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<A NAME="CHILD_LINKS"><STRONG>Subsections</STRONG></A>

<UL>
<LI><A NAME="tex2html1784"
  HREF="#SECTION00710000000000000000">4.1 The <TT>
<FONT COLOR="#0000ff">ls</FONT></TT> Command, Hidden Files, Command-Line Options</A>
<LI><A NAME="tex2html1785"
  HREF="#SECTION00720000000000000000">4.2 Error Messages</A>
<LI><A NAME="tex2html1786"
  HREF="#SECTION00730000000000000000">4.3 Wildcards, Names, Extensions, and <I>glob</I> Expressions</A>
<UL>
<LI><A NAME="tex2html1787"
  HREF="#SECTION00731000000000000000">4.3.1 File naming</A>
<LI><A NAME="tex2html1788"
  HREF="#SECTION00732000000000000000">4.3.2 Glob expressions</A>
</UL>
<LI><A NAME="tex2html1789"
  HREF="#SECTION00740000000000000000">4.4 Usage Summaries and the Copy Command</A>
<LI><A NAME="tex2html1790"
  HREF="#SECTION00750000000000000000">4.5 Directory Manipulation</A>
<LI><A NAME="tex2html1791"
  HREF="#SECTION00760000000000000000">4.6 <I>Relative</I> vs. <I>Absolute</I> Pathnames</A>
<LI><A NAME="tex2html1792"
  HREF="#SECTION00770000000000000000">4.7 System Manual Pages</A>
<LI><A NAME="tex2html1793"
  HREF="#SECTION00780000000000000000">4.8 System <TT>
<FONT COLOR="#0000ff">info</FONT></TT> Pages</A>
<LI><A NAME="tex2html1794"
  HREF="#SECTION00790000000000000000">4.9 Some Basic Commands</A>
<LI><A NAME="tex2html1795"
  HREF="#SECTION007100000000000000000">4.10 The <TT>
<FONT COLOR="#0000ff">mc</FONT></TT> File Manager</A>
<LI><A NAME="tex2html1796"
  HREF="#SECTION007110000000000000000">4.11 Multimedia Commands for Fun</A>
<LI><A NAME="tex2html1797"
  HREF="#SECTION007120000000000000000">4.12 Terminating Commands</A>
<LI><A NAME="tex2html1798"
  HREF="#SECTION007130000000000000000">4.13 Compressed Files</A>
<LI><A NAME="tex2html1799"
  HREF="#SECTION007140000000000000000">4.14 Searching for Files</A>
<LI><A NAME="tex2html1800"
  HREF="#SECTION007150000000000000000">4.15 Searching <I>Within</I> Files</A>
<LI><A NAME="tex2html1801"
  HREF="#SECTION007160000000000000000">4.16 Copying to MS-DOS and Windows Formatted Floppy Disks</A>
<LI><A NAME="tex2html1802"
  HREF="#SECTION007170000000000000000">4.17 Archives and Backups</A>
<LI><A NAME="tex2html1803"
  HREF="#SECTION007180000000000000000">4.18 The <TT>
<FONT COLOR="#0000ff">PATH</FONT></TT> Where Commands Are Searched For</A>
<LI><A NAME="tex2html1804"
  HREF="#SECTION007190000000000000000">4.19 The <TT>
<FONT COLOR="#0000ff">&#45;&#45;</FONT></TT> Option</A>
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<HR>

<H1><A NAME="SECTION00700000000000000000">
4. Basic Commands</A>
</H1>

<P>
<A NAME="chap:basiccmd"></A>
<P>
<DIV ALIGN="CENTER">

<TABLE width="100%" border="0" cellspacing="0" cellpadding="0">
<TR><TD bgcolor="#FFE0FF">
<I>All of U<SMALL>NIX</SMALL> is
<I>case sensitive</I>. A command with even a single letter's
capitalization altered is considered to be a completely
different command. The same goes for files, directories,
configuration file formats, and the syntax of all native programming
languages.</I>

</TD></TR>
</TABLE>

</DIV>

<P>

<H1><A NAME="SECTION00710000000000000000">
4.1 The <TT>
<FONT COLOR="#0000ff">ls</FONT></TT> Command, Hidden Files,
<BR>
Command-Line Options</A>
</H1>

<P>
In addition to directories and ordinary text files, there are
other types of files, although all files contain the same kind
of data (i.e., a list of bytes). The <I>hidden</I> file is a file
that will not ordinarily appear when you type the command
<TT>
<FONT COLOR="#0000ff">ls</FONT></TT> to <I>list</I> the contents of a directory. To see a
hidden file you must use the command <TT>
<FONT COLOR="#0000ff">ls&nbsp;-a</FONT></TT>. The
<TT>
<FONT COLOR="#0000ff">-a</FONT></TT> option means to list <I>all</I> files as well as
hidden files. Another variant is <TT>
<FONT COLOR="#0000ff">ls -l</FONT></TT>, which lists the
contents in <I>long</I> format. The <TT>
<FONT COLOR="#0000ff">&nbsp;-&nbsp;</FONT></TT> is used in this way to
indicate variations on a command. These are called

<I>command-line options</I> or <I>command-line arguments</I>,
and most U<SMALL>NIX</SMALL> commands can take a number of them. They can be
strung together in any way that is convenient <FONT COLOR="#ffa500">[Commands
under the GNU free software license are superior in this way:
they have a greater number of options than traditional U<SMALL>NIX</SMALL>
commands and are therefore more flexible.]</FONT>, for example,
<TT>
<FONT COLOR="#0000ff">ls&nbsp;-a&nbsp;-l</FONT></TT>, <TT>
<FONT COLOR="#0000ff">ls&nbsp;-l&nbsp;-a</FONT></TT>, or <TT>
<FONT COLOR="#0000ff">ls&nbsp;-al</FONT></TT> &nbsp;--any
of these will list <I>all</I> files in <I>long</I>
format.

<P>
All GNU commands take the additional arguments <TT>
<FONT COLOR="#0000ff">-h</FONT></TT> and
<TT>
<FONT COLOR="#0000ff">&#45;&#45;help</FONT></TT>. You can type a command with just this on the
command-line and get a <I>usage summary</I>. This is some brief
help that will summarize options that you may have forgotten if
you are <I>already</I> familiar with the command--it will
never be an exhaustive description of the usage. See the later
explanation about <TT>
<FONT COLOR="#0000ff">man</FONT></TT> pages.

<P>
The difference between a <I>hidden</I> file and an ordinary file
is merely that the file name of a <I>hidden</I> file starts with
a period. Hiding files in this way is not for security, but for
convenience.

<P>
The option <TT>
<FONT COLOR="#0000ff">ls&nbsp;-l</FONT></TT> is somewhat cryptic for the novice.
Its more explanatory version is <TT>
<FONT COLOR="#0000ff">ls&nbsp;&#45;&#45;format=long</FONT></TT>.
Similarly, the <I>all</I> option can be given as
<TT>
<FONT COLOR="#0000ff">ls&nbsp;&#45;&#45;all</FONT></TT>, and means the same thing as <TT>
<FONT COLOR="#0000ff">ls&nbsp;-a</FONT></TT>.

<P>

<H1><A NAME="SECTION00720000000000000000">
4.2 Error Messages</A>
</H1>

<P>
Although commands usually do not display a message when they <I>execute</I> <FONT COLOR="#ffa500">[The computer accepted and processed the command.
]</FONT> successfully, commands do report <I>errors</I> in a consistent format. The format
varies from one command to another but often appears as follows: <I>command-name</I><TT>
<FONT COLOR="#0000ff">:</FONT></TT>
<I>what was attempted</I><TT>
<FONT COLOR="#0000ff">:</FONT></TT> <I>error message</I>. For example, the command
<TT>
<FONT COLOR="#0000ff">ls&nbsp;-l&nbsp;qwerty</FONT></TT> gives an error <TT>
<FONT COLOR="#0000ff">ls:&nbsp;qwerty:&nbsp;No&nbsp;such&nbsp;file&nbsp;or
directory</FONT></TT>. What actually happened was that the command <TT>
<FONT COLOR="#0000ff">ls</FONT></TT> attempted
to read the file <TT>
<FONT COLOR="#0000ff">qwerty</FONT></TT>. Since this file does not exist, an error code
2 arose. This error code corresponds to a situation where a file or directory
is not being found. The error code is automatically translated into the sentence
<TT>
<FONT COLOR="#0000ff">No such file or directory</FONT></TT>. It is important to understand the distinction between
an explanatory message that a command gives (such as the messages reported by
the <TT>
<FONT COLOR="#0000ff">passwd</FONT></TT> command in the previous chapter) and an error code that
was just translated into a sentence. The reason is that a lot of different kinds
of problems can result in an identical error code (there are only about a hundred
different error codes). Experience will teach you that error messages do <I>not</I>
tell you what to do, only what went wrong, and should not be taken as gospel.

<P>
The file <TT>
<FONT COLOR="#0000ff">/usr/include/asm/errno.h</FONT></TT>
contains a complete list of basic error codes. In addition to these, several
other header files <FONT COLOR="#ffa500">[Files ending in <TT>
<FONT COLOR="#0000ff">.h</FONT></TT>]</FONT> might
define their own error codes. Under U<SMALL>NIX</SMALL>, however, these are 99%
of all the errors you are ever likely to get. Most of them will
be meaningless to you at the moment but are included in
Table&nbsp;<A HREF="node7.html#tab:errorcodes">4.1</A> as a reference.

