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diff --git a/misc/slackbook/html/shell-bash.html b/misc/slackbook/html/shell-bash.html deleted file mode 100644 index 13ffdf08..00000000 --- a/misc/slackbook/html/shell-bash.html +++ /dev/null @@ -1,234 +0,0 @@ -<!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>The Bourne Again Shell (bash)</title> -<meta name="GENERATOR" content="Modular DocBook HTML Stylesheet Version 1.7" /> -<link rel="HOME" title="Slackware Linux Essentials" href="index.html" /> -<link rel="UP" title="The Shell" href="shell.html" /> -<link rel="PREVIOUS" title="The Command Line" href="shell-command-line.html" /> -<link rel="NEXT" title="Virtual Terminals" href="shell-vt.html" /> -<link rel="STYLESHEET" type="text/css" href="docbook.css" /> -<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" /> -</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">Slackware Linux Essentials</th> -</tr> - -<tr> -<td width="10%" align="left" valign="bottom"><a href="shell-command-line.html" -accesskey="P">Prev</a></td> -<td width="80%" align="center" valign="bottom">Chapter 8 The Shell</td> -<td width="10%" align="right" valign="bottom"><a href="shell-vt.html" -accesskey="N">Next</a></td> -</tr> -</table> - -<hr align="LEFT" width="100%" /> -</div> - -<div class="SECT1"> -<h1 class="SECT1"><a id="SHELL-BASH" name="SHELL-BASH">8.3 The Bourne Again Shell -(bash)</a></h1> - -<div class="SECT2"> -<h2 class="SECT2"><a id="SHELL-BASH-ENVIRONMENT" name="SHELL-BASH-ENVIRONMENT">8.3.1 -Environment Variables</a></h2> - -<p>A Linux system is a complex beast, and there's a lot to keep track of, a lot of little -details that come into play in your normal interactions with various programs (some of -which you might not even need to be aware of). Nobody wants to pass a bunch of options to -every program that gets run, telling it what kind of terminal is being used, the hostname -of the computer, how their prompt should look...</p> - -<p>So as a coping mechanism, users have what's called an environment. The environment -defines the conditions in which programs run, and some of this definition is variable; -the user can alter and play with it, as is only right in a Linux system. Pretty much any -shell will have environment variables (if not, it's probably not a very useable shell). -Here we will give an overview of the commands bash provides for manipulating its -environment variables.</p> - -<p><tt class="COMMAND">set</tt> by itself will show you all of the environment variables -that are currently defined, as well as their values. Like most <tt -class="COMMAND">bash</tt> built-ins, it can also do several other things (with -parameters); we'll leave it to the <tt class="COMMAND">bash</tt>(1) man page to cover -that, though. <a href="shell-bash.html#EX-SHELL-BASH-ENVIRONMENT">Example 8-1</a> shows -an excerpt from a <tt class="COMMAND">set</tt> command run on one of the author's -computers. Notice in this example the <tt class="ENVAR">PATH</tt> variable that was -discussed earlier. Programs in any of those directories can be run simply by typing the -base filename.</p> - -<div class="EXAMPLE"><a id="EX-SHELL-BASH-ENVIRONMENT" -name="EX-SHELL-BASH-ENVIRONMENT"></a> -<p><b>Example 8-1. Listing Environment Variables with <tt -class="COMMAND">set</tt></b></p> - -<table border="0" bgcolor="#E0E0E0" width="100%"> -<tr> -<td> -<pre class="SCREEN"> -<samp class="PROMPT">%</samp> <kbd class="USERINPUT">set</kbd> -PATH=/usr/local/lib/qt/bin:/usr/local/bin:/usr/bin:/bin:/usr/X11R6/bin: -/usr/openwin/bin:/usr/games:.:/usr/local/ssh2/bin:/usr/local/ssh1/bin: -/usr/share/texmf/bin:/usr/local/sbin:/usr/sbin:/home/logan/bin -PIPESTATUS=([0]="0") -PPID=4978 -PS1='\h:\w\$ ' -PS2='> ' -PS4='+ ' -PWD=/home/logan -QTDIR=/usr/local/lib/qt -REMOTEHOST=ninja.tdn -SHELL=/bin/bash -</pre> -</td> -</tr> -</table> -</div> - -<table border="0" bgcolor="#E0E0E0" width="100%"> -<tr> -<td> -<pre class="SCREEN"> -<samp class="PROMPT">%</samp> <kbd class="USERINPUT">unset <var -class="REPLACEABLE">VARIABLE</var></kbd> -</pre> -</td> -</tr> -</table> - -<p><tt class="COMMAND">unset</tt> will remove any variables that you give it, wiping out -both the variable and its value; <tt class="COMMAND">bash</tt> will forget that variable -ever existed. (Don't worry. Unless it's something you explicitly defined in that shell -session, it'll probably get redefined in any other session.)