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Mac OS X: What Are All ThoseProcesses?

A short list of background processes and

daemons

By Gordon Davisson

Copyright (c) 2005, Westwind Computing inc.

Mac OS X (like any unixish OS) always has a number of things going on

in the background -- processes that take care of business behind the

scenes. Normally, you won't even notice them, unless you use something

like Activity Monitor (ProcessViewer under 10.2 or before) or the ps ortop

commands to look at the process list. If you do notice them, you may

wonder what on earth they're all there for. This list is here to answer that

question.

Note: this list is far from complete. If you see processes on your Mac that

aren't on this list, it doesn't mean there's something wrong or that you'vebeen hacked; just that I'm not as dilligent as I could be in maintaining the

list.

System Processes (mostly owned by root):

Process Its function

AppleFileServer

The personal file sharing (AFP over IP) server. It should only be

present if file sharing is enabled (in the System Preferences' Sharing

pane).

autodiskmount Responsible for mounting removable disks and media.

automountAutomatically mounts and unmounts network (NFS and AFP) file

systems as they are accessed / left idle.

configdMaintains dynamic configuration information about the computer and

its environment (mainly the network).

Mac OS X: What Are All Those Processes? http://www.westwind.com/reference/os-x/background-proces

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CrashReporter

Logs information about program crashes. It can be configured (via

editing /etc/hostconfig in OS X 10.0, and the Console utility's

preferences on OS X 10.1) to log crashes in ~/Library/Logs.

cron

Runs various scheduled programs and scripts, mostly to perform

perodic maintenance on the computer. Note: in Mac OS X, this is set to

run system maintenance late at night; if the computer is turned offevery night, the maintenance may never get done. Either leave the

computer on overnight occasionally, or use something like Brian R.

Hill's program MacJanitorto perform maintenance manually. In Mac

OS X 10.4 it was mostly replaced by launchd, but is kept around for

compatibility.

DirectoryService

This process acts as a central clearinghouse for "Directory" information

-- mainly users/groups/authentication, and service location (e.g. file

servers, printers, etc). It gathers information from a variety of plugins

(NetInfo, LDAP, Active Directory, NIS, Bonjour/Rendesvous/,

AppleTalk, SMB) and hands it out to whatever program requested it.

DesktopDB

Keeps track of information on currently known applications and their

document types. Used by the Finder to associate documents with the

appropriate application.

distnoted Provides distributed notifications services.

dynamic_pager Assists the kernel with managing swap files for virtual memory.

ftpd

Handles incoming FTP (File Transfer Protocol) connections. This

process is created dynamically by xinetd (orinetd in earlier versions of

OS X), so it should only appear when someone is actually connected

to your computer.

httpd

This is Apache, the web server that ships with OS X. It should only be

present if web sharing is enabled (in the System Preferences' Sharing

pane). It is normal for there to be several of these running, one owned

by root, the rest by www.

init

(10.0-10.3 only)

The master of the computer from the BSD/unix point of view. This is

responsible for creating (via the /etc/rc* scripts and StartupItems) and

looking after many of the other background processes. In Mac OS X

10.4 it was replaced by launchd.

inetd

(10.0-10.3 only)

Responsible for starting and looking after some internet services

(mainly FTP and telnet) provided by this computer. As of version 10.2

this was functionally replaced by xinetd (which was then replaced by

launchd), but was kept around through Mac OS X 10.3 for


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compatibility.

ipconfigd

(10.0-10.1.1 only)

Automatically configures the network. Now merged into configd (since

OS X 10.1.2, if I'm reading right).

KernelEventAgent

Handles notifications about file system status (e.g. "A server you are

using is no longer available. Do you want to continue trying to contact

it?" and "Your startup disk is almost full. You need to make more space

available on your startup disk by deleting files.")

kextdResponsible for loading and unloading kernel extensions (e.g. device

drivers) as they are needed.

launchd

(v10.4 and later)

This process replaces init and mach_init, and takes over most of the

functions ofcron and xinetd.

lookupd Handles looking up information from network information services suchas NetInfo and DNS, and acts as a bridge to allow unix/BSD/posix

programs to get information from DirectoryService.

mach_init

(10.0-10.3 only)

The Mach kernel's bootstrap port server. This is the first process

created during bootup, and creates the BSD init process (which then

creates everything else). In Mac OS X 10.3, it's also used to create

several daemons that used to be created via StartupItems. In Mac OS

X 10.4, it's replaced by launchd.

mDNSResponder

The multicast DNS (a component ofBonjour/Rendezvous) responder;

this advertises network services (such as AFP file sharing) provided bythis computer, as well as the computer's self-chosen ".local" name.

