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	diff --git a/en_US.ISO8859-1/books/handbook/basics/chapter.xml b/en_US.ISO8859-1/books/handbook/basics/chapter.xml
	index 2ade36e715..dfa2d22d5a 100644
	--- a/en_US.ISO8859-1/books/handbook/basics/chapter.xml
	+++ b/en_US.ISO8859-1/books/handbook/basics/chapter.xml
	@@ -1,3487 +1,3646 @@
	<?xml version="1.0" encoding="iso-8859-1"?>
	<!--
	The FreeBSD Documentation Project

	$FreeBSD$
	-->
	-<chapter xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" version="5.0" xml:id="basics">
	+<chapter xmlns="http://docbook.org/ns/docbook"
	+ xmlns:xlink="http://www.w3.org/1999/xlink" version="5.0"
	+ xml:id="basics">
	+
	<!--
	<chapterinfo>
	<authorgroup>
	<author>
	<firstname>Chris</firstname>
	<surname>Shumway</surname>
	<contrib>Rewritten by in Mar 2000</contrib>
	</author>
	</authorgroup>
	</chapterinfo>
	-->

	<title>UNIX Basics</title>

	<sect1 xml:id="basics-synopsis">
	<title>Synopsis</title>

	<para>This chapter covers the basic commands and functionality of
	the &os; operating system. Much of this material is relevant
	for any &unix;-like operating system. New &os; users are
	encouraged to read through this chapter carefully.</para>

	<para>After reading this chapter, you will know:</para>

	<itemizedlist>
	<listitem>
	<para>How to use and configure virtual consoles.</para>
	</listitem>

	<listitem>
	<para>How to create and manage users and groups on
	&os;.</para>
	</listitem>

	<listitem>
	<para>How &unix; file permissions and &os; file flags
	work.</para>
	</listitem>

	<listitem>
	<para>The default &os; file system layout.</para>
	</listitem>

	<listitem>
	<para>The &os; disk organization.</para>
	</listitem>

	<listitem>
	<para>How to mount and unmount file systems.</para>
	</listitem>

	<listitem>
	<para>What processes, daemons, and signals are.</para>
	</listitem>

	<listitem>
	<para>What a shell is, and how to change the default login
	environment.</para>
	</listitem>

	<listitem>
	<para>How to use basic text editors.</para>
	</listitem>

	<listitem>
	<para>What devices and device nodes are.</para>
	</listitem>

	<listitem>
	<para>How to read manual pages for more information.</para>
	</listitem>
	</itemizedlist>
	</sect1>

	<sect1 xml:id="consoles">
	<title>Virtual Consoles and Terminals</title>

	- <indexterm><primary>virtual consoles</primary></indexterm>
	- <indexterm><primary>terminals</primary></indexterm>
	- <indexterm><primary>console</primary></indexterm>
	+ <indexterm>
	+ <primary>virtual consoles</primary>
	+ </indexterm>
	+ <indexterm>
	+ <primary>terminals</primary>
	+ </indexterm>
	+ <indexterm>
	+ <primary>console</primary>
	+ </indexterm>

	<para>Unless &os; has been configured to automatically start a
	graphical environment during startup, the system will boot
	into a command line login prompt, as seen in this
	example:</para>

	<screen>FreeBSD/amd64 (pc3.example.org) (ttyv0)

	login:</screen>

	<para>The first line contains some information about the system.
	The <literal>amd64</literal> indicates that the system in this
	example is running a 64-bit version of &os;. The hostname is
	<systemitem>pc3.example.org</systemitem>, and
	<filename>ttyv0</filename> indicates that this is the
	<quote>system console</quote>. The second line is the login
	prompt.</para>

	<para>Since &os; is a multiuser system, it needs some way to
	distinguish between different users. This is accomplished by
	requiring every user to log into the system before gaining
	access to the programs on the system. Every user has a
	unique name <quote>username</quote> and a personal
	<quote>password</quote>.</para>

	<para>To log into the system console, type the username that
	was configured during system installation, as described in
	<xref linkend="bsdinstall-addusers"/>, and press
	<keycap>Enter</keycap>. Then enter the password associated
	with the username and press <keycap>Enter</keycap>. The
	password is <emphasis>not echoed</emphasis> for security
	reasons.</para>

	<para>Once the correct password is input, the message of the
	day (<acronym>MOTD</acronym>) will be displayed followed
	by a command prompt. Depending upon the shell that was
	selected when the user was created, this prompt will be a
	<literal>#</literal>, <literal>$</literal>, or
	<literal>%</literal> character. The prompt indicates that
	the user is now logged into the &os; system console and ready
	to try the available commands.</para>

	<sect2 xml:id="consoles-virtual">
	<title>Virtual Consoles</title>

	<para>While the system console can be used to interact with
	the system, a user working from the command line at the
	keyboard of a &os; system will typically instead log into a
	virtual console. This is because system messages are
	configured by default to display on the system console.
	These messages will appear over the command or file that the
	user is working on, making it difficult to concentrate on
	the work at hand.</para>

	<para>By default, &os; is configured to provide several virtual
	consoles for inputting commands. Each virtual console has
	its own login prompt and shell and it is easy to switch
	between virtual consoles. This essentially provides the
	command line equivalent of having several windows open at the
	same time in a graphical environment.</para>

	<para>The key combinations
	<keycombo><keycap>Alt</keycap><keycap>F1</keycap></keycombo>
	through
	<keycombo><keycap>Alt</keycap><keycap>F8</keycap></keycombo>
	have been reserved by &os; for switching between virtual
	consoles. Use
	<keycombo><keycap>Alt</keycap><keycap>F1</keycap></keycombo>
	to switch to the system console
	(<filename>ttyv0</filename>),
	<keycombo><keycap>Alt</keycap><keycap>F2</keycap></keycombo>
	to access the first virtual console
	(<filename>ttyv1</filename>),
	<keycombo><keycap>Alt</keycap><keycap>F3</keycap></keycombo>
	to access the second virtual console
	(<filename>ttyv2</filename>), and so on.</para>

	<para>When switching from one console to the next, &os; takes
	manages the screen output. The result is an illusion of
	having multiple virtual screens and keyboards that can be used
	to type commands for &os; to run. The programs that are
	launched in one virtual console do not stop running when
	the user switches to a different virtual console.</para>

	<para>Refer to &man.syscons.4;, &man.atkbd.4;,
	&man.vidcontrol.1; and &man.kbdcontrol.1; for a more
	technical description of the &os; console and its keyboard
	drivers.</para>

	<para>In &os;, the number of available virtual consoles is
	configured in this section of
	<filename>/etc/ttys</filename>:</para>

	<programlisting># name getty type status comments
	#
	ttyv0 "/usr/libexec/getty Pc" cons25 on secure
	# Virtual terminals
	ttyv1 "/usr/libexec/getty Pc" cons25 on secure
	ttyv2 "/usr/libexec/getty Pc" cons25 on secure
	ttyv3 "/usr/libexec/getty Pc" cons25 on secure
	ttyv4 "/usr/libexec/getty Pc" cons25 on secure
	ttyv5 "/usr/libexec/getty Pc" cons25 on secure
	ttyv6 "/usr/libexec/getty Pc" cons25 on secure
	ttyv7 "/usr/libexec/getty Pc" cons25 on secure
	ttyv8 "/usr/X11R6/bin/xdm -nodaemon" xterm off secure</programlisting>


	<para>To disable a virtual console, put a comment symbol
	(<literal>#</literal>) at the beginning of the line
	- representing that virtual console. For example, to reduce
	- the number of available virtual consoles from eight to four,
	- put a <literal>#</literal> in front of the last four lines
	- representing virtual consoles
	- <filename>ttyv5</filename> through
	- <filename>ttyv8</filename>. <emphasis>Do not</emphasis>
	- comment out the line for the system console
	- <filename>ttyv0</filename>. Note that the last virtual
	- console (<filename>ttyv8</filename>) is used to access
	+ representing that virtual console. For example, to reduce the
	+ number of available virtual consoles from eight to four, put a
	+ <literal>#</literal> in front of the last four lines
	+ representing virtual consoles <filename>ttyv5</filename>
	+ through <filename>ttyv8</filename>.
	+ <emphasis>Do not</emphasis> comment out the line for the
	+ system console <filename>ttyv0</filename>. Note that the last
	+ virtual console (<filename>ttyv8</filename>) is used to access
	the graphical environment if <application>&xorg;</application>
	- has been installed and configured as described in <xref linkend="x11"/>.</para>
	+ has been installed and configured as described in
	+ <xref linkend="x11"/>.</para>

	<para>For a detailed description of every column in this file
	and the available options for the virtual consoles, refer to
	&man.ttys.5;.</para>
	</sect2>

	<sect2 xml:id="consoles-singleuser">
	<title>Single User Mode</title>

	<para>The &os; boot menu provides an option labelled as
	<quote>Boot Single User</quote>. If this option is selected,
	the system will boot into a special mode known as
	<quote>single user mode</quote>. This mode is typically used
	to repair a system that will not boot or to reset the
	- <systemitem class="username">root</systemitem> password when it is not known.
	- While in single user mode, networking and other virtual
	- consoles are not available. However, full
	- <systemitem class="username">root</systemitem> access to the system is available,
	- and by default, the <systemitem class="username">root</systemitem> password is not
	- needed. For these reasons, physical access to the keyboard
	- is needed to boot into this mode and determining who has
	- physical access to the keyboard is something to consider when
	- securing a &os; system.</para>
	+ <systemitem class="username">root</systemitem> password when
	+ it is not known. While in single user mode, networking and
	+ other virtual consoles are not available. However, full
	+ <systemitem class="username">root</systemitem> access to the
	+ system is available, and by default, the
	+ <systemitem class="username">root</systemitem> password is not
	+ needed. For these reasons, physical access to the keyboard is
	+ needed to boot into this mode and determining who has physical
	+ access to the keyboard is something to consider when securing
	+ a &os; system.</para>

	<para>The settings which control single user mode are found in
	this section of <filename>/etc/ttys</filename>:</para>

	<programlisting># name getty type status comments
	#
	# If console is marked "insecure", then init will ask for the root password
	# when going to single-user mode.
	console none unknown off secure</programlisting>

	<para>By default, the status is set to
	- <literal>secure</literal>. This assumes that who has
	- physical access to the keyboard is either not important or it
	- is controlled by a physical security policy. If this setting
	- is changed to <literal>insecure</literal>, the assumption is
	- that the environment itself is insecure because anyone can
	- access the keyboard. When this line is changed to
	+ <literal>secure</literal>. This assumes that who has physical
	+ access to the keyboard is either not important or it is
	+ controlled by a physical security policy. If this setting is
	+ changed to <literal>insecure</literal>, the assumption is that
	+ the environment itself is insecure because anyone can access
	+ the keyboard. When this line is changed to
	<literal>insecure</literal>, &os; will prompt for the
	- <systemitem class="username">root</systemitem> password when a user selects to
	- boot into single user mode.</para>
	+ <systemitem class="username">root</systemitem> password when a
	+ user selects to boot into single user mode.</para>

	<note>
	<para><emphasis>Be careful when changing this setting to
	<literal>insecure</literal></emphasis>! If the
	- <systemitem class="username">root</systemitem> password is forgotten, booting
	- into single user mode is still possible, but may be
	- difficult for someone who is not familiar with the &os;
	- booting process.</para>
	+ <systemitem class="username">root</systemitem> password is
	+ forgotten, booting into single user mode is still possible,
	+ but may be difficult for someone who is not familiar with
	+ the &os; booting process.</para>
	</note>
	</sect2>

	<sect2 xml:id="consoles-vidcontrol">
	<title>Changing Console Video Modes</title>

	<para>The &os; console default video mode may be adjusted to
	1024x768, 1280x1024, or any other size supported by the
	graphics chip and monitor. To use a different video mode
	load the <literal>VESA</literal> module:</para>

	<screen>&prompt.root; <userinput>kldload vesa</userinput></screen>

	<para>To determine which video modes are supported by the
	hardware, use &man.vidcontrol.1;. To get a list of supported
	video modes issue the following:</para>

	<screen>&prompt.root; <userinput>vidcontrol -i mode</userinput></screen>

	<para>The output of this command lists the video modes that are
	supported by the hardware. To select a new video mode,
	specify the mode using &man.vidcontrol.1; as the
	<systemitem class="username">root</systemitem> user:</para>

	<screen>&prompt.root; <userinput>vidcontrol MODE_279</userinput></screen>

	<para>If the new video mode is acceptable, it can be permanently
	set on boot by adding it to
	<filename>/etc/rc.conf</filename>:</para>

	<programlisting>allscreens_flags="MODE_279"</programlisting>
	</sect2>
	</sect1>

	<!--
	<chapterinfo>
	<authorgroup>
	<author>
	<firstname>Neil</firstname>
	<surname>Blakey-Milner</surname>
	<contrib>Contributed by in Feb 2000</contrib>
	</author>
	</authorgroup>
	</chapterinfo>
	-->

	<sect1 xml:id="users-synopsis">
	<title>Users and Basic Account Management</title>

	<para>&os; allows multiple users to use the computer at the same
	time. While only one user can sit in front of the screen and
	use the keyboard at any one time, any number of users can log
	in to the system through the network. To use the system, each
	user should have their own user account.</para>

	<para>This chapter describes:</para>

	<itemizedlist>
	<listitem>
	<para>The different types of user accounts on a
	&os; system.</para>
	</listitem>

	<listitem>
	<para>How to add, remove, and modify user accounts.</para>
	</listitem>

	<listitem>
	<para>How to set limits to control the
	resources that users and
	groups are allowed to access.</para>
	</listitem>

	<listitem>
	<para>How to create groups and add users as members of a
	group.</para>
	</listitem>
	</itemizedlist>

	<sect2 xml:id="users-introduction">
	<title>Account Types</title>

	<para>Since all access to the &os; system is achieved using
	accounts and all processes are run by users, user and account
	management is important.</para>

	<para>There are three main types of accounts: system accounts,
	user accounts, and the superuser account.</para>

	<sect3 xml:id="users-system">
	<title>System Accounts</title>

	<indexterm>
	<primary>accounts</primary>
	<secondary>system</secondary>
	</indexterm>

	<para>System accounts are used to run services such as DNS,
	mail, and web servers. The reason for this is security; if
	all services ran as the superuser, they could act without
	restriction.</para>

	<indexterm>
	<primary>accounts</primary>
	- <secondary><systemitem class="username">daemon</systemitem></secondary>
	+ <secondary><systemitem
	+ class="username">daemon</systemitem></secondary>
	</indexterm>
	<indexterm>
	<primary>accounts</primary>
	- <secondary><systemitem class="username">operator</systemitem></secondary>
	+ <secondary><systemitem
	+ class="username">operator</systemitem></secondary>
	</indexterm>

	<para>Examples of system accounts are
	- <systemitem class="username">daemon</systemitem>, <systemitem class="username">operator</systemitem>,
	- <systemitem class="username">bind</systemitem>, <systemitem class="username">news</systemitem>, and
	+ <systemitem class="username">daemon</systemitem>,
	+ <systemitem class="username">operator</systemitem>,
	+ <systemitem class="username">bind</systemitem>,
	+ <systemitem class="username">news</systemitem>, and
	<systemitem class="username">www</systemitem>.</para>

	<indexterm>
	<primary>accounts</primary>
	- <secondary><systemitem class="username">nobody</systemitem></secondary>
	+ <secondary><systemitem
	+ class="username">nobody</systemitem></secondary>
	</indexterm>

	- <para><systemitem class="username">nobody</systemitem> is the generic unprivileged
	- system account. However, the more services that use
	- <systemitem class="username">nobody</systemitem>, the more files and processes
	- that user will become associated with, and hence the more
	- privileged that user becomes.</para>
	+ <para><systemitem class="username">nobody</systemitem> is the
	+ generic unprivileged system account. However, the more
	+ services that use
	+ <systemitem class="username">nobody</systemitem>, the more
	+ files and processes that user will become associated with,
	+ and hence the more privileged that user becomes.</para>
	</sect3>

	<sect3 xml:id="users-user">
	<title>User Accounts</title>

	<indexterm>
	<primary>accounts</primary>
	<secondary>user</secondary>
	</indexterm>

	<para>User accounts are assigned to real people and are used
	to log in and use the system. Every person accessing the
	system should have a unique user account. This allows the
	administrator to find out who is doing what and prevents
	users from clobbering the settings of other users.</para>

	<para>Each user can set up their own environment to
	accommodate their use of the system, by configuring their
	default shell, editor, key bindings, and language
	settings.</para>

	<para>Every user account on a &os; system has certain
	information associated with it:</para>

	<variablelist>
	<varlistentry>
	<term>User name</term>

	- <listitem>
	- <para>The user name is typed at the <prompt>login:</prompt>
	- prompt. User names must be unique on the system as no two
	- users can have the same user name. There are a number of
	- rules for creating valid user names which are documented
	- in &man.passwd.5;. It is recommended to use user names
	- that consist of eight or fewer, all lower case characters
	- in order to maintain backwards compatibility with
	- applications.</para>
	- </listitem>
	- </varlistentry>
	-
	- <varlistentry>
	- <term>Password</term>
	+ <listitem>
	+ <para>The user name is typed at the
	+ <prompt>login:</prompt> prompt. User names must be
	+ unique on the system as no two users can have the same
	+ user name. There are a number of rules for creating
	+ valid user names which are documented in
	+ &man.passwd.5;. It is recommended to use user names
	+ that consist of eight or fewer, all lower case
	+ characters in order to maintain backwards
	+ compatibility with applications.</para>
	+ </listitem>
	+ </varlistentry>

	- <listitem>
	- <para>Each user account should have an associated password.
	- While the password can be blank, this is highly
	- discouraged.</para>
	- </listitem>
	- </varlistentry>
	-
	- <varlistentry>
	- <term>User ID (<acronym>UID</acronym>)</term>
	-
	- <listitem>
	- <para>The User ID (<acronym>UID</acronym>) is a number used
	- to uniquely identify the user to the &os; system.
	- Commands that allow a user name to be specified will
	- first convert it to the <acronym>UID</acronym>. It is
	- recommended to use a UID of 65535 or lower as higher UIDs
	- may cause compatibility issues with software that does
	- not support integers larger than 32-bits.</para>
	- </listitem>
	- </varlistentry>
	+ <varlistentry>
	+ <term>Password</term>

	- <varlistentry>
	- <term>Group ID (<acronym>GID</acronym>)</term>
	+ <listitem>
	+ <para>Each user account should have an associated
	+ password. While the password can be blank, this is
	+ highly discouraged.</para>
	+ </listitem>
	+ </varlistentry>

	- <listitem>
	- <para>The Group ID (<acronym>GID</acronym>) is a number
	- used to uniquely identify the primary group that the user
	- belongs to. Groups are a mechanism for controlling
	- access to resources based on a user's
	- <acronym>GID</acronym> rather than their
	- <acronym>UID</acronym>. This can significantly reduce the
	- size of some configuration files and allows users to be
	- members of more than one group. It is recommended to use
	- a GID of 65535 or lower as higher GIDs may break some
	- software.</para>
	- </listitem>
	- </varlistentry>
	-
	- <varlistentry>
	- <term>Login class</term>
	+ <varlistentry>
	+ <term>User ID (<acronym>UID</acronym>)</term>
	+
	+ <listitem>
	+ <para>The User ID (<acronym>UID</acronym>) is a number
	+ used to uniquely identify the user to the &os; system.
	+ Commands that allow a user name to be specified will
	+ first convert it to the <acronym>UID</acronym>. It is
	+ recommended to use a UID of 65535 or lower as higher
	+ UIDs may cause compatibility issues with software that
	+ does not support integers larger than 32-bits.</para>
	+ </listitem>
	+ </varlistentry>