<P>
<A NAME="3800"></A>
<TABLE CELLPADDING=1 BORDER="1">
<CAPTION><STRONG>Table 4.1:</STRONG>
L<SMALL>INUX</SMALL> error codes</CAPTION>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2">
<A NAME="tab:errorcodes"></A><B>Number</B> </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2"> &nbsp;<B><B>C</B> define</B> </FONT></TD>
<TH ALIGN="LEFT"><FONT SIZE="-2"> <B>Message</B> </FONT></TH>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
0       </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       &nbsp;               </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Success                 </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
1       </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EPERM</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Operation not permitted </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
2       </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENOENT</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       No such file or directory       </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
3       </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ESRCH</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       No such process         </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
4       </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EINTR</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Interrupted system call </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
5       </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EIO</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Input/output error      </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
6       </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENXIO</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Device not configured   </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
7       </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">E2BIG</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Argument list too long  </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
8       </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENOEXEC</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Exec format error       </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
9       </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EBADF</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Bad file descriptor     </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
10      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ECHILD</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       No child processes      </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
11      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EAGAIN</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Resource temporarily unavailable        </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
11      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EWOULDBLOCK</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Resource temporarily unavailable        </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
12      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENOMEM</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Cannot allocate memory  </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
13      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EACCES</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Permission denied       </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
14      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EFAULT</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Bad address     </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
15      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENOTBLK</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Block device required   </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
16      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EBUSY</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Device or resource busy </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
17      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EEXIST</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       File exists     </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
18      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EXDEV</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Invalid cross-device link       </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
19      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENODEV</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       No such device  </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
20      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENOTDIR</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Not a directory </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
21      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EISDIR</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Is a directory  </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
22      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EINVAL</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Invalid argument        </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
23      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENFILE</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Too many open files in system   </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
24      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EMFILE</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Too many open files     </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
25      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENOTTY</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Inappropriate ioctl for device  </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
26      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ETXTBSY</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Text file busy  </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
27      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EFBIG</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       File too large  </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
28      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENOSPC</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       No space left on device </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
29      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ESPIPE</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Illegal seek    </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
30      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EROFS</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Read-only file system   </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
31      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EMLINK</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Too many links  </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
32      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EPIPE</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Broken pipe     </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
33      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EDOM</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Numerical argument out of domain        </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
34      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ERANGE</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Numerical result out of range   </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
35      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EDEADLK</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Resource deadlock avoided       </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
35      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EDEADLOCK</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Resource deadlock avoided       </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
36      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENAMETOOLONG</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       File name too long      </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
37      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENOLCK</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       No locks available      </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
38      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENOSYS</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Function not implemented        </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
39      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENOTEMPTY</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Directory not empty     </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
40      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ELOOP</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Too many levels of symbolic links       </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">	<TT>
<FONT COLOR="#0000ff">EWOULDBLOCK</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2"> (<I>same as</I> <TT>
<FONT COLOR="#0000ff">EAGAIN</FONT></TT>)	</FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
42      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENOMSG</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       No message of desired type      </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
43      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EIDRM</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Identifier removed      </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
44      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ECHRNG</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Channel number out of range     </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
45      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EL2NSYNC</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Level 2 not synchronized        </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
46      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EL3HLT</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Level 3 halted  </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
47      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EL3RST</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Level 3 reset   </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
48      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ELNRNG</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Link number out of range        </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
49      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EUNATCH</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Protocol driver not attached    </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
50      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENOCSI</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       No CSI structure available      </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
51      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EL2HLT</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Level 2 halted  </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
52      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EBADE</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Invalid exchange        </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
53      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EBADR</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Invalid request descriptor      </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
54      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EXFULL</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Exchange full   </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
55      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENOANO</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       No anode        </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
56      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EBADRQC</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Invalid request code    </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
57      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EBADSLT</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Invalid slot    </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">	<TT>
<FONT COLOR="#0000ff">EDEADLOCK</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2"> (<I>same as</I> <TT>
<FONT COLOR="#0000ff">EDEADLK</FONT></TT>) </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
59      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EBFONT</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Bad font file format    </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
60      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENOSTR</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Device not a stream     </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
61      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENODATA</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       No data available       </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
62      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ETIME</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Timer expired   </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
63      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENOSR</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Out of streams resources        </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
64      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENONET</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Machine is not on the network   </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
65      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENOPKG</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Package not installed   </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
66      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EREMOTE</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Object is remote        </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
67      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENOLINK</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Link has been severed   </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
68      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EADV</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Advertise error </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
69      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ESRMNT</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Srmount error   </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
70      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ECOMM</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Communication error on send     </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
71      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EPROTO</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Protocol error  </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
72      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EMULTIHOP</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Multihop attempted      </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
73      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EDOTDOT</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       RFS specific error      </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
74      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EBADMSG</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Bad message     </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
75      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EOVERFLOW</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Value too large for defined data type   </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
76      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENOTUNIQ</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Name not unique on network      </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
77      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EBADFD</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       File descriptor in bad state    </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
78      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EREMCHG</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Remote address changed  </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
79      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ELIBACC</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Can not access a needed shared library  </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
80      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ELIBBAD</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Accessing a corrupted shared library    </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
81      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ELIBSCN</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       .lib section in a.out corrupted </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
82      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ELIBMAX</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Attempting to link in too many shared libraries </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
83      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ELIBEXEC</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Cannot exec a shared library directly   </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
84      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EILSEQ</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Invalid or incomplete multibyte or wide character       </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
85      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ERESTART</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Interrupted system call should be restarted     </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
86      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ESTRPIPE</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Streams pipe error      </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
87      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EUSERS</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Too many users  </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
88      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENOTSOCK</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Socket operation on non-socket  </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
89      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EDESTADDRREQ</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Destination address required    </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
90      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EMSGSIZE</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Message too long        </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
91      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EPROTOTYPE</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Protocol wrong type for socket  </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
92      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENOPROTOOPT</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Protocol not available  </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
93      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EPROTONOSUPPORT</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Protocol not supported  </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
94      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ESOCKTNOSUPPORT</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Socket type not supported       </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
95      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EOPNOTSUPP</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Operation not supported </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
96      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EPFNOSUPPORT</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Protocol family not supported   </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
97      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EAFNOSUPPORT</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Address family not supported by protocol        </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
98      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EADDRINUSE</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Address already in use  </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
99      </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EADDRNOTAVAIL</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Cannot assign requested address </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
100     </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENETDOWN</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Network is down </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
101     </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENETUNREACH</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Network is unreachable  </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
102     </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENETRESET</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Network dropped connection on reset     </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
103     </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ECONNABORTED</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Software caused connection abort        </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
104     </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ECONNRESET</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Connection reset by peer        </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
105     </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENOBUFS</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       No buffer space available       </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
106     </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EISCONN</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Transport endpoint is already connected </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
107     </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENOTCONN</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Transport endpoint is not connected     </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
108     </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ESHUTDOWN</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Cannot send after transport endpoint shutdown   </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
109     </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ETOOMANYREFS</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Too many references: cannot splice      </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
110     </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ETIMEDOUT</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Connection timed out    </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
111     </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ECONNREFUSED</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Connection refused      </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
112     </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EHOSTDOWN</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Host is down    </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
113     </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EHOSTUNREACH</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       No route to host        </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
114     </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EALREADY</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Operation already in progress   </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
115     </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EINPROGRESS</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Operation now in progress       </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
116     </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ESTALE</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Stale NFS file handle   </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
117     </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EUCLEAN</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Structure needs cleaning        </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
118     </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENOTNAM</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Not a XENIX named type file     </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
119     </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENAVAIL</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       No XENIX semaphores available   </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
120     </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EISNAM</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Is a named type file    </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
121     </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EREMOTEIO</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Remote I/O error        </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
122     </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EDQUOT</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Disk quota exceeded     </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
123     </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">ENOMEDIUM</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       No medium found </FONT></TD>
</TR>
<TR><TD ALIGN="LEFT"><FONT SIZE="-2"> 
124     </FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       <TT>
<FONT COLOR="#0000ff">EMEDIUMTYPE</FONT></TT>	</FONT></TD>
<TD ALIGN="LEFT"><FONT SIZE="-2">       Wrong medium type       </FONT></TD>
</TR>
</TABLE>

<P>

<H1><A NAME="SECTION00730000000000000000">
4.3 Wildcards, Names, Extensions, and <I>glob</I> Expressions</A>
</H1>

<P>
<A NAME="sec:wildcardsextglob"></A>
<P>

<TT>
<FONT COLOR="#0000ff">ls</FONT></TT> can produce a lot of output if there are a large number of files
in a directory. Now say that we are only interested in files that ended with
the letters <TT>
<FONT COLOR="#0000ff">tter</FONT></TT>. To list only these files, you can use <TT>
<FONT COLOR="#0000ff">ls&nbsp;*tter</FONT></TT>.
The <TT>
<FONT COLOR="#0000ff">*</FONT></TT> matches any number of any other characters. So, for example,
the files <TT>
<FONT COLOR="#0000ff">Tina.letter</FONT></TT>, <TT>
<FONT COLOR="#0000ff">Mary_Jones.letter</FONT></TT> and the file <TT>
<FONT COLOR="#0000ff">splatter</FONT></TT>,
would all be listed if they were present, whereas a file <TT>
<FONT COLOR="#0000ff">Harlette</FONT></TT> would
not be listed. While the <TT>
<FONT COLOR="#0000ff">*</FONT></TT> matches any length of characters, the
<TT>
<FONT COLOR="#0000ff">?</FONT></TT> matches only one character. For example, the command <TT>
<FONT COLOR="#0000ff">ls&nbsp;?ar*</FONT></TT>
would list the files <TT>
<FONT COLOR="#0000ff">Mary_Jones.letter</FONT></TT> and <TT>
<FONT COLOR="#0000ff">Harlette</FONT></TT>.

<P>

<H2><A NAME="SECTION00731000000000000000">
4.3.1 File naming</A>
</H2>

<P>
When naming files, it is a good idea to choose names that group files of the
same type together. You do this by adding an <I>extension</I> to the file name
that describes the type of file it is. We have already demonstrated this by
calling a file <TT>
<FONT COLOR="#0000ff">Mary_Jones.letter</FONT></TT> instead of just <TT>
<FONT COLOR="#0000ff">Mary_Jones</FONT></TT>.
If you keep this convention, you will be able to easily list all the files that
are letters by entering <TT>
<FONT COLOR="#0000ff">ls&nbsp;*.letter</FONT></TT>. The file name <TT>
<FONT COLOR="#0000ff">Mary_Jones.letter</FONT></TT>
is then said to be composed of two parts: the <I>name</I>, <TT>
<FONT COLOR="#0000ff">Mary_Jones</FONT></TT>,
and the <I>extension</I>, <TT>
<FONT COLOR="#0000ff">letter</FONT></TT>.

<P>
Some common U<SMALL>NIX</SMALL> extensions you may see are:

