemon are usually run so that several requests can be handled simultaneously. However, too many copies of nfsd can increase the demand for CPU time to the point where a drop in performance results. For the best performance the number of copies of nfsd should be set to four.
4. SSHD daemon command:- OpenSSH or SSH daemon is called sshd on Linux and used by ssh command. We use ssh and sshd for secure encrypted communications between two untrusted hosts over an insecure network or internet. OpenSSH server listens for connections from clients on TCP port number 22. The server is normally started at boot from /etc/init.d/ssh or /etc/init.d/sshd script.