b63d83cc04
Also, mention the compatibility between shells with regards to scripts. Two other xml tag inconsistencies were fixed. PR: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=193892 Differential Revision: https://reviews.freebsd.org/D2834 Submitted by: kpaasial icloud com Patch by: Anthony Perkins (plus a minor change based on the review) Reviewed by: allanjude
508 lines
20 KiB
XML
508 lines
20 KiB
XML
<?xml version="1.0" encoding="iso-8859-1"?>
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<!DOCTYPE article PUBLIC "-//FreeBSD//DTD DocBook XML V5.0-Based Extension//EN"
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"http://www.FreeBSD.org/XML/share/xml/freebsd50.dtd">
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<article xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" version="5.0" xml:lang="en">
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<info>
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<title>FreeBSD Quickstart Guide for &linux; Users</title>
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<authorgroup>
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<author><personname><firstname>John</firstname><surname>Ferrell</surname></personname></author>
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</authorgroup>
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<copyright>
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<year>2008</year>
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<holder>The FreeBSD Documentation Project</holder>
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</copyright>
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<pubdate>$FreeBSD$</pubdate>
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<releaseinfo>$FreeBSD$</releaseinfo>
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<legalnotice xml:id="trademarks" role="trademarks">
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&tm-attrib.freebsd;
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&tm-attrib.linux;
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&tm-attrib.intel;
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&tm-attrib.redhat;
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&tm-attrib.unix;
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&tm-attrib.general;
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</legalnotice>
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<abstract>
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<para>This document is intended to quickly familiarize
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intermediate to advanced &linux; users with the basics of
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&os;.</para>
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</abstract>
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</info>
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<sect1 xml:id="intro">
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<title>Introduction</title>
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<para>This document highlights some of the technical differences
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between &os; and &linux; so that intermediate to advanced
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&linux; users can quickly familiarize themselves with the basics
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of &os;.</para>
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<para>This document assumes that &os; is already installed. Refer
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to the <link
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xlink:href="&url.base;/doc/en_US.ISO8859-1/books/handbook/bsdinstall.html">
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Installing &os;</link> chapter of the &os; Handbook for
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help with the installation process.</para>
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</sect1>
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<sect1 xml:id="shells">
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<title>Default Shell</title>
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<para>&linux; users are often surprised to find that
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<application>Bash</application> is not the default shell in
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&os;. In fact, <application>Bash</application> is not included
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in the default installation. Instead, &os; uses &man.tcsh.1;
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as the default root shell, and the <application>Bourne
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shell</application>-compatible &man.sh.1; as the default user
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shell. &man.sh.1; is very similar to <application>Bash</application>
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but with a much smaller feature-set. Generally shell scripts
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written for &man.sh.1; will run in <application>Bash</application>,
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but the reverse is not always true.</para>
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<para>However, <application>Bash</application> and other shells
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are available for installation using the &os; <link
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xlink:href="&url.base;/doc/en_US.ISO8859-1/books/handbook/ports.html">Packages
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and Ports Collection</link>.</para>
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<para>After installing another shell, use &man.chsh.1; to change
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a user's default shell. It is recommended that the
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<systemitem class="username">root</systemitem> user's default
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shell remain unchanged since shells which are not included in
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the base distribution are installed to
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<filename>/usr/local/bin</filename>. In the event of a problem,
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the file system where <filename>/usr/local/bin</filename> is
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located may not be mounted. In this case, <systemitem
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class="username">root</systemitem> would not have access to
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its default shell, preventing <systemitem
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class="username">root</systemitem> from logging in and fixing
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the problem.</para>
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</sect1>
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<sect1 xml:id="software">
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<title>Packages and Ports: Adding Software in &os;</title>
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<para>&os; provides two methods for installing applications:
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binary packages and compiled ports. Each method has its own
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benefits:</para>