	- <listitem>
	- <para>Login classes are an extension to the group mechanism
	- that provide additional flexibility when tailoring the
	- system to different users. Login classes are discussed
	- further in <xref linkend="users-limiting"/></para>
	- </listitem>
	- </varlistentry>
	+ <varlistentry>
	+ <term>Group ID (<acronym>GID</acronym>)</term>
	+
	+ <listitem>
	+ <para>The Group ID (<acronym>GID</acronym>) is a number
	+ used to uniquely identify the primary group that the
	+ user belongs to. Groups are a mechanism for
	+ controlling access to resources based on a user's
	+ <acronym>GID</acronym> rather than their
	+ <acronym>UID</acronym>. This can significantly reduce
	+ the size of some configuration files and allows users
	+ to be members of more than one group. It is
	+ recommended to use a GID of 65535 or lower as higher
	+ GIDs may break some software.</para>
	+ </listitem>
	+ </varlistentry>

	- <varlistentry>
	- <term>Password change time</term>
	+ <varlistentry>
	+ <term>Login class</term>

	- <listitem>
	- <para>By default, &os; does not force users to change their
	- passwords periodically. Password expiration can be
	- enforced on a per-user basis using &man.pw.8;, forcing
	- some or all users to change their passwords after a
	- certain amount of time has elapsed.</para>
	- </listitem>
	- </varlistentry>
	+ <listitem>
	+ <para>Login classes are an extension to the group
	+ mechanism that provide additional flexibility when
	+ tailoring the system to different users. Login
	+ classes are discussed further in
	+ <xref linkend="users-limiting"/></para>
	+ </listitem>
	+ </varlistentry>

	- <varlistentry>
	- <term>Account expiry time</term>
	+ <varlistentry>
	+ <term>Password change time</term>

	- <listitem>
	- <para>By default, &os; does not expire accounts. When
	- creating accounts that need a limited lifespan, such as
	- student accounts in a school, specify the account expiry
	- date using &man.pw.8;. After the expiry time has
	- elapsed, the account cannot be used to log in to the
	- system, although the account's directories and files will
	- remain.</para>
	- </listitem>
	- </varlistentry>
	+ <listitem>
	+ <para>By default, &os; does not force users to change
	+ their passwords periodically. Password expiration can
	+ be enforced on a per-user basis using &man.pw.8;,
	+ forcing some or all users to change their passwords
	+ after a certain amount of time has elapsed.</para>
	+ </listitem>
	+ </varlistentry>

	- <varlistentry>
	- <term>User's full name</term>
	+ <varlistentry>
	+ <term>Account expiry time</term>
	+
	+ <listitem>
	+ <para>By default, &os; does not expire accounts. When
	+ creating accounts that need a limited lifespan, such
	+ as student accounts in a school, specify the account
	+ expiry date using &man.pw.8;. After the expiry time
	+ has elapsed, the account cannot be used to log in to
	+ the system, although the account's directories and
	+ files will remain.</para>
	+ </listitem>
	+ </varlistentry>

	- <listitem>
	- <para>The user name uniquely identifies the account to &os;,
	- but does not necessarily reflect the user's real name.
	- Similar to a comment, this information can contain a
	- space, uppercase characters, and be more than 8
	- characters long.</para>
	- </listitem>
	- </varlistentry>
	+ <varlistentry>
	+ <term>User's full name</term>

	- <varlistentry>
	- <term>Home directory</term>
	+ <listitem>
	+ <para>The user name uniquely identifies the account to
	+ &os;, but does not necessarily reflect the user's real
	+ name. Similar to a comment, this information can
	+ contain a space, uppercase characters, and be more
	+ than 8 characters long.</para>
	+ </listitem>
	+ </varlistentry>

	- <listitem>
	- <para>The home directory is the full path to a directory on
	- the system. This is the user's starting directory when
	- the user logs in. A common convention is to put all user
	- home directories under <filename>/home/username</filename>
	- or <filename>/usr/home/username</filename>.
	- Each user stores their personal files and subdirectories
	- in their own home directory.</para>
	- </listitem>
	- </varlistentry>
	+ <varlistentry>
	+ <term>Home directory</term>
	+
	+ <listitem>
	+ <para>The home directory is the full path to a directory
	+ on the system. This is the user's starting directory
	+ when the user logs in. A common convention is to put
	+ all user home directories under
	+ <filename>/home/username</filename> or
	+ <filename>/usr/home/username</filename>. Each user
	+ stores their personal files and subdirectories in
	+ their own home directory.</para>
	+ </listitem>
	+ </varlistentry>

	- <varlistentry>
	- <term>User shell</term>
	+ <varlistentry>
	+ <term>User shell</term>
	+
	+ <listitem>
	+ <para>The shell provides the user's default environment
	+ for interacting with the system. There are many
	+ different kinds of shells and experienced users will
	+ have their own preferences, which can be reflected in
	+ their account settings.</para>
	+ </listitem>
	+ </varlistentry>
	+ </variablelist>
	+ </sect3>

	- <listitem>
	- <para>The shell provides the user's default environment for
	- interacting with the system. There are many different
	- kinds of shells and experienced users will have their own
	- preferences, which can be reflected in their account
	- settings.</para>
	- </listitem>
	- </varlistentry>
	- </variablelist>
	- </sect3>
	+ <sect3 xml:id="users-superuser">
	+ <title>The Superuser Account</title>

	- <sect3 xml:id="users-superuser">
	- <title>The Superuser Account</title>
	+ <indexterm>
	+ <primary>accounts</primary>
	+ <secondary>superuser (root)</secondary>
	+ </indexterm>

	- <indexterm>
	- <primary>accounts</primary>
	- <secondary>superuser (root)</secondary>
	- </indexterm>
	+ <para>The superuser account, usually called
	+ <systemitem class="username">root</systemitem>, is used to
	+ manage the system with no limitations on privileges. For
	+ this reason, it should not be used for day-to-day tasks like
	+ sending and receiving mail, general exploration of the
	+ system, or programming.</para>
	+
	+ <para>The superuser, unlike other user accounts, can operate
	+ without limits, and misuse of the superuser account may
	+ result in spectacular disasters. User accounts are unable
	+ to destroy the operating system by mistake, so it is
	+ recommended to login as a user account and to only become
	+ the superuser when a command requires extra
	+ privilege.</para>
	+
	+ <para>Always double and triple-check any commands issued as
	+ the superuser, since an extra space or missing character can
	+ mean irreparable data loss.</para>
	+
	+ <para>There are several ways to become gain superuser
	+ privilege. While one can log in as
	+ <systemitem class="username">root</systemitem>, this is
	+ highly discouraged.</para>
	+
	+ <para>Instead, use &man.su.1; to become the superuser. If
	+ <literal>-</literal> is specified when running this command,
	+ the user will also inherit the root user's environment. The
	+ user running this command must be in the
	+ <systemitem class="groupname">wheel</systemitem> group or
	+ else the command will fail. The user must also know the
	+ password for the
	+ <systemitem class="username">root</systemitem> user
	+ account.</para>

	- <para>The superuser account, usually called
	- <systemitem class="username">root</systemitem>, is used to
	- manage the system with no limitations on privileges. For this
	- reason, it should not be used for day-to-day
	- tasks like sending and receiving mail, general exploration of
	- the system, or programming.</para>
	-
	- <para>The superuser, unlike other user
	- accounts, can operate without limits, and misuse of the
	- superuser account may result in spectacular disasters. User
	- accounts are unable to destroy the operating system by
	- mistake, so it is recommended to login as a user account and
	- to only become the superuser when a command requires extra
	- privilege.</para>
	-
	- <para>Always double and triple-check any commands issued as the
	- superuser, since an extra space or missing character can mean
	- irreparable data loss.</para>
	-
	- <para>There are several ways to become gain superuser privilege.
	- While one can log in as <systemitem class="username">root</systemitem>, this is
	- highly discouraged.</para>
	-
	- <para>Instead, use &man.su.1; to become the superuser. If
	- <literal>-</literal> is specified when running this command,
	- the user will also inherit the root user's environment. The
	- user running this command must be in the
	- <systemitem class="groupname">wheel</systemitem> group or else the command will
	- fail. The user must also know the password for the
	- <systemitem class="username">root</systemitem> user account.</para>
	-
	- <para>In this example, the user only becomes superuser in order
	- to run <command>make install</command> as this step requires
	- superuser privilege. Once the command completes, the user
	- types <command>exit</command> to leave the superuser account
	- and return to the privilege of their user account.</para>
	+ <para>In this example, the user only becomes superuser in
	+ order to run <command>make install</command> as this step
	+ requires superuser privilege. Once the command completes,
	+ the user types <command>exit</command> to leave the
	+ superuser account and return to the privilege of their user
	+ account.</para>

	- <example>
	- <title>Install a Program As the Superuser</title>
	+ <example>
	+ <title>Install a Program As the Superuser</title>

	- <screen>&prompt.user; <userinput>configure</userinput>
	+ <screen>&prompt.user; <userinput>configure</userinput>
	&prompt.user; <userinput>make</userinput>
	&prompt.user; <userinput>su -</userinput>
	Password:
	&prompt.root; <userinput>make install</userinput>
	&prompt.root; <userinput>exit</userinput>
	&prompt.user;</screen>
	- </example>
	-
	- <para>The built-in &man.su.1; framework works well for single
	- systems or small networks with just one system administrator.
	- An alternative is to install the <package>security/sudo</package> package or port.
	- This software provides activity logging and allows the
	- administrator to configure which users can run which commands
	- as the superuser.</para>
	- </sect3>
	- </sect2>
	-
	- <sect2 xml:id="users-modifying">
	- <title>Managing Accounts</title>
	+ </example>
	+
	+ <para>The built-in &man.su.1; framework works well for single
	+ systems or small networks with just one system
	+ administrator. An alternative is to install the
	+ <package>security/sudo</package> package or port. This
	+ software provides activity logging and allows the
	+ administrator to configure which users can run which
	+ commands as the superuser.</para>
	+ </sect3>
	+ </sect2>

	- <indexterm>
	- <primary>accounts</primary>
	- <secondary>modifying</secondary>
	- </indexterm>
	+ <sect2 xml:id="users-modifying">
	+ <title>Managing Accounts</title>

	- <para>&os; provides a variety of different commands to manage
	- user accounts. The most common commands are summarized in Table
	- 4.1, followed by some examples of their usage. Refer to the
	- manual page for each utility for more details and usage
	- examples.</para>
	+ <indexterm>
	+ <primary>accounts</primary>
	+ <secondary>modifying</secondary>
	+ </indexterm>

	- <table frame="none" pgwide="1">
	- <title>Utilities for Managing User Accounts</title>
	+ <para>&os; provides a variety of different commands to manage
	+ user accounts. The most common commands are summarized in
	+ Table 4.1, followed by some examples of their usage. Refer to
	+ the manual page for each utility for more details and usage
	+ examples.</para>

	- <tgroup cols="2">
	- <colspec colwidth="1*"/>
	- <colspec colwidth="2*"/>
	+ <table frame="none" pgwide="1">
	+ <title>Utilities for Managing User Accounts</title>

	- <thead>
	- <row>
	- <entry>Command</entry>
	- <entry>Summary</entry>
	- </row>
	- </thead>
	- <tbody>
	- <row>
	- <entry>&man.adduser.8;</entry>
	- <entry>The recommended command-line application for adding
	- new users.</entry>
	- </row>
	+ <tgroup cols="2">
	+ <colspec colwidth="1*"/>
	+ <colspec colwidth="2*"/>

	- <row>
	- <entry>&man.rmuser.8;</entry>
	- <entry>The recommended command-line application for
	- removing users.</entry>
	- </row>
	+ <thead>
	+ <row>
	+ <entry>Command</entry>
	+ <entry>Summary</entry>
	+ </row>
	+ </thead>
	+ <tbody>
	+ <row>
	+ <entry>&man.adduser.8;</entry>
	+ <entry>The recommended command-line application for
	+ adding new users.</entry>
	+ </row>

	- <row>
	- <entry>&man.chpass.1;</entry>
	- <entry>A flexible tool for changing user database
	- information.</entry>
	- </row>
	+ <row>
	+ <entry>&man.rmuser.8;</entry>
	+ <entry>The recommended command-line application for
	+ removing users.</entry>
	+ </row>

	- <row>
	- <entry>&man.passwd.1;</entry>
	- <entry>The command-line tool to change user
	- passwords.</entry>
	- </row>
	+ <row>
	+ <entry>&man.chpass.1;</entry>
	+ <entry>A flexible tool for changing user database
	+ information.</entry>
	+ </row>

	- <row>
	- <entry>&man.pw.8;</entry>
	- <entry>A powerful and flexible tool for modifying all
	- aspects of user accounts.</entry>
	- </row>
	- </tbody>
	- </tgroup>
	- </table>
	+ <row>
	+ <entry>&man.passwd.1;</entry>
	+ <entry>The command-line tool to change user
	+ passwords.</entry>
	+ </row>

	- <sect3 xml:id="users-adduser">
	- <title><command>adduser</command></title>
	+ <row>
	+ <entry>&man.pw.8;</entry>
	+ <entry>A powerful and flexible tool for modifying all
	+ aspects of user accounts.</entry>
	+ </row>
	+ </tbody>
	+ </tgroup>
	+ </table>

	- <indexterm>
	- <primary>accounts</primary>
	- <secondary>adding</secondary>
	- </indexterm>
	- <indexterm>
	- <primary><command>adduser</command></primary>
	- </indexterm>
	- <indexterm>
	- <primary><filename>/usr/share/skel</filename></primary>
	- </indexterm>
	- <indexterm><primary>skeleton directory</primary></indexterm>
	- <para>The recommended program for adding new users is
	- &man.adduser.8;. When a new user is added, this program
	- automatically updates <filename>/etc/passwd</filename> and
	- <filename>/etc/group</filename>. It also creates a home
	- directory for the new user, copies in the default
	- configuration files from <filename>/usr/share/skel</filename>, and can
	- optionally mail the new user a welcome message. This utility
	- must be run as the <systemitem class="username">superuser</systemitem></para>
	-
	- <para>The &man.adduser.8; utility is interactive and walks
	- through the steps for creating a new user account. As seen in
	- Example 4.2, either input the required information or press
	- <keycap>Return</keycap> to accept the default value shown in
	- square brackets. In this example, the user has been invited
	- into the <systemitem class="groupname">wheel</systemitem> group, which is
	- required to provide the account with superuser access. When
	- finished, the utility will prompt to either create another
	- user or to exit.</para>
	+ <sect3 xml:id="users-adduser">
	+ <title><command>adduser</command></title>

	- <example>
	- <title>Adding a User on &os;</title>
	+ <indexterm>
	+ <primary>accounts</primary>
	+ <secondary>adding</secondary>
	+ </indexterm>
	+ <indexterm>
	+ <primary><command>adduser</command></primary>
	+ </indexterm>
	+ <indexterm>
	+ <primary><filename>/usr/share/skel</filename></primary>
	+ </indexterm>
	+ <indexterm>
	+ <primary>skeleton directory</primary>
	+ </indexterm>

	- <screen>&prompt.root; <userinput>adduser</userinput>
	+ <para>The recommended program for adding new users is
	+ &man.adduser.8;. When a new user is added, this program
	+ automatically updates <filename>/etc/passwd</filename> and
	+ <filename>/etc/group</filename>. It also creates a home
	+ directory for the new user, copies in the default
	+ configuration files from
	+ <filename>/usr/share/skel</filename>, and can optionally
	+ mail the new user a welcome message. This utility must be
	+ run as the
	+ <systemitem class="username">superuser</systemitem></para>
	+
	+ <para>The &man.adduser.8; utility is interactive and walks
	+ through the steps for creating a new user account. As seen
	+ in Example 4.2, either input the required information or
	+ press <keycap>Return</keycap> to accept the default value
	+ shown in square brackets. In this example, the user has
	+ been invited into the
	+ <systemitem class="groupname">wheel</systemitem> group,
	+ which is required to provide the account with superuser
	+ access. When finished, the utility will prompt to either
	+ create another user or to exit.</para>
	+
	+ <example>
	+ <title>Adding a User on &os;</title>
	+
	+ <screen>&prompt.root; <userinput>adduser</userinput>
	Username: <userinput>jru</userinput>
	Full name: <userinput>J. Random User</userinput>
	Uid (Leave empty for default):
	Login group [jru]:
	Login group is jru. Invite jru into other groups? []: <userinput>wheel</userinput>
	Login class [default]:
	Shell (sh csh tcsh zsh nologin) [sh]: <userinput>zsh</userinput>
	Home directory [/home/jru]:
	Home directory permissions (Leave empty for default):
	Use password-based authentication? [yes]:
	Use an empty password? (yes/no) [no]:
	Use a random password? (yes/no) [no]:
	Enter password:
	Enter password again:
	Lock out the account after creation? [no]:
	Username : jru
	Password : ****
	Full Name : J. Random User
	Uid : 1001
	Class :
	Groups : jru wheel
	Home : /home/jru
	Shell : /usr/local/bin/zsh
	Locked : no
	OK? (yes/no): <userinput>yes</userinput>
	adduser: INFO: Successfully added (jru) to the user database.
	Add another user? (yes/no): <userinput>no</userinput>
	Goodbye!
	&prompt.root;</screen>
	- </example>
	-
	- <note>
	- <para>Since the password is not echoed when typed, be careful
	- to not mistype the password when creating the user
	- account.</para>
	- </note>
	- </sect3>
	-
	- <sect3 xml:id="users-rmuser">
	- <title><command>rmuser</command></title>
	-
	- <indexterm><primary><command>rmuser</command></primary></indexterm>
	- <indexterm>
	- <primary>accounts</primary>
	- <secondary>removing</secondary>
	- </indexterm>
	-
	- <para>To completely remove a user from the system, run
	- &man.rmuser.8; as the superuser. This command performs the
	- following steps:</para>
	-
	- <procedure>
	- <step>
	- <para>Removes the user's &man.crontab.1; entry, if one
	- exists.</para>
	- </step>
	-
	- <step>
	- <para>Removes any &man.at.1; jobs belonging to the
	- user.</para>
	- </step>
	+ </example>

	- <step>
	- <para>Kills all processes owned by the user.</para>
	- </step>
	-
	- <step>
	- <para>Removes the user from the system's local password
	- file.</para>
	- </step>
	-
	- <step>
	- <para>Optionally removes the user's home directory, if it is
	- owned by the user.</para>
	- </step>
	-
	- <step>
	- <para>Removes the incoming mail files belonging to the user
	- from <filename>/var/mail</filename>.</para>
	- </step>
	-
	- <step>
	- <para>Removes all files owned by the user from temporary
	- file storage areas such as <filename>/tmp</filename>.</para>
	- </step>
	-
	- <step>
	- <para>Finally, removes the username from all groups to which
	- it belongs in <filename>/etc/group</filename>. If a group
	- becomes empty and the group name is the same as the
	- username, the group is removed. This complements the
	- per-user unique groups created by &man.adduser.8;.</para>
	- </step>
	- </procedure>
	-
	- <para>&man.rmuser.8; cannot be used to remove superuser
	- accounts since that is almost always an indication of massive
	- destruction.</para>
	+ <note>
	+ <para>Since the password is not echoed when typed, be
	+ careful to not mistype the password when creating the user
	+ account.</para>
	+ </note>
	+ </sect3>

