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<html><head><title>The Unix Shell: An Overview (UNIX in a Nutshell: System V Edition)</title><link rel="stylesheet" type="text/css" href="../style/style1.css" /><meta name="DC.Creator" content="Arnold Robbins" /><meta name="DC.Format" content="text/xml" scheme="MIME" /><meta name="DC.Language" content="en-US" /><meta name="DC.Publisher" content="O'Reilly & Associates, Inc." /><meta name="DC.Source" scheme="ISBN" content="1-56592-427-4" /><meta name="DC.Subject.Keyword" content="stuff" /><meta name="DC.Title" content="UNIX in a Nutshell: System V Edition" /><meta name="DC.Type" content="Text.Monograph" /></head><body bgcolor="#ffffff"><img src="gifs/smbanner.gif" usemap="#banner-map" border="0" alt="Book Home" /><map name="banner-map"><area shape="rect" coords="1,-2,616,66" href="index.htm" alt="Book Title" /><area shape="rect" coords="629,-11,726,25" href="jobjects/fsearch.htm" alt="Search this book" /></map><div class="navbar"><table width="684" border="0"><tr><td align="left" valign="top" width="228"><a href="ch02_01.htm"><img src="../gifs/txtpreva.gif" alt="Previous" border="0" /></a></td><td align="center" valign="top" width="228" /><td align="right" valign="top" width="228"><a href="ch03_02.htm"><img src="../gifs/txtnexta.gif" alt="Next" border="0" /></a></td></tr></table></div><h1 class="chapter">Chapter 3. The Unix Shell: An Overview</h1><div class="htmltoc"><h4 class="tochead">Contents:</h4><p><a href="ch03_01.htm#sect1">Introduction to the Shell</a><br /><a href="ch03_02.htm">Purpose of the Shell</a><br /><a href="ch03_03.htm">Shell Flavors</a><br /><a href="ch03_04.htm">Common Features</a><br /><a href="ch03_05.htm">Differing Features</a><br /></p></div><p>For novice users, this chapter presents basic concepts about the Unixshell. For advanced users, this chapter also summarizes the majorsimilarities and differences between the Bourne, Korn, and C shells.Details on the three shells are provided in<a href="ch04_01.htm">Chapter 4</a>, and <a href="ch05_01.htm">Chapter 5</a>.<a name="IXT-3-122623" /><a name="unut-ch-3-ix-shells-overview-of" /></p><p>The following topics are presented:</p><ul><li><p>Introduction to the shell</p></li><li><p>Purpose of the shell</p></li><li><p>Shell flavors</p></li><li><p>Common features</p></li><li><p>Differing features</p></li></ul><div class="sect1"><a name="unut-ch-3-sect-1" /><h2 class="sect1"><a name="sect1" />3.1. Introduction to the Shell</h2><p>Let's suppose that the Unix operating system is a car. When you drive, you issue a variety of “commands”:you turn the steering wheel, press the accelerator, or pressthe brake. But how does the car translate your commandsinto the action you want? The car's drive mechanism,which can be thought of as the car's user interface, is responsible.Cars can be equipped with front-wheel drive, rear-wheel drive,four-wheel drive, and sometimes combinations of these.</p><p>The shell is the user interface to Unix,and by the same token, several shells are available in Unix.Most systems provide more thanone for you to choose from. Each shell has different features,but all of them affect how commands will be interpreted andprovide tools to create your Unix environment.</p><p><a name="IXT-3-122624" />The shell is simply a program that allows the system to understand yourcommands. (That's why the shell is often called a <em class="emphasis">command interpreter</em>.)For many users, the shell works invisibly--“behind the scenes.”Your onlyconcern is that the system does what you tell it to do;you don't care aboutthe inner workings. In our car analogy, this is comparable to pressingthe brake.Most of us don't care whether the user interface involvesdisk brakes or drum brakes, as long as the car stops.</p></div><hr width="684" align="left" /><div class="navbar"><table width="684" border="0"><tr><td align="left" valign="top" width="228"><a href="ch02_01.htm"><img src="../gifs/txtpreva.gif" alt="Previous" border="0" /></a></td><td align="center" valign="top" width="228"><a href="index.htm"><img src="../gifs/txthome.gif" alt="Home" border="0" /></a></td><td align="right" valign="top" width="228"><a href="ch03_02.htm"><img src="../gifs/txtnexta.gif" alt="Next" border="0" /></a></td></tr><tr><td align="left" valign="top" width="228">2. Unix Commands</td><td align="center" valign="top" width="228"><a href="index/index.htm"><img src="../gifs/index.gif" alt="Book Index" border="0" /></a></td><td align="right" valign="top" width="228">3.2. Purpose of the Shell</td></tr></table></div><hr width="684" align="left" /><img src="../gifs/navbar.gif" usemap="#library-map" border="0" alt="Library Navigation Links" /><p><p><font size="-1"><a href="copyrght.htm">Copyright © 2003</a> O'Reilly & Associates. All rights reserved.</font></p><map name="library-map"><area shape="rect" coords="1,0,88,96" href="../index.htm"><area shape="rect" coords="90,0,165,96" href="../upt/index.htm"><area shape="rect" coords="168,1,253,107" href="../mac/index.htm"><area shape="rect" coords="255,0,335,97" href="../korn/index.htm"><area shape="rect" coords="337,0,415,109" href="../unixnut/index.htm"><area shape="rect" coords="417,0,512,122" href="../sedawk/index.htm"><area shape="rect" coords="514,0,605,105" href="../lunix/index.htm"><area shape="rect" coords="611,2,694,121" href="../vi/index.htm"> </map></body></html>⌨️ 快捷键说明
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