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<itemizedlist>
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<title>Binary Packages</title>
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<listitem>
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<simpara>Faster installation as compared to
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compiling large applications.</simpara>
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</listitem>
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<listitem>
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<simpara>Does not require an understanding of how to
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compile software.</simpara>
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</listitem>
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<listitem>
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<simpara>No need to install a compiler.</simpara>
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</listitem>
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</itemizedlist>
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<itemizedlist>
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<title>Ports</title>
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<listitem>
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<simpara>Ability to customize installation options.</simpara>
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</listitem>
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<listitem>
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<simpara>Custom patches can be applied.</simpara>
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</listitem>
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</itemizedlist>
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<para>If an application installation does not require any
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customization, installing the package is sufficient. Compile
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the port instead whenever an application requires customization
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of the default options. If needed, a custom package can be
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compiled from ports using <command>make</command>
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<buildtarget>package</buildtarget>.</para>
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<para>A complete list of all available ports and packages can
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be found <link
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xlink:href="http://www.freebsd.org/ports/master-index.html">here</link>.</para>
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<sect2 xml:id="packages">
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<title>Packages</title>
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<para>Packages are pre-compiled applications, the &os;
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equivalents of <filename>.deb</filename> files on
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Debian/Ubuntu based systems and <filename>.rpm</filename>
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files on Red Hat/Fedora based systems. Packages are
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installed using <command>pkg</command>. For example,
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the following command installs
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<application>Apache 2.4</application>:</para>
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<screen>&prompt.root; <userinput>pkg install <replaceable>apache24</replaceable></userinput></screen>
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<para>For more information on packages refer to section 5.4 of
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the &os; Handbook: <link
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xlink:href="&url.base;/doc/en_US.ISO8859-1/books/handbook/pkgng-intro.html">Using
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pkgng for Binary Package Management</link>.</para>
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</sect2>
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<sect2 xml:id="ports">
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<title>Ports</title>
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<para>The &os; Ports Collection is a framework of
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<filename>Makefiles</filename> and patches specifically
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customized for installing applications from source on &os;.
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When installing a port, the system will fetch the source code,
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apply any required patches, compile the code, and install the
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application and any required dependencies.</para>
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<para>The Ports Collection, sometimes referred to as the ports
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tree, can be installed to <filename>/usr/ports</filename>
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using &man.portsnap.8;. Detailed instructions for installing
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the Ports Collection can be found in <link
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xlink:href="&url.base;/doc/en_US.ISO8859-1/books/handbook/ports-using.html">section
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5.5</link> of the &os; Handbook.</para>
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<para>To compile a port, change to the port's directory and
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start the build process. The following example installs
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<application>Apache 2.4</application> from the Ports
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Collection:</para>
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<screen>&prompt.root; <userinput>cd /usr/ports/www/apache24</userinput>
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&prompt.root; <userinput>make install clean</userinput></screen>
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<para>A benefit of using ports to install software is the
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ability to customize the installation options. This example
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specifies that the <application>mod_ldap</application> module
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should also be installed:</para>
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<screen>&prompt.root; <userinput>cd /usr/ports/www/apache24</userinput>
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&prompt.root; <userinput>make WITH_LDAP="YES" install clean</userinput></screen>
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<para>Refer to <link
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xlink:href="&url.base;/doc/en_US.ISO8859-1/books/handbook/ports-using.html">Using
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the Ports Collection</link> for more information.</para>
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</sect2>
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</sect1>