<DL>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.a</FONT></TT></STRONG></DT>
<DD>Archive. <TT>
<FONT COLOR="#0000ff">lib*.a</FONT></TT> is a static library.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.alias</FONT></TT></STRONG></DT>
<DD>X Window System font alias catalog.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.avi</FONT></TT></STRONG></DT>
<DD>Video format.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.au</FONT></TT></STRONG></DT>
<DD>Audio format (original Sun Microsystems generic sound file).
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.awk</FONT></TT></STRONG></DT>
<DD><TT>
<FONT COLOR="#0000ff">awk</FONT></TT> program source file.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.bib</FONT></TT></STRONG></DT>
<DD><TT>
<FONT COLOR="#0000ff">bibtex</FONT></TT> L<SUP><SMALL>A</SMALL></SUP>T<SMALL>E</SMALL>X bibliography source file.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.bmp</FONT></TT></STRONG></DT>
<DD>Microsoft Bitmap file image format.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.bz2</FONT></TT></STRONG></DT>
<DD>File compressed with the <TT>
<FONT COLOR="#0000ff">bzip2</FONT></TT> compression program.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.cc</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.cxx</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.C</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.cpp</FONT></TT></STRONG></DT>
<DD>C++ program source code.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.cf</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.cfg</FONT></TT></STRONG></DT>
<DD>Configuration file or script.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.cgi</FONT></TT></STRONG></DT>
<DD>Executable script that produces web page output.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.conf</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.config</FONT></TT></STRONG></DT>
<DD>Configuration file.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.csh</FONT></TT></STRONG></DT>
<DD><TT>
<FONT COLOR="#0000ff">csh</FONT></TT> shell script.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.c</FONT></TT></STRONG></DT>
<DD>&nbsp;<B>C</B> program source code.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.db</FONT></TT></STRONG></DT>
<DD>Database file.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.dir</FONT></TT></STRONG></DT>
<DD>X Window System font/other database directory.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.deb</FONT></TT></STRONG></DT>
<DD>Debian package for the Debian distribution.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.diff</FONT></TT></STRONG></DT>
<DD>Output of the <TT>
<FONT COLOR="#0000ff">diff</FONT></TT> program indicating the difference between files or source trees.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.dvi</FONT></TT></STRONG></DT>
<DD>Device-independent file. Formatted output of <TT>
<FONT COLOR="#0000ff">.tex</FONT></TT> L<SUP><SMALL>A</SMALL></SUP>T<SMALL>E</SMALL>X file.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.el</FONT></TT></STRONG></DT>
<DD>Lisp program source.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.g3</FONT></TT></STRONG></DT>
<DD>G3 fax format image file.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.gif</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.giff</FONT></TT></STRONG></DT>
<DD>GIF image file.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.gz</FONT></TT></STRONG></DT>
<DD>File compressed with the <TT>
<FONT COLOR="#0000ff">gzip</FONT></TT> compression program.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.htm</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.html</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.shtm</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.html</FONT></TT></STRONG></DT>
<DD>Hypertext Markup Language. A web page of some sort.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.h</FONT></TT></STRONG></DT>
<DD>&nbsp;<B>C</B>/C++ program header file.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.i</FONT></TT></STRONG></DT>
<DD>SWIG source, or <B>C</B> preprocessor output.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.in</FONT></TT></STRONG></DT>
<DD><TT>
<FONT COLOR="#0000ff">configure</FONT></TT> input file.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.info</FONT></TT></STRONG></DT>
<DD>Info pages read with the <TT>
<FONT COLOR="#0000ff">info</FONT></TT> command.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.jpg</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.jpeg</FONT></TT></STRONG></DT>
<DD>JPEG image file.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.lj</FONT></TT></STRONG></DT>
<DD>LaserJet file. Suitable input to a HP LaserJet printer.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.log</FONT></TT></STRONG></DT>
<DD>Log file of a system service. This file grows with status messages of some system program.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.lsm</FONT></TT></STRONG></DT>
<DD>L<SMALL>INUX</SMALL> Software Map entry.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.lyx</FONT></TT></STRONG></DT>
<DD>LyX word processor document.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.man</FONT></TT></STRONG></DT>
<DD>Man page.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.mf</FONT></TT></STRONG></DT>
<DD>Meta-Font font program source file.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.pbm</FONT></TT></STRONG></DT>
<DD>PBM image file format.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.pcf</FONT></TT></STRONG></DT>
<DD>PCF image file--intermediate representation for fonts. X Window System font.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.pcx</FONT></TT></STRONG></DT>
<DD>PCX image file.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.pfb</FONT></TT></STRONG></DT>
<DD>X Window System font file.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.pdf</FONT></TT></STRONG></DT>
<DD>Formatted document similar to PostScript or dvi.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.php</FONT></TT></STRONG></DT>
<DD>PHP program source code (used for web page design).
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.pl</FONT></TT></STRONG></DT>
<DD>Perl program source code.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.ps</FONT></TT></STRONG></DT>
<DD>PostScript file, for printing or viewing.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.py</FONT></TT></STRONG></DT>
<DD>Python program source code.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.rpm</FONT></TT></STRONG></DT>
<DD>RedHat Package Manager <TT>
<FONT COLOR="#0000ff">rpm</FONT></TT> file.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.sgml</FONT></TT></STRONG></DT>
<DD>Standard Generalized Markup Language. Used to create documents to be converted to many different formats.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.sh</FONT></TT></STRONG></DT>
<DD><TT>
<FONT COLOR="#0000ff">sh</FONT></TT> shell script.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.so</FONT></TT></STRONG></DT>
<DD>Shared object file.  <TT>
<FONT COLOR="#0000ff">lib*.so</FONT></TT> is a <I>Dynamically Linked Library</I>. <FONT COLOR="#ffa500">[Executable program code shared by more
than one program to save disk space and memory.]</FONT>
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.spd</FONT></TT></STRONG></DT>
<DD>Speedo X Window System font file.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.tar</FONT></TT></STRONG></DT>
<DD><TT>
<FONT COLOR="#0000ff">tar</FONT></TT>red directory tree.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.tcl</FONT></TT></STRONG></DT>
<DD>Tcl/Tk source code (programming language).
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.texi</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.texinfo</FONT></TT></STRONG></DT>
<DD>Texinfo source. Info pages are compiled from these.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.tex</FONT></TT></STRONG></DT>
<DD>T<SMALL>E</SMALL>X or L<SUP><SMALL>A</SMALL></SUP>T<SMALL>E</SMALL>X document. L<SUP><SMALL>A</SMALL></SUP>T<SMALL>E</SMALL>X is for document processing and typesetting.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.tga</FONT></TT></STRONG></DT>
<DD>TARGA image file.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.tgz</FONT></TT></STRONG></DT>
<DD>Directory tree that has been archived with <TT>
<FONT COLOR="#0000ff">tar</FONT></TT>, and then compressed with <TT>
<FONT COLOR="#0000ff">gzip</FONT></TT>. Also a package for the Slackware distribution.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.tiff</FONT></TT></STRONG></DT>
<DD>TIFF image file.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.tfm</FONT></TT></STRONG></DT>
<DD>L<SUP><SMALL>A</SMALL></SUP>T<SMALL>E</SMALL>X font metric file.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.ttf</FONT></TT></STRONG></DT>
<DD>Truetype font.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.txt</FONT></TT></STRONG></DT>
<DD>Plain English text file.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.voc</FONT></TT></STRONG></DT>
<DD>Audio format (Soundblaster's own format).
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.wav</FONT></TT></STRONG></DT>
<DD>Audio format (sound files common to Microsoft Windows).
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.xpm</FONT></TT></STRONG></DT>
<DD>XPM image file.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.y</FONT></TT></STRONG></DT>
<DD><TT>
<FONT COLOR="#0000ff">yacc</FONT></TT> source file.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.Z</FONT></TT></STRONG></DT>
<DD>File compressed with the <TT>
<FONT COLOR="#0000ff">compress</FONT></TT> compression program.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.zip</FONT></TT></STRONG></DT>
<DD>File compressed with the <TT>
<FONT COLOR="#0000ff">pkzip</FONT></TT> (or <TT>
<FONT COLOR="#0000ff">PKZIP.EXE</FONT></TT> for DOS) compression program.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">.1</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.2</FONT></TT> ...</STRONG></DT>
<DD>Man page.
</DD>
</DL>

<P>
In addition, files that have no extension and a capitalized descriptive name are
usually plain English text and meant for your reading. They come bundled with
packages and are for documentation purposes. You will see them hanging around all over
the place.

<P>
Some full file names you may see are:
<DL>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">AUTHORS</FONT></TT></STRONG></DT>
<DD>List of people who contributed to or wrote a package.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">ChangeLog</FONT></TT></STRONG></DT>
<DD>List of developer changes made to a package.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">COPYING</FONT></TT></STRONG></DT>
<DD>Copyright (usually GPL) for a package.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">INSTALL</FONT></TT></STRONG></DT>
<DD>Installation instructions.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">README</FONT></TT></STRONG></DT>
<DD>Help information to be read first, pertaining to the directory the <TT>
<FONT COLOR="#0000ff">README</FONT></TT> is in.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">TODO</FONT></TT></STRONG></DT>
<DD>List of future desired work to be done to package.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">BUGS</FONT></TT></STRONG></DT>
<DD>List of errata.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">NEWS</FONT></TT></STRONG></DT>
<DD>Info about new features and changes for the layman about this package.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">THANKS</FONT></TT></STRONG></DT>
<DD>List of contributors to a package.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">VERSION</FONT></TT></STRONG></DT>
<DD>Version information of the package.
</DD>
</DL>

<P>

<H2><A NAME="SECTION00732000000000000000">
4.3.2 Glob expressions</A>
</H2>

<P>
There is a way to restrict file listings to within the ranges of certain characters.
If you only want to list the files that begin with A through M, you can
run <TT>
<FONT COLOR="#0000ff">ls&nbsp;[A-M]*</FONT></TT>. Here the brackets have a special meaning--they
match a single character like a <TT>
<FONT COLOR="#0000ff">?</FONT></TT>, but only those given by the range.
You can use this feature in a variety of ways, for example, <TT>
<FONT COLOR="#0000ff">[a-dJW-Y]*</FONT></TT>
matches all files beginning with <TT>
<FONT COLOR="#0000ff">a</FONT></TT>, <TT>
<FONT COLOR="#0000ff">b</FONT></TT>, <TT>
<FONT COLOR="#0000ff">c</FONT></TT>, <TT>
<FONT COLOR="#0000ff">d</FONT></TT>,
<TT>
<FONT COLOR="#0000ff">J</FONT></TT>, <TT>
<FONT COLOR="#0000ff">W</FONT></TT>, <TT>
<FONT COLOR="#0000ff">X</FONT></TT> or <TT>
<FONT COLOR="#0000ff">Y</FONT></TT>; and <TT>
<FONT COLOR="#0000ff">*[a-d]id</FONT></TT> matches
all files ending with <TT>
<FONT COLOR="#0000ff">aid</FONT></TT>, <TT>
<FONT COLOR="#0000ff">bid</FONT></TT>, <TT>
<FONT COLOR="#0000ff">cid</FONT></TT> or <TT>
<FONT COLOR="#0000ff">did</FONT></TT>;
and <TT>
<FONT COLOR="#0000ff">*.&#123;cpp,c,cxx&#125;</FONT></TT> matches all files ending in <TT>
<FONT COLOR="#0000ff">.cpp</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.c</FONT></TT>
or <TT>
<FONT COLOR="#0000ff">.cxx</FONT></TT>.
This way of specifying a file name is called a <I>glob</I> expression. <I>Glob</I>
expressions are used in many different contexts, as you will see later.

<P>

<H1><A NAME="SECTION00740000000000000000">
4.4 Usage Summaries and the Copy Command</A>
</H1>

<P>
<A NAME="sec:usagesumm"></A>
<P>
The command <TT>
<FONT COLOR="#0000ff">cp</FONT></TT> stands for <I>copy</I>. It duplicates one or more files. The format is
<BLOCKQUOTE>
<TT>
<FONT COLOR="#0000ff">cp&nbsp;&lt;file&gt;&nbsp;&lt;newfile&gt;</FONT></TT>
<BR><TT>
<FONT COLOR="#0000ff">cp&nbsp;&lt;file&gt;&nbsp;[&lt;file&gt;&nbsp;...]&nbsp;&lt;dir&gt;</FONT></TT>

</BLOCKQUOTE>
or
<BLOCKQUOTE>
<TT>
<FONT COLOR="#0000ff">cp&nbsp;</FONT></TT><I>file</I><TT>
<FONT COLOR="#0000ff">&nbsp;</FONT></TT><I>newfile</I>
<BR><TT>
<FONT COLOR="#0000ff">cp&nbsp;</FONT></TT><I>file</I><TT>
<FONT COLOR="#0000ff">&nbsp;</FONT></TT>[<I>file</I><TT>
<FONT COLOR="#0000ff">&nbsp;</FONT></TT><I>...</I>]<TT>
<FONT COLOR="#0000ff">&nbsp;</FONT></TT><I>dir</I>

</BLOCKQUOTE>

The above lines are called a <I>usage summary</I>. The <TT>
<FONT COLOR="#0000ff">&lt;</FONT></TT>
and <TT>
<FONT COLOR="#0000ff">&gt;</FONT></TT> signs mean that you don't actually type out these
characters but replace <TT>
<FONT COLOR="#0000ff">&lt;file&gt;</FONT></TT> with a file name of your own.
These are also sometimes written in italics like, <TT>
<FONT COLOR="#0000ff">cp</FONT></TT> <I>file</I>
<I>newfile</I>. In rare cases they are written in capitals like,
<TT>
<FONT COLOR="#0000ff">cp FILE NEWFILE</FONT></TT>. <TT>
<FONT COLOR="#0000ff">&lt;file&gt;</FONT></TT> and <TT>
<FONT COLOR="#0000ff">&lt;dir&gt;</FONT></TT> are called
<I>parameters</I>. Sometimes they are obviously numeric, like a
command that takes <TT>
<FONT COLOR="#0000ff">&lt;ioport&gt;</FONT></TT>. <FONT COLOR="#ffa500">[Anyone emailing me to
ask why typing in literal, <TT>
<FONT COLOR="#0000ff">&lt;</FONT></TT>, <TT>
<FONT COLOR="#0000ff">i</FONT></TT>, <TT>
<FONT COLOR="#0000ff">o</FONT></TT>, <TT>
<FONT COLOR="#0000ff">p</FONT></TT>,
<TT>
<FONT COLOR="#0000ff">o</FONT></TT>, <TT>
<FONT COLOR="#0000ff">r</FONT></TT>, <TT>
<FONT COLOR="#0000ff">t</FONT></TT> and <TT>
<FONT COLOR="#0000ff">&gt;</FONT></TT> characters did not work will
get a rude reply.]</FONT> These are common conventions used to specify
the usage of a command. The <TT>
<FONT COLOR="#0000ff">[</FONT></TT> and <TT>
<FONT COLOR="#0000ff">]</FONT></TT> brackets are
also not actually typed but mean that the contents between them are
optional. The ellipses <TT>
<FONT COLOR="#0000ff">...</FONT></TT> mean that <TT>
<FONT COLOR="#0000ff">&lt;file&gt;</FONT></TT> can be
given repeatedly, and these also are never actually typed. From
now on you will be expected to substitute your own parameters by
interpreting the usage summary. You can see that the second of the
above lines is actually just saying that one or more file names can
be listed with a directory name last.

