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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta name="generator" content="HTML Tidy, see www.w3.org" /><title>Welcome to FreeBSD!</title><meta name="GENERATOR" content="Modular DocBook HTML Stylesheet Version 1.7" /><link rel="HOME" title="FreeBSD Handbook" href="index.html" /><link rel="UP" title="Introduction" href="introduction.html" /><link rel="PREVIOUS" title="Introduction" href="introduction.html" /><link rel="NEXT" title="About the FreeBSD Project" href="history.html" /><link rel="STYLESHEET" type="text/css" href="docbook.css" /></head><body class="SECT1" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#840084"alink="#0000FF"><div class="NAVHEADER"><table summary="Header navigation table" width="100%" border="0" cellpadding="0"cellspacing="0"><tr><th colspan="3" align="center">FreeBSD Handbook</th></tr><tr><td width="10%" align="left" valign="bottom"><a href="introduction.html"accesskey="P">Prev</a></td><td width="80%" align="center" valign="bottom">Chapter 1 Introduction</td><td width="10%" align="right" valign="bottom"><a href="history.html"accesskey="N">Next</a></td></tr></table><hr align="LEFT" width="100%" /></div><div class="SECT1"><h1 class="SECT1"><a id="NUTSHELL" name="NUTSHELL">1.2 Welcome to FreeBSD!</a></h1><p>FreeBSD is a 4.4BSD-Lite based operating system for Intel (x86 and <spanclass="TRADEMARK">Itanium</span>®), AMD64, <spanclass="TRADEMARK">Alpha</span>™, Sun <span class="TRADEMARK">UltraSPARC</span>®computers. Ports to other architectures are also underway. You can also read about <ahref="history.html">the history of FreeBSD</a>, or the <ahref="history.html#RELNOTES">current release</a>. If you are interested in contributingsomething to the Project (code, hardware, unmarked bills), see the <ahref="../../../../doc/en_US.ISO8859-1/articles/contributing/index.html"target="_top">Contributing to FreeBSD</a> article.</p><div class="SECT2"><h2 class="SECT2"><a id="OS-OVERVIEW" name="OS-OVERVIEW">1.2.1 What Can FreeBSDDo?</a></h2><p>FreeBSD has many noteworthy features. Some of these are:</p><ul><li><p><span class="emphasis"><i class="EMPHASIS">Preemptive multitasking</i></span> withdynamic priority adjustment to ensure smooth and fair sharing of the computer betweenapplications and users, even under the heaviest of loads.</p></li><li><p><span class="emphasis"><i class="EMPHASIS">Multi-user facilities</i></span> whichallow many people to use a FreeBSD system simultaneously for a variety of things. Thismeans, for example, that system peripherals such as printers and tape drives are properlyshared between all users on the system or the network and that individual resource limitscan be placed on users or groups of users, protecting critical system resources fromover-use.</p></li><li><p>Strong <span class="emphasis"><i class="EMPHASIS">TCP/IP networking</i></span> withsupport for industry standards such as SLIP, PPP, NFS, DHCP, and NIS. This means thatyour FreeBSD machine can interoperate easily with other systems as well as act as anenterprise server, providing vital functions such as NFS (remote file access) and emailservices or putting your organization on the Internet with WWW, FTP, routing and firewall(security) services.</p></li><li><p><span class="emphasis"><i class="EMPHASIS">Memory protection</i></span> ensures thatapplications (or users) cannot interfere with each other. One application crashing willnot affect others in any way.</p></li><li><p>FreeBSD is a <span class="emphasis"><i class="EMPHASIS">32-bit</i></span> operatingsystem (<span class="emphasis"><i class="EMPHASIS">64-bit</i></span> on the Alpha, <spanclass="TRADEMARK">Itanium</span>, AMD64, and <span class="TRADEMARK">UltraSPARC</span>)and was designed as such from the ground up.</p></li><li><p>The industry standard <span class="emphasis"><i class="EMPHASIS">X WindowSystem</i></span> (X11R6) provides a graphical user interface (GUI) for the cost of acommon VGA card and monitor and comes with full sources.</p></li><li><p><span class="emphasis"><i class="EMPHASIS">Binary compatibility</i></span> with manyprograms built for Linux, SCO, SVR4, BSDI and NetBSD.</p></li><li><p>Thousands of <span class="emphasis"><i class="EMPHASIS">ready-to-run</i></span>applications are available from the FreeBSD <span class="emphasis"><iclass="EMPHASIS">ports</i></span> and <span class="emphasis"><iclass="EMPHASIS">packages</i></span> collection. Why search the net when you can find itall right here?