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<sect1 xml:id="startup">
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<title>System Startup</title>
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<para>Many &linux; distributions use the SysV init system, whereas
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&os; uses the traditional BSD-style &man.init.8;. Under the
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BSD-style &man.init.8;, there are no run-levels and
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<filename>/etc/inittab</filename> does not exist. Instead,
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startup is controlled by &man.rc.8; scripts. At system boot,
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<filename>/etc/rc</filename> reads
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<filename>/etc/rc.conf</filename> and
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<filename>/etc/defaults/rc.conf</filename>
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to determine which services are to be started. The specified
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services are then started by running the corresponding service
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initialization scripts located in
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<filename>/etc/rc.d/</filename> and
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<filename>/usr/local/etc/rc.d/</filename>. These scripts are
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similar to the scripts located in
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<filename>/etc/init.d/</filename> on &linux; systems.</para>
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<para>The scripts found in <filename>/etc/rc.d/</filename> are for
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applications that are part of the <quote>base</quote> system,
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such as &man.cron.8;, &man.sshd.8;, and &man.syslog.3;. The
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scripts in <filename>/usr/local/etc/rc.d/</filename> are for
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user-installed applications such as
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<application>Apache</application> and
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<application>Squid</application>.</para>
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<para>Since &os; is developed as a complete operating system,
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user-installed applications are not considered to be part of
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the <quote>base</quote> system. User-installed applications
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are generally installed using <link
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xlink:href="&url.base;/doc/en_US.ISO8859-1/books/handbook/ports-using.html">Packages
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or Ports</link>. In order to keep them separate from the base
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system, user-installed applications are installed under
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<filename>/usr/local/</filename>. Therefore, user-installed
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binaries reside in <filename>/usr/local/bin/</filename>,
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configuration files are in <filename>/usr/local/etc/</filename>,
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and so on.</para>
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<para>Services are enabled by adding an entry for the service in
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<filename>/etc/rc.conf</filename> . The system defaults are
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found in <filename>/etc/defaults/rc.conf</filename> and these
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default settings are overridden by settings in
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<filename>/etc/rc.conf</filename>. Refer to &man.rc.conf.5; for
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more information about the available entries. When installing
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additional applications, review the application's install
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message to determine how to enable any associated
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services.</para>
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<para>The following entries in <filename>/etc/rc.conf</filename>
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enable &man.sshd.8;, enable <application>Apache
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2.4</application>, and specify that
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<application>Apache</application> should be started with
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<acronym>SSL</acronym>.</para>
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<programlisting># enable SSHD
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sshd_enable="YES"
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# enable Apache with SSL
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apache24_enable="YES"
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apache24_flags="-DSSL"</programlisting>
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<para>Once a service has been enabled in
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<filename>/etc/rc.conf</filename>, it can be started without
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rebooting the system:</para>
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<screen>&prompt.root; <userinput>service <replaceable>sshd</replaceable> start</userinput>
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&prompt.root; <userinput>service <replaceable>apache24</replaceable> start</userinput></screen>
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<para>If a service has not been enabled, it can be started from
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the command line using <option>onestart</option>:</para>
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<screen>&prompt.root; <userinput>service <replaceable>sshd</replaceable> onestart</userinput></screen>
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</sect1>
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<sect1 xml:id="network">
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<title>Network Configuration</title>
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<para>Instead of a generic <emphasis>ethX</emphasis> identifier
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that &linux; uses to identify a network interface, &os; uses the
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driver name followed by a number. The following output from
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&man.ifconfig.8; shows two &intel; Pro 1000 network
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interfaces (<filename>em0</filename> and
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<filename>em1</filename>):</para>
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<screen>&prompt.user; <userinput>ifconfig</userinput>
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em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