<P>
From the above usage summary it is obvious that there are two ways to use the
<TT>
<FONT COLOR="#0000ff">cp</FONT></TT> command. If the last name is not a directory, then <TT>
<FONT COLOR="#0000ff">cp</FONT></TT>
copies that file and renames it to the file name given. If the last name is
a directory, then <TT>
<FONT COLOR="#0000ff">cp</FONT></TT> copies all the files listed <I>into</I> that
directory.

<P>
The usage summary of the <TT>
<FONT COLOR="#0000ff">ls</FONT></TT> command is as follows:


<P><TABLE nowrap="1" width="100%" border="0" cellspacing="0" cellpadding="0">
<TR>
<TD valign="top" class="source" width="2%"><FONT color=red>
<code>&nbsp;</code><br>
<code>&nbsp;</code><br>
</FONT></TD><TD valign="top" class="source" bgcolor="#FFE0C0"><FONT color=blue>
<code>ls&nbsp;[-l,&nbsp;--format=long]&nbsp;[-a,&nbsp;--all]&nbsp;&#060;file&#062;&nbsp;&#060;file&#062;&nbsp;...</code><br>
<code>ls&nbsp;-al</code><br>
</FONT></TD></TR></TABLE><P>
where the comma indicates that either option is valid. Similarly,
with the <TT>
<FONT COLOR="#0000ff">passwd</FONT></TT> command:


<P><TABLE nowrap="1" width="100%" border="0" cellspacing="0" cellpadding="0">
<TR>
<TD valign="top" class="source" width="2%"><FONT color=red>
<code>&nbsp;</code><br>
</FONT></TD><TD valign="top" class="source" bgcolor="#FFE0C0"><FONT color=blue>
<code>passwd&nbsp;[&#060;username&#062;]</code><br>
</FONT></TD></TR></TABLE><P>
You should practice using the <TT>
<FONT COLOR="#0000ff">cp</FONT></TT> command now by moving some of your
files from place to place.

<P>

<H1><A NAME="SECTION00750000000000000000">
4.5 Directory Manipulation</A>
</H1>

<P>
The <TT>
<FONT COLOR="#0000ff">cd</FONT></TT> command is used to take you to different directories. Create
a directory <TT>
<FONT COLOR="#0000ff">new</FONT></TT> with <TT>
<FONT COLOR="#0000ff">mkdir&nbsp;new</FONT></TT>. You <I>could</I> create a
directory <TT>
<FONT COLOR="#0000ff">one</FONT></TT> by doing <TT>
<FONT COLOR="#0000ff">cd&nbsp;new</FONT></TT> and then <TT>
<FONT COLOR="#0000ff">mkdir&nbsp;one</FONT></TT>,
but there is a more direct way of doing this with <TT>
<FONT COLOR="#0000ff">mkdir&nbsp;new/one</FONT></TT>. You
can then change directly to the <TT>
<FONT COLOR="#0000ff">one</FONT></TT> directory with <TT>
<FONT COLOR="#0000ff">cd new/one</FONT></TT>.
And similarly you can get back to where you were with <TT>
<FONT COLOR="#0000ff">cd&nbsp;../..</FONT></TT>. In
this way, the <TT>
<FONT COLOR="#0000ff">/</FONT></TT> is used to represent directories within directories.
The directory <TT>
<FONT COLOR="#0000ff">one</FONT></TT> is called a <I>subdirectory</I> of <TT>
<FONT COLOR="#0000ff">new</FONT></TT>.

<P>
The command <TT>
<FONT COLOR="#0000ff">pwd</FONT></TT> stands for <I>present working directory</I> (also called
the <I>current directory</I>) and tells what directory you are
currently in. Entering <TT>
<FONT COLOR="#0000ff">pwd</FONT></TT> gives some output like <TT>
<FONT COLOR="#0000ff">/home/&lt;username&gt;</FONT></TT>.
Experiment by changing to the root directory (with <TT>
<FONT COLOR="#0000ff">cd&nbsp;/</FONT></TT>) and then back
into the directory <TT>
<FONT COLOR="#0000ff">/home/&lt;username&gt;</FONT></TT> (with <TT>
<FONT COLOR="#0000ff">cd&nbsp;/home/&lt;username&gt;</FONT></TT>).
The directory <TT>
<FONT COLOR="#0000ff">/home/&lt;username&gt;</FONT></TT> is called your <I>home directory</I>,
and is where all your personal files are kept. It can be used at any time with
the abbreviation <TT>
<FONT COLOR="#0000ff">~</FONT></TT>. In other words, entering <TT>
<FONT COLOR="#0000ff">cd&nbsp;/home/&lt;username&gt;</FONT></TT>
is the same as entering <TT>
<FONT COLOR="#0000ff">cd&nbsp;~</FONT></TT>. The process whereby a <TT>
<FONT COLOR="#0000ff">~</FONT></TT>
is substituted for your home directory is called <I>tilde expansion</I>.

<P>
To remove (i.e., erase or delete) a file, use the command
<TT>
<FONT COLOR="#0000ff">rm&nbsp;&lt;filename&gt;</FONT></TT>. To remove a directory,
use the command <TT>
<FONT COLOR="#0000ff">rmdir&nbsp;&lt;dir&gt;</FONT></TT>. Practice using these two commands. Note
that you cannot remove a directory unless it is empty. To remove a directory
as well as any contents it might contain, use the command <TT>
<FONT COLOR="#0000ff">rm&nbsp;-R&nbsp;&lt;dir&gt;</FONT></TT>.
The <TT>
<FONT COLOR="#0000ff">-R</FONT></TT> option specifies to dive into any subdirectories of <TT>
<FONT COLOR="#0000ff">&lt;dir&gt;</FONT></TT>
and delete their contents. The process whereby a command dives into subdirectories
of subdirectories of ... is called recursion. <TT>
<FONT COLOR="#0000ff">-R</FONT></TT> stands for <I>recursively</I>.
This is a very dangerous command. Although you may be used to ``undeleting'' files
on other systems, on U<SMALL>NIX</SMALL> a deleted file is, at best, extremely difficult to
recover.

<P>
The <TT>
<FONT COLOR="#0000ff">cp</FONT></TT> command also takes the <TT>
<FONT COLOR="#0000ff">-R</FONT></TT> option, allowing it to copy
whole directories. The <TT>
<FONT COLOR="#0000ff">mv</FONT></TT> command is used to move files and directories.
It really just renames a file to a different directory. Note that with <TT>
<FONT COLOR="#0000ff">cp</FONT></TT>
you should use the option <TT>
<FONT COLOR="#0000ff">-p</FONT></TT> and <TT>
<FONT COLOR="#0000ff">-d</FONT></TT> with <TT>
<FONT COLOR="#0000ff">-R</FONT></TT> to preserve all
attributes of a file and properly reproduce symlinks (discussed later). Hence, always
use <TT>
<FONT COLOR="#0000ff">cp&nbsp;-dpR&nbsp;&lt;dir&gt;&nbsp;&lt;newdir&gt;</FONT></TT> instead of <TT>
<FONT COLOR="#0000ff">cp&nbsp;-R&nbsp;&lt;dir&gt;&nbsp;&lt;newdir&gt;</FONT></TT>.

<P>

<H1><A NAME="SECTION00760000000000000000">
4.6 <I>Relative</I> vs. <I>Absolute</I> Pathnames</A>
</H1>

<P>
<A NAME="sec:relvsabspath"></A>
Commands can be given file name arguments in two ways. If you
are in the same directory as the file (i.e., the file is in the current directory),
then you can just enter the file name on its own (e.g., <TT>
<FONT COLOR="#0000ff">cp&nbsp;my_file&nbsp;new_file</FONT></TT>).
Otherwise, you can enter the <I>full path name</I>, like <TT>
<FONT COLOR="#0000ff">cp&nbsp;/home/jack/my_file
/home/jack/new_file</FONT></TT>. Very often administrators use the notation <TT>
<FONT COLOR="#0000ff">./my_file</FONT></TT>
to be clear about the distinction, for instance, <TT>
<FONT COLOR="#0000ff">cp&nbsp;./my_file&nbsp;./new_file</FONT></TT>.
The leading <TT>
<FONT COLOR="#0000ff">./</FONT></TT> makes it clear that both files are relative to the current
directory. File names not starting with a <TT>
<FONT COLOR="#0000ff">/</FONT></TT> are called <I>relative</I> path names,
and otherwise, <I>absolute</I> path names.

<P>

<H1><A NAME="SECTION00770000000000000000">
4.7 System Manual Pages</A>
</H1>

<P>
<A NAME="sec:man"></A>
<P>
(See Chapter <A HREF="node19.html#chap:alldoc">16</A> for a complete overview of all 
documentation on the system, and also how to print manual pages
in a properly typeset format.)

<P>
The command <TT>
<FONT COLOR="#0000ff">man&nbsp;[&lt;section&gt;&#124;-a]&nbsp;&lt;command&gt;</FONT></TT> displays help on
a particular topic and stands for <I>manual</I>. Every command on the entire
system is documented in so-named <I>man pages</I>. 
In the past few years a new format of documentation, called <I>info</I>, has evolved.
This is considered the modern way to document commands, but most system documentation
is still available only through <TT>
<FONT COLOR="#0000ff">man</FONT></TT>. Very few packages
are not documented in <TT>
<FONT COLOR="#0000ff">man</FONT></TT> however.

<P>
Man pages are the authoritative reference on how a command works because they
are usually written by the very programmer who created the command.
Under U<SMALL>NIX</SMALL>,
any printed documentation should be considered as being second-hand information.
Man pages, however, will often not contain the underlying concepts needed for understanding
the context in which a command is used. Hence, it is not possible for a person to
learn about U<SMALL>NIX</SMALL> purely from man pages. However, once you have the necessary background
for a command, then its man page becomes an indispensable source of information
and you can discard other introductory material.