	- <para>By default, an interactive mode is used, as shown
	- in the following example.</para>
	+ <sect3 xml:id="users-rmuser">
	+ <title><command>rmuser</command></title>

	- <example>
	- <title><command>rmuser</command> Interactive Account
	- Removal</title>
	+ <indexterm>
	+ <primary><command>rmuser</command></primary>
	+ </indexterm>
	+ <indexterm>
	+ <primary>accounts</primary>
	+ <secondary>removing</secondary>
	+ </indexterm>

	- <screen>&prompt.root; <userinput>rmuser jru</userinput>
	+ <para>To completely remove a user from the system, run
	+ &man.rmuser.8; as the superuser. This command performs the
	+ following steps:</para>
	+
	+ <procedure>
	+ <step>
	+ <para>Removes the user's &man.crontab.1; entry, if one
	+ exists.</para>
	+ </step>
	+
	+ <step>
	+ <para>Removes any &man.at.1; jobs belonging to the
	+ user.</para>
	+ </step>
	+
	+ <step>
	+ <para>Kills all processes owned by the user.</para>
	+ </step>
	+
	+ <step>
	+ <para>Removes the user from the system's local password
	+ file.</para>
	+ </step>
	+
	+ <step>
	+ <para>Optionally removes the user's home directory, if it
	+ is owned by the user.</para>
	+ </step>
	+
	+ <step>
	+ <para>Removes the incoming mail files belonging to the
	+ user from <filename>/var/mail</filename>.</para>
	+ </step>
	+
	+ <step>
	+ <para>Removes all files owned by the user from temporary
	+ file storage areas such as
	+ <filename>/tmp</filename>.</para>
	+ </step>
	+
	+ <step>
	+ <para>Finally, removes the username from all groups to
	+ which it belongs in <filename>/etc/group</filename>. If
	+ a group becomes empty and the group name is the same as
	+ the username, the group is removed. This complements
	+ the per-user unique groups created by
	+ &man.adduser.8;.</para>
	+ </step>
	+ </procedure>
	+
	+ <para>&man.rmuser.8; cannot be used to remove superuser
	+ accounts since that is almost always an indication of
	+ massive destruction.</para>
	+
	+ <para>By default, an interactive mode is used, as shown
	+ in the following example.</para>
	+
	+ <example>
	+ <title><command>rmuser</command> Interactive Account
	+ Removal</title>
	+
	+ <screen>&prompt.root; <userinput>rmuser jru</userinput>
	Matching password entry:
	jru:*:1001:1001::0:0:J. Random User:/home/jru:/usr/local/bin/zsh
	Is this the entry you wish to remove? <userinput>y</userinput>
	Remove user's home directory (/home/jru)? <userinput>y</userinput>
	Removing user (jru): mailspool home passwd.
	&prompt.root;</screen>
	- </example>
	- </sect3>
	-
	- <sect3 xml:id="users-chpass">
	- <title><command>chpass</command></title>
	-
	- <indexterm><primary><command>chpass</command></primary></indexterm>
	- <para>Any user can use &man.chpass.1; to change their default
	- shell and personal information associated with their user
	- account. The superuser can use this utility to change
	- additional account information for any user.</para>
	-
	- <para>When passed no options, aside from an optional username,
	- &man.chpass.1; displays an editor containing user information.
	- When the user exists from the editor, the user database is
	- updated with the new information.</para>
	-
	- <note>
	- <para>This utility will prompt for the user's password when
	- exiting the editor, unless the utility is run as the
	- superuser.</para>
	- </note>
	+ </example>
	+ </sect3>

	- <para>In Example 4.4, the superuser has typed
	- <command>chpass jru</command> and is now viewing the fields
	- that can be changed for this user. If
	- <systemitem class="username">jru</systemitem> runs this command instead, only the
	- last six fields will be displayed and available for editing.
	- This is shown in Example 4.5.</para>
	+ <sect3 xml:id="users-chpass">
	+ <title><command>chpass</command></title>

	- <example>
	- <title>Using <command>chpass</command> as
	- Superuser</title>
	+ <indexterm>
	+ <primary><command>chpass</command></primary>
	+ </indexterm>

	- <screen>#Changing user database information for jru.
	+ <para>Any user can use &man.chpass.1; to change their default
	+ shell and personal information associated with their user
	+ account. The superuser can use this utility to change
	+ additional account information for any user.</para>
	+
	+ <para>When passed no options, aside from an optional username,
	+ &man.chpass.1; displays an editor containing user
	+ information. When the user exists from the editor, the user
	+ database is updated with the new information.</para>
	+
	+ <note>
	+ <para>This utility will prompt for the user's password when
	+ exiting the editor, unless the utility is run as the
	+ superuser.</para>
	+ </note>
	+
	+ <para>In Example 4.4, the superuser has typed
	+ <command>chpass jru</command> and is now viewing the fields
	+ that can be changed for this user. If
	+ <systemitem class="username">jru</systemitem> runs this
	+ command instead, only the last six fields will be displayed
	+ and available for editing. This is shown in Example
	+ 4.5.</para>
	+
	+ <example>
	+ <title>Using <command>chpass</command> as
	+ Superuser</title>
	+
	+ <screen>#Changing user database information for jru.
	Login: jru
	Password: *
	Uid [#]: 1001
	Gid [# or name]: 1001
	Change [month day year]:
	Expire [month day year]:
	Class:
	Home directory: /home/jru
	Shell: /usr/local/bin/zsh
	Full Name: J. Random User
	Office Location:
	Office Phone:
	Home Phone:
	Other information:</screen>
	- </example>
	+ </example>

	- <example>
	- <title>Using <command>chpass</command> as Regular
	- User</title>
	+ <example>
	+ <title>Using <command>chpass</command> as Regular
	+ User</title>

	- <screen>#Changing user database information for jru.
	+ <screen>#Changing user database information for jru.
	Shell: /usr/local/bin/zsh
	Full Name: J. Random User
	Office Location:
	Office Phone:
	Home Phone:
	Other information:</screen>
	- </example>
	+ </example>
	+
	+ <note>
	+ <para>&man.chfn.1; and &man.chsh.1; are links to
	+ &man.chpass.1;, as are &man.ypchpass.1;, &man.ypchfn.1;,
	+ and &man.ypchsh.1;. Since <acronym>NIS</acronym> support
	+ is automatic, specifying the <literal>yp</literal> before
	+ the command is not necessary. How to configure NIS is
	+ covered in <xref linkend="network-servers"/>.</para>
	+ </note>
	+ </sect3>

	- <note>
	- <para>&man.chfn.1; and &man.chsh.1; are links to
	- &man.chpass.1;, as are &man.ypchpass.1;, &man.ypchfn.1;, and
	- &man.ypchsh.1;. Since <acronym>NIS</acronym> support is
	- automatic, specifying the <literal>yp</literal> before
	- the command is not necessary. How to configure NIS is
	- covered in <xref linkend="network-servers"/>.</para>
	- </note>
	- </sect3>
	- <sect3 xml:id="users-passwd">
	- <title><command>passwd</command></title>
	+ <sect3 xml:id="users-passwd">
	+ <title><command>passwd</command></title>

	- <indexterm><primary><command>passwd</command></primary></indexterm>
	- <indexterm>
	- <primary>accounts</primary>
	- <secondary>changing password</secondary>
	- </indexterm>
	- <para>Any user can easily change their password using
	- &man.passwd.1;. To prevent accidental or unauthorized
	- changes, this command will prompt for the user's original
	- password before a new password can be set:</para>
	+ <indexterm>
	+ <primary><command>passwd</command></primary>
	+ </indexterm>
	+ <indexterm>
	+ <primary>accounts</primary>
	+ <secondary>changing password</secondary>
	+ </indexterm>

	- <example>
	- <title>Changing Your Password</title>
	+ <para>Any user can easily change their password using
	+ &man.passwd.1;. To prevent accidental or unauthorized
	+ changes, this command will prompt for the user's original
	+ password before a new password can be set:</para>
	+
	+ <example>
	+ <title>Changing Your Password</title>

	- <screen>&prompt.user; <userinput>passwd</userinput>
	+ <screen>&prompt.user; <userinput>passwd</userinput>
	Changing local password for jru.
	Old password:
	New password:
	Retype new password:
	passwd: updating the database...
	passwd: done</screen>
	- </example>
	+ </example>

	- <para>The superuser can change any user's password by specifying
	- the username when running &man.passwd.1;. When this utility
	- is run as the superuser, it will not prompt for the user's
	- current password. This allows the password to be changed when
	- a user cannot remember the original password.</para>
	+ <para>The superuser can change any user's password by
	+ specifying the username when running &man.passwd.1;. When
	+ this utility is run as the superuser, it will not prompt for
	+ the user's current password. This allows the password to be
	+ changed when a user cannot remember the original
	+ password.</para>

	- <example>
	- <title>Changing Another User's Password as the
	- Superuser</title>
	+ <example>
	+ <title>Changing Another User's Password as the
	+ Superuser</title>

	- <screen>&prompt.root; <userinput>passwd jru</userinput>
	+ <screen>&prompt.root; <userinput>passwd jru</userinput>
	Changing local password for jru.
	New password:
	Retype new password:
	passwd: updating the database...
	passwd: done</screen>
	- </example>
	+ </example>
	+
	+ <note>
	+ <para>As with &man.chpass.1;, &man.yppasswd.1; is a link to
	+ &man.passwd.1;, so <acronym>NIS</acronym> works with
	+ either command.</para>
	+ </note>
	+ </sect3>
	+
	+ <sect3 xml:id="users-pw">
	+ <title><command>pw</command></title>
	+
	+ <indexterm>
	+ <primary><command>pw</command></primary>
	+ </indexterm>
	+
	+ <para>&man.pw.8; is a command line utility to create, remove,
	+ modify, and display users and groups. It functions as a
	+ front end to the system user and group files. &man.pw.8;
	+ has a very powerful set of command line options that make it
	+ suitable for use in shell scripts, but new users may find it
	+ more complicated than the other commands presented in this
	+ section.</para>
	+ </sect3>
	+ </sect2>
	+
	+ <sect2 xml:id="users-limiting">
	+ <title>Limiting Users</title>
	+
	+ <indexterm>
	+ <primary>limiting users</primary>
	+ </indexterm>
	+ <indexterm>
	+ <primary>accounts</primary>
	+ <secondary>limiting</secondary>
	+ </indexterm>
	+
	+ <para>&os; provides several methods for an administrator to
	+ limit the amount of system resources an individual may use.
	+ These limits are discussed in two sections: disk quotas and
	+ other resource limits.</para>
	+
	+ <indexterm>
	+ <primary>quotas</primary>
	+ </indexterm>
	+ <indexterm>
	+ <primary>limiting users</primary>
	+ <secondary>quotas</secondary>
	+ </indexterm>
	+ <indexterm>
	+ <primary>disk quotas</primary>
	+ </indexterm>
	+
	+ <para>Disk quotas limit the amount of disk space available to
	+ users and provide a way to quickly check that usage without
	+ calculating it every time. Quotas are discussed in
	+ <xref linkend="quotas"/>.</para>
	+
	+ <para>The other resource limits include ways to limit the amount
	+ of CPU, memory, and other resources a user may consume. These
	+ are defined using login classes and are discussed here.</para>
	+
	+ <indexterm>
	+ <primary><filename>/etc/login.conf</filename></primary>
	+ </indexterm>
	+
	+ <para>Login classes are defined in
	+ <filename>/etc/login.conf</filename> and are described in
	+ detail in &man.login.conf.5;. Each user account is assigned
	+ to a login class, <literal>default</literal> by default, and
	+ each login class has a set of login capabilities associated
	+ with it. A login capability is a
	+ <literal>name=value</literal> pair, where
	+ <replaceable>name</replaceable> is a well-known identifier and
	+ <replaceable>value</replaceable> is an arbitrary string which
	+ is processed accordingly depending on the
	+ <replaceable>name</replaceable>. Setting up login classes and
	+ capabilities is rather straightforward and is also described
	+ in &man.login.conf.5;.</para>

	<note>
	- <para>As with &man.chpass.1;, &man.yppasswd.1; is a link to
	- &man.passwd.1;, so <acronym>NIS</acronym> works with either
	- command.</para>
	+ <para>&os; does not normally read the configuration in
	+ <filename>/etc/login.conf</filename> directly, but instead
	+ reads the <filename>/etc/login.conf.db</filename> database
	+ which provides faster lookups. Whenever
	+ <filename>/etc/login.conf</filename> is edited, the
	+ <filename>/etc/login.conf.db</filename> must be updated by
	+ executing the following command:</para>
	+
	+ <screen>&prompt.root; <userinput>cap_mkdb /etc/login.conf</userinput></screen>
	</note>
	- </sect3>

	+ <para>Resource limits differ from the default login capabilities
	+ in two ways. First, for every limit, there is a soft
	+ (current) and hard limit. A soft limit may be adjusted by the
	+ user or application, but may not be set higher than the hard
	+ limit. The hard limit may be lowered by the user, but can
	+ only be raised by the superuser. Second, most resource limits
	+ apply per process to a specific user, not to the user as a
	+ whole. These differences are mandated by the specific
	+ handling of the limits, not by the implementation of the login
	+ capability framework.</para>
	+
	+ <para>Below are the most commonly used resource limits. The
	+ rest of the limits, along with all the other login
	+ capabilities, can be found in &man.login.conf.5;.</para>

	- <sect3 xml:id="users-pw">
	- <title><command>pw</command></title>
	+ <variablelist>
	+ <varlistentry>
	+ <term><literal>coredumpsize</literal></term>

	- <indexterm><primary><command>pw</command></primary></indexterm>
	+ <listitem>
	+ <para>The limit on the size of a core file
	+ <indexterm>
	+ <primary>coredumpsize</primary>
	+ </indexterm>
	+ generated by a program is subordinate to other limits
	+ <indexterm>
	+ <primary>limiting users</primary>
	+ <secondary>coredumpsize</secondary>
	+ </indexterm>
	+ on disk usage, such as <literal>filesize</literal>, or
	+ disk quotas. This limit is often used as a less-severe
	+ method of controlling disk space consumption. Since
	+ users do not generate core files themselves, and often
	+ do not delete them, setting this may save them from
	+ running out of disk space should a large program
	+ crash.</para>
	+ </listitem>
	+ </varlistentry>

	- <para>&man.pw.8; is a command line utility to create, remove,
	- modify, and display users and groups. It functions as a front
	- end to the system user and group files. &man.pw.8; has a very
	- powerful set of command line options that make it suitable for
	- use in shell scripts, but new users may find it more
	- complicated than the other commands presented in this
	- section.</para>
	- </sect3>
	- </sect2>
	+ <varlistentry>
	+ <term><literal>cputime</literal></term>

	- <sect2 xml:id="users-limiting">
	- <title>Limiting Users</title>
	+ <listitem>
	+ <para>The maximum amount of CPU
	+ <indexterm>
	+ <primary>cputime</primary>
	+ </indexterm>
	+ <indexterm>
	+ <primary>limiting users</primary>
	+ <secondary>cputime</secondary>
	+ </indexterm>
	+ time a user's process may consume. Offending processes
	+ will be killed by the kernel.</para>
	+
	+ <note>
	+ <para>This is a limit on CPU <emphasis>time</emphasis>
	+ consumed, not percentage of the CPU as displayed in
	+ some fields by &man.top.1; and &man.ps.1;.</para>
	+ </note>
	+ </listitem>
	+ </varlistentry>

	- <indexterm><primary>limiting users</primary></indexterm>
	- <indexterm>
	- <primary>accounts</primary>
	- <secondary>limiting</secondary>
	- </indexterm>
	- <para>&os; provides several methods for an administrator to limit
	- the amount of system resources an individual may use. These
	- limits are discussed in two sections: disk quotas and other
	- resource limits.</para>
	+ <varlistentry>
	+ <term><literal>filesize</literal></term>

	- <indexterm><primary>quotas</primary></indexterm>
	- <indexterm>
	- <primary>limiting users</primary>
	- <secondary>quotas</secondary>
	- </indexterm>
	- <indexterm><primary>disk quotas</primary></indexterm>
	- <para>Disk quotas limit the amount of disk space available to
	- users and provide a way to quickly check that usage without
	- calculating it every time. Quotas are discussed in <xref linkend="quotas"/>.</para>
	+ <listitem>
	+ <para>The maximum size of a file
	+ <indexterm>
	+ <primary>filesize</primary>
	+ </indexterm>
	+ <indexterm>
	+ <primary>limiting users</primary>
	+ <secondary>filesize</secondary>
	+ </indexterm>
	+ the user may own. Unlike
	+ <link linkend="quotas">disk quotas</link>, this limit is
	+ enforced on individual files, not the set of all files a
	+ user owns.</para>
	+ </listitem>
	+ </varlistentry>

	- <para>The other resource limits include ways to limit the amount
	- of CPU, memory, and other resources a user may consume. These
	- are defined using login classes and are discussed here.</para>
	+ <varlistentry>
	+ <term><literal>maxproc</literal></term>

	- <indexterm>
	- <primary><filename>/etc/login.conf</filename></primary>
	- </indexterm>
	- <para>Login classes are defined in
	- <filename>/etc/login.conf</filename> and are described in detail
	- in &man.login.conf.5;. Each user account is assigned to a login
	- class, <literal>default</literal> by default, and each login
	- class has a set of login capabilities associated with it. A
	- login capability is a
	- <literal>name=value</literal>
	- pair, where <replaceable>name</replaceable> is a well-known
	- identifier and <replaceable>value</replaceable> is an arbitrary
	- string which is processed accordingly depending on the
	- <replaceable>name</replaceable>. Setting up login classes and
	- capabilities is rather straightforward and is also described in
	- &man.login.conf.5;.</para>
	-
	- <note>
	- <para>&os; does not normally read the configuration in
	- <filename>/etc/login.conf</filename> directly, but instead
	- reads the <filename>/etc/login.conf.db</filename> database
	- which provides faster lookups. Whenever
	- <filename>/etc/login.conf</filename> is edited, the
	- <filename>/etc/login.conf.db</filename> must be updated by
	- executing the following command:</para>
	-
	- <screen>&prompt.root; <userinput>cap_mkdb /etc/login.conf</userinput></screen>
	- </note>
	-
	- <para>Resource limits differ from the default login capabilities
	- in two ways. First, for every limit, there is a soft (current)
	- and hard limit. A soft limit may be adjusted by the user or
	- application, but may not be set higher than the hard limit. The
	- hard limit may be lowered by the user, but can only be raised
	- by the superuser. Second, most resource limits apply per
	- process to a specific user, not to the user as a whole. These
	- differences are mandated by the specific handling of the limits,
	- not by the implementation of the login capability
	- framework.</para>
	-
	- <para>Below are the most commonly used resource limits. The rest
	- of the limits, along with all the other login capabilities, can
	- be found in &man.login.conf.5;.</para>
	-
	- <variablelist>
	- <varlistentry>
	- <term><literal>coredumpsize</literal></term>
	+ <listitem>
	+ <para>The maximum number of processes
	+ <indexterm>
	+ <primary>maxproc</primary>
	+ </indexterm>
	+ <indexterm>
	+ <primary>limiting users</primary>
	+ <secondary>maxproc</secondary>
	+ </indexterm>
	+ a user can run. This includes foreground and background
	+ processes. This limit may not be larger than the system
	+ limit specified by the <varname>kern.maxproc</varname>
	+ &man.sysctl.8;. Setting this limit too small may hinder
	+ a user's productivity as it is often useful to be logged
	+ in multiple times or to execute pipelines. Some tasks,
	+ such as compiling a large program, spawn multiple
	+ processes and other intermediate preprocessors.</para>
	+ </listitem>
	+ </varlistentry>