</p> - -<table border="0" bgcolor="#E0E0E0" width="100%"> -<tr> -<td> -<pre class="SCREEN"> -<samp class="PROMPT">%</samp> <kbd class="USERINPUT">export <var -class="REPLACEABLE">VARIABLE=some_value</var></kbd> -</pre> -</td> -</tr> -</table> - -<p>Now, <tt class="COMMAND">export</tt> is truly handy. Using it, you give the -environment variable <tt class="ENVAR">VARIABLE</tt> the value “<var -class="LITERAL">some_value</var>”; if <tt class="ENVAR">VARIABLE</tt> didn't exist, -it does now. If <tt class="ENVAR">VARIABLE</tt> already had a value, well, it's gone. -That's not so good, if you're just trying to add a directory to your <tt -class="ENVAR">PATH</tt>. In that case, you probably want to do something like this:</p> - -<table border="0" bgcolor="#E0E0E0" width="100%"> -<tr> -<td> -<pre class="SCREEN"> -<samp class="PROMPT">%</samp> <kbd class="USERINPUT">export PATH=$PATH:<var -class="REPLACEABLE">/some/new/directory</var></kbd> -</pre> -</td> -</tr> -</table> - -<p>Note the use of <tt class="ENVAR">$PATH</tt> there: when you want <tt -class="COMMAND">bash</tt> to interpret a variable (replace it with its value), tack a -<var class="LITERAL">$</var> onto the beginning of the variable's name. For instance, <tt -class="COMMAND">echo $PATH</tt> will echo the value of <tt class="ENVAR">PATH</tt>, in my -case:</p> - -<table border="0" bgcolor="#E0E0E0" width="100%"> -<tr> -<td> -<pre class="SCREEN"> -<samp class="PROMPT">%</samp> <kbd class="USERINPUT">echo $PATH</kbd> -/usr/local/lib/qt/bin:/usr/local/bin:/usr/bin:/bin:/usr/X11R6/bin: -/usr/openwin/bin:/usr/games:.:/usr/local/ssh2/bin:/usr/local/ssh1/bin: -/usr/share/texmf/bin:/usr/local/sbin:/usr/sbin:/home/logan/bin -</pre> -</td> -</tr> -</table> -</div> - -<div class="SECT2"> -<h2 class="SECT2"><a id="SHELL-BASH-TAB" name="SHELL-BASH-TAB">8.3.2 Tab -Completion</a></h2> - -<p>(Here comes something cool again.)</p> - -<ol type="1"> -<li> -<p>A commandline interface means lots of typing.</p> -</li> - -<li> -<p>Typing is work.</p> -</li> - -<li> -<p>Nobody likes work.</p> -</li> -</ol> - -<p>From 3 and 2, we can determine that (4) nobody likes typing. Fortunately, <tt -class="COMMAND">bash</tt> saves us from (5) (nobody likes a commandline interface).</p> - -<p>How does <tt class="COMMAND">bash</tt> accomplish this wonderful feat, you ask? In -addition to the wildcard expansion we discussed before, <tt class="COMMAND">bash</tt> -features tab completion.</p> - -<p>Tab completion works something like this: You're typing the name of a file. Maybe it's -in your <tt class="ENVAR">PATH</tt>, maybe you're typing it out explicitly. All you have -to do is type enough of the filename to uniquely identify it. Then hit the tab key. <tt -class="COMMAND">bash</tt> will figure out what you want and finish typing it for you!</p> - -<p>Example time. <tt class="FILENAME">/usr/src</tt> contains two subdirectories: <tt -class="FILENAME">/usr/src/linux</tt> and <tt class="FILENAME">/usr/src/sendmail</tt>. I -want to see what's in <tt class="FILENAME">/usr/src/linux</tt>. So I just type <tt -class="COMMAND">ls /usr/src/l</tt>, hit the <kbd class="USERINPUT">TAB</kbd> key, and <tt -class="COMMAND">bash</tt> gives me <tt class="COMMAND">ls /usr/src/linux</tt>.</p> - -<p>Now, suppose there are two directories <tt class="FILENAME">/usr/src/linux</tt> and -<tt class="FILENAME">/usr/src/linux-old</tt>; If I type <tt -class="FILENAME">/usr/src/l</tt> and hit <kbd class="USERINPUT">TAB</kbd>, <tt -class="COMMAND">bash</tt> will fill in as much as it can, and I'll get <tt -class="FILENAME">/usr/src/linux</tt>. I can stop there, or I can hit <kbd -class="USERINPUT">TAB</kbd> again, and <tt class="COMMAND">bash</tt> will show a list of -directories that match what I've typed so far.</p> - -<p>Hence, less typing (and hence, people can like commandline interfaces). I told you it -was cool.</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="shell-command-line.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="shell-vt.html" -accesskey="N">Next</a></td> -</tr> - -<tr> -<td width="33%" align="left" valign="top">The Command Line</td> -<td width="34%" align="center" valign="top"><a href="shell.html" -accesskey="U">Up</a></td> -<td width="33%" align="right" valign="top">Virtual Terminals</td> -</tr> -</table> -</div> -</body> -</html> - |