<P>
Now, man pages are divided into sections, numbered 1 through 9. Section&nbsp;1 contains
all man pages for system commands like the ones you have been using. Sections
2-7 contain information for programmers and the like, which
you will probably not have to refer to just yet. Section&nbsp;8 contains pages specifically
for system administration commands. There are some additional sections labeled
with letters; other than these, there are no manual pages besides the sections
1 through 9. The sections are
<TABLE CELLPADDING=1 BORDER="1">
<TR><TD ALIGN="LEFT">...<TT>
<FONT COLOR="#0000ff">/man1</FONT></TT></TD>
<TD ALIGN="LEFT">User programs</TD>
</TR>
<TR><TD ALIGN="LEFT">...<TT>
<FONT COLOR="#0000ff">/man2</FONT></TT></TD>
<TD ALIGN="LEFT">System calls</TD>
</TR>
<TR><TD ALIGN="LEFT">...<TT>
<FONT COLOR="#0000ff">/man3</FONT></TT></TD>
<TD ALIGN="LEFT">Library calls</TD>
</TR>
<TR><TD ALIGN="LEFT">...<TT>
<FONT COLOR="#0000ff">/man4</FONT></TT></TD>
<TD ALIGN="LEFT">Special files</TD>
</TR>
<TR><TD ALIGN="LEFT">...<TT>
<FONT COLOR="#0000ff">/man5</FONT></TT></TD>
<TD ALIGN="LEFT">File formats</TD>
</TR>
<TR><TD ALIGN="LEFT">...<TT>
<FONT COLOR="#0000ff">/man6</FONT></TT></TD>
<TD ALIGN="LEFT">Games</TD>
</TR>
<TR><TD ALIGN="LEFT">...<TT>
<FONT COLOR="#0000ff">/man7</FONT></TT></TD>
<TD ALIGN="LEFT">Miscellaneous</TD>
</TR>
<TR><TD ALIGN="LEFT">...<TT>
<FONT COLOR="#0000ff">/man8</FONT></TT></TD>
<TD ALIGN="LEFT">System administration</TD>
</TR>
<TR><TD ALIGN="LEFT">...<TT>
<FONT COLOR="#0000ff">/man9</FONT></TT></TD>
<TD ALIGN="LEFT">Kernel documentation</TD>
</TR>
</TABLE>

<P>
You should now use the <TT>
<FONT COLOR="#0000ff">man</FONT></TT> command to look up the manual pages for
all the commands that you have learned. Type <TT>
<FONT COLOR="#0000ff">man&nbsp;cp</FONT></TT>, <TT>
<FONT COLOR="#0000ff">man&nbsp;mv</FONT></TT>,
<TT>
<FONT COLOR="#0000ff">man&nbsp;rm</FONT></TT>, <TT>
<FONT COLOR="#0000ff">man&nbsp;mkdir</FONT></TT>, <TT>
<FONT COLOR="#0000ff">man&nbsp;rmdir</FONT></TT>, <TT>
<FONT COLOR="#0000ff">man&nbsp;passwd</FONT></TT>,
<TT>
<FONT COLOR="#0000ff">man&nbsp;cd</FONT></TT>, <TT>
<FONT COLOR="#0000ff">man&nbsp;pwd</FONT></TT>, and of course <TT>
<FONT COLOR="#0000ff">man&nbsp;man</FONT></TT>. Much of the
information might be incomprehensible to you at this stage. Skim through the pages
to get an idea of how they are structured and what headings they usually contain.
Man pages are referenced with notation like <TT>
<FONT COLOR="#0000ff">cp</FONT></TT>(1), for the <TT>
<FONT COLOR="#0000ff">cp</FONT></TT>
command in Section&nbsp;1, which can be read with <TT>
<FONT COLOR="#0000ff">man&nbsp;1&nbsp;cp</FONT></TT>. This notation
will be used from here on.

<P>

<H1><A NAME="SECTION00780000000000000000">
4.8 System <TT>
<FONT COLOR="#0000ff">info</FONT></TT> Pages</A>
</H1>

<P>
<A NAME="sec:info"></A>
<P>

<TT>
<FONT COLOR="#0000ff">info</FONT></TT> pages contain some excellent reference and tutorial information
in hypertext linked format. Type <TT>
<FONT COLOR="#0000ff">info</FONT></TT> on its own to go
to the top-level menu of the entire <TT>
<FONT COLOR="#0000ff">info</FONT></TT> hierarchy. You can also
type <TT>
<FONT COLOR="#0000ff">info &lt;command&gt;</FONT></TT> for help on many basic commands.
Some packages will, however, not have info pages, and other U<SMALL>NIX</SMALL>
systems do not support <TT>
<FONT COLOR="#0000ff">info</FONT></TT> at all.

<P>
<TT>
<FONT COLOR="#0000ff">info</FONT></TT> is an interactive program with keys to
navigate and search documentation. Inside info, typing <IMG ALIGN=ABSMIDDLE BORDER=0 SRC="key-H.png" ALT="H">
will invoke the help screen from where you can learn more commands.

<P>

<H1><A NAME="SECTION00790000000000000000">
4.9 Some Basic Commands</A>
</H1>

<P>
You should practice using each of these commands.
<DL>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">bc</FONT></TT></STRONG></DT>
<DD>A calculator program that handles arbitrary precision (very large)
numbers. It is useful for doing any kind of calculation on the command-line.
Its use is left as an exercise.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">cal&nbsp;&#91;&#91;0-12&#93;&nbsp;1-9999&#93;</FONT></TT></STRONG></DT>
<DD>Prints out a nicely formatted calender
of the current month, a specified month, or a specified whole year. Try
<TT>
<FONT COLOR="#0000ff">cal 1</FONT></TT> for fun, and <TT>
<FONT COLOR="#0000ff">cal&nbsp;9&nbsp;1752</FONT></TT>, when the pope had a few days
scrapped to compensate for round-off error.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">cat&nbsp;&lt;filename&gt;&nbsp;[&lt;filename&gt;&nbsp;...]</FONT></TT></STRONG></DT>
<DD>Writes the contents of all the
files listed to the screen. <TT>
<FONT COLOR="#0000ff">cat</FONT></TT> can join a lot of files together with
<TT>
<FONT COLOR="#0000ff">cat&nbsp;&lt;filename&gt;&nbsp;&lt;filename&gt;&nbsp;...&nbsp;&gt;&nbsp;&lt;newfile&gt;</FONT></TT>. The file <TT>
<FONT COLOR="#0000ff">&lt;newfile&gt;</FONT></TT> will
be an end-on-end <I>concatenation</I> of all the files specified.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">clear</FONT></TT></STRONG></DT>
<DD>Erases all the text in the current terminal.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">date</FONT></TT></STRONG></DT>
<DD>Prints out the current date and time. (The command <TT>
<FONT COLOR="#0000ff">time</FONT></TT>,
though, does something entirely different.)
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">df</FONT></TT></STRONG></DT>
<DD>Stands for <I>disk free</I> and tells you how much free space
is left on your system. The available space usually has the units of kilobytes
(1024 bytes) (although on some other U<SMALL>NIX</SMALL> systems this will be 512 bytes or
2048 bytes). The right-most column tells the directory (in combination with
any directories below that) under which that much space is available.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">dircmp</FONT></TT></STRONG></DT>
<DD>Directory compare. This command compares directories
to see if changes have been made between them. You will often want to see where
two trees differ (e.g., check for missing files), possibly on different computers.
Run <TT>
<FONT COLOR="#0000ff">man&nbsp;dircmp</FONT></TT> (that is, <TT>
<FONT COLOR="#0000ff">dircmp</FONT></TT>(1)). (This is a System 5 command and is not present on L<SMALL>INUX</SMALL>.
You can, however, compare directories with the Midnight Commander, <TT>
<FONT COLOR="#0000ff">mc</FONT></TT>).
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">du&nbsp;&lt;directory&gt;</FONT></TT></STRONG></DT>
<DD>Stands for <I>disk usage</I> and prints out the amount
of space occupied by a directory. It recurses into any subdirectories and can
print only a summary with <TT>
<FONT COLOR="#0000ff">du&nbsp;-s&nbsp;&lt;directory&gt;</FONT></TT>. Also try <TT>
<FONT COLOR="#0000ff">du &#45;&#45;max-depth=1
/var</FONT></TT> and <TT>
<FONT COLOR="#0000ff">du&nbsp;-x&nbsp;/</FONT></TT> on a system with <TT>
<FONT COLOR="#0000ff">/usr</FONT></TT> and <TT>
<FONT COLOR="#0000ff">/home</FONT></TT>
on separate <I>partitions</I>. <FONT COLOR="#ffa500">[See page <A HREF="node21.html#page:partition"><IMG  ALIGN="BOTTOM" BORDER="1" ALT="[*]" SRC="crossref.png"></A>.]</FONT>
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">dmesg</FONT></TT></STRONG></DT>
<DD>Prints a complete log of all messages
printed to the screen during the bootup process.
This is useful if you blinked when your machine was initializing. These messages
might not yet be meaningful, however.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">echo</FONT></TT></STRONG></DT>
<DD>Prints a message to the terminal. Try <TT>
<FONT COLOR="#0000ff">echo 'hello there'</FONT></TT>,
<TT>
<FONT COLOR="#0000ff">echo $[10*3+2]</FONT></TT>, <TT>
<FONT COLOR="#0000ff">echo `$[10*3+2]'</FONT></TT>. The command <TT>
<FONT COLOR="#0000ff">echo
-e</FONT></TT> allows interpretation of certain <I>backslash</I> sequences, for example
<TT>
<FONT COLOR="#0000ff">echo&nbsp;-e&nbsp;&#34;&#92;a&#34;</FONT></TT>, which prints a <I>bell</I>,
or in other words, beeps the terminal. <TT>
<FONT COLOR="#0000ff">echo&nbsp;-n</FONT></TT> does the same without
printing the trailing newline. In other words, it does not cause a wrap to the
next line after the text is printed. <TT>
<FONT COLOR="#0000ff">echo&nbsp;-e&nbsp;-n&nbsp;&#34;&#92;b&#34;</FONT></TT>,
prints a back-space character only, which will erase the last character printed.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">exit</FONT></TT></STRONG></DT>
<DD>Logs you out.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">expr&nbsp;&lt;expression&gt;</FONT></TT></STRONG></DT>
<DD>Calculates the numerical expression <TT>
<FONT COLOR="#0000ff">expression</FONT></TT>.
Most arithmetic operations that you are accustomed to will work. Try <TT>
<FONT COLOR="#0000ff">expr
5&nbsp;+&nbsp;10&nbsp;'*'&nbsp;2</FONT></TT>. Observe how mathematical precedence is obeyed (i.e., the <TT>
<FONT COLOR="#0000ff">*</FONT></TT>
is worked out before the <TT>
<FONT COLOR="#0000ff">+</FONT></TT>).
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">file&nbsp;&lt;filename&gt;</FONT></TT></STRONG></DT>
<DD><A NAME="sec:filemagic"></A>Prints out the type of data contained
in a file. <TT>
<FONT COLOR="#0000ff">file&nbsp;portrait.jpg</FONT></TT> will tell you that <TT>
<FONT COLOR="#0000ff">portrait.jpg</FONT></TT>
is a <TT>
<FONT COLOR="#0000ff">JPEG&nbsp;image&nbsp;data,&nbsp;JFIF&nbsp;standard</FONT></TT>. The command <TT>
<FONT COLOR="#0000ff">file</FONT></TT> detects an enormous
amount of file types, across every platform. <TT>
<FONT COLOR="#0000ff">file</FONT></TT> works by checking whether
the first few bytes of a file match certain tell-tale byte sequences. The byte
sequences are called <I>magic numbers</I>. Their complete list is stored
in <TT>
<FONT COLOR="#0000ff">/usr/share/magic</FONT></TT>. <FONT COLOR="#ffa500">[The word ``magic'' under U<SMALL>NIX</SMALL> normally
refers to byte sequences or numbers that have a specific meaning or implication.
So-called <I>magic numbers</I> are invented for source code,
file formats, and file systems.]</FONT>
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">free</FONT></TT></STRONG></DT>
<DD>Prints out available free memory. You will notice two listings:
swap space and physical memory. These are contiguous as far as the user is concerned.
The swap space is a continuation of your installed memory that exists on disk.
It is obviously slow to access but provides the illusion of much more
available RAM and avoids the possibility of ever running out of memory
(which can be quite fatal).
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">head&nbsp;[-n&nbsp;&lt;lines&gt;]&nbsp;&lt;filename&gt;</FONT></TT></STRONG></DT>
<DD>Prints the first <TT>
<FONT COLOR="#0000ff">&lt;lines&gt;</FONT></TT>
lines of a file or 10 lines if the <TT>
<FONT COLOR="#0000ff">-n</FONT></TT> option is not given. (See also <TT>
<FONT COLOR="#0000ff">tail</FONT></TT> below).
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">hostname [&lt;new-name&gt;]</FONT></TT></STRONG></DT>
<DD>With no options, <TT>
<FONT COLOR="#0000ff">hostname</FONT></TT>
prints the name of your machine, otherwise it sets the name to <TT>
<FONT COLOR="#0000ff">&lt;new-name&gt;</FONT></TT>.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">kbdrate&nbsp;-r&nbsp;&lt;chars-per-second&gt;&nbsp;-d&nbsp;&lt;repeat-delay&gt;</FONT></TT></STRONG></DT>
<DD>Changes the
repeat rate of your keys.
Most users will like this rate set to <TT>
<FONT COLOR="#0000ff">kbdrate&nbsp;-r&nbsp;32&nbsp;-d&nbsp;250</FONT></TT>
which unfortunately is the fastest the PC can go.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">more</FONT></TT></STRONG></DT>
<DD>Displays a long file by stopping at the end of each page. Run
the following: <TT>
<FONT COLOR="#0000ff">ls&nbsp;-l&nbsp;/bin&nbsp;&gt;&nbsp;bin-ls</FONT></TT>, and then try <TT>
<FONT COLOR="#0000ff">more&nbsp;bin-ls</FONT></TT>. The first
command creates a file with the contents of the output of <TT>
<FONT COLOR="#0000ff">ls</FONT></TT>. This
will be a long file because the directory <TT>
<FONT COLOR="#0000ff">/bin</FONT></TT> has a great many entries.
The second command views the file. Use the space bar to page through
the file. When you get bored, just press <IMG ALIGN=ABSMIDDLE BORDER=0 SRC="key-Q.png" ALT="Q">. You can also try <TT>
<FONT COLOR="#0000ff">ls&nbsp;-l&nbsp;/bin&nbsp;&#124;&nbsp;more</FONT></TT>
which will do the same thing in one go.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">less</FONT></TT></STRONG></DT>
<DD>The GNU version of <TT>
<FONT COLOR="#0000ff">more</FONT></TT>, but with extra features. On your
system, the two commands may be the same. With <TT>
<FONT COLOR="#0000ff">less</FONT></TT>, you can use the
arrow keys to page up and down through the file. You can do searches by pressing
<IMG ALIGN=ABSMIDDLE BORDER=0 SRC="key-question.png" ALT="?">, and then typing in a word to search for
and then pressing <IMG ALIGN=ABSMIDDLE BORDER=0 SRC="key-enter.png" ALT="Enter">. Found words will
be highlighted, and the text will be scrolled to the first found word. The important
commands are:
<DL>
<DT><STRONG><IMG ALIGN=ABSMIDDLE BORDER=0 SRC="key-shift.png" ALT="Shift">-<IMG ALIGN=ABSMIDDLE BORDER=0 SRC="key-G.png" ALT="G"></STRONG></DT>
<DD>Go to the end of a file.
</DD>
<DT><STRONG><IMG ALIGN=ABSMIDDLE BORDER=0 SRC="key-shift.png" ALT="Shift">-<IMG ALIGN=ABSMIDDLE BORDER=0 SRC="key-question.png" ALT="?"><I>ssss</I></STRONG></DT>
<DD>Search backward through a file for the text <I>ssss</I>.
</DD>
<DT><STRONG><IMG ALIGN=ABSMIDDLE BORDER=0 SRC="key-question.png" ALT="?"><I>ssss</I></STRONG></DT>
<DD>Search forward through a file for the text <I>ssss</I>.
 <FONT COLOR="#ffa500">[Actually <I>ssss</I> is a <I>regular expression</I>. See Chapter <A HREF="node8.html#chap:regexp">5</A> for more info.]</FONT>
</DD>
<DT><STRONG><IMG ALIGN=ABSMIDDLE BORDER=0 SRC="key-shift.png" ALT="Shift">-<IMG ALIGN=ABSMIDDLE BORDER=0 SRC="key-F.png" ALT="F"></STRONG></DT>
<DD>Scroll forward and keep trying to read more of the file in case
some other program is appending to it--useful for log files.
</DD>
<DT><STRONG><I>nnn</I>-<IMG ALIGN=ABSMIDDLE BORDER=0 SRC="key-G.png" ALT="G"></STRONG></DT>
<DD>Go to line <I>nnn</I> of the file.
</DD>
<DT><STRONG><IMG ALIGN=ABSMIDDLE BORDER=0 SRC="key-Q.png" ALT="Q"></STRONG></DT>
<DD>Quit. Used by many U<SMALL>NIX</SMALL> text-based applications (sometimes <IMG ALIGN=ABSMIDDLE BORDER=0 SRC="key-Q.png" ALT="Q">-<IMG ALIGN=ABSMIDDLE BORDER=0 SRC="key-enter.png" ALT="Enter">).
</DD>
</DL>
(You can make <TT>
<FONT COLOR="#0000ff">less</FONT></TT> stop beeping in the irritating way that it does by
editing the file <TT>
<FONT COLOR="#0000ff">/etc/profile</FONT></TT> and adding the lines
</DD>
</DL>