	- <listitem>
	- <para>The limit on the size of a core file
	- <indexterm><primary>coredumpsize</primary></indexterm>
	- generated by a program is subordinate to other
	- limits <indexterm><primary>limiting users
	- </primary><secondary>coredumpsize</secondary></indexterm>
	- on disk usage, such as <literal>filesize</literal>, or
	- disk quotas. This limit is often used as a less-severe
	- method of controlling disk space consumption. Since
	- users do not generate core files themselves, and often do
	- not delete them, setting this may save them from running
	- out of disk space should a large program crash.</para>
	- </listitem>
	- </varlistentry>
	+ <varlistentry>
	+ <term><literal>memorylocked</literal></term>

	- <varlistentry>
	- <term><literal>cputime</literal></term>
	+ <listitem>
	+ <para>The maximum amount of memory
	+ <indexterm>
	+ <primary>memorylocked</primary>
	+ </indexterm>
	+ <indexterm>
	+ <primary>limiting users</primary>
	+ <secondary>memorylocked</secondary>
	+ </indexterm>
	+ a process may request to be locked into main memory
	+ using &man.mlock.2;. Some system-critical programs,
	+ such as &man.amd.8;, lock into main memory so that if
	+ the system begins to swap, they do not contribute to
	+ disk thrashing.</para>
	+ </listitem>
	+ </varlistentry>

	- <listitem>
	- <para>The maximum amount of CPU
	- <indexterm><primary>cputime</primary></indexterm><indexterm><primary>
	- limiting users
	- </primary><secondary>cputime</secondary></indexterm>
	- time a user's process may consume. Offending processes
	- will be killed by the kernel.</para>
	+ <varlistentry>
	+ <term><literal>memoryuse</literal></term>

	- <note>
	- <para>This is a limit on CPU <emphasis>time</emphasis>
	- consumed, not percentage of the CPU as displayed in
	- some fields by &man.top.1; and &man.ps.1;.</para>
	- </note>
	- </listitem>
	- </varlistentry>
	+ <listitem>
	+ <para>The maximum amount of memory
	+ <indexterm>
	+ <primary>memoryuse</primary>
	+ </indexterm>
	+ <indexterm>
	+ <primary>limiting users</primary>
	+ <secondary>memoryuse</secondary>
	+ </indexterm>
	+ a process may consume at any given time. It includes
	+ both core memory and swap usage. This is not a
	+ catch-all limit for restricting memory consumption, but
	+ is a good start.</para>
	+ </listitem>
	+ </varlistentry>

	- <varlistentry>
	- <term><literal>filesize</literal></term>
	+ <varlistentry>
	+ <term><literal>openfiles</literal></term>

	- <listitem>
	- <para>The maximum size of a file
	- <indexterm><primary>filesize</primary></indexterm><indexterm><primary>
	- limiting users
	- </primary><secondary>filesize</secondary></indexterm>
	- the user may own. Unlike <link linkend="quotas">disk
	- quotas</link>, this limit is enforced on individual
	- files, not the set of all files a user owns.</para>
	- </listitem>
	- </varlistentry>
	+ <listitem>
	+ <para>The maximum number of files a process may have open
	+ <indexterm>
	+ <primary>openfiles</primary>
	+ </indexterm>
	+ <indexterm>
	+ <primary>limiting users</primary>
	+ <secondary>openfiles</secondary>
	+ </indexterm>.
	+ In &os;, files are used to represent sockets and IPC
	+ channels, so be careful not to set this too low. The
	+ system-wide limit for this is defined by the
	+ <varname>kern.maxfiles</varname> &man.sysctl.8;.</para>
	+ </listitem>
	+ </varlistentry>

	- <varlistentry>
	- <term><literal>maxproc</literal></term>
	+ <varlistentry>
	+ <term><literal>sbsize</literal></term>

	- <listitem>
	- <para>The maximum number of processes
	- <indexterm><primary>maxproc</primary></indexterm><indexterm><primary>
	- limiting users
	- </primary><secondary>maxproc</secondary></indexterm> a
	- user can run. This includes foreground and background
	- processes. This limit may not be larger than the system
	- limit specified by the
	- <varname>kern.maxproc</varname> &man.sysctl.8;. Setting
	- this limit too small may hinder a user's productivity as
	- it is often useful to be logged in multiple times or to
	- execute pipelines. Some tasks, such as compiling a large
	- program, spawn multiple processes and other intermediate
	- preprocessors.</para>
	- </listitem>
	- </varlistentry>
	+ <listitem>
	+ <para>The limit on the amount of network memory, and
	+ thus mbufs
	+ <indexterm>
	+ <primary>sbsize</primary>
	+ </indexterm>
	+ <indexterm>
	+ <primary>limiting users</primary>
	+ <secondary>sbsize</secondary>
	+ </indexterm>,
	+ a user may consume in order to limit network
	+ communications.</para>
	+ </listitem>
	+ </varlistentry>

	- <varlistentry>
	- <term><literal>memorylocked</literal></term>
	+ <varlistentry>
	+ <term><literal>stacksize</literal></term>

	- <listitem>
	- <para>The maximum amount of memory
	- <indexterm><primary>memorylocked</primary></indexterm><indexterm><primary>
	- limiting users
	- </primary><secondary>memorylocked</secondary></indexterm>
	- a process may request to be locked into main memory using
	- &man.mlock.2;. Some system-critical programs, such as
	- &man.amd.8;, lock into main memory so that if the system
	- begins to swap, they do not contribute to disk
	- thrashing.</para>
	- </listitem>
	- </varlistentry>
	+ <listitem>
	+ <para>The maximum size of a process stack
	+ <indexterm>
	+ <primary>stacksize</primary>
	+ </indexterm>
	+ <indexterm>
	+ <primary>limiting users</primary>
	+ <secondary>stacksize</secondary>
	+ </indexterm>.
	+ This alone is not sufficient to limit the amount of
	+ memory a program may use so it should be used in
	+ conjunction with other limits.</para>
	+ </listitem>
	+ </varlistentry>
	+ </variablelist>

	- <varlistentry>
	- <term><literal>memoryuse</literal></term>
	+ <para>There are a few other things to remember when setting
	+ resource limits. Following are some general tips,
	+ suggestions, and miscellaneous comments.</para>

	+ <itemizedlist>
	<listitem>
	- <para>The maximum amount of memory
	- <indexterm><primary>memoryuse</primary></indexterm><indexterm><primary>
	- limiting
	- users</primary><secondary>memoryuse</secondary></indexterm>
	- a process may consume at any given time. It includes both
	- core memory and swap usage. This is not a catch-all limit
	- for restricting memory consumption, but is a good
	- start.</para>
	+ <para>Processes started at system startup by
	+ <filename>/etc/rc</filename> are assigned to the
	+ <literal>daemon</literal> login class.</para>
	</listitem>
	- </varlistentry>
	-
	- <varlistentry>
	- <term><literal>openfiles</literal></term>

	<listitem>
	- <para>The maximum number of files a process may have open
	- <indexterm><primary>openfiles</primary></indexterm><indexterm><primary>
	- limiting
	- users</primary><secondary>openfiles</secondary></indexterm>.
	- In &os;, files are used to represent sockets and IPC
	- channels, so be careful not to set this too low. The
	- system-wide limit for this is defined by the
	- <varname>kern.maxfiles</varname> &man.sysctl.8;.</para>
	+ <para>Although the <filename>/etc/login.conf</filename> that
	+ comes with the system is a good source of reasonable
	+ values for most limits, they may not be appropriate for
	+ every system. Setting a limit too high may open the
	+ system up to abuse, while setting it too low may put a
	+ strain on productivity.</para>
	</listitem>
	- </varlistentry>
	-
	- <varlistentry>
	- <term><literal>sbsize</literal></term>

	<listitem>
	- <para>The limit on the amount of network memory, and
	- thus mbufs
	- <indexterm><primary>sbsize</primary></indexterm><indexterm><primary>limiting
	- users</primary><secondary>sbsize</secondary></indexterm>,
	- a user may consume in order to limit network
	- communications.</para>
	+ <para>Users of <application>&xorg;</application> should
	+ probably be granted more resources than other users.
	+ <application>&xorg;</application> by itself takes a lot of
	+ resources, but it also encourages users to run more
	+ programs simultaneously.</para>
	</listitem>
	- </varlistentry>
	-
	- <varlistentry>
	- <term><literal>stacksize</literal></term>

	<listitem>
	- <para>The maximum size of a process stack
	- <indexterm><primary>stacksize</primary></indexterm><indexterm><primary>limiting
	- users</primary><secondary>stacksize</secondary></indexterm>.
	- This alone is not sufficient to limit the amount of memory
	- a program may use so it should be used in conjunction with
	- other limits.</para>
	+ <para>Many limits apply to individual processes, not the
	+ user as a whole. For example, setting
	+ <varname>openfiles</varname> to 50 means that each process
	+ the user runs may open up to 50 files. The total amount
	+ of files a user may open is the value of
	+ <literal>openfiles</literal> multiplied by the value of
	+ <literal>maxproc</literal>. This also applies to memory
	+ consumption.</para>
	</listitem>
	- </varlistentry>
	- </variablelist>
	-
	- <para>There are a few other things to remember when setting
	- resource limits. Following are some general tips, suggestions,
	- and miscellaneous comments.</para>
	+ </itemizedlist>

	- <itemizedlist>
	- <listitem>
	- <para>Processes started at system startup by
	- <filename>/etc/rc</filename> are assigned to the
	- <literal>daemon</literal> login class.</para>
	- </listitem>
	+ <para>For further information on resource limits and login
	+ classes and capabilities in general, refer to
	+ &man.cap.mkdb.1;, &man.getrlimit.2;, and
	+ &man.login.conf.5;.</para>
	+ </sect2>

	- <listitem>
	- <para>Although the <filename>/etc/login.conf</filename> that
	- comes with the system is a good source of reasonable values
	- for most limits, they may not be appropriate for every
	- system. Setting a limit too high may open the system up to
	- abuse, while setting it too low may put a strain on
	- productivity.</para>
	- </listitem>
	+ <sect2 xml:id="users-groups">
	+ <title>Managing Groups</title>

	- <listitem>
	- <para>Users of <application>&xorg;</application> should
	- probably be granted more resources than other users.
	- <application>&xorg;</application> by itself takes a lot of
	- resources, but it also encourages users to run more programs
	- simultaneously.</para>
	- </listitem>
	-
	- <listitem>
	- <para>Many limits apply to individual processes, not the user
	- as a whole. For example, setting
	- <varname>openfiles</varname> to 50 means that each process
	- the user runs may open up to 50 files. The total amount
	- of files a user may open is the value of
	- <literal>openfiles</literal> multiplied by the value of
	- <literal>maxproc</literal>. This also applies to memory
	- consumption.</para>
	- </listitem>
	- </itemizedlist>
	+ <indexterm>
	+ <primary>groups</primary>
	+ </indexterm>
	+ <indexterm>
	+ <primary><filename>/etc/groups</filename></primary>
	+ </indexterm>
	+ <indexterm>
	+ <primary>accounts</primary>
	+ <secondary>groups</secondary>
	+ </indexterm>

	- <para>For further information on resource limits and login classes
	- and capabilities in general, refer to &man.cap.mkdb.1;,
	- &man.getrlimit.2;, and &man.login.conf.5;.</para>
	- </sect2>
	+ <para>A group is a list of users. A group is identified by its
	+ group name and <acronym>GID</acronym>. In &os;, the kernel
	+ uses the <acronym>UID</acronym> of a process, and the list of
	+ groups it belongs to, to determine what the process is allowed
	+ to do. Most of the time, the <acronym>GID</acronym> of a user
	+ or process usually means the first group in the list.</para>
	+
	+ <para>The group name to <acronym>GID</acronym> mapping is listed
	+ in <filename>/etc/group</filename>. This is a plain text file
	+ with four colon-delimited fields. The first field is the
	+ group name, the second is the encrypted password, the third
	+ the <acronym>GID</acronym>, and the fourth the comma-delimited
	+ list of members. For a more complete description of the
	+ syntax, refer to &man.group.5;.</para>
	+
	+ <para>The superuser can modify <filename>/etc/group</filename>
	+ using a text editor. Alternatively, &man.pw.8; can be used to
	+ add and edit groups. For example, to add a group called
	+ <systemitem class="groupname">teamtwo</systemitem> and then
	+ confirm that it exists:</para>

	- <sect2 xml:id="users-groups">
	- <title>Managing Groups</title>
	+ <example>
	+ <title>Adding a Group Using &man.pw.8;</title>

	- <indexterm><primary>groups</primary></indexterm>
	- <indexterm>
	- <primary><filename>/etc/groups</filename></primary>
	- </indexterm>
	- <indexterm>
	- <primary>accounts</primary>
	- <secondary>groups</secondary>
	- </indexterm>
	- <para>A group is a list of users. A group is identified by its
	- group name and <acronym>GID</acronym>. In &os;, the
	- kernel uses the <acronym>UID</acronym> of a process, and the
	- list of groups it belongs to, to determine what the process is
	- allowed to do. Most of the time, the <acronym>GID</acronym> of
	- a user or process usually means the first group in the
	- list.</para>
	-
	- <para>The group name to <acronym>GID</acronym> mapping is listed
	- in <filename>/etc/group</filename>. This is a plain text file
	- with four colon-delimited fields. The first field is the group
	- name, the second is the encrypted password, the third the
	- <acronym>GID</acronym>, and the fourth the comma-delimited list
	- of members. For a more complete description of the syntax,
	- refer to &man.group.5;.</para>
	-
	- <para>The superuser can modify <filename>/etc/group</filename>
	- using a text editor. Alternatively, &man.pw.8; can be used to
	- add and edit groups. For example, to add a group called
	- <systemitem class="groupname">teamtwo</systemitem> and then confirm that it
	- exists:</para>
	-
	- <example>
	- <title>Adding a Group Using &man.pw.8;</title>
	-
	- <screen>&prompt.root; <userinput>pw groupadd teamtwo</userinput>
	+ <screen>&prompt.root; <userinput>pw groupadd teamtwo</userinput>
	&prompt.root; <userinput>pw groupshow teamtwo</userinput>
	teamtwo:*:1100:</screen>
	- </example>
	+ </example>

	- <para>In this example, <literal>1100</literal> is the
	- <acronym>GID</acronym> of <systemitem class="groupname">teamtwo</systemitem>. Right
	- now, <systemitem class="groupname">teamtwo</systemitem> has no members. This
	- command will add <systemitem class="username">jru</systemitem> as a member of
	- <systemitem class="groupname">teamtwo</systemitem>.</para>
	+ <para>In this example, <literal>1100</literal> is the
	+ <acronym>GID</acronym> of
	+ <systemitem class="groupname">teamtwo</systemitem>. Right
	+ now, <systemitem class="groupname">teamtwo</systemitem> has no
	+ members. This command will add
	+ <systemitem class="username">jru</systemitem> as a member of
	+ <systemitem class="groupname">teamtwo</systemitem>.</para>

	- <example>
	- <title>Adding User Accounts to a New Group Using
	- &man.pw.8;</title>
	+ <example>
	+ <title>Adding User Accounts to a New Group Using
	+ &man.pw.8;</title>

	- <screen>&prompt.root; <userinput>pw groupmod teamtwo -M jru</userinput>
	+ <screen>&prompt.root; <userinput>pw groupmod teamtwo -M jru</userinput>
	&prompt.root; <userinput>pw groupshow teamtwo</userinput>
	teamtwo:*:1100:jru</screen>
	- </example>
	+ </example>
	+
	+ <para>The argument to <option>-M</option> is a comma-delimited
	+ list of users to be added to a new (empty) group or to replace
	+ the members of an existing group. To the user, this group
	+ membership is different from (and in addition to) the user's
	+ primary group listed in the password file. This means that
	+ the user will not show up as a member when using
	+ <option>groupshow</option> with &man.pw.8;, but will show up
	+ when the information is queried via &man.id.1; or a similar
	+ tool. When &man.pw.8; is used to add a user to a group, it
	+ only manipulates <filename>/etc/group</filename> and does not
	+ attempt to read additional data from
	+ <filename>/etc/passwd</filename>.</para>

	- <para>The argument to <option>-M</option> is a comma-delimited
	- list of users to be added to a new (empty) group or to replace
	- the members of an existing group. To the user, this group
	- membership is different from (and in addition to) the user's
	- primary group listed in the password file. This means that
	- the user will not show up as a member when using
	- <option>groupshow</option> with &man.pw.8;, but will show up
	- when the information is queried via &man.id.1; or a similar
	- tool. When &man.pw.8; is used to add a user to a group, it only
	- manipulates <filename>/etc/group</filename> and does not attempt
	- to read additional data from
	- <filename>/etc/passwd</filename>.</para>
	-
	- <example>
	- <title>Adding a New Member to a Group Using &man.pw.8;</title>
	-
	- <screen>&prompt.root; <userinput>pw groupmod teamtwo -m db</userinput>
	+ <example>
	+ <title>Adding a New Member to a Group Using &man.pw.8;</title>
	+
	+ <screen>&prompt.root; <userinput>pw groupmod teamtwo -m db</userinput>
	&prompt.root; <userinput>pw groupshow teamtwo</userinput>
	teamtwo:*:1100:jru,db</screen>
	- </example>
	+ </example>

	- <para>In this example, the argument to <option>-m</option> is a
	- comma-delimited list of users who are to be added to the group.
	- Unlike the previous example, these users are appended to the
	- group list and do not replace the list of existing users in the
	- group.</para>
	+ <para>In this example, the argument to <option>-m</option> is a
	+ comma-delimited list of users who are to be added to the
	+ group. Unlike the previous example, these users are appended
	+ to the group list and do not replace the list of existing
	+ users in the group.</para>

	- <example>
	- <title>Using &man.id.1; to Determine Group Membership</title>
	+ <example>
	+ <title>Using &man.id.1; to Determine Group Membership</title>

	- <screen>&prompt.user; <userinput>id jru</userinput>
	+ <screen>&prompt.user; <userinput>id jru</userinput>
	uid=1001(jru) gid=1001(jru) groups=1001(jru), 1100(teamtwo)</screen>
	</example>

