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docs/Install-Guide/install-guide-2.2.2/node118.html
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<!DOCTYPE HTML PUBLIC "-//W3O//DTD W3 HTML 2.0//EN">
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<!Converted with LaTeX2HTML 95.1 (Fri Jan 20 1995) by Nikos Drakos (nikos@cbl.leeds.ac.uk), CBLU, University of Leeds >
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<HEAD>
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<TITLE>3.7 Wildcards</TITLE>
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</HEAD>
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<BODY>
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<meta name="description" value="3.7 Wildcards">
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<meta name="keywords" value="gs">
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<meta name="resource-type" value="document">
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<meta name="distribution" value="global">
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<P>
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<BR> <HR><A NAME=tex2html3250 HREF="node119.html"><IMG ALIGN=BOTTOM ALT="next" SRC="next_motif.gif"></A> <A NAME=tex2html3248 HREF="node93.html"><IMG ALIGN=BOTTOM ALT="up" SRC="up_motif.gif"></A> <A NAME=tex2html3242 HREF="node117.html"><IMG ALIGN=BOTTOM ALT="previous" SRC="previous_motif.gif"></A> <A NAME=tex2html3252 HREF="node1.html"><IMG ALIGN=BOTTOM ALT="contents" SRC="contents_motif.gif"></A> <A NAME=tex2html3253 HREF="node250.html"><IMG ALIGN=BOTTOM ALT="index" SRC="index_motif.gif"></A> <BR>
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<B> Next:</B> <A NAME=tex2html3251 HREF="node119.html">3.8 UNIX Plumbing</A>
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<B>Up:</B> <A NAME=tex2html3249 HREF="node93.html">3 Linux Tutorial</A>
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<B> Previous:</B> <A NAME=tex2html3243 HREF="node117.html">3.6 Types of shells</A>
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<BR> <HR> <P>
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<H1><A NAME=SECTION00570000000000000000>3.7 Wildcards</A></H1>
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<P>
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<A NAME=2908> </A>
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<A NAME=2909> </A>
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<A NAME=2910> </A>
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<A NAME=2911> </A>
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A key feature of most Unix shells is the ability to reference more
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than one filename using special characters. These so-called <b>wildcards</b>
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allow you to refer to, say, all filenames which contain the character
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``<tt>n</tt>''.
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<P>
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<A NAME=3024> </A>
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<A NAME=3025> </A>
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The wildcard ``<tt>*</tt>'' refers to any character or string of characters in
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a filename. For example, when you use the character ``<tt>*</tt>'' in a filename,
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the shell replaces it with all possible substitutions from filenames in
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the directory which you're referencing.
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<P>
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Here's a quick example. Let's suppose that Larry has the files <tt>frog</tt>,
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<tt>joe</tt>, and <tt>stuff</tt> in his current directory.
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<P><TT> /home/larry# <em>ls</em> <BR>
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frog joe stuff <BR>
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/home/larry#
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<P></TT>
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<P>
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To access all files with the letter ``o'' in the filename, we can use
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the command
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<P><TT> /home/larry# <em>ls *o*</em> <BR>
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frog joe <BR>
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/home/larry#
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<P></TT>
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As you can see, the use of the ``<tt>*</tt>'' wildcard was replaced with
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all substitutions which matched the wildcard from filenames in the
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current directory.
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<P>
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The use of ``<tt>*</tt>'' by itself simply matches all filenames, because
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all characters match the wildcard.
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<P><TT> /home/larry# <em>ls *</em> <BR>
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frog joe stuff <BR>
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/home/larry#
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<P></TT>
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<P>
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Here are a few more examples.
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<P><TT> /home/larry# <em>ls f*</em> <BR>
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frog <BR>
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/home/larry# <em>ls *ff</em> <BR>
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stuff <BR>
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/home/larry# <em>ls *f*</em> <BR>
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frog stuff <BR>
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/home/larry# <em>ls s*f</em> <BR>
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stuff <BR>
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/home/larry#
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<P></TT>
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<P>
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<A NAME=2938> </A>
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<A NAME=2939> </A>
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The process of changing a ``<tt>*</tt>'' into filenames is called <b>wildcard
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expansion</b> and is done by the shell. This is
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important: the individual commands, such as <tt>ls</tt>, <em>never</em> see
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the ``<tt>*</tt>'' in their list of parameters. The shell expands the
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wildcard to include all of the filenames which match. So, the command
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<P><TT> /home/larry# <em>ls *o*</em>
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<P></TT>
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is expanded by the shell to actually be
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<P><TT> /home/larry# <em>ls frog joe</em>
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<P></TT>
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<P>
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<A NAME=2951> </A>
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One important note about the ``<tt>*</tt>'' wildcard. Using this wildcard
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will <em>not</em> match filenames which begin with a single period (``<tt>.</tt>'').
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These files are treated as ``hidden'' files---while they are not really
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hidden, they don't show up on normal <tt>ls</tt> listings, and aren't
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touched by the use of the ``<tt>*</tt>'' wildcard.
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<P>
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Here's an example. We already mentioned that each directory has two
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special entries in it: ``<tt>.</tt>'' refers to the current directory,
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and ``<tt>..</tt>'' refers to the parent directory. However, when you use
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<tt>ls</tt>, these two entries don't show up.