<P><TABLE nowrap="1" width="100%" border="0" cellspacing="0" cellpadding="0">
<TR>
<TD valign="top" class="source" width="2%"><FONT color=red>
<code>&nbsp;</code><br>
<code>&nbsp;</code><br>
</FONT></TD><TD valign="top" class="source" bgcolor="#FFE0C0"><FONT color=blue>
<code>LESS=-Q</code><br>
<code>export&nbsp;LESS</code><br>
</FONT></TD></TR></TABLE><P>
<DL>
<DT></DT>
<DD>and then logging out and logging in again.
But this is an aside that will make more sense later.)
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">lynx&nbsp;&lt;url&gt;</FONT></TT></STRONG></DT>
<DD>Opens a URL <FONT COLOR="#ffa500">[URL stands for <I>Uniform Resource Locator</I>--a web address.]</FONT>at the console. Try <TT>
<FONT COLOR="#0000ff">lynx&nbsp;http://lwn.net/</FONT></TT>.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">links&nbsp;&lt;url&gt;</FONT></TT></STRONG></DT>
<DD>Another text-based web browser.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">nohup&nbsp;&lt;command&gt;&nbsp;&amp;</FONT></TT></STRONG></DT>
<DD>Runs a command in the background, appending any
output the command may produce to the file <TT>
<FONT COLOR="#0000ff">nohup.out</FONT></TT> in your home directory.
<TT>
<FONT COLOR="#0000ff">nohup</FONT></TT> has the useful feature that the command will continue to run even
after you have logged out. Uses for <TT>
<FONT COLOR="#0000ff">nohup</FONT></TT> will become obvious later.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">sleep&nbsp;&lt;seconds&gt;</FONT></TT></STRONG></DT>
<DD>Pauses for <TT>
<FONT COLOR="#0000ff">&lt;seconds&gt;</FONT></TT> seconds. See also <TT>
<FONT COLOR="#0000ff">usleep</FONT></TT>.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">sort&nbsp;&lt;filename&gt;</FONT></TT></STRONG></DT>
<DD>Prints a file with lines sorted in alphabetical
order. Create a file called <TT>
<FONT COLOR="#0000ff">telephone</FONT></TT> with each line containing a short
telephone book entry. Then type <TT>
<FONT COLOR="#0000ff">sort&nbsp;telephone</FONT></TT>, or <TT>
<FONT COLOR="#0000ff">sort&nbsp;telephone
|&nbsp;less</FONT></TT> and see what happens. <TT>
<FONT COLOR="#0000ff">sort</FONT></TT> takes many interesting options to sort in
reverse (<TT>
<FONT COLOR="#0000ff">sort&nbsp;-r</FONT></TT>), to eliminate duplicate entries (<TT>
<FONT COLOR="#0000ff">sort&nbsp;-u</FONT></TT>),
to ignore leading whitespace (<TT>
<FONT COLOR="#0000ff">sort&nbsp;-b</FONT></TT>), and so on. See the <TT>
<FONT COLOR="#0000ff">sort</FONT></TT>(1)
for details.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">strings&nbsp;[-n &lt;len&gt;]&nbsp;&lt;filename&gt;</FONT></TT></STRONG></DT>
<DD>Writes out a binary file, but strips any unreadable
characters. Readable groups of characters are placed on separate lines. If you
have a binary file that you think may contain something interesting but looks
completely garbled when viewed normally, use <TT>
<FONT COLOR="#0000ff">strings</FONT></TT> to sift out the interesting
stuff: try <TT>
<FONT COLOR="#0000ff">less&nbsp;/bin/cp</FONT></TT> and then try <TT>
<FONT COLOR="#0000ff">strings&nbsp;/bin/cp</FONT></TT>.
By default <TT>
<FONT COLOR="#0000ff">strings</FONT></TT> does not print sequences smaller than 4. The <TT>
<FONT COLOR="#0000ff">-n</FONT></TT>
option can alter this limit.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">split&nbsp;...</FONT></TT></STRONG></DT>
<DD>Splits a file into many separate files. This might have
been used when a file was too big to be copied onto a floppy disk and needed
to be split into, say, 360-KB pieces. Its sister, <TT>
<FONT COLOR="#0000ff">csplit</FONT></TT>, can split
files along specified lines of text within the file. The commands are seldom
used on their own but are very useful within programs that manipulate text.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">tac&nbsp;&lt;filename&gt;&nbsp;[&lt;filename&gt;&nbsp;...]</FONT></TT></STRONG></DT>
<DD>Writes the contents of all the
files listed to the screen, reversing the order of the lines--that is, printing
the last line of the file first. <TT>
<FONT COLOR="#0000ff">tac</FONT></TT> is <TT>
<FONT COLOR="#0000ff">cat</FONT></TT> backwards and behaves
similarly.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">tail&nbsp;[-f]&nbsp;[-n&nbsp;&lt;lines&gt;]&nbsp;&lt;filename&gt;</FONT></TT></STRONG></DT>
<DD>Prints the last <TT>
<FONT COLOR="#0000ff">&lt;lines&gt;</FONT></TT>
lines of a file or 10 lines if the <TT>
<FONT COLOR="#0000ff">-n</FONT></TT> option is not given. The <TT>
<FONT COLOR="#0000ff">-f</FONT></TT>
option means to watch the file for lines being appended to the end of it.
(See also <TT>
<FONT COLOR="#0000ff">head</FONT></TT> above.)
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">uname</FONT></TT></STRONG></DT>
<DD>Prints the name of the U<SMALL>NIX</SMALL> <I>operating system</I>
you are currently using. In this case, L<SMALL>INUX</SMALL>.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">uniq&nbsp;&lt;filename&gt;</FONT></TT></STRONG></DT>
<DD>Prints a file with duplicate lines deleted. The
file must first be sorted.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">usleep&nbsp;&lt;microseconds&gt;</FONT></TT></STRONG></DT>
<DD>Pauses for <TT>
<FONT COLOR="#0000ff">&lt;microseconds&gt;</FONT></TT>
microseconds (1/1,000,000 of a second).
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">wc [-c] [-w] [-l] &lt;filename&gt;</FONT></TT></STRONG></DT>
<DD>Counts the number of bytes
(with <TT>
<FONT COLOR="#0000ff">-c</FONT></TT> for <TT>
<FONT COLOR="#0000ff">c</FONT></TT>haracter), or words (with <TT>
<FONT COLOR="#0000ff">-w</FONT></TT>), or lines (with <TT>
<FONT COLOR="#0000ff">-l</FONT></TT>) in a file.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">whatis&nbsp;&lt;command&gt;</FONT></TT><A NAME="page:whatiscommand"></A></STRONG></DT>
<DD>Gives the first
line of the man page corresponding to <TT>
<FONT COLOR="#0000ff">&lt;command&gt;</FONT></TT>, unless no such
page exists, in which case it prints <TT>
<FONT COLOR="#0000ff">nothing appropriate</FONT></TT>.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">whoami</FONT></TT></STRONG></DT>
<DD>Prints your login name.
</DD>
</DL>

<P>

<H1><A NAME="SECTION007100000000000000000">
4.10 The <TT>
<FONT COLOR="#0000ff">mc</FONT></TT> File Manager</A>
</H1>

<P>
Those who come from the DOS world may remember the famous

<I>Norton Commander</I> file manager. The GNU project has a
Free clone called the <I>Midnight Commander</I>, <TT>
<FONT COLOR="#0000ff">mc</FONT></TT>.
It is essential to at least try out this package--it allows
you to move around files and directories extremely rapidly,
giving a wide-angle picture of the file system. This will
drastically reduce the number of tedious commands you will
have to type by hand.