</p></li><li><p>Thousands of additional and <span class="emphasis"><iclass="EMPHASIS">easy-to-port</i></span> applications are available on the Internet.FreeBSD is source code compatible with most popular commercial <spanclass="TRADEMARK">UNIX</span>® systems and thus most applications require few, ifany, changes to compile.</p></li><li><p>Demand paged <span class="emphasis"><i class="EMPHASIS">virtual memory</i></span> and``merged VM/buffer cache'' design efficiently satisfies applications with large appetitesfor memory while still maintaining interactive response to other users.</p></li><li><p><span class="emphasis"><i class="EMPHASIS">SMP</i></span> support for machines withmultiple CPUs.</p></li><li><p>A full complement of <span class="emphasis"><i class="EMPHASIS">C</i></span>, <spanclass="emphasis"><i class="EMPHASIS">C++</i></span>, <span class="emphasis"><iclass="EMPHASIS">Fortran</i></span>, and <span class="emphasis"><iclass="EMPHASIS">Perl</i></span> development tools. Many additional languages foradvanced research and development are also available in the ports and packagescollection.</p></li><li><p><span class="emphasis"><i class="EMPHASIS">Source code</i></span> for the entiresystem means you have the greatest degree of control over your environment. Why be lockedinto a proprietary solution at the mercy of your vendor when you can have a truly opensystem?</p></li><li><p>Extensive <span class="emphasis"><i class="EMPHASIS">onlinedocumentation</i></span>.</p></li><li><p><span class="emphasis"><i class="EMPHASIS">And many more!</i></span></p></li></ul><p>FreeBSD is based on the 4.4BSD-Lite release from Computer Systems Research Group(CSRG) at the University of California at Berkeley, and carries on the distinguishedtradition of BSD systems development. In addition to the fine work provided by CSRG, theFreeBSD Project has put in many thousands of hours in fine tuning the system for maximumperformance and reliability in real-life load situations. As many of the commercialgiants struggle to field PC operating systems with such features, performance andreliability, FreeBSD can offer them <span class="emphasis"><iclass="EMPHASIS">now</i></span>!</p><p>The applications to which FreeBSD can be put are truly limited only by your ownimagination. From software development to factory automation, inventory control toazimuth correction of remote satellite antennae; if it can be done with a commercial<span class="TRADEMARK">UNIX</span> product then it is more than likely that you can doit with FreeBSD too! FreeBSD also benefits significantly from literally thousands of highquality applications developed by research centers and universities around the world,often available at little to no cost. Commercial applications are also available andappearing in greater numbers every day.</p><p>Because the source code for FreeBSD itself is generally available, the system can alsobe customized to an almost unheard of degree for special applications or projects, and inways not generally possible with operating systems from most major commercial vendors.Here is just a sampling of some of the applications in which people are currently usingFreeBSD:</p><ul><li><p><span class="emphasis"><i class="EMPHASIS">Internet Services:</i></span> The robustTCP/IP networking built into FreeBSD makes it an ideal platform for a variety of Internetservices such as:</p><ul><li><p>FTP servers</p></li><li><p>World Wide Web servers (standard or secure [SSL])</p></li><li><p>Firewalls and NAT (``IP masquerading'') gateways</p></li><li><p>Electronic Mail servers</p></li><li><p>USENET News or Bulletin Board Systems</p></li><li><p>And more...</p></li></ul><p>With FreeBSD, you can easily start out small with an inexpensive 386 class PC andupgrade all the way up to a quad-processor Xeon with RAID storage as your enterprisegrows.</p></li><li><p><span class="emphasis"><i class="EMPHASIS">Education:</i></span> Are you a student ofcomputer science or a related engineering field? There is no better way of learning aboutoperating systems, computer architecture and networking than the hands on, under the hoodexperience that FreeBSD can provide. A number of freely available CAD, mathematical andgraphic design packages also make it highly useful to those whose primary interest in acomputer is to get <span class="emphasis"><i class="EMPHASIS">other</i></span> workdone!