	- <para>In this example, <systemitem class="username">jru</systemitem> is a member of
	+ <para>In this example,
	+ <systemitem class="username">jru</systemitem> is a member of
	the groups <systemitem class="groupname">jru</systemitem> and
	<systemitem class="groupname">teamtwo</systemitem>.</para>

	<para>For more information about this command and the format of
	<filename>/etc/group</filename>, refer to &man.pw.8; and
	&man.group.5;.</para>
	</sect2>
	</sect1>

	<sect1 xml:id="permissions">
	<title>Permissions</title>

	- <indexterm><primary>UNIX</primary></indexterm>
	+ <indexterm>
	+ <primary>UNIX</primary>
	+ </indexterm>

	<para>In &os;, every file and directory has an associated set of
	permissions and several utilities are available for viewing
	and modifying these permissions. Understanding how permissions
	work is necessary to make sure that users are able to access
	the files that they need and are unable to improperly access
	the files used by the operating system or owned by other
	users.</para>

	<para>This section discusses the traditional &unix; permissions
	used in &os;. For finer grained file system access control,
	refer to <xref linkend="fs-acl"/>.</para>

	<para>In &unix;, basic permissions are assigned using
	three types of access: read, write, and execute. These access
	types are used to determine file access to the file's owner,
	group, and others (everyone else). The read, write, and execute
	permissions can be represented as the letters
	<literal>r</literal>, <literal>w</literal>, and
	<literal>x</literal>. They can also be represented as binary
	numbers as each permission is either on or off
	(<literal>0</literal>). When represented as a number, the
	order is always read as <literal>rwx</literal>, where
	<literal>r</literal> has an on value of <literal>4</literal>,
	<literal>w</literal> has an on value of <literal>2</literal>
	and <literal>x</literal> has an on value of
	<literal>1</literal>.</para>

	<para>Table 4.1 summarizes the possible numeric and alphabetic
	possibilities. When reading the <quote>Directory
	Listing</quote> column, a <literal>-</literal> is used to
	represent a permission that is set to off.</para>

	- <indexterm><primary>permissions</primary></indexterm>
	+ <indexterm>
	+ <primary>permissions</primary>
	+ </indexterm>
	<indexterm>
	<primary>file permissions</primary>
	</indexterm>
	+
	<table frame="none" pgwide="1">
	<title>&unix; Permissions</title>

	<tgroup cols="3">
	<thead>
	<row>
	<entry>Value</entry>
	<entry>Permission</entry>
	<entry>Directory Listing</entry>
	</row>
	</thead>

	<tbody>
	<row>
	<entry>0</entry>
	<entry>No read, no write, no execute</entry>
	<entry><literal>---</literal></entry>
	</row>

	<row>
	<entry>1</entry>
	<entry>No read, no write, execute</entry>
	<entry><literal>--x</literal></entry>
	</row>

	<row>
	<entry>2</entry>
	<entry>No read, write, no execute</entry>
	<entry><literal>-w-</literal></entry>
	</row>

	<row>
	<entry>3</entry>
	<entry>No read, write, execute</entry>
	<entry><literal>-wx</literal></entry>
	</row>

	<row>
	<entry>4</entry>
	<entry>Read, no write, no execute</entry>
	<entry><literal>r--</literal></entry>
	</row>

	<row>
	<entry>5</entry>
	<entry>Read, no write, execute</entry>
	<entry><literal>r-x</literal></entry>
	</row>

	<row>
	<entry>6</entry>
	<entry>Read, write, no execute</entry>
	<entry><literal>rw-</literal></entry>
	</row>

	<row>
	<entry>7</entry>
	<entry>Read, write, execute</entry>
	<entry><literal>rwx</literal></entry>
	</row>
	</tbody>
	</tgroup>
	</table>

	<indexterm>
	<primary>&man.ls.1;</primary>
	</indexterm>
	- <indexterm><primary>directories</primary></indexterm>
	+ <indexterm>
	+ <primary>directories</primary>
	+ </indexterm>

	<para>Use the <option>-l</option> argument to &man.ls.1; to view a
	long directory listing that includes a column of information
	about a file's permissions for the owner, group, and everyone
	else. For example, a <command>ls -l</command> in an arbitrary
	directory may show:</para>

	<screen>&prompt.user; <userinput>ls -l</userinput>
	total 530
	-rw-r--r-- 1 root wheel 512 Sep 5 12:31 myfile
	-rw-r--r-- 1 root wheel 512 Sep 5 12:31 otherfile
	-rw-r--r-- 1 root wheel 7680 Sep 5 12:31 email.txt</screen>

	<para>The first (leftmost) character in the first column indicates
	whether this file is a regular file, a directory, a special
	character device, a socket, or any other special pseudo-file
	device. In this example, the <literal>-</literal> indicates a
	regular file. The next three characters, <literal>rw-</literal>
	in this example, give the permissions for the owner of the file.
	The next three characters, <literal>r--</literal>, give the
	permissions for the group that the file belongs to. The final
	three characters, <literal>r--</literal>, give the permissions
	for the rest of the world. A dash means that the permission is
	turned off. In this example, the permissions are set so the
	owner can read and write to the file, the group can read the
	file, and the rest of the world can only read the file.
	According to the table above, the permissions for this file
	would be <literal>644</literal>, where each digit represents the
	three parts of the file's permission.</para>

	<para>How does the system control permissions on devices? &os;
	treats most hardware devices as a file that programs can open,
	read, and write data to. These special device files are
	stored in <filename>/dev/</filename>.</para>

	<para>Directories are also treated as files. They have read,
	write, and execute permissions. The executable bit for a
	directory has a slightly different meaning than that of files.
	When a directory is marked executable, it means it is possible
	to change into that directory using &man.cd.1;. This also
	means that it is possible to access the files within that
	directory, subject to the permissions on the files
	themselves.</para>

	<para>In order to perform a directory listing, the read permission
	must be set on the directory. In order to delete a file that
	one knows the name of, it is necessary to have write
	<emphasis>and</emphasis> execute permissions to the directory
	containing the file.</para>

	<para>There are more permission bits, but they are primarily used
	in special circumstances such as setuid binaries and sticky
	directories. For more information on file permissions and how
	to set them, refer to &man.chmod.1;.</para>

	<sect2>
	- <info><title>Symbolic Permissions</title>
	+ <info>
	+ <title>Symbolic Permissions</title>
	+
	<authorgroup>
	- <author><personname><firstname>Tom</firstname><surname>Rhodes</surname></personname><contrib>Contributed by </contrib></author>
	+ <author>
	+ <personname>
	+ <firstname>Tom</firstname>
	+ <surname>Rhodes</surname>
	+ </personname>
	+ <contrib>Contributed by </contrib>
	+ </author>
	</authorgroup>
	</info>

	-
	-
	<indexterm>
	<primary>permissions</primary>
	<secondary>symbolic</secondary>
	</indexterm>

	<para>Symbolic permissions use characters instead of octal
	values to assign permissions to files or directories.
	Symbolic permissions use the syntax of (who) (action)
	(permissions), where the following values are
	available:</para>

	<informaltable frame="none" pgwide="1">
	<tgroup cols="3">
	<thead>
	<row>
	<entry>Option</entry>
	<entry>Letter</entry>
	<entry>Represents</entry>
	</row>
	</thead>

	<tbody>
	<row>
	<entry>(who)</entry>
	<entry>u</entry>
	<entry>User</entry>
	</row>

	<row>
	<entry>(who)</entry>
	<entry>g</entry>
	<entry>Group owner</entry>
	</row>

	<row>
	<entry>(who)</entry>
	<entry>o</entry>
	<entry>Other</entry>
	</row>

	<row>
	<entry>(who)</entry>
	<entry>a</entry>
	<entry>All (<quote>world</quote>)</entry>
	</row>

	<row>
	<entry>(action)</entry>
	<entry>+</entry>
	<entry>Adding permissions</entry>
	</row>

	<row>
	<entry>(action)</entry>
	<entry>-</entry>
	<entry>Removing permissions</entry>
	</row>

	<row>
	<entry>(action)</entry>
	<entry>=</entry>
	<entry>Explicitly set permissions</entry>
	</row>

	<row>
	<entry>(permissions)</entry>
	<entry>r</entry>
	<entry>Read</entry>
	</row>

	<row>
	<entry>(permissions)</entry>
	<entry>w</entry>
	<entry>Write</entry>
	</row>

	<row>
	<entry>(permissions)</entry>
	<entry>x</entry>
	<entry>Execute</entry>
	</row>

	<row>
	<entry>(permissions)</entry>
	<entry>t</entry>
	<entry>Sticky bit</entry>
	</row>

	<row>
	<entry>(permissions)</entry>
	<entry>s</entry>
	<entry>Set UID or GID</entry>
	</row>
	</tbody>
	</tgroup>
	</informaltable>

	<para>These values are used with &man.chmod.1;, but with
	letters instead of numbers. For example, the following
	command would block other users from accessing
	<replaceable>FILE</replaceable>:</para>

	<screen>&prompt.user; <userinput>chmod go= FILE</userinput></screen>

	<para>A comma separated list can be provided when more than one
	set of changes to a file must be made. For example, the
	following command removes the group and
	<quote>world</quote> write permission on
	<replaceable>FILE</replaceable>, and adds the execute
	permissions for everyone:</para>

	<screen>&prompt.user; <userinput>chmod go-w,a+x FILE</userinput></screen>

	<!--
	<para>Most users will not notice this, but it should be pointed
	out that using the octal method will only set or assign
	permissions to a file; it does not add or delete them.</para>
	-->
	</sect2>

	<sect2>
	- <info><title>&os; File Flags</title>
	+ <info>
	+ <title>&os; File Flags</title>
	+
	<authorgroup>
	- <author><personname><firstname>Tom</firstname><surname>Rhodes</surname></personname><contrib>Contributed by </contrib></author>
	+ <author>
	+ <personname>
	+ <firstname>Tom</firstname>
	+ <surname>Rhodes</surname>
	+ </personname>
	+ <contrib>Contributed by </contrib>
	+ </author>
	</authorgroup>
	</info>

	-
	-
	<para>In addition to file permissions, &os; supports the use of
	<quote>file flags</quote>. These flags add an additional
	level of security and control over files, but not directories.
	- With file flags, even <systemitem class="username">root</systemitem> can be
	+ With file flags, even
	+ <systemitem class="username">root</systemitem> can be
	prevented from removing or altering files.</para>

	<para>File flags are modified using &man.chflags.1;. For
	example, to enable the system undeletable flag on the file
	<filename>file1</filename>, issue the following
	command:</para>

	<screen>&prompt.root; <userinput>chflags sunlink file1</userinput></screen>

	<para>To disable the system undeletable flag, put a
	<quote>no</quote> in front of the
	<option>sunlink</option>:</para>

	<screen>&prompt.root; <userinput>chflags nosunlink file1</userinput></screen>

	<para>To view the flags of a file, use <option>-lo</option> with
	&man.ls.1;:</para>

	<screen>&prompt.root; <userinput>ls -lo file1</userinput></screen>

	<programlisting>-rw-r--r-- 1 trhodes trhodes sunlnk 0 Mar 1 05:54 file1</programlisting>

	<para>Several file flags may only be added or removed by the
	- <systemitem class="username">root</systemitem> user. In other cases, the file
	- owner may set its file flags. Refer to &man.chflags.1; and
	- &man.chflags.2; for more information.</para>
	+ <systemitem class="username">root</systemitem> user. In other
	+ cases, the file owner may set its file flags. Refer to
	+ &man.chflags.1; and &man.chflags.2; for more
	+ information.</para>
	</sect2>

	<sect2>
	- <info><title>The <literal>setuid</literal>, <literal>setgid</literal>,
	- and <literal>sticky</literal> Permissions</title>
	+ <info>
	+ <title>The <literal>setuid</literal>,
	+ <literal>setgid</literal>, and <literal>sticky</literal>
	+ Permissions</title>
	+
	<authorgroup>
	- <author><personname><firstname>Tom</firstname><surname>Rhodes</surname></personname><contrib>Contributed by </contrib></author>
	+ <author>
	+ <personname>
	+ <firstname>Tom</firstname>
	+ <surname>Rhodes</surname>
	+ </personname>
	+ <contrib>Contributed by </contrib>
	+ </author>
	</authorgroup>
	</info>

	-
	-
	<para>Other than the permissions already discussed, there are
	three other specific settings that all administrators should
	know about. They are the <literal>setuid</literal>,
	<literal>setgid</literal>, and <literal>sticky</literal>
	permissions.</para>

	<para>These settings are important for some &unix; operations
	as they provide functionality not normally granted to normal
	users. To understand them, the difference between the real
	user ID and effective user ID must be noted.</para>

	<para>The real user ID is the <acronym>UID</acronym> who owns
	or starts the process. The effective <acronym>UID</acronym>
	is the user ID the process runs as. As an example,
	&man.passwd.1; runs with the real user ID when a user changes
	their password. However, in order to update the password
	database, the command runs as the effective ID of the
	- <systemitem class="username">root</systemitem> user. This allows users to change
	- their passwords without seeing a
	+ <systemitem class="username">root</systemitem> user. This
	+ allows users to change their passwords without seeing a
	<errorname>Permission Denied</errorname> error.</para>

	<para>The setuid permission may be set by prefixing a permission
	set with the number four (4) as shown in the following
	example:</para>

	<screen>&prompt.root; <userinput>chmod 4755 suidexample.sh</userinput></screen>

	<para>The permissions on
	<filename>suidexample.sh</filename>
	now look like the following:</para>

	<programlisting>-rwsr-xr-x 1 trhodes trhodes 63 Aug 29 06:36 suidexample.sh</programlisting>

	<para>Note that a <literal>s</literal> is now part of the
	permission set designated for the file owner, replacing the
	executable bit. This allows utilities which need elevated
	permissions, such as &man.passwd.1;.</para>

	<note>
	<para>The <literal>nosuid</literal> &man.mount.8; option will
	cause such binaries to silently fail without alerting
	the user. That option is not completely reliable as a
	<literal>nosuid</literal> wrapper may be able to circumvent
	it.</para>
	</note>

	<para>To view this in real time, open two terminals. On
	one, type <command>passwd</command> as a normal user.
	While it waits for a new password, check the process
	table and look at the user information for
	&man.passwd.1;:</para>

	<para>In terminal A:</para>

	<screen>Changing local password for trhodes
	Old Password:</screen>

	<para>In terminal B:</para>

	<screen>&prompt.root; <userinput>ps aux \| grep passwd</userinput></screen>

	<screen>trhodes 5232 0.0 0.2 3420 1608 0 R+ 2:10AM 0:00.00 grep passwd
	root 5211 0.0 0.2 3620 1724 2 I+ 2:09AM 0:00.01 passwd</screen>

	<para>Although &man.passwd.1; is run as a normal user, it is
	using the effective <acronym>UID</acronym> of
	<systemitem class="username">root</systemitem>.</para>

	<para>The <literal>setgid</literal> permission performs the
	same function as the <literal>setuid</literal> permission;
	except that it alters the group settings. When an application
	or utility executes with this setting, it will be granted the
	permissions based on the group that owns the file, not the
	user who started the process.</para>

	<para>To set the <literal>setgid</literal> permission on a
	file, provide &man.chmod.1; with a leading two (2):</para>

	<screen>&prompt.root; <userinput>chmod 2755 sgidexample.sh</userinput></screen>

	<para>In the following listing, notice that the
	<literal>s</literal> is now in the field designated for the
	group permission settings:</para>

	<screen>-rwxr-sr-x 1 trhodes trhodes 44 Aug 31 01:49 sgidexample.sh</screen>

	<note>
	<para>In these examples, even though the shell script in
	question is an executable file, it will not run with
	a different <acronym>EUID</acronym> or effective user ID.
	This is because shell scripts may not access the
	&man.setuid.2; system calls.</para>
	</note>

	<para>The <literal>setuid</literal> and
	<literal>setgid</literal> permission bits may lower system
	security, by allowing for elevated permissions. The third
	special permission, the <literal>sticky bit</literal>, can
	strengthen the security of a system.</para>

	<para>When the <literal>sticky bit</literal> is set on a
	directory, it allows file deletion only by the file owner.
	This is useful to prevent file deletion in public directories,
	such as <filename>/tmp</filename>, by users
	who do not own the file. To utilize this permission, prefix
	the permission set with a one (1):</para>

	<screen>&prompt.root; <userinput>chmod 1777 /tmp</userinput></screen>

	<para>The <literal>sticky bit</literal> permission will display
	as a <literal>t</literal> at the very end of the permission
	set:</para>

	<screen>&prompt.root; <userinput>ls -al / \| grep tmp</userinput></screen>

	<screen>drwxrwxrwt 10 root wheel 512 Aug 31 01:49 tmp</screen>

	</sect2>
	</sect1>

	<sect1 xml:id="dirstructure">
	<title>Directory Structure</title>

	- <indexterm><primary>directory hierarchy</primary></indexterm>
	+ <indexterm>
	+ <primary>directory hierarchy</primary>
	+ </indexterm>

	<para>The &os; directory hierarchy is fundamental to obtaining
	an overall understanding of the system. The most important
	directory is root or, <quote>/</quote>. This directory is the
	first one mounted at boot time and it contains the base system
	necessary to prepare the operating system for multi-user
	operation. The root directory also contains mount points for
	other file systems that are mounted during the transition to
	multi-user operation.</para>

	<para>A mount point is a directory where additional file systems
	can be grafted onto a parent file system (usually the root file
	- system). This is further described in <xref linkend="disk-organization"/>. Standard mount points
	- include <filename>/usr/</filename>,
	- <filename>/var/</filename>,
	- <filename>/tmp/</filename>,
	- <filename>/mnt/</filename>, and
	- <filename>/cdrom/</filename>. These
	- directories are usually referenced to entries in
	- <filename>/etc/fstab</filename>. This file is a table of
	- various file systems and mount points and is read by the system.
	- Most of the file systems in <filename>/etc/fstab</filename> are
	- mounted automatically at boot time from the script &man.rc.8;
	- unless their entry includes <option>noauto</option>. Details
	- can be found in <xref linkend="disks-fstab"/>.</para>
	+ system). This is further described in
	+ <xref linkend="disk-organization"/>. Standard mount points
	+ include <filename>/usr/</filename>, <filename>/var/</filename>,
	+ <filename>/tmp/</filename>, <filename>/mnt/</filename>, and
	+ <filename>/cdrom/</filename>. These directories are usually
	+ referenced to entries in <filename>/etc/fstab</filename>. This
	+ file is a table of various file systems and mount points and is
	+ read by the system. Most of the file systems in
	+ <filename>/etc/fstab</filename> are mounted automatically at
	+ boot time from the script &man.rc.8; unless their entry includes
	+ <option>noauto</option>. Details can be found in
	+ <xref linkend="disks-fstab"/>.</para>

	<para>A complete description of the file system hierarchy is
	available in &man.hier.7;. The following table provides a brief
	overview of the most common directories.</para>

	<para>
	<informaltable frame="none" pgwide="1">
	<tgroup cols="2">
	<thead>
	<row>
	<entry>Directory</entry>
	<entry>Description</entry>
	</row>
	</thead>
	<tbody valign="top">
	<row>
	<entry><filename>/</filename></entry>
	<entry>Root directory of the file system.</entry>
	</row>