<P>

<H1><A NAME="SECTION007110000000000000000">
4.11 Multimedia Commands for Fun</A>
</H1>

<P>
You should practice using each of these commands if you have
your sound card configured. <FONT COLOR="#ffa500">[I don't want to give the
impression that L<SMALL>INUX</SMALL> does not have graphical applications to do
all the functions in this section, but you should be aware that for every
graphical application, there is a text-mode one that works better and
consumes fewer resources.]</FONT> You may also find that some of these
packages are not installed, in which case you can come back to
this later.
<DL>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">play [-v &lt;volume&gt;] &lt;filename&gt;</FONT></TT></STRONG></DT>
<DD>Plays linear audio formats
out through your sound card. These formats are
<TT>
<FONT COLOR="#0000ff">.8svx</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.aiff</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.au</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.cdr</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.cvs</FONT></TT>,
<TT>
<FONT COLOR="#0000ff">.dat</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.gsm</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.hcom</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.maud</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.sf</FONT></TT>,
<TT>
<FONT COLOR="#0000ff">.smp</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.txw</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.vms</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.voc</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.wav</FONT></TT>,
<TT>
<FONT COLOR="#0000ff">.wve</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.raw</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.ub</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.sb</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.uw</FONT></TT>,
<TT>
<FONT COLOR="#0000ff">.sw</FONT></TT>, or <TT>
<FONT COLOR="#0000ff">.ul</FONT></TT> files. In other words, it plays almost
every type of ``basic'' sound file there is: most often this will be
a simple Windows <TT>
<FONT COLOR="#0000ff">.wav</FONT></TT> file. Specify <TT>
<FONT COLOR="#0000ff">&lt;volume&gt;</FONT></TT> in percent.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">rec &lt;filename&gt;</FONT></TT></STRONG></DT>
<DD>Records from your microphone into a file.
(<TT>
<FONT COLOR="#0000ff">play</FONT></TT> and <TT>
<FONT COLOR="#0000ff">rec</FONT></TT> are from the same package.)
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">mpg123 &lt;filename&gt;</FONT></TT></STRONG></DT>
<DD>Plays audio from MPEG files level
1, 2, or 3. Useful options are <TT>
<FONT COLOR="#0000ff">-b 1024</FONT></TT> (for increasing the
buffer size to prevent jumping) and <TT>
<FONT COLOR="#0000ff">&#45;&#45;2to1</FONT></TT> (down-samples by
a factor of 2 for reducing CPU load). MPEG files contain sound
and/or video, stored very compactly using digital signal processing
techniques that the commercial software industry seems to think are very
sophisticated.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">cdplay</FONT></TT></STRONG></DT>
<DD>Plays a regular music CD. <TT>
<FONT COLOR="#0000ff">cdp</FONT></TT> is the
interactive version.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">aumix</FONT></TT></STRONG></DT>
<DD>Sets your sound card's volume, gain, recording
volume, etc. You can use it interactively or just enter <TT>
<FONT COLOR="#0000ff">aumix
-v &lt;volume&gt;</FONT></TT> to immediately set the volume in percent. Note that
this is a dedicated <I>mixer</I> program and is considered to be an
application separate from any that play music. Preferably do not set the
volume from within a sound-playing application, even if it claims
this feature--you have much better control with <TT>
<FONT COLOR="#0000ff">aumix</FONT></TT>.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">mikmod &#45;&#45;interpolate -hq &#45;&#45;renice Y &lt;filename&gt;</FONT></TT></STRONG></DT>
<DD>Plays
<I>Mod</I> files. Mod files are a special type of audio format that
stores only the duration and pitch of the notes that constitute a song,
along with samples of each musical instrument needed to play the
song. This makes for high-quality audio with phenomenally small
file size. <TT>
<FONT COLOR="#0000ff">mikmod</FONT></TT> supports 669, AMF, DSM, FAR, GDM, IMF,
IT, MED, MOD, MTM, S3M, STM, STX, ULT, UNI, and XM audio
formats--that is, probably every type in existence. Actually,
a lot of excellent listening music is available on the Internet in Mod
file format. The most common formats are <TT>
<FONT COLOR="#0000ff">.it</FONT></TT>, <TT>
<FONT COLOR="#0000ff">.mod</FONT></TT>,
<TT>
<FONT COLOR="#0000ff">.s3m</FONT></TT>, and <TT>
<FONT COLOR="#0000ff">.xm</FONT></TT>. <FONT COLOR="#ffa500">[Original <TT>
<FONT COLOR="#0000ff">.mod</FONT></TT> files are the
product of Commodore-Amiga computers and had only four tracks. Today's 16
(and more) track Mod files are comparable to any recorded music.]</FONT>
</DD>
</DL>

<P>

<H1><A NAME="SECTION007120000000000000000">
4.12 Terminating Commands</A>
</H1>

<P>
You usually use <IMG ALIGN=ABSMIDDLE BORDER=0 SRC="key-ctrl.png" ALT="Ctrl">-<IMG ALIGN=ABSMIDDLE BORDER=0 SRC="key-C.png" ALT="C"> to stop an application or command that runs
continuously. You must type this at the same prompt where you
entered the command. If this doesn't work, the section on
<I>processes</I> (Section <A HREF="node12.html#sec:killingproc">9.5</A>) will explain
about <I>signalling</I> a running application to quit.

<P>

<H1><A NAME="SECTION007130000000000000000">
4.13 Compressed Files</A>
</H1>

<P>
Files typically contain a lot of data that one can imagine might be
represented with a smaller number of bytes. Take for example the
letter you typed out. The word ``the'' was probably repeated many
times. You were probably also using lowercase letters most of the
time. The file was by far not a completely random set of bytes, and
it repeatedly used spaces as well as using some letters more than
others. <FONT COLOR="#ffa500">[English text in fact contains, on average, only about
1.3 useful bits (there are eight bits in a byte) of data per byte.]</FONT>Because of this the file can be <I>compressed</I> to take up less
space. Compression involves representing the same data by using a
smaller number of bytes, in such a way that the original data can be
reconstructed exactly. Such usually involves finding patterns in the
data. The command to compress a file is <TT>
<FONT COLOR="#0000ff">gzip&nbsp;&lt;filename&gt;</FONT></TT>,
which stands for <I>GNU zip</I>. Run <TT>
<FONT COLOR="#0000ff">gzip</FONT></TT> on a file in your home
directory and then run <TT>
<FONT COLOR="#0000ff">ls</FONT></TT> to see what happened. Now, use
<TT>
<FONT COLOR="#0000ff">more</FONT></TT> to view the compressed file. To uncompress the file
use <TT>
<FONT COLOR="#0000ff">gzip&nbsp;-d&nbsp;&lt;filename&gt;</FONT></TT>. Now, use <TT>
<FONT COLOR="#0000ff">more</FONT></TT> to view
the file again. Many files on the system are stored
in compressed format. For example, man pages are often stored
compressed and are uncompressed automatically when you read
them.

<P>
You previously used the command <TT>
<FONT COLOR="#0000ff">cat</FONT></TT> to view a file. You can use the
command <TT>
<FONT COLOR="#0000ff">zcat</FONT></TT> to do the same thing with a compressed file. Gzip a file
and then type <TT>
<FONT COLOR="#0000ff">zcat&nbsp;&lt;filename&gt;</FONT></TT>. You will see that the contents of the
file are written to the screen. Generally, when commands and files have a <TT>
<FONT COLOR="#0000ff">z</FONT></TT>
in them they have something to do with compression--the letter <TT>
<FONT COLOR="#0000ff">z</FONT></TT> stands for
<I>zip</I>. You can use <TT>
<FONT COLOR="#0000ff">zcat&nbsp;&lt;filename&gt;&nbsp;&#124;&nbsp;less</FONT></TT> to view a compressed
file proper. You can also use the command <TT>
<FONT COLOR="#0000ff">zless&nbsp;&lt;filename&gt;</FONT></TT>, which does
the same as <TT>
<FONT COLOR="#0000ff">zcat&nbsp;&lt;filename&gt;&nbsp;&#124;&nbsp;less</FONT></TT>. (Note that your <TT>
<FONT COLOR="#0000ff">less</FONT></TT> may
actually have the functionality of <TT>
<FONT COLOR="#0000ff">zless</FONT></TT> combined.)

<P>
A new addition to the arsenal is <TT>
<FONT COLOR="#0000ff">bzip2</FONT></TT>. This is a compression program
very much like <TT>
<FONT COLOR="#0000ff">gzip</FONT></TT>, except that it is slower and compresses 20%-30%
better. It is useful for compressing files that will be downloaded from the
Internet (to reduce the transfer volume). Files that are compressed with <TT>
<FONT COLOR="#0000ff">bzip2</FONT></TT>
have an extension <TT>
<FONT COLOR="#0000ff">.bz2</FONT></TT>. Note that the improvement in compression depends
very much on the type of data being compressed. Sometimes there will be negligible
size reduction at the expense of a huge speed penalty, while occasionally it is
well worth it. Files that are frequently compressed and uncompressed should never
use <TT>
<FONT COLOR="#0000ff">bzip2</FONT></TT>.

<P>

<H1><A NAME="SECTION007140000000000000000">
4.14 Searching for Files</A>
</H1>

<P>
<A NAME="sec:searchingforfiles"></A>
<P>
You can use the command <TT>
<FONT COLOR="#0000ff">find</FONT></TT> to search for files. Change to the root
directory, and enter <TT>
<FONT COLOR="#0000ff">find</FONT></TT>. It will spew out all the files it can see
by <I>recursively descending</I> <FONT COLOR="#ffa500">[Goes into each subdirectory and all its subdirectories, and repeats the command
<TT>
<FONT COLOR="#0000ff">find</FONT></TT>.
]</FONT> into all subdirectories. In other words, <TT>
<FONT COLOR="#0000ff">find</FONT></TT>, when executed from
the root directory, prints all the files on the system. <TT>
<FONT COLOR="#0000ff">find</FONT></TT>
will work for a long time if you enter it as you have--press <IMG ALIGN=ABSMIDDLE BORDER=0 SRC="key-ctrl.png" ALT="Ctrl">-<IMG ALIGN=ABSMIDDLE BORDER=0 SRC="key-C.png" ALT="C"> to stop
it.

