What is technical difference between daemon, service and process ? [closed]

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A daemon is a background, non-interactive program. It is detached from the keyboard and display of any interactive user. The word daemon for denoting a background program is from the Unix culture; it is not universal.

A service is a program which responds to requests from other programs over some inter-process communication mechanism (usually over a network). A service is what a server provides. For example, the NFS port mapping service is provided as a separate portmap service, which is implemented as the portmapd daemon.

A service doesn't have to be a daemon, but usually is. A user application with a GUI could have a service built into it: for instance, a file-sharing application. Another example is the X Window service, which is anything but in the background: it takes over your screen, keyboard and pointing device. It is a service because it responds to requests from applications (to create and manipulate windows, et cetera), which can even be elsewhere on the...

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I want to know that what are differences in behavior of a daemon, process and service running in ubuntu desktop.

Daemons - Daemon does not stand for Disk and Execution Monitor (http://www.takeourword.com/TOW146/page4.html). They are the processes which run in the background and are not interactive. They have no controlling terminal.

They perform certain actions at predefined times or in response to certain events. In *NIX, the names of daemons end in d.

Services - In Windows, daemons are called services.

If you're wondering why *NIX has a command named service, it is just used to run init scripts (shorthand for initialization scriptrunlevel).

Process - Process is a running program. At a particular instant of time, it can be either running, sleeping, or zombie (completed process, but waiting for it's parent process to pick up the return value).

Sources and further information:

green
September 23, 2012 10:23...

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Answers

Daemons - Daemon does not stand for Disk and Execution Monitor (http://www.takeourword.com/TOW146/page4.html). They are the processes which run in the background and are not interactive. They have no controlling terminal.

They perform certain actions at predefined times or in response to certain events. In *NIX, the names of daemons end in d.

Services - In Windows, daemons are called services.

If you're wondering why *NIX has a command named service, it is just used to run init scripts (shorthand for initialization scriptrunlevel).

Process - Process is a running program. At a particular instant of time, it can be either running, sleeping, or zombie (completed process, but waiting for it's parent process to pick up the return value).

Sources and further information:

A daemon is a background, non-interactive program. It is detached from the keyboard and display of any interactive user. The word daemon for denoting a background...
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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...

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A background-job (ie. started with &) still has it's stdin, stdout and stderr connected to the terminal it was started in. It may suddenly write (eg. error-messages) to the terminal ("disturbing" the job in the foreground) or pause waiting for input from the keyboard (you must first put it in the foreground). You may of course redirect stdout and stderr to a file or to /dev/null to prevent the background-job from writing to the terminal.

A background-job can also be put in foreground - eg. the current foreground-job is stopped, and the fg (foreground) command is used to put a background-job in the foreground. A background-job can also be reached by signals from the terminal - eg. SIGHUP when you close the terminal, which usually end (most) programs started in the terminal.

A daemon - like the ones started automatically by init.d, but which also can be started manually from a terminal - on the other hand, runs disconnected from any terminals. Even if it was manually...

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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 -> DaemonBrowser 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...

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An application is a program which you interact with on the desktop.

A process is an instance of a particular executable (.exe program file) running.

A service is a process which runs in the background and does not interact with the desktop. In Windows, services almost always run as an instance of the svchost.exe process, the windows service host process; however there are sometimes exceptions to this.

Sometimes, processes may run in the background without interacting with the desktop, but without being installed as a service.

Antivirus programs usually employ a service so they can continue running even when the user is not logged in.

Processes usually exit when an application is closed, however this is not always the case. Some programs, particularly download and backup programs, may continue to run in the background without displaying any windows. Antivirus is also an example of this - in addition to using a service, many antivirus applications...

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What is difference between Process and Daemon in Solaris?

Submitted by: Administrator

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)
'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
Submitted by:...

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Lua Unofficial FAQ (uFAQ)

Maintainer: Steve Donovan (steve j donovan at gmail com), 2009-2011; version 2.0.

Creative Commons License; Reproduction in any form is permitted as long as this attribution is kept.

1 Language

1.1 Where to start?

The official lua.org FAQ is here, which is the place to go for essential information like Lua availability and licensing issues.

There is also an incomplete Lua Wiki FAQ; this unofficial FAQ aims to fill in the holes and answer as many questions as possible, in a useful way.

Lua is a modern dynamic language with conventional syntax:

function sqr(x) return x*x end local t = {} for i = 1,10 do t[i] = sqr(i) if i == 10 then print('finished '..i) end end

Although at first glance it looks like Basic, Lua is more akin to JavaScript; such as no explicit class mechanism and equivalence of a['x'] with a.x. There are very few types; string, number, table, function, thread and userdata. This...

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Cisco Unity Express Module Configuration

Mentioned in Part-1 of our Cisco Unity Express installation article, the Cisco Unity Express setup procedure is identical for ISM-SRE-300-K9 and SM-SRE-700-K9 modules. We will be using the smaller ISM-SRE-300-K9 for this article. The only notable difference in the CallManager Express configuration will be the module’s interface that connects to CallManager Express.

For the SRE-300, the module’s interface name is interface ISM0/0, whereas for the SM-SRE-700 it is service-module sm2/0. Both interfaces are GigabitEthernet, connected via each router’s internal bus.

The ISM-SRE-300-K9 module is configured with its own IP address and acts as a separate machine inside the router. Before we can begin configuring Unity Express, preinstalled by Cisco, we must configure IP connectivity with the router so we can then access the ISM-SRE-300-K9 module and initialize the Unity Express setup.

When physically installing an SRE...

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4.3.1. Logging

The software provides logs for

Authentication

authentication log = log_destination

Authorization

authorization log = log_destination

Accounting

accounting log = log_destination

Logs may be written to multiple destinations:

authentication log = log_1 authentication log = log_2 ... authentication log = log_n

Valid log destinations are:

Files

For logging to plain disk files fcntl(2) file locking is used, so it is recommended that file resides on a local filesystem. Although fcntl locking over NFS is supported on some Unix implementations, it is notoriously unreliable, and eVen if your implementation is reliable, locking is likely to be extremely inefficient over NFS.

If the underlying file system supports atomic appends, fcntl(2) file locking may not be necessary. Prepending the log destination with a > character will turn file locking off and switch log file handling to synchronous mode.

#...
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Long gone are the days of OS 9, watching our Macs boot up with a series of extensions and control panels that we could always identify. Today with the Unix underpinnings of OS X, many users are entirely unaware of what is going on behind the scenes. So what exactly happens during the Mac OS X boot process? A segment at KernelThread carefully lists the sequence of events, from start to finish. It is fairly thorough and worth a read. It is repeated below for the inquisitive Mac OS X users out there.


Note: As a reader pointed out, PPC uses OF, i386 uses EFI

You turn on your Mac, and this is what happens:

Power is turned on. OF or EFI code is executed. Hardware information is collected and hardware is initialized. Something (usually the OS, but also things like the Apple Hardware Test, etc.) is selected to boot. The user may be prompted to select what to boot. Control passes to /System/Library/CoreServices/BootX, the boot loader. BootX loads the kernel and also...
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