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options=b<RXCSUM,TXCSUM,VLAN_MTU>
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inet 10.10.10.100 netmask 0xffffff00 broadcast 10.10.10.255
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ether 00:50:56:a7:70:b2
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media: Ethernet autoselect (1000baseTX <full-duplex>)
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status: active
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em1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
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options=b<RXCSUM,TXCSUM,VLAN_MTU>
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inet 192.168.10.222 netmask 0xffffff00 broadcast 192.168.10.255
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ether 00:50:56:a7:03:2b
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media: Ethernet autoselect (1000baseTX <full-duplex>)
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status: active</screen>
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<para>An <acronym>IP</acronym> address can be assigned to an
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interface using &man.ifconfig.8;. To remain persistent across
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reboots, the <acronym>IP</acronym> configuration must be
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included in <filename>/etc/rc.conf</filename>. The following
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<filename>/etc/rc.conf</filename> entries specify the hostname,
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<acronym>IP</acronym> address, and default gateway:</para>
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<programlisting>hostname="server1.example.com"
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ifconfig_em0="inet 10.10.10.100 netmask 255.255.255.0"
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defaultrouter="10.10.10.1"</programlisting>
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<para>Use the following entries to instead configure an interface
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for <acronym>DHCP</acronym>:</para>
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<programlisting>hostname="server1.example.com"
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ifconfig_em0="DHCP"</programlisting>
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</sect1>
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<sect1 xml:id="firewall">
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<title>Firewall</title>
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<para>&os; does not use &linux;
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<application>IPTABLES</application> for its firewall. Instead,
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&os; offers a choice of three kernel level firewalls:</para>
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<itemizedlist>
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<listitem>
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<simpara><link
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xlink:href="&url.base;/doc/en_US.ISO8859-1/books/handbook/firewalls-pf.html">PF</link></simpara>
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</listitem>
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<listitem>
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<simpara><link
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xlink:href="&url.base;/doc/en_US.ISO8859-1/books/handbook/firewalls-ipf.html">IPFILTER</link></simpara>
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</listitem>
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<listitem>
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<simpara><link
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xlink:href="&url.base;/doc/en_US.ISO8859-1/books/handbook/firewalls-ipfw.html">IPFW</link></simpara>
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</listitem>
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</itemizedlist>
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<para><application>PF</application> is developed by the OpenBSD
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project and ported to &os;. <application>PF</application> was
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created as a replacement for <application>IPFILTER</application>
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and its syntax is similar to that of
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<application>IPFILTER</application>.
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<application>PF</application> can be paired with &man.altq.4; to
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provide <acronym>QoS</acronym> features.</para>
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<para>This sample <application>PF</application> entry allows
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inbound <application>SSH</application>:</para>
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<programlisting>pass in on $ext_if inet proto tcp from any to ($ext_if) port 22</programlisting>
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<para><application>IPFILTER</application> is the firewall
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application developed by Darren Reed. It is not specific to
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&os; and has been ported to several operating systems including
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NetBSD, OpenBSD, SunOS, HP/UX, and Solaris.</para>
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<para>The <application>IPFILTER</application> syntax to allow
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inbound <application>SSH</application> is:</para>
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<programlisting>pass in on $ext_if proto tcp from any to any port = 22</programlisting>
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<para><application>IPFW</application> is the firewall developed
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and maintained by &os;. It can be paired with &man.dummynet.4;
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to provide traffic shaping capabilities and simulate different
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types of network connections.</para>
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<para>The <application>IPFW</application> syntax to allow inbound
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<application>SSH</application> would be:</para>
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<programlisting>ipfw add allow tcp from any to me 22 in via $ext_if</programlisting>
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</sect1>
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<sect1 xml:id="updates">
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<title>Updating &os;</title>
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<para>There are two methods for updating a &os; system: from
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source or binary updates.</para>
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<para>Updating from source is the most involved update method, but
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offers the greatest amount of flexibility. The process involves