</p></li><li><p><span class="emphasis"><i class="EMPHASIS">Research:</i></span> With source code forthe entire system available, FreeBSD is an excellent platform for research in operatingsystems as well as other branches of computer science. FreeBSD's freely available naturealso makes it possible for remote groups to collaborate on ideas or shared developmentwithout having to worry about special licensing agreements or limitations on what may bediscussed in open forums.</p></li><li><p><span class="emphasis"><i class="EMPHASIS">Networking:</i></span> Need a new router? Aname server (DNS)? A firewall to keep people out of your internal network? FreeBSD caneasily turn that unused 386 or 486 PC sitting in the corner into an advanced router withsophisticated packet-filtering capabilities.</p></li><li><p><span class="emphasis"><i class="EMPHASIS">X Window workstation:</i></span> FreeBSD isa fine choice for an inexpensive X terminal solution, either using the freely available<span class="TRADEMARK">XFree86</span>™ server or one of the excellent commercialservers provided by <a href="http://www.xig.com" target="_top">Xi Graphics</a>. Unlike anX terminal, FreeBSD allows many applications to be run locally if desired, thus relievingthe burden on a central server. FreeBSD can even boot ``diskless'', making individualworkstations even cheaper and easier to administer.</p></li><li><p><span class="emphasis"><i class="EMPHASIS">Software Development:</i></span> The basicFreeBSD system comes with a full complement of development tools including the renownedGNU C/C++ compiler and debugger.</p></li></ul><p>FreeBSD is available in both source and binary form on CDROM, DVD, and via anonymousFTP. Please see <a href="mirrors.html">Appendix A</a> for more information aboutobtaining FreeBSD.</p></div><div class="SECT2"><h2 class="SECT2"><a id="AEN702" name="AEN702">1.2.2 Who Uses FreeBSD?</a></h2><p>FreeBSD is used to power some of the biggest sites on the Internet, including:</p><ul><li><p><a href="http://www.yahoo.com/" target="_top">Yahoo!</a></p></li><li><p><a href="http://www.apache.org/" target="_top">Apache</a></p></li><li><p><a href="http://www.bluemountain.com/" target="_top">Blue Mountain Arts</a></p></li><li><p><a href="http://www.pair.com/" target="_top">Pair Networks</a></p></li><li><p><a href="http://www.sony.co.jp/" target="_top">Sony Japan</a></p></li><li><p><a href="http://www.netcraft.com/" target="_top">Netcraft</a></p></li><li><p><a href="http://www.wni.com/" target="_top">Weathernews</a></p></li><li><p><a href="http://www.supervalu.com/" target="_top">Supervalu</a></p></li><li><p><a href="http://www.telehouse.com/" target="_top">TELEHOUSE America</a></p></li><li><p><a href="http://www.sophos.com/" target="_top">Sophos Anti-Virus</a></p></li><li><p><a href="http://www.jmawired.com/" target="_top">JMA Wired</a></p></li></ul><p>and many more.</p></div></div><div class="NAVFOOTER"><hr align="LEFT" width="100%" /><table summary="Footer navigation table" width="100%" border="0" cellpadding="0"cellspacing="0"><tr><td width="33%" align="left" valign="top"><a href="introduction.html"accesskey="P">Prev</a></td><td width="34%" align="center" valign="top"><a href="index.html"accesskey="H">Home</a></td><td width="33%" align="right" valign="top"><a href="history.html"accesskey="N">Next</a></td></tr><tr><td width="33%" align="left" valign="top">Introduction</td><td width="34%" align="center" valign="top"><a href="introduction.html"accesskey="U">Up</a></td><td width="33%" align="right" valign="top">About the FreeBSD Project</td></tr></table></div><p align="center"><small>This, and other documents, can be downloaded from <ahref="ftp://ftp.FreeBSD.org/pub/FreeBSD/doc/">ftp://ftp.FreeBSD.org/pub/FreeBSD/doc/</a>.</small></p><p align="center"><small>For questions about FreeBSD, read the <ahref="http://www.FreeBSD.org/docs.html">documentation</a> before contacting <<ahref="mailto:questions@FreeBSD.org">questions@FreeBSD.org</a>>.<br />For questions about this documentation, e-mail <<ahref="mailto:doc@FreeBSD.org">doc@FreeBSD.org</a>>.</small></p></body></html>⌨️ 快捷键说明
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