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<P><TT> /home/larry# <em>ls</em> <BR>
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frog joe stuff <BR>
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/home/larry#
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<P></TT>
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If you use the <tt>-a</tt> switch with <tt>ls</tt>, however, you can display
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filenames which begin with ``<tt>.</tt>''. Observe:
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<P><TT> /home/larry# <em>ls -a</em> <BR>
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. .. .bash_profile .bashrc frog
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joe stuff <BR>
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/home/larry#
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<P></TT>
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Now we can see the two special entries, ``<tt>.</tt>'' and ``<tt>..</tt>'',
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as well as two other ``hidden'' files---<tt>.bash_profile</tt> and
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<tt>.bashrc</tt>. These two files are startup files used by <tt>bash</tt>
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when larry logs in. More on them in Section <A HREF="node153.html#secinitscripts">3.13.3</A>.
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<P>
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Note that when we use the ``<tt>*</tt>'' wildcard, none of the filenames
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beginning with ``<tt>.</tt>'' are displayed.
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<P><TT> /home/larry# <em>ls *</em> <BR>
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frog joe stuff <BR>
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/home/larry#
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<P></TT>
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This is a safety feature: if the ``<tt>*</tt>'' wildcard matched filenames
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beginning with ``<tt>.</tt>'', it would also match the directory names
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``<tt>.</tt>'' and ``<tt>..</tt>''. This can be dangerous when using certain
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commands.
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<P>
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<A NAME=3026> </A>
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<A NAME=3027> </A>
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Another wildcard is ``<tt>?</tt>''. The ``<tt>?</tt>'' wildcard will only
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expand a single character. Thus, ``<tt>ls ?</tt>'' will display all one
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character filenames, and ``<tt>ls termca?</tt>'' would display ``<tt>termcap</tt>''
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but <em>not</em> ``<tt>termcap.backup</tt>''.
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Here's another example:
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<P><TT> /home/larry# <em>ls j?e</em> <BR>
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joe <BR>
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/home/larry# <em>ls f??g</em> <BR>
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frog <BR>
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/home/larry# <em>ls ????f</em> <BR>
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stuff <BR>
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/home/larry#
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<P></TT>
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<P>
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As you can see, wildcards allow you to specify many files at one time.
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In the simple command summary, in Section <A HREF="node115.html#seccommandsumm">3.4</A>, we
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said that the <tt>cp</tt> and <tt>mv</tt> commands actually can copy or
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move multiple files at one time. For example,
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<P><TT> /home/larry# <em>cp /etc/s* /home/larry</em>
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<P></TT>
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will copy all filenames in <tt>/etc</tt> beginning with ``<tt>s</tt>'' to the
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directory <tt>/home/larry</tt>. Therefore, the format of the <tt>cp</tt> command
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is really
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<P><TT> cp <IMG BORDER=0 ALIGN=BOTTOM ALT="" SRC="img172.gif"> <IMG BORDER=0 ALIGN=BOTTOM ALT="" SRC="img173.gif"> <IMG BORDER=0 ALIGN=BOTTOM ALT="" SRC="img174.gif"> ...<IMG BORDER=0 ALIGN=BOTTOM ALT="" SRC="img175.gif">
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<IMG BORDER=0 ALIGN=BOTTOM ALT="" SRC="img176.gif"> <P></TT>
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where <IMG BORDER=0 ALIGN=BOTTOM ALT="" SRC="img177.gif"> through <IMG BORDER=0 ALIGN=BOTTOM ALT="" SRC="img178.gif"> is a list of filenames to
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copy, and <IMG BORDER=0 ALIGN=BOTTOM ALT="" SRC="img179.gif"> is the destination file or directory to
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copy them to. <tt>mv</tt> has an identical syntax.
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<P>
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Note that if you are copying or moving more than one file, the
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<IMG BORDER=0 ALIGN=BOTTOM ALT="" SRC="img180.gif"> must be a directory. You can only copy or move
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a <em>single</em> file to another file.
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<P>
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<A NAME=3021> </A>
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<A NAME=3022> </A>
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<A NAME=3023> </A>
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<P>
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<BR> <HR><A NAME=tex2html3250 HREF="node119.html"><IMG ALIGN=BOTTOM ALT="next" SRC="next_motif.gif"></A> <A NAME=tex2html3248 HREF="node93.html"><IMG ALIGN=BOTTOM ALT="up" SRC="up_motif.gif"></A> <A NAME=tex2html3242 HREF="node117.html"><IMG ALIGN=BOTTOM ALT="previous" SRC="previous_motif.gif"></A> <A NAME=tex2html3252 HREF="node1.html"><IMG ALIGN=BOTTOM ALT="contents" SRC="contents_motif.gif"></A> <A NAME=tex2html3253 HREF="node250.html"><IMG ALIGN=BOTTOM ALT="index" SRC="index_motif.gif"></A> <BR>
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<B> Next:</B> <A NAME=tex2html3251 HREF="node119.html">3.8 UNIX Plumbing</A>
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<B>Up:</B> <A NAME=tex2html3249 HREF="node93.html">3 Linux Tutorial</A>
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<B> Previous:</B> <A NAME=tex2html3243 HREF="node117.html">3.6 Types of shells</A>
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<BR> <HR> <P>
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<BR> <HR>
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<P><ADDRESS>
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<I>Matt Welsh <BR>
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mdw@sunsite.unc.edu</I>
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</ADDRESS>
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</BODY>
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