	<row>
	<entry><filename>/bin/</filename></entry>
	<entry>User utilities fundamental to both single-user
	and multi-user environments.</entry>
	</row>

	<row>
	<entry><filename>/boot/</filename></entry>
	<entry>Programs and configuration files used during
	operating system bootstrap.</entry>
	</row>

	<row>
	<entry><filename>/boot/defaults/</filename></entry>
	<entry>Default boot configuration files. Refer to
	&man.loader.conf.5; for details.</entry>
	</row>

	<row>
	<entry><filename>/dev/</filename></entry>
	<entry>Device nodes. Refer to &man.intro.4; for
	details.</entry>
	</row>

	<row>
	<entry><filename>/etc/</filename></entry>
	<entry>System configuration files and scripts.</entry>
	</row>

	<row>
	<entry><filename>/etc/defaults/</filename></entry>
	<entry>Default system configuration files. Refer to
	&man.rc.8; for details.</entry>
	</row>

	<row>
	<entry><filename>/etc/mail/</filename></entry>
	<entry>Configuration files for mail transport agents
	such as &man.sendmail.8;.</entry>
	</row>

	<row>
	<entry><filename>/etc/namedb/</filename></entry>
	<entry>&man.named.8; configuration files.</entry>
	</row>

	<row>
	<entry><filename>/etc/periodic/</filename></entry>
	<entry>Scripts that run daily, weekly, and monthly,
	via &man.cron.8;. Refer to &man.periodic.8; for
	details.</entry>
	</row>

	<row>
	<entry><filename>/etc/ppp/</filename></entry>
	<entry>&man.ppp.8; configuration files.</entry>
	</row>

	<row>
	<entry><filename>/mnt/</filename></entry>
	<entry>Empty directory commonly used by system
	administrators as a temporary mount point.</entry>
	</row>

	<row>
	<entry><filename>/proc/</filename></entry>
	<entry>Process file system. Refer to &man.procfs.5;,
	&man.mount.procfs.8; for details.</entry>
	</row>

	<row>
	<entry><filename>/rescue/</filename></entry>
	<entry>Statically linked programs for emergency
	recovery as described in &man.rescue.8;.</entry>
	</row>

	<row>
	<entry><filename>/root/</filename></entry>
	- <entry>Home directory for the <systemitem class="username">root</systemitem>
	+ <entry>Home directory for the
	+ <systemitem class="username">root</systemitem>
	account.</entry>
	</row>

	<row>
	<entry><filename>/sbin/</filename></entry>
	<entry>System programs and administration utilities
	fundamental to both single-user and multi-user
	environments.</entry>
	</row>

	<row>
	<entry><filename>/tmp/</filename></entry>
	<entry>Temporary files which are usually
	<emphasis>not</emphasis> preserved across a system
	reboot. A memory-based file system is often mounted
	- at <filename>/tmp</filename>. This
	- can be automated using the tmpmfs-related variables of
	- &man.rc.conf.5; or with an entry in
	- <filename>/etc/fstab</filename>; refer to
	- &man.mdmfs.8; for details.</entry>
	+ at <filename>/tmp</filename>. This can be automated
	+ using the tmpmfs-related variables of &man.rc.conf.5;
	+ or with an entry in <filename>/etc/fstab</filename>;
	+ refer to &man.mdmfs.8; for details.</entry>
	</row>

	<row>
	<entry><filename>/usr/</filename></entry>
	<entry>The majority of user utilities and
	applications.</entry>
	</row>

	<row>
	<entry><filename>/usr/bin/</filename></entry>
	<entry>Common utilities, programming tools, and
	applications.</entry>
	</row>

	<row>
	<entry><filename>/usr/include/</filename></entry>
	<entry>Standard C include files.</entry>
	</row>

	<row>
	<entry><filename>/usr/lib/</filename></entry>
	<entry>Archive libraries.</entry>
	</row>


	<row>
	<entry><filename>/usr/libdata/</filename></entry>
	<entry>Miscellaneous utility data files.</entry>
	</row>

	<row>
	<entry><filename>/usr/libexec/</filename></entry>
	<entry>System daemons and system utilities executed
	by other programs.</entry>
	</row>

	<row>
	<entry><filename>/usr/local/</filename></entry>
	<entry>Local executables and libraries. Also used as
	the default destination for the &os; ports framework.
	- Within <filename>/usr/local</filename>, the
	- general layout sketched out by &man.hier.7; for
	- <filename>/usr</filename> should be
	- used. Exceptions are the man directory, which is
	- directly under <filename>/usr/local</filename>
	- rather than under <filename>/usr/local/share</filename>,
	- and the ports documentation is in <filename>share/doc/port</filename>.</entry>
	+ Within <filename>/usr/local</filename>, the general
	+ layout sketched out by &man.hier.7; for
	+ <filename>/usr</filename> should be used. Exceptions
	+ are the man directory, which is directly under
	+ <filename>/usr/local</filename> rather than under
	+ <filename>/usr/local/share</filename>, and the ports
	+ documentation is in
	+ <filename>share/doc/port</filename>.</entry>
	</row>

	<row>
	<entry><filename>/usr/obj/</filename></entry>
	<entry>Architecture-specific target tree produced by
	building the <filename>/usr/src</filename>
	tree.</entry>
	</row>

	<row>
	<entry><filename>/usr/ports/</filename></entry>
	<entry>The &os; Ports Collection (optional).</entry>
	</row>

	<row>
	<entry><filename>/usr/sbin/</filename></entry>
	<entry>System daemons and system utilities executed
	by users.</entry>
	</row>

	<row>
	<entry><filename>/usr/share/</filename></entry>
	<entry>Architecture-independent files.</entry>
	</row>

	<row>
	<entry><filename>/usr/src/</filename></entry>
	<entry>BSD and/or local source files.</entry>
	</row>

	<row>
	<entry><filename>/var/</filename></entry>
	<entry>Multi-purpose log, temporary, transient, and
	spool files. A memory-based file system is sometimes
	mounted at
	<filename>/var</filename>. This can
	be automated using the varmfs-related variables in
	&man.rc.conf.5; or with an entry in
	<filename>/etc/fstab</filename>; refer to
	&man.mdmfs.8; for details.</entry>
	</row>

	<row>
	<entry><filename>/var/log/</filename></entry>
	<entry>Miscellaneous system log files.</entry>
	</row>

	<row>
	<entry><filename>/var/mail/</filename></entry>
	<entry>User mailbox files.</entry>
	</row>

	<row>
	<entry><filename>/var/spool/</filename></entry>
	<entry>Miscellaneous printer and mail system spooling
	directories.</entry>
	</row>

	<row>
	<entry><filename>/var/tmp/</filename></entry>
	<entry>Temporary files which are usually preserved
	across a system reboot, unless
	<filename>/var</filename> is a
	memory-based file system.</entry>
	</row>

	<row>
	<entry><filename>/var/yp/</filename></entry>
	<entry>NIS maps.</entry>
	</row>
	</tbody>
	</tgroup>
	</informaltable></para>
	</sect1>

	<sect1 xml:id="disk-organization">
	<title>Disk Organization</title>

	<para>The smallest unit of organization that &os; uses to find
	files is the filename. Filenames are case-sensitive, which
	means that <filename>readme.txt</filename> and
	<filename>README.TXT</filename> are two separate files. &os;
	does not use the extension of a file to determine whether the
	file is a program, document, or some other form of data.</para>

	<para>Files are stored in directories. A directory may contain no
	files, or it may contain many hundreds of files. A directory
	can also contain other directories, allowing a hierarchy of
	directories within one another in order to organize
	data.</para>

	<para>Files and directories are referenced by giving the file or
	directory name, followed by a forward slash,
	<literal>/</literal>, followed by any other directory names that
	are necessary. For example, if the directory
	<filename>foo</filename> contains a directory
	<filename>bar</filename> which contains the
	file <filename>readme.txt</filename>, the full name, or
	<firstterm>path</firstterm>, to the file is
	<filename>foo/bar/readme.txt</filename>. Note that this is
	different from &windows; which uses <literal>\</literal> to
	separate file and directory names. &os; does not use drive
	letters, or other drive names in the path. For example, one
	would not type <filename>c:/foo/bar/readme.txt</filename> on
	&os;.</para>

	<para>Directories and files are stored in a file system. Each
	file system contains exactly one directory at the very top
	level, called the <firstterm>root directory</firstterm> for that
	file system. This root directory can contain other directories.
	One file system is designated the
	<firstterm>root file system</firstterm> or <literal>/</literal>.
	Every other file system is <firstterm>mounted</firstterm> under
	the root file system. No matter how many disks are on the &os;
	system, every directory appears to be part of the same
	disk.</para>

	<para>Consider three file systems, called <literal>A</literal>,
	<literal>B</literal>, and <literal>C</literal>. Each file
	system has one root directory, which contains two other
	directories, called <literal>A1</literal>, <literal>A2</literal>
	(and likewise <literal>B1</literal>, <literal>B2</literal> and
	<literal>C1</literal>, <literal>C2</literal>).</para>

	<para>Call <literal>A</literal> the root file system. If
	&man.ls.1; is used to view the contents of this directory,
	it will show two subdirectories, <literal>A1</literal> and
	<literal>A2</literal>. The directory tree looks like
	this:</para>

	<mediaobject>
	<imageobject>
	<imagedata fileref="install/example-dir1"/>
	</imageobject>

	<textobject>
	<literallayout class="monospaced"> /
	\|
	+--- A1
	\|
	`--- A2</literallayout>
	</textobject>
	</mediaobject>

	<para>A file system must be mounted on to a directory in another
	file system. When mounting file system <literal>B</literal>
	on to the directory <literal>A1</literal>, the root directory
	of <literal>B</literal> replaces <literal>A1</literal>, and
	the directories in <literal>B</literal> appear
	accordingly:</para>

	<mediaobject>
	<imageobject>
	<imagedata fileref="install/example-dir2"/>
	</imageobject>

	<textobject>
	<literallayout class="monospaced"> /
	\|
	+--- A1
	\| \|
	\| +--- B1
	\| \|
	\| `--- B2
	\|
	`--- A2</literallayout>
	</textobject>
	</mediaobject>

	<para>Any files that are in the <literal>B1</literal> or
	<literal>B2</literal> directories can be reached with the path
	<filename>/A1/B1</filename> or
	<filename>/A1/B2</filename> as necessary. Any
	files that were in <filename>/A1</filename>
	have been temporarily hidden. They will reappear if
	<literal>B</literal> is <firstterm>unmounted</firstterm> from
	<literal>A</literal>.</para>

	<para>If <literal>B</literal> had been mounted on
	<literal>A2</literal> then the diagram would look like
	this:</para>

	<mediaobject>
	<imageobject>
	<imagedata fileref="install/example-dir3"/>
	</imageobject>

	<textobject>
	<literallayout class="monospaced"> /
	\|
	+--- A1
	\|
	`--- A2
	\|
	+--- B1
	\|
	`--- B2</literallayout>
	</textobject>
	</mediaobject>

	<para>and the paths would be
	<filename>/A2/B1</filename> and
	<filename>/A2/B2</filename>
	respectively.</para>

	<para>File systems can be mounted on top of one another.
	Continuing the last example, the <literal>C</literal> file
	system could be mounted on top of the <literal>B1</literal>
	directory in the <literal>B</literal> file system, leading to
	this arrangement:</para>

	<mediaobject>
	<imageobject>
	<imagedata fileref="install/example-dir4"/>
	</imageobject>

	<textobject>
	<literallayout class="monospaced"> /
	\|
	+--- A1
	\|
	`--- A2
	\|
	+--- B1
	\| \|
	\| +--- C1
	\| \|
	\| `--- C2
	\|
	`--- B2</literallayout>
	</textobject>
	</mediaobject>

	<para>Or <literal>C</literal> could be mounted directly on to the
	<literal>A</literal> file system, under the
	<literal>A1</literal> directory:</para>

	<mediaobject>
	<imageobject>
	<imagedata fileref="install/example-dir5"/>
	</imageobject>

	<textobject>
	<literallayout class="monospaced"> /
	\|
	+--- A1
	\| \|
	\| +--- C1
	\| \|
	\| `--- C2
	\|
	`--- A2
	\|
	+--- B1
	\|
	`--- B2</literallayout>
	</textobject>
	</mediaobject>

	<para>It is entirely possible to have one large root file system,
	and not need to create any others. There are some drawbacks to
	this approach, and one advantage.</para>

	<itemizedlist>
	<title>Benefits of Multiple File Systems</title>

	<listitem>
	<para>Different file systems can have different
	<firstterm>mount options</firstterm>. For example, the root
	file system can be mounted read-only, making it impossible
	for users to inadvertently delete or edit a critical file.
	Separating user-writable file systems, such as
	<filename>/home</filename>, from other
	file systems allows them to be mounted
	<firstterm>nosuid</firstterm>. This option prevents the
	<firstterm>suid</firstterm>/<firstterm>guid</firstterm> bits
	on executables stored on the file system from taking effect,
	possibly improving security.</para>
	</listitem>

	<listitem>
	<para>&os; automatically optimizes the layout of files on a
	file system, depending on how the file system is being used.
	So a file system that contains many small files that are
	written frequently will have a different optimization to one
	that contains fewer, larger files. By having one big file
	system this optimization breaks down.</para>
	</listitem>

	<listitem>
	<para>&os;'s file systems are robust if power is lost.
	However, a power loss at a critical point could still damage
	the structure of the file system. By splitting data over
	multiple file systems it is more likely that the system will
	still come up, making it easier to restore from backup as
	necessary.</para>
	</listitem>
	</itemizedlist>

	<itemizedlist>
	<title>Benefit of a Single File System</title>

	<listitem>
	<para>File systems are a fixed size. If you create a file
	system when you install &os; and give it a specific size,
	you may later discover that you need to make the partition
	bigger. This is not easily accomplished without backing up,
	recreating the file system with the new size, and then
	restoring the backed up data.</para>

	<important>
	<para>&os; features the &man.growfs.8; command, which makes
	it possible to increase the size of file system on the
	fly, removing this limitation.</para>
	</important>
	</listitem>
	</itemizedlist>

	<para>File systems are contained in partitions. This does not
	have the same meaning as the common usage of the term partition
	(for example, &ms-dos; partition), because of &os;'s &unix;
	heritage. Each partition is identified by a letter from
	<literal>a</literal> through to <literal>h</literal>. Each
	partition can contain only one file system, which means that
	file systems are often described by either their typical mount
	point in the file system hierarchy, or the letter of the
	partition they are contained in.</para>

	<para>&os; also uses disk space for
	<firstterm>swap space</firstterm> to provide
	<firstterm>virtual memory</firstterm>. This allows your
	computer to behave as though it has much more memory than it
	actually does. When &os; runs out of memory, it moves some of
	the data that is not currently being used to the swap space, and
	moves it back in (moving something else out) when it needs
	it.</para>

	<para>Some partitions have certain conventions associated with
	them.</para>

	<informaltable frame="none" pgwide="1">
	<tgroup cols="2">
	<colspec colwidth="1*"/>
	<colspec colwidth="5*"/>

	<thead>
	<row>
	<entry>Partition</entry>
	<entry>Convention</entry>
	</row>
	</thead>

	<tbody valign="top">
	<row>
	<entry><literal>a</literal></entry>
	<entry>Normally contains the root file system.</entry>
	</row>

	<row>
	<entry><literal>b</literal></entry>
	<entry>Normally contains swap space.</entry>
	</row>

	<row>
	<entry><literal>c</literal></entry>
	<entry>Normally the same size as the enclosing slice.
	This allows utilities that need to work on the entire
	slice, such as a bad block scanner, to work on the
	<literal>c</literal> partition. A file system would not
	normally be created on this partition.</entry>
	</row>

	<row>
	<entry><literal>d</literal></entry>
	<entry>Partition <literal>d</literal> used to have a
	special meaning associated with it, although that is now
	gone and <literal>d</literal> may work as any normal
	partition.</entry>
	</row>
	</tbody>
	</tgroup>
	</informaltable>

	<para>Disks in &os; are divided into slices, referred to in
	&windows; as partitions, which are numbered from 1 to 4. These
	are then divided into partitions, which contain file systems,
	and are labeled using letters.</para>

	- <indexterm><primary>slices</primary></indexterm>
	- <indexterm><primary>partitions</primary></indexterm>
	- <indexterm><primary>dangerously dedicated</primary></indexterm>
	+ <indexterm>
	+ <primary>slices</primary>
	+ </indexterm>
	+ <indexterm>
	+ <primary>partitions</primary>
	+ </indexterm>
	+ <indexterm>
	+ <primary>dangerously dedicated</primary>
	+ </indexterm>

	<para>Slice numbers follow the device name, prefixed with an
	<literal>s</literal>, starting at 1. So
	<quote>da0<emphasis>s1</emphasis></quote> is the first slice on
	the first SCSI drive. There can only be four physical slices on
	a disk, but there can be logical slices inside physical slices
	of the appropriate type. These extended slices are numbered
	starting at 5, so <quote>ad0<emphasis>s5</emphasis></quote> is
	the first extended slice on the first IDE disk. These devices
	are used by file systems that expect to occupy a slice.</para>

	<para>Slices, <quote>dangerously dedicated</quote> physical
	drives, and other drives contain
	<firstterm>partitions</firstterm>, which are represented as
	letters from <literal>a</literal> to <literal>h</literal>. This
	letter is appended to the device name, so
	<quote>da0<emphasis>a</emphasis></quote> is the
	<literal>a</literal> partition on the first
	<literal>da</literal> drive, which is
	<quote>dangerously dedicated</quote>.
	<quote>ad1s3<emphasis>e</emphasis></quote> is the fifth
	partition in the third slice of the second IDE disk
	drive.</para>

	<para>Finally, each disk on the system is identified. A disk name
	starts with a code that indicates the type of disk, and then a
	number, indicating which disk it is. Unlike slices, disk
	numbering starts at 0. Common codes are listed in
	<xref linkend="basics-dev-codes"/>.</para>

	<para>When referring to a partition, include the disk name,
	<literal>s</literal>, the slice number, and then the partition
	letter. Examples are shown in
	<xref linkend="basics-disk-slice-part"/>.</para>

	<para><xref linkend="basics-concept-disk-model"/> shows a
	conceptual model of a disk layout.</para>

	<para>When installing &os;, configure the disk slices, create
	partitions within the slice to be used for &os;, create a file
	system or swap space in each partition, and decide where each
	file system will be mounted.</para>

	<table frame="none" pgwide="1" xml:id="basics-dev-codes">
	<title>Disk Device Codes</title>

	<tgroup cols="2">
	<colspec colwidth="1*"/>
	<colspec colwidth="5*"/>

	<thead>
	<row>
	<entry>Code</entry>
	<entry>Meaning</entry>
	</row>
	</thead>

	<tbody>
	<row>
	<entry><filename>ad</filename></entry>
	<entry>ATAPI (IDE) disk</entry>
	</row>

	<row>
	<entry><filename>da</filename></entry>
	<entry>SCSI direct access disk</entry>
	</row>

	<row>
	<entry><filename>acd</filename></entry>
	<entry>ATAPI (IDE) CDROM</entry>
	</row>