Note: this runs under the pseudo-user "nobody" (presumably for

security reasons).

netinfod

Serves out NetInfo data. There will be one of these processes for each

NetInfo domain served from the computer (normally just one, for the

local domain). ProcessViewer/Activity Monitor won't tell you which

daemon process serves which NetInfo domain, but the ps command

will.

nfsiodServices asynchronous requests to an NFS server. It is normal for

there to be several of these.

nibindd

Finds, creates, and destroys NetInfo servers (i.e. netinfod). This

process will only exist if you have something beyond the standard local

NetInfo domain set up.

notifyd Passes event notifications between processes.


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ntpd Synchronizes the Mac's clock with network time servers.

pitondThe Retrospect backup client (only present if you've installed

Retrospect Client).

pmToolThis is actually a user process that happens to run as root. Activity

Monitor uses it to collect information on running processes.

portmapDynamically assigns RPC (network Remote Procedure Call) services

(such as NetInfo and NFS) to TCP/UDP ports.

slpd

The Service Location Protocol (SLP) responder; this advertises

network services (such as AFP file sharing) provided by this computer.

SLP has been functionally replaced by Bonjour/Rendezvous, but is

kept active for compatibility with older computers on the network.

slpdLoad

This process frequently shows up as a Zombie in ProcessViewer's

listing (with semirandom owner, parent, and statistics) under early

versions of OS X. Don't worry, it's harmless, just a little confused.(More technically: a zombie process is one that has finished (i.e. died),

but whose parent process has not received notification of its death. In

order to keep process information around until the parent process is

notified, the zombie's entry is left in the process table even though the

process itself is gone. A bit morbid, perhaps, but since it doesn't

consume resources, it's not really a problem.)

sshd

The secure shell server -- listens for and handles incoming SSH

(encrypted remote login) connections. It was added in version 10.0.1

and should only be present if "Allow remote login" is enabled (in the

System Preferences' Sharing pane).

Note: In 10.3, sshd no longer runs continuously to listen for incoming

ssh connections. Instead, xinetd (v10.3) orlaunchd (v10.4) does the

listening, and only starts sshd when it's actually needed.

syslogd Logs and/or dispatches system status and error messages.

telnetd

Handles incoming telnet (remote login) connections. It's enabled by the

"Allow remote login" option in the System Preferences' Sharing pane of

Mac OS X 10.0; in later versions it's disbled, and SSH is used instead

(although telnetd can be reenabled manually by editing the

/etc/inetd.conf file). This process is created dynamically by inetd, so it

should only appear when someone is actually telnetted into yourcomputer.

updateResponsible for keeping disks synchronized with the file system cache,

to keep data loss to a minimum in case of a crash.


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xinetd

Responsible for starting and looking after some internet services

(mainly ssh, FTP and telnet) provided by this computer. This is

essentially an extended version ofinetd. In Mac OS X 10.4 it was

mostly replaced by launchd, but is kept around for compatibility.

User processes (generally owned by the current user):

Process Its function

ATSServerThe Apple Type Solution Server; responsible for managing the

available fonts and making them available to applications.

Dock Maintains and displays the Dock.

DocklingServer Keeps docklings' status and displays up to date.

Finder The Finder.

hdid Handles mounted disk image (.img and .dmg) files.

LaunchCFMApp

Applications in the old-style Macintosh format (Code Fragment

Manager format, aka CFM, aka PEF) will show up in Process

Viewer under this name. LaunchCFMApp is actually a wrapper

program provided for compatibility with this old application format;

Process Viewer just can't see through the wrapper to the actual

application inside.

(Note: the distinction between the old (CFM) and new (mach-o)

formats is not the same as the distinction betweem the old

(Carbon) and new (Cocoa) application environments. Many of theCarbon apps you're likely to run into on OS X are in mach-o

format.)

loginwindow

This is only partly a user process -- it starts before anyone logs

into the computer, and is responsible for displaying the login

screen (or not, if autologin is set), validating login attempts, and

setting up the user environment (launching the Finder, Dock, any

login apps, etc) at login. It also acts as a process monitor for user

processes, restarts the Finder or Dock if they crash, and

implements the Force Quit Applications window. Finally, it handles

the logout, restart, and shutdown procedures.

pbsThe pasteboard server; analogous to the clipboard under Mac OS

9.

pmTool

a background process that Activity Monitor uses to collect

information on running processes.

Note that this process runs as root (despite being part of a


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user-level program).

SystemUIServer(OS X 10.1 and later)

Maintains the Menu Items in the right end of the menu bar.

TruBlueEnvironment

or "(null)"

The Classic (OS 9 compatibility) environment. This single process

includes OS 9 and all running classic applications. The name

derives from an early Apple code-name for the Classic

environment: "the Blue Box".

For some reason, Activity Monitor (under Mac OS X v10.3) has

trouble reading this process's name, and tends to display it as

"(null)".

WindowServer (aka

Window Manager)

Responsible for managing the computer's display and mediating

between the various Applications and other processes that want to

display information on it. It also does the grunt work of launching

new user applications, so most user processes are actually its

children in the process hierarchy.

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