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synchronizing a local copy of the &os; source code with the &os;
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<application>Subversion</application> servers. Once the local
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source code is up-to-date, a new version of the kernel and
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userland can be compiled.</para>
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<para>Binary updates are similar to using <command>yum</command>
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or <command>apt-get</command> to update a &linux; system. In
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&os;, &man.freebsd-update.8; can be used fetch new binary
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updates and install them. These updates can be scheduled using
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&man.cron.8;.</para>
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<note>
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<para>When using &man.cron.8; to schedule updates, use
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<command>freebsd-update cron</command> in the &man.crontab.1;
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to reduce the possibility of a large number of machines all
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pulling updates at the same time:</para>
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<programlisting>0 3 * * * root /usr/sbin/freebsd-update cron</programlisting>
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</note>
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<para>For more information on source and binary updates, refer to
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<link
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xlink:href="&url.base;/doc/en_US.ISO8859-1/books/handbook/updating-upgrading.html">the
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chapter on updating</link> in the &os; Handbook.</para>
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</sect1>
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|
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<sect1 xml:id="procfs">
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<title>procfs: Gone But Not Forgotten</title>
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<para>In some &linux; distributions, one could look at
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<filename>/proc/sys/net/ipv4/ip_forward</filename> to determine
|
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if <acronym>IP</acronym> forwarding is enabled. In &os;,
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&man.sysctl.8; is instead used to view this and other system
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settings.</para>
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<para>For example, use the following to determine if
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<acronym>IP</acronym> forwarding is enabled on a &os;
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system:</para>
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<screen>&prompt.user; <userinput>sysctl net.inet.ip.forwarding</userinput>
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net.inet.ip.forwarding: 0</screen>
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<para>Use <option>-a</option> to list all the system
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settings:</para>
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<screen>&prompt.user; <userinput>sysctl -a | more</userinput></screen>
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<para>If an application requires procfs, add the following entry
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to <filename>/etc/fstab</filename>:</para>
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<screen>proc /proc procfs rw,noauto 0 0</screen>
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<para>Including <option>noauto</option> will prevent
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<filename>/proc</filename> from being automatically mounted at
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boot.</para>
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<para>To mount the file system without rebooting:</para>
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<screen>&prompt.root; <userinput>mount /proc</userinput></screen>
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</sect1>
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<sect1 xml:id="commands">
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<title>Common Commands</title>
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<para>Some common command equivalents are as follows:</para>
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<para>
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<informaltable frame="none" pgwide="1">
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<tgroup cols="3">
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<thead>
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<row>
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<entry>&linux; command (Red Hat/Debian)</entry>
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<entry>&os; equivalent</entry>
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<entry>Purpose</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry><command>yum install <replaceable>package</replaceable></command> /
|
|
<command>apt-get install <replaceable>package</replaceable></command></entry>
|
|
<entry><command>pkg install <replaceable>package</replaceable></command></entry>
|
|
<entry>Install package from remote repository</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><command>rpm -ivh <replaceable>package</replaceable></command>
|
|
/ <command>dpkg -i <replaceable>package</replaceable></command></entry>
|
|
<entry><command>pkg add <replaceable>package</replaceable></command></entry>
|
|
<entry>Install local package</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><command>rpm -qa</command>
|
|
/ <command>dpkg -l</command></entry>
|
|
<entry><command>pkg info</command></entry>
|
|
<entry>List installed packages</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><command>lspci</command></entry>
|
|
<entry><command>pciconf</command></entry>
|
|
<entry>List <acronym>PCI</acronym> devices</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><command>lsmod</command></entry>
|
|
<entry><command>kldstat</command></entry>
|
|
<entry>List loaded kernel modules</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><command>modprobe</command></entry>
|
|
<entry><command>kldload</command>
|
|
/ <command>kldunload</command></entry>
|
|
<entry>Load/Unload kernel modules</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><command>strace</command></entry>
|
|
<entry><command>truss</command></entry>
|
|
<entry>Trace system calls</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</informaltable></para>
|
|
</sect1>
|
|
|
|
<sect1 xml:id="conclusion">
|
|
<title>Conclusion</title>
|
|
|
|
<para>This document has provided an overview of &os;. Refer to
|
|
the <link
|
|
xlink:href="&url.base;/doc/en_US.ISO8859-1/books/handbook/index.html">&os; Handbook</link>
|
|
for more in-depth coverage of these topics as well as the many
|
|
topics not covered by this document.</para>
|
|
</sect1>
|
|
</article>
|