	<row>
	<entry><filename>cd</filename></entry>
	<entry>SCSI CDROM</entry>
	</row>

	<row>
	<entry><filename>fd</filename></entry>
	<entry>Floppy disk</entry>
	</row>
	</tbody>
	</tgroup>
	</table>

	<example xml:id="basics-disk-slice-part">
	<title>Sample Disk, Slice, and Partition Names</title>

	<informaltable frame="none" pgwide="1">
	<tgroup cols="2">
	<colspec colwidth="1*"/>
	<colspec colwidth="5*"/>

	<thead>
	<row>
	<entry>Name</entry>
	<entry>Meaning</entry>
	</row>
	</thead>

	<tbody>
	<row>
	<entry><literal>ad0s1a</literal></entry>
	<entry>The first partition (<literal>a</literal>) on the
	first slice (<literal>s1</literal>) on the first IDE
	disk (<literal>ad0</literal>).</entry>
	</row>

	<row>
	<entry><literal>da1s2e</literal></entry>
	<entry>The fifth partition (<literal>e</literal>) on the
	second slice (<literal>s2</literal>) on the second
	SCSI disk (<literal>da1</literal>).</entry>
	</row>
	</tbody>
	</tgroup>
	</informaltable>
	</example>

	<example xml:id="basics-concept-disk-model">
	<title>Conceptual Model of a Disk</title>

	<para>This diagram shows &os;'s view of the first IDE disk
	attached to the system. Assume that the disk is 4 GB in
	size, and contains two 2 GB slices (&ms-dos; partitions).
	The first slice contains a &ms-dos; disk,
	<filename>C:</filename>, and the second slice contains a
	&os; installation. This example &os; installation has three
	data partitions, and a swap partition.</para>

	<para>The three partitions will each hold a file system.
	Partition <literal>a</literal> will be used for the root file
	system, <literal>e</literal> for the
	<filename>/var/</filename> directory
	hierarchy, and <literal>f</literal> for the
	<filename>/usr/</filename> directory
	hierarchy.</para>

	<mediaobject>
	<imageobject>
	<imagedata fileref="install/disk-layout"/>
	</imageobject>

	<textobject>
	<literallayout class="monospaced">.-----------------. --.
	\| \| \|
	\| DOS / Windows \| \|
	: : > First slice, ad0s1
	: : \|
	\| \| \|
	:=================: ==: --.
	\| \| \| Partition a, mounted as / \|
	\| \| > referred to as ad0s2a \|
	\| \| \| \|
	:-----------------: ==: \|
	\| \| \| Partition b, used as swap \|
	\| \| > referred to as ad0s2b \|
	\| \| \| \|
	:-----------------: ==: \| Partition c, no
	\| \| \| Partition e, used as /var > file system, all
	\| \| > referred to as ad0s2e \| of FreeBSD slice,
	\| \| \| \| ad0s2c
	:-----------------: ==: \|
	\| \| \| \|
	: : \| Partition f, used as /usr \|
	: : > referred to as ad0s2f \|
	: : \| \|
	\| \| \| \|
	\| \| --' \|
	`-----------------' --'</literallayout>
	</textobject>
	</mediaobject>
	</example>
	</sect1>

	<sect1 xml:id="mount-unmount">
	<title>Mounting and Unmounting File Systems</title>

	<para>The file system is best visualized as a tree, rooted, as it
	were, at <filename>/</filename>.
	<filename>/dev</filename>,
	<filename>/usr</filename>, and the other
	directories in the root directory are branches, which may have
	their own branches, such as
	<filename>/usr/local</filename>, and so
	on.</para>

	- <indexterm><primary>root file system</primary></indexterm>
	+ <indexterm>
	+ <primary>root file system</primary>
	+ </indexterm>
	+
	<para>There are various reasons to house some of these
	directories on separate file systems.
	<filename>/var</filename> contains the
	directories <filename>log/</filename>,
	<filename>spool/</filename>, and various types
	of temporary files, and as such, may get filled up. Filling up
	the root file system is not a good idea, so splitting
	<filename>/var</filename> from
	<filename>/</filename> is often
	favorable.</para>

	<para>Another common reason to contain certain directory trees on
	other file systems is if they are to be housed on separate
	physical disks, or are separate virtual disks, such as Network
	File System mounts, described in <xref linkend="network-nfs"/>,
	or CDROM drives.</para>

	<sect2 xml:id="disks-fstab">
	<title>The <filename>fstab</filename> File</title>

	<indexterm>
	<primary>file systems</primary>
	<secondary>mounted with fstab</secondary>
	</indexterm>

	<para>During the boot process (<xref linkend="boot"/>), file
	systems listed in <filename>/etc/fstab</filename> are
	automatically mounted except for the entries containing
	<option>noauto</option>. This file contains entries in the
	following format:</para>

	<programlisting><replaceable>device</replaceable> <replaceable>/mount-point</replaceable> <replaceable>fstype</replaceable> <replaceable>options</replaceable> <replaceable>dumpfreq</replaceable> <replaceable>passno</replaceable></programlisting>

	<variablelist>
	<varlistentry>
	<term><literal>device</literal></term>
	<listitem>
	<para>An existing device name as explained in
	<xref linkend="disks-naming"/>.</para>
	</listitem>
	</varlistentry>

	<varlistentry>
	<term><literal>mount-point</literal></term>

	<listitem>
	<para>An existing directory on which to mount the file
	system.</para>
	</listitem>
	</varlistentry>

	<varlistentry>
	<term><literal>fstype</literal></term>

	<listitem>
	<para>The file system type to pass to &man.mount.8;. The
	default &os; file system is
	<literal>ufs</literal>.</para>
	</listitem>
	</varlistentry>

	<varlistentry>
	<term><literal>options</literal></term>

	<listitem>
	<para>Either <option>rw</option> for read-write file
	systems, or <option>ro</option> for read-only file
	systems, followed by any other options that may be
	needed. A common option is <option>noauto</option> for
	file systems not normally mounted during the boot
	sequence. Other options are listed in
	&man.mount.8;.</para>
	</listitem>
	</varlistentry>

	<varlistentry>
	<term><literal>dumpfreq</literal></term>

	<listitem>
	<para>Used by &man.dump.8; to determine which file systems
	require dumping. If the field is missing, a value of
	zero is assumed.</para>
	</listitem>
	</varlistentry>

	<varlistentry>
	<term><literal>passno</literal></term>

	<listitem>
	<para>Determines the order in which file systems should be
	checked. File systems that should be skipped should
	have their <literal>passno</literal> set to zero. The
	root file system needs to be checked before everything
	else and should have its <literal>passno</literal> set
	to one. The other file systems should be set to
	values greater than one. If more than one file system
	has the same <literal>passno</literal>, &man.fsck.8;
	will attempt to check file systems in parallel if
	possible.</para>
	</listitem>
	</varlistentry>
	</variablelist>

	<para>Refer to &man.fstab.5; for more information on the format
	of <filename>/etc/fstab</filename> and its options.</para>
	</sect2>

	<sect2 xml:id="disks-mount">
	<title>Using &man.mount.8;</title>

	<indexterm>
	<primary>file systems</primary>
	<secondary>mounting</secondary>
	</indexterm>

	<para>File systems are mounted using &man.mount.8;. The most
	basic syntax is as follows:</para>

	<informalexample>
	<screen>&prompt.root; <userinput>mount device mountpoint</userinput></screen>
	</informalexample>

	<para>This command provides many options which are described in
	&man.mount.8;, The most commonly used options include:</para>

	<variablelist>
	<title>Mount Options</title>

	<varlistentry>
	<term><option>-a</option></term>

	<listitem>
	<para>Mount all the file systems listed in
	<filename>/etc/fstab</filename>, except those marked as
	<quote>noauto</quote>, excluded by the
	<option>-t</option> flag, or those that are already
	mounted.</para>
	</listitem>
	</varlistentry>

	<varlistentry>
	<term><option>-d</option></term>

	<listitem>

	<para>Do everything except for the actual mount system
	call. This option is useful in conjunction with the
	<option>-v</option> flag to determine what &man.mount.8;
	is actually trying to do.</para>
	</listitem>
	</varlistentry>

	<varlistentry>
	<term><option>-f</option></term>

	<listitem>
	<para>Force the mount of an unclean file system
	(dangerous), or the revocation of write access when
	downgrading a file system's mount status from read-write
	to read-only.</para>
	</listitem>
	</varlistentry>

	<varlistentry>
	<term><option>-r</option></term>

	<listitem>
	<para>Mount the file system read-only. This is identical
	to using <option>-o ro</option>.</para>
	</listitem>
	</varlistentry>

	<varlistentry>
	<term><option>-t</option>
	<replaceable>fstype</replaceable></term>

	<listitem>
	<para>Mount the specified file system type or mount only
	file systems of the given type, if <option>-a</option>
	is included. <quote>ufs</quote> is the default file
	system type.</para>
	</listitem>
	</varlistentry>

	<varlistentry>
	<term><option>-u</option></term>

	<listitem>
	<para>Update mount options on the file system.</para>
	</listitem>
	</varlistentry>

	<varlistentry>
	<term><option>-v</option></term>

	<listitem>
	<para>Be verbose.</para>
	</listitem>
	</varlistentry>

	<varlistentry>
	<term><option>-w</option></term>

	<listitem>
	<para>Mount the file system read-write.</para>
	</listitem>
	</varlistentry>
	</variablelist>

	<para>The following options can be passed to <option>-o</option>
	as a comma-separated list:</para>

	<variablelist>
	<varlistentry>
	<term>nosuid</term>

	<listitem>
	<para>Do not interpret setuid or setgid flags on the
	file system. This is also a useful security
	option.</para>
	</listitem>
	</varlistentry>
	</variablelist>
	</sect2>

	<sect2 xml:id="disks-umount">
	<title>Using &man.umount.8;</title>

	<indexterm>
	<primary>file systems</primary>
	<secondary>unmounting</secondary>
	</indexterm>

	<para>To unmount a file system use &man.umount.8;. This command
	takes one parameter which can be a mountpoint, device name,
	<option>-a</option> or <option>-A</option>.</para>

	<para>All forms take <option>-f</option> to force unmounting,
	and <option>-v</option> for verbosity. Be warned that
	<option>-f</option> is not generally a good idea as it might
	crash the computer or damage data on the file system.</para>

	<para>To unmount all mounted file systems, or just the file
	system types listed after <option>-t</option>, use
	<option>-a</option> or <option>-A</option>. Note that
	<option>-A</option> does not attempt to unmount the root file
	system.</para>
	</sect2>
	</sect1>

	<sect1 xml:id="basics-processes">
	<title>Processes and Daemons</title>

	<para>&os; is a multi-tasking operating system. Each program
	running at any one time is called a
	<firstterm>process</firstterm>. Every running command starts
	at least one new process and there are a number of system
	processes that are run by &os;.</para>

	<para>Each process is uniquely identified by a number called a
	<firstterm>process ID</firstterm> (<acronym>PID</acronym>).
	Similar to files, each process has one owner and group, and
	the owner and group permissions are used to determine which
	files and devices the process can open. Most processes also
	have a parent process that started them. For example, the
	shell is a process, and any command started in the shell is a
	process which has the shell as its parent process. The
	exception is a special process called &man.init.8; which is
	always the first process to start at boot time and which always
	has a <acronym>PID</acronym> of <literal>1</literal>.</para>

	<para>Some programs are not designed to be run with continuous
	user input and disconnect from the terminal at the first
	opportunity. For example, a web server responds to web
	requests, rather than user input. Mail servers are another
	example of this type of application. These types of programs
	are known as <firstterm>daemons</firstterm>. The term daemon
	comes from Greek mythology and represents an entity that is
	neither good nor evil, and which invisibly performs useful
	tasks. This is why the BSD mascot is the cheerful-looking
	daemon with sneakers and a pitchfork.</para>

	<para>There is a convention to name programs that normally run as
	daemons with a trailing <quote>d</quote>. For example,
	<application>BIND</application> is the Berkeley Internet Name
	Domain, but the actual program that executes is
	<command>named</command>. The
	<application>Apache</application> web server program is
	<command>httpd</command> and the line printer spooling daemon
	is <command>lpd</command>. This is only a naming convention.
	For example, the main mail daemon for the
	<application>Sendmail</application> application is
	<command>sendmail</command>, and not
	<literal>maild</literal>.</para>

	<sect2>
	<title>Viewing Processes</title>

	<para>To see the processes running on the system, use &man.ps.1;
	or &man.top.1;. To display a static list of the currently
	running processes, their <acronym>PID</acronym>s, how much
	memory they are using, and the command they were started with,
	use &man.ps.1;. To display all the running processes and
	update the display every few seconds in order to interactively
	see what the computer is doing, use &man.top.1;.</para>

	<para>By default, &man.ps.1; only shows the commands that are
	running and owned by the user. For example:</para>

	<screen>&prompt.user; <userinput>ps</userinput>
	PID TT STAT TIME COMMAND
	8203 0 Ss 0:00.59 /bin/csh
	8895 0 R+ 0:00.00 ps</screen>

	<para>The output from &man.ps.1; is organized into a number of
	columns. The <literal>PID</literal> column displays the
	process ID. <acronym>PID</acronym>s are assigned starting at
	1, go up to 99999, then wrap around back to the beginning.
	However, a <acronym>PID</acronym> is not reassigned if it is
	already in use. The <literal>TT</literal> column shows the
	tty the program is running on and <literal>STAT</literal>
	shows the program's state. <literal>TIME</literal> is the
	amount of time the program has been running on the CPU. This
	is usually not the elapsed time since the program was started,
	as most programs spend a lot of time waiting for things to
	happen before they need to spend time on the CPU. Finally,
	<literal>COMMAND</literal> is the command that was used to
	start the program.</para>

	<para>A number of different options are available to change the
	information that is displayed. One of the most useful sets is
	<literal>auxww</literal>, where <option>a</option> displays
	information about all the running processes of all users,
	<option>u</option> displays the username and memory usage of
	the process' owner, <option>x</option> displays
	information about daemon processes, and <option>ww</option>
	causes &man.ps.1; to display the full command line for each
	process, rather than truncating it once it gets too long to
	fit on the screen.</para>

	<para>The output from &man.top.1; is similar:</para>

	<screen>&prompt.user; <userinput>top</userinput>
	last pid: 72257; load averages: 0.13, 0.09, 0.03 up 0+13:38:33 22:39:10
	47 processes: 1 running, 46 sleeping
	CPU states: 12.6% user, 0.0% nice, 7.8% system, 0.0% interrupt, 79.7% idle
	Mem: 36M Active, 5256K Inact, 13M Wired, 6312K Cache, 15M Buf, 408K Free
	Swap: 256M Total, 38M Used, 217M Free, 15% Inuse

	last pid: 9609; load averages: 0.56, 0.45, 0.36 up 0+00:20:03 10:21:46
	107 processes: 2 running, 104 sleeping, 1 zombie
	CPU: 6.2% user, 0.1% nice, 8.2% system, 0.4% interrupt, 85.1% idle
	Mem: 541M Active, 450M Inact, 1333M Wired, 4064K Cache, 1498M Free
	ARC: 992M Total, 377M MFU, 589M MRU, 250K Anon, 5280K Header, 21M Other
	Swap: 2048M Total, 2048M Free

	PID USERNAME THR PRI NICE SIZE RES STATE C TIME WCPU COMMAND
	557 root 1 -21 r31 136M 42296K select 0 2:20 9.96% Xorg
	8198 dru 2 52 0 449M 82736K select 3 0:08 5.96% kdeinit4
	8311 dru 27 30 0 1150M 187M uwait 1 1:37 0.98% firefox
	431 root 1 20 0 14268K 1728K select 0 0:06 0.98% moused
	9551 dru 1 21 0 16600K 2660K CPU3 3 0:01 0.98% top
	2357 dru 4 37 0 718M 141M select 0 0:21 0.00% kdeinit4
	8705 dru 4 35 0 480M 98M select 2 0:20 0.00% kdeinit4
	8076 dru 6 20 0 552M 113M uwait 0 0:12 0.00% soffice.bin
	2623 root 1 30 10 12088K 1636K select 3 0:09 0.00% powerd
	2338 dru 1 20 0 440M 84532K select 1 0:06 0.00% kwin
	1427 dru 5 22 0 605M 86412K select 1 0:05 0.00% kdeinit4</screen>

	<para>The output is split into two sections. The header (the
	first five or six lines) shows the <acronym>PID</acronym> of
	the last process to run, the system load averages (which are a
	measure of how busy the system is), the system uptime (time
	since the last reboot) and the current time. The other
	figures in the header relate to how many processes are
	running, how much memory and swap space has been used, and how
	much time the system is spending in different CPU states. If
	the system has been formatted with the <acronym>ZFS</acronym>
	file system, the <literal>ARC</literal> line provides an
	indication of how much data was read from the memory cache
	instead of from disk.</para>

	<para>Below the header is a series of columns containing similar
	information to the output from &man.ps.1;, such as the
	<acronym>PID</acronym>, username, amount of CPU time, and the
	command that started the process. By default, &man.top.1;
	also displays the amount of memory space taken by the process.
	This is split into two columns: one for total size and one for
	resident size. Total size is how much memory the application
	has needed and the resident size is how much it is actually
	using now.</para>

	<para>&man.top.1; automatically updates the display every two
	seconds. A different interval can be specified with
	<option>-s</option>.</para>
	</sect2>

	<sect2 xml:id="basics-daemons">
	<title>Killing Processes</title>

	<para>One way to communicate with any running process or daemon
	is to send a <firstterm>signal</firstterm> using &man.kill.1;.
	There are a number of different signals; some have a specific
	meaning while others are described in the application's
	documentation. A user can only send a signal to a process
	they own and sending a signal to someone else's process will
	result in a permission denied error. The exception is the
	- <systemitem class="username">root</systemitem> user, who can send signals to
	- anyone's processes.</para>
	+ <systemitem class="username">root</systemitem> user, who can
	+ send signals to anyone's processes.</para>

	<para>The operating system can also send a signal to a process.
	If an application is badly written and tries to access memory
	that it is not supposed to, &os; will send the process the
	<quote>Segmentation Violation</quote> signal
	(<literal>SIGSEGV</literal>). If an application has been
	written to use the &man.alarm.3; system call to be alerted
	after a period of time has elapsed, it will be sent the
	<quote>Alarm</quote> signal
	(<literal>SIGALRM</literal>).</para>

	<para>Two signals can be used to stop a process:
	<literal>SIGTERM</literal> and <literal>SIGKILL</literal>.
	<literal>SIGTERM</literal> is the polite way to kill a process
	as the process can read the signal, close any log files it may
	have open, and attempt to finish what it is doing before
	shutting down. In some cases, a process may ignore
	<literal>SIGTERM</literal> if it is in the middle of some task
	that can not be interrupted.</para>

	<para><literal>SIGKILL</literal> can not be ignored by a
	process. Sending a <literal>SIGKILL</literal> to a
	process will usually stop that process there and then.
	- <footnote>
	- <para>There are a few tasks that can not be interrupted. For
	- example, if the process is trying to read from a file that
	- is on another computer on the network, and the other
	- computer is unavailable, the process is said to be
	- <quote>uninterruptible</quote>. Eventually the process will
	- time out, typically after two minutes. As soon as this time
	- out occurs the process will be killed.</para>
	- </footnote>.</para>
	+ <footnote><para>There are a few tasks that can not be
	+ interrupted. For example, if the process is trying to
	+ read from a file that is on another computer on the
	+ network, and the other computer is unavailable, the
	+ process is said to be <quote>uninterruptible</quote>.
	+ Eventually the process will time out, typically after two
	+ minutes. As soon as this time out occurs the process will
	+ be killed.</para></footnote>.</para>

	<para>Other commonly used signals are <literal>SIGHUP</literal>,
	<literal>SIGUSR1</literal>, and <literal>SIGUSR2</literal>.
	Since these are general purpose signals, different
	applications will respond differently.</para>

	<para>For example, after changing a web server's configuration
	file, the web server needs to be told to re-read its
	configuration. Restarting <command>httpd</command> would
	result in a brief outage period on the web server. Instead,
	send the daemon the <literal>SIGHUP</literal> signal. Be
	aware that different daemons will have different behavior, so
	refer to the documentation for the daemon to determine if
	<literal>SIGHUP</literal> will achieve the desired
	results.</para>

	<procedure>
	<title>Sending a Signal to a Process</title>

	<para>This example shows how to send a signal to
	&man.inetd.8;. The &man.inetd.8; configuration file is
	<filename>/etc/inetd.conf</filename>, and &man.inetd.8; will
	re-read this configuration file when it is sent a
	<literal>SIGHUP</literal>.</para>

	<step>
	<para>Find the <acronym>PID</acronym> of the process to send
	the signal to using &man.pgrep.1;. In this example, the
	<acronym>PID</acronym> for &man.inetd.8; is 198:</para>

	<screen>&prompt.user; <userinput>pgrep -l inetd</userinput>
	198 inetd -wW</screen>

	</step>

	<step>
	<para>Use &man.kill.1; to send the signal. Because
	- &man.inetd.8; is owned by <systemitem class="username">root</systemitem>, use
	- &man.su.1; to become <systemitem class="username">root</systemitem>
	+ &man.inetd.8; is owned by
	+ <systemitem class="username">root</systemitem>, use
	+ &man.su.1; to become
	+ <systemitem class="username">root</systemitem>
	first.</para>

	<screen>&prompt.user; <userinput>su</userinput>
	<prompt>Password:</prompt>
	&prompt.root; <userinput>/bin/kill -s HUP 198</userinput></screen>

	<para>Like most &unix; commands, &man.kill.1; will not print
	any output if it is successful. If a signal is sent to a
	process not owned by that user, the message
	<errorname>kill: <replaceable>PID</replaceable>: Operation
	not permitted</errorname> will be displayed. Mistyping
	the <acronym>PID</acronym> will either send the signal to
	the wrong process, which could have negative results, or
	will send the signal to a <acronym>PID</acronym> that is
	not currently in use, resulting in the error
	<errorname>kill: <replaceable>PID</replaceable>: No such
	process</errorname>.</para>

	<note>
	<title>Why Use <command>/bin/kill</command>?</title>

	<para>Many shells provide <command>kill</command> as a
	built in command, meaning that the shell will send the
	signal directly, rather than running
	<filename>/bin/kill</filename>. Be aware that different
	shells have a different syntax for specifying the name
	of the signal to send. Rather than try to learn all of
	them, it can be simpler to specify
	<command>/bin/kill</command>.</para>
	</note>
	</step>
	</procedure>

	<para>When sending other signals, substitute
	<literal>TERM</literal> or <literal>KILL</literal> with the
	name of the signal.</para>

	<important>
	<para>Killing a random process on the system is a bad idea.
	In particular, &man.init.8;, <acronym>PID</acronym> 1, is
	special. Running <command>/bin/kill -s KILL 1</command> is
	a quick, and unrecommended, way to shutdown the system.
	<emphasis>Always</emphasis> double check the arguments to
	&man.kill.1; <emphasis>before</emphasis> pressing
	<keycap>Return</keycap>.</para>
	</important>
	</sect2>
	</sect1>

	<sect1 xml:id="shells">
	<title>Shells</title>

	- <indexterm><primary>shells</primary></indexterm>
	- <indexterm><primary>command line</primary></indexterm>
	+ <indexterm>
	+ <primary>shells</primary>
	+ </indexterm>
	+ <indexterm>
	+ <primary>command line</primary>
	+ </indexterm>

	<para>A <firstterm>shell</firstterm> provides a command line
	interface for interacting with the operating system. A shell
	receives commands from the input channel and executes them.
	Many shells provide built in functions to help with everyday
	tasks such as file management, file globbing, command line
	editing, command macros, and environment variables. &os; comes
	with several shells, including the Bourne shell (&man.sh.1;) and
	the extended C shell (&man.tcsh.1;). Other shells are available
	from the &os; Ports Collection, such as
	<command>zsh</command> and <command>bash</command>.</para>

	<para>The shell that is used is really a matter of taste. A C
	programmer might feel more comfortable with a C-like shell such
	as &man.tcsh.1;. A &linux; user might prefer
	<command>bash</command>. Each shell has unique properties that
	may or may not work with a user's preferred working environment,
	which is why there is a choice of which shell to use.</para>

	<para>One common shell feature is filename completion. After a
	user types the first few letters of a command or filename and
	- presses <keycap>Tab</keycap>, the shell completes
	- the rest of the command or filename. Consider two files called
	+ presses <keycap>Tab</keycap>, the shell completes the rest of
	+ the command or filename. Consider two files called
	<filename>foobar</filename> and <filename>football</filename>.
	- To delete <filename>foobar</filename>, the user might type <command>rm
	- foo</command> and press <keycap>Tab</keycap> to complete the filename.</para>
	-
	- <para>But the shell only shows
	- <command>rm foo</command>.
	- It was unable to complete the filename because
	- both <filename>foobar</filename> and
	- <filename>football</filename> start with <literal>foo</literal>.
	- Some shells sound a beep or show all the choices if more than one name matches.
	- The user must then type more characters to identify the desired filename. Typing a <literal>t</literal> and pressing
	- <keycap>Tab</keycap> again is enough to let the shell determine which filename is desired and fill in the
	- rest.</para>
	+ To delete <filename>foobar</filename>, the user might type
	+ <command>rm foo</command> and press <keycap>Tab</keycap> to
	+ complete the filename.</para>
	+
	+ <para>But the shell only shows <command>rm foo</command>. It was
	+ unable to complete the filename because both
	+ <filename>foobar</filename> and <filename>football</filename>
	+ start with <literal>foo</literal>. Some shells sound a beep or
	+ show all the choices if more than one name matches. The user
	+ must then type more characters to identify the desired filename.
	+ Typing a <literal>t</literal> and pressing <keycap>Tab</keycap>
	+ again is enough to let the shell determine which filename is
	+ desired and fill in the rest.</para>

	- <indexterm><primary>environment variables</primary></indexterm>
	+ <indexterm>
	+ <primary>environment variables</primary>
	+ </indexterm>

	<para>Another feature of the shell is the use of environment
	variables. Environment variables are a variable/key pair stored
	in the shell's environment. This environment can be read by any
	program invoked by the shell, and thus contains a lot of program
	- configuration. <xref linkend="shell-env-vars"/> provides a list of common environment
	- variables and their meanings. Note that the names of
	- environment variables are always in uppercase.</para>
	+ configuration. <xref linkend="shell-env-vars"/> provides a list
	+ of common environment variables and their meanings. Note that
	+ the names of environment variables are always in
	+ uppercase.</para>

	<table xml:id="shell-env-vars" frame="none" pgwide="1">
	<title>Common Environment Variables</title>

	<tgroup cols="2">
	<thead>
	<row>
	<entry>Variable</entry>
	<entry>Description</entry>
	</row>
	</thead>

	<tbody>
	<row>
	<entry><envar>USER</envar></entry>
	<entry>Current logged in user's name.</entry>
	</row>

	<row>
	<entry><envar>PATH</envar></entry>
	<entry>Colon-separated list of directories to search for
	binaries.</entry>
	</row>

	<row>
	<entry><envar>DISPLAY</envar></entry>
	<entry>Network name of the
	<application>&xorg;</application>
	display to connect to, if available.</entry>
	</row>

	<row>
	<entry><envar>SHELL</envar></entry>
	<entry>The current shell.</entry>
	</row>

	<row>
	<entry><envar>TERM</envar></entry>

	<entry>The name of the user's type of terminal. Used to
	determine the capabilities of the terminal.</entry>
	</row>

	<row>
	<entry><envar>TERMCAP</envar></entry>

	<entry>Database entry of the terminal escape codes to
	perform various terminal functions.</entry>
	</row>

	<row>
	<entry><envar>OSTYPE</envar></entry>
	<entry>Type of operating system.</entry>
	</row>

	<row>
	<entry><envar>MACHTYPE</envar></entry>
	<entry>The system's CPU architecture.</entry>
	</row>

	<row>
	<entry><envar>EDITOR</envar></entry>
	<entry>The user's preferred text editor.</entry>
	</row>

	<row>
	<entry><envar>PAGER</envar></entry>
	<entry>The user's preferred utility for viewing text one
	page at a time.</entry>
	</row>

	<row>
	<entry><envar>MANPATH</envar></entry>
	<entry>Colon-separated list of directories to search for
	manual pages.</entry>
	</row>
	</tbody>
	</tgroup>
	</table>

	- <indexterm><primary>Bourne shells</primary></indexterm>
	+ <indexterm>
	+ <primary>Bourne shells</primary>
	+ </indexterm>

	<para>How to set an environment variable differs between shells.
	In &man.tcsh.1; and &man.csh.1;, use
	<command>setenv</command> to set environment variables. In
	&man.sh.1; and <command>bash</command>, use
	<command>export</command> to set the current environment
	variables. This example sets the default <envar>EDITOR</envar>
	to <filename>/usr/local/bin/emacs</filename> for the
	&man.tcsh.1; shell:</para>

	<screen>&prompt.user; <userinput>setenv EDITOR /usr/local/bin/emacs</userinput></screen>

	<para>The equivalent command for <command>bash</command>
	would be:</para>

	<screen>&prompt.user; <userinput>export EDITOR="/usr/local/bin/emacs"</userinput></screen>

	<para>To expand an environment variable in order to see its
	current setting, type a <literal>$</literal> character in front
	of its name on the command line. For example,
	<command>echo $TERM</command> displays the current
	<envar>$TERM</envar> setting.</para>

	<para>Shells treat special characters, known as meta-characters,
	as special representations of data. The most common
	meta-character is <literal>*</literal>, which represents any
	number of characters in a filename. Meta-characters can be used
	to perform filename globbing. For example, <command>echo
	*</command> is equivalent to <command>ls</command> because
	the shell takes all the files that match <literal>*</literal>
	and <command>echo</command> lists them on the command
	line.</para>

	<para>To prevent the shell from interpreting a special character,
	escape it from the shell by starting it with a backslash
	(<literal>\</literal>). For example, <command>echo
	$TERM</command> prints the terminal setting whereas
	<command>echo \$TERM</command> literally prints the string
	<literal>$TERM</literal>.</para>

	<sect2 xml:id="changing-shells">
	<title>Changing the Shell</title>

	<para>The easiest way to permanently change the default shell is
	to use <command>chsh</command>. Running this command will
	open the editor that is configured in the
	<envar>EDITOR</envar> environment variable, which by default
	is set to &man.vi.1;. Change the <literal>Shell:</literal>
	line to the full path of the new shell.</para>

	<para>Alternately, use <command>chsh -s</command> which will set
	the specified shell without opening an editor. For example,
	to change the shell to <command>bash</command>:</para>

	<screen>&prompt.user; <userinput>chsh -s /usr/local/bin/bash</userinput></screen>

	<note>
	<para>The new shell <emphasis>must</emphasis> be present in
	<filename>/etc/shells</filename>. If the shell was
	installed from the &os; Ports Collection as described in
	<xref linkend="ports"/>, it should be automatically added
	to this file. If it is missing, add it using this command,
	replacing the path with the path of the shell:</para>

	<screen>&prompt.root; <userinput>echo /usr/local/bin/bash >> /etc/shells</userinput></screen>

	<para>Then, rerun &man.chsh.1;.</para>
	</note>
	</sect2>
	</sect1>

	<sect1 xml:id="editors">
	<title>Text Editors</title>

	- <indexterm><primary>text editors</primary></indexterm>
	- <indexterm><primary>editors</primary></indexterm>
	+ <indexterm>
	+ <primary>text editors</primary>
	+ </indexterm>
	+ <indexterm>
	+ <primary>editors</primary>
	+ </indexterm>

	<para>Most &os; configuration is done by editing text files.
	Because of this, it is a good idea to become familiar with a
	text editor. &os; comes with a few as part of the base system,
	and many more are available in the Ports Collection.</para>

	<indexterm>
	<primary><command>ee</command></primary>
	</indexterm>
	<indexterm>
	<primary>editors</primary>
	<secondary>&man.ee.1;</secondary>
	</indexterm>

	<para>A simple editor to learn is &man.ee.1;, which stands for
	easy editor. To start this editor, type <command>ee
	filename</command> where
	<replaceable>filename</replaceable> is the name of the file to
	be edited. Once inside the editor, all of the commands for
	manipulating the editor's functions are listed at the top of the
	display. The caret (<literal>^</literal>) represents
	<keycap>Ctrl</keycap>, so <literal>^e</literal> expands to
	- <keycombo action="simul"><keycap>Ctrl</keycap><keycap>e</keycap></keycombo>.
	- To leave &man.ee.1;, press <keycap>Esc</keycap>, then choose the
	- <quote>leave editor</quote> option from the main menu. The
	- editor will prompt to save any changes if the file has been
	- modified.</para>
	+ <keycombo action="simul">
	+ <keycap>Ctrl</keycap>
	+ <keycap>e</keycap>
	+ </keycombo>. To leave &man.ee.1;, press <keycap>Esc</keycap>,
	+ then choose the <quote>leave editor</quote> option from the main
	+ menu. The editor will prompt to save any changes if the file
	+ has been modified.</para>

	<indexterm>
	<primary><command>vi</command></primary>
	</indexterm>
	<indexterm>
	<primary>editors</primary>
	</indexterm>
	<indexterm>
	<primary><command>emacs</command></primary>
	</indexterm>

	<para>&os; also comes with more powerful text editors, such as
	&man.vi.1;, as part of the base system. Other editors, like
	<package>editors/emacs</package> and
	<package>editors/vim</package>, are part of the
	&os; Ports Collection. These editors offer more functionality
	at the expense of being more complicated to learn. Learning a
	more powerful editor such as <application>vim</application> or
	<application>Emacs</application> can save more time in the long
	run.</para>

	<para>Many applications which modify files or require typed input
	will automatically open a text editor. To change the default
	editor, set the <envar>EDITOR</envar> environment
	variable as described in <xref linkend="shells"/>.</para>
	</sect1>

	<sect1 xml:id="basics-devices">
	<title>Devices and Device Nodes</title>

	<para>A device is a term used mostly for hardware-related
	activities in a system, including disks, printers, graphics
	cards, and keyboards. When &os; boots, the majority of the boot
	messages refer to devices being detected. A copy of the boot
	messages are saved to
	<filename>/var/run/dmesg.boot</filename>.</para>

	<para>Each device has a device name and number. For example,
	<filename>acd0</filename> is the first IDE CD-ROM drive,
	while <filename>kbd0</filename> represents the
	keyboard.</para>

	<para>Most devices in a &os; must be accessed through special
	files called device nodes, which are located in
	<filename>/dev</filename>.</para>
	</sect1>

	<sect1 xml:id="basics-more-information">
	<title>Manual Pages</title>

	- <indexterm><primary>manual pages</primary></indexterm>
	+ <indexterm>
	+ <primary>manual pages</primary>
	+ </indexterm>

	<para>The most comprehensive documentation on &os; is in the form
	of manual pages. Nearly every program on the system comes with
	a short reference manual explaining the basic operation and
	available arguments. These manuals can be viewed using
	<command>man</command>:</para>

	<screen>&prompt.user; <userinput>man command</userinput></screen>

	<para>where <replaceable>command</replaceable> is the name of the
	command to learn about. For example, to learn more about
	&man.ls.1;, type:</para>

	<screen>&prompt.user; <userinput>man ls</userinput></screen>

	<para>Manual pages are divided into sections which represent the
	type of topic. In &os;, the following sections are
	available:</para>

	<orderedlist>
	<listitem>
	<para>User commands.</para>
	</listitem>

	<listitem>
	<para>System calls and error numbers.</para>
	</listitem>

	<listitem>
	<para>Functions in the C libraries.</para>
	</listitem>

	<listitem>
	<para>Device drivers.</para>
	</listitem>

	<listitem>
	<para>File formats.</para>
	</listitem>

	<listitem>
	<para>Games and other diversions.</para>
	</listitem>

	<listitem>
	<para>Miscellaneous information.</para>
	</listitem>

	<listitem>
	<para>System maintenance and operation commands.</para>
	</listitem>

	<listitem>
	<para>System kernel interfaces.</para>
	</listitem>
	</orderedlist>

	<para>In some cases, the same topic may appear in more than one
	section of the online manual. For example, there is a
	<command>chmod</command> user command and a
	<function>chmod()</function> system call. To tell &man.man.1;
	which section to display, specify the section number:</para>

	<screen>&prompt.user; <userinput>man 1 chmod</userinput></screen>

	<para>This will display the manual page for the user command
	&man.chmod.1;. References to a particular section of the
	online manual are traditionally placed in parenthesis in
	written documentation, so &man.chmod.1; refers to the user
	command and &man.chmod.2; refers to the system call.</para>

	<para>If the name of the manual page is unknown, use <command>man
	-k</command> to search for keywords in the manual page
	descriptions:</para>

	<screen>&prompt.user; <userinput>man -k mail</userinput></screen>

	<para>This command displays a list of commands that have the
	keyword <quote>mail</quote> in their descriptions. This is
	equivalent to using &man.apropos.1;.</para>

	- <para>To read the descriptions for the commands in <filename>/usr/bin</filename>, type:</para>
	+ <para>To read the descriptions for the commands in
	+ <filename>/usr/bin</filename>, type:</para>

	<screen>&prompt.user; <userinput>cd /usr/bin</userinput>
	&prompt.user; <userinput>man -f * \| more</userinput></screen>

	<para>or</para>

	<screen>&prompt.user; <userinput>cd /usr/bin</userinput>
	&prompt.user; <userinput>whatis * \|more</userinput></screen>

	<sect2 xml:id="basics-info">
	<title>GNU Info Files</title>

	<indexterm>
	<primary>Free Software Foundation</primary>
	</indexterm>

	<para>&os; includes many applications and utilities produced by
	the Free Software Foundation (FSF). In addition to manual
	pages, these programs may include hypertext documents called
	<literal>info</literal> files. These can be viewed using
	- &man.info.1; or, if <package>editors/emacs</package> is installed, the
	- info mode of <application>emacs</application>.</para>
	+ &man.info.1; or, if <package>editors/emacs</package> is
	+ installed, the info mode of
	+ <application>emacs</application>.</para>

	<para>To use &man.info.1;, type:</para>

	<screen>&prompt.user; <userinput>info</userinput></screen>

	<para>For a brief introduction, type <literal>h</literal>. For
	a quick command reference, type <literal>?</literal>.</para>
	</sect2>
	</sect1>
	</chapter>

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