<P>
Now change back to your home directory and type <TT>
<FONT COLOR="#0000ff">find</FONT></TT> again. You will
see <I>all</I> your personal files. You can specify a number of options to <TT>
<FONT COLOR="#0000ff">find</FONT></TT>
to look for specific files.

<P>
<DL>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">find&nbsp;-type&nbsp;d</FONT></TT></STRONG></DT>
<DD>Shows only directories and not the files they contain.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">find&nbsp;-type&nbsp;f</FONT></TT></STRONG></DT>
<DD>Shows only files and not the directories that contain
them, even though it will still descend into all directories.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">find&nbsp;-name&nbsp;&lt;filename&gt;</FONT></TT></STRONG></DT>
<DD>Finds only files that have the name <TT>
<FONT COLOR="#0000ff">&lt;filename&gt;</FONT></TT>.
For instance, <TT>
<FONT COLOR="#0000ff">find&nbsp;-name&nbsp;'*.c'</FONT></TT> will find all files that end in a
<TT>
<FONT COLOR="#0000ff">.c</FONT></TT> extension (<TT>
<FONT COLOR="#0000ff">find&nbsp;-name&nbsp;*.c</FONT></TT> without the quote characters
will not work. You will see why later). <TT>
<FONT COLOR="#0000ff">find&nbsp;-name&nbsp;Mary_Jones.letter</FONT></TT>
will find the file with the name <TT>
<FONT COLOR="#0000ff">Mary_Jones.letter</FONT></TT>.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">find&nbsp;-size&nbsp;&#91;&#91;+&#124;-&#93;&#93;&lt;size&gt;</FONT></TT></STRONG></DT>
<DD>Finds only files that have a
size larger (for <TT>
<FONT COLOR="#0000ff">+</FONT></TT>) or smaller (for <TT>
<FONT COLOR="#0000ff">-</FONT></TT>) than <TT>
<FONT COLOR="#0000ff">&lt;size&gt;</FONT></TT>
kilobytes, or the same as <TT>
<FONT COLOR="#0000ff">&lt;size&gt;</FONT></TT> kilobytes if the sign is not specified.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">find&nbsp;&lt;directory&gt;&nbsp;&#91;&lt;directory&gt;&nbsp;...&#93;</FONT></TT></STRONG></DT>
<DD>Starts <TT>
<FONT COLOR="#0000ff">find</FONT></TT> in each of the specified directories.
</DD>
</DL>
There are many more options for doing just about any type of search
for a file. See <TT>
<FONT COLOR="#0000ff">find</FONT></TT>(1) for more details (that is, run <TT>
<FONT COLOR="#0000ff">man 1 find</FONT></TT>).
Look also at the <TT>
<FONT COLOR="#0000ff">-exec</FONT></TT> option which causes <TT>
<FONT COLOR="#0000ff">find</FONT></TT> to execute a command
for each file it finds, for example:


<P><TABLE nowrap="1" width="100%" border="0" cellspacing="0" cellpadding="0">
<TR>
<TD valign="top" class="source" width="2%"><FONT color=red>
<code>&nbsp;</code><br>
</FONT></TD><TD valign="top" class="source" bgcolor="#FFE0C0"><FONT color=blue>
<code>find&nbsp;/usr&nbsp;-type&nbsp;f&nbsp;-exec&nbsp;ls&nbsp;'-al'&nbsp;'{}'&nbsp;'&#059;'</code><br>
</FONT></TD></TR></TABLE><P>

<P>
<TT>
<FONT COLOR="#0000ff">find</FONT></TT> has the deficiency of actively reading directories to find files. This process is slow,
especially when you start from the root directory. An alternative command is
<A NAME="page:locatecommand"></A><TT>
<FONT COLOR="#0000ff">locate&nbsp;&lt;filename&gt;</FONT></TT>. This searches through a previously created database
of all the files on the system and hence finds files instantaneously. Its counterpart
<TT>
<FONT COLOR="#0000ff">updatedb</FONT></TT> updates the database of files used by <TT>
<FONT COLOR="#0000ff">locate</FONT></TT>.
On some systems, <TT>
<FONT COLOR="#0000ff">updatedb</FONT></TT> runs automatically every day at 04h00.

<P>
Try these (<TT>
<FONT COLOR="#0000ff">updatedb</FONT></TT> will take several minutes):

<P><TABLE nowrap="1" width="100%" border="0" cellspacing="0" cellpadding="0">
<TR>
<TD valign="top" class="source" width="2%"><FONT color=red>
<code>&nbsp;</code><br>
<code>&nbsp;</code><br>
<code>&nbsp;</code><br>
<code>&nbsp;</code><br>
<font size="-1"><code>5</code></font><code>&nbsp;</code><br>
<code>&nbsp;</code><br>
</FONT></TD><TD valign="top" class="source" bgcolor="#FFE0C0"><FONT color=blue>
<code>updatedb</code><br>
<code>locate&nbsp;rpm</code><br>
<code>locate&nbsp;deb</code><br>
<code>locate&nbsp;passwd</code><br>
<code>locate&nbsp;HOWTO</code><br>
<code>locate&nbsp;README</code><br>
</FONT></TD></TR></TABLE><P>

<P>

<H1><A NAME="SECTION007150000000000000000">
4.15 Searching <I>Within</I> Files</A>
</H1>

<P>
Very often you will want to  search through a number of files to find a particular
word or phrase, for example, when a number of files contain lists of
telephone numbers with people's names and addresses. The command <TT>
<FONT COLOR="#0000ff">grep</FONT></TT>
does a line-by-line search through a file and prints only those lines that
contain a word that you have specified. <TT>
<FONT COLOR="#0000ff">grep</FONT></TT> has the command summary:

<P><TABLE nowrap="1" width="100%" border="0" cellspacing="0" cellpadding="0">
<TR>
<TD valign="top" class="source" width="2%"><FONT color=red>
<code>&nbsp;</code><br>
</FONT></TD><TD valign="top" class="source" bgcolor="#FFE0C0"><FONT color=blue>
<code>grep&nbsp;[options]&nbsp;&#060;pattern&#062;&nbsp;&#060;filename&#062;&nbsp;[&#060;filename&#062;&nbsp;...]</code><br>
</FONT></TD></TR></TABLE><P>
 <FONT COLOR="#ffa500">[The words <I>word</I>, <I>string</I>, or <I>pattern</I> are used synonymously
in this context, basically meaning a short length of letters and-or numbers
that you are trying to find matches for. A <I>pattern</I> can also be a string
with kinds of wildcards in it that match different characters, as we shall see
later.]</FONT>
<P>
Run <TT>
<FONT COLOR="#0000ff">grep</FONT></TT> for the word ``the'' to display all lines containing it: <TT>
<FONT COLOR="#0000ff">grep
'the'&nbsp;Mary_Jones.letter</FONT></TT>. Now try <TT>
<FONT COLOR="#0000ff">grep&nbsp;'the'&nbsp;*.letter</FONT></TT>.

<P>
<DL>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">grep&nbsp;-n&nbsp;&lt;pattern&gt;&nbsp;&lt;filename&gt;</FONT></TT></STRONG></DT>
<DD>shows the line number in the file where the word was found.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">grep&nbsp;-&lt;num&gt;&nbsp;&lt;pattern&gt;&nbsp;&lt;filename&gt;</FONT></TT></STRONG></DT>
<DD>prints out <TT>
<FONT COLOR="#0000ff">&lt;num&gt;</FONT></TT> of
the lines that came before and after each of the lines in which the word was
found.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">grep&nbsp;-A&nbsp;&lt;num&gt;&nbsp;&lt;pattern&gt;&nbsp;&lt;filename&gt;</FONT></TT></STRONG></DT>
<DD>prints out <TT>
<FONT COLOR="#0000ff">&lt;num&gt;</FONT></TT> of
the lines that came <TT>
<FONT COLOR="#0000ff">A</FONT></TT>fter each of the lines in which the word was found.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">grep&nbsp;-B&nbsp;&lt;num&gt;&nbsp;&lt;pattern&gt;&nbsp;&lt;filename&gt;</FONT></TT></STRONG></DT>
<DD>prints out <TT>
<FONT COLOR="#0000ff">&lt;num&gt;</FONT></TT> of
the lines that came <TT>
<FONT COLOR="#0000ff">B</FONT></TT>efore each of the lines in which the word was
found.
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">grep&nbsp;-v&nbsp;&lt;pattern&gt;&nbsp;&lt;filename&gt;</FONT></TT></STRONG></DT>
<DD>prints out only those lines that
do <I>not</I> contain the word you are searching for. <FONT COLOR="#ffa500">[
You may think that the <TT>
<FONT COLOR="#0000ff">-v</FONT></TT> option is no longer
doing the same kind of thing that <TT>
<FONT COLOR="#0000ff">grep</FONT></TT> is advertised
to do: i.e., <I>searching</I> for strings. In fact, U<SMALL>NIX</SMALL> commands
often suffer from this--they have such versatility that their functionality
often overlaps with that of other commands. One actually never stops learning
new and nifty ways of doing things hidden in the dark corners of man pages.]</FONT>
</DD>
<DT><STRONG><TT>
<FONT COLOR="#0000ff">grep&nbsp;-i&nbsp;&lt;pattern&gt;&nbsp;&lt;filename&gt;</FONT></TT></STRONG></DT>
<DD>does the same as an ordinary <TT>
<FONT COLOR="#0000ff">grep</FONT></TT> but
is case insensitive.
</DD>
</DL>

<P>

<H1><A NAME="SECTION007160000000000000000">
4.16 Copying to MS-DOS and Windows Formatted Floppy Disks</A>
</H1>

<P>
<A NAME="sec:mtools"></A>
A package, called the <TT>
<FONT COLOR="#0000ff">mtools</FONT></TT> package, enables
reading and writing to MS-DOS/Windows floppy
disks.
These are not standard U<SMALL>NIX</SMALL> commands but are packaged with most L<SMALL>INUX</SMALL>
distributions. The commands support Windows ``long file name'' floppy disks. Put
an MS-DOS disk in your <TT>
<FONT COLOR="#0000ff">A:</FONT></TT> drive. Try

<P><TABLE nowrap="1" width="100%" border="0" cellspacing="0" cellpadding="0">
<TR>
<TD valign="top" class="source" width="2%"><FONT color=red>
<code>&nbsp;</code><br>
<code>&nbsp;</code><br>
<code>&nbsp;</code><br>
<code>&nbsp;</code><br>
</FONT></TD><TD valign="top" class="source" bgcolor="#FFE0C0"><FONT color=blue>
<code>mdir&nbsp;A:</code><br>
<code>touch&nbsp;myfile</code><br>
<code>mcopy&nbsp;myfile&nbsp;A:</code><br>
<code>mdir&nbsp;A:</code><br>
</FONT></TD></TR></TABLE><P>
Note that there is <I>no</I> such thing as an <TT>
<FONT COLOR="#0000ff">A:</FONT></TT> disk
under L<SMALL>INUX</SMALL>. Only the <TT>
<FONT COLOR="#0000ff">mtools</FONT></TT> package understands <TT>
<FONT COLOR="#0000ff">A:</FONT></TT> in order to retain
familiarity for MS-DOS users. The complete list of  commands is

<P><TABLE nowrap="1" width="100%" border="0" cellspacing="0" cellpadding="0">
<TR>
<TD valign="top" class="source" width="2%"><FONT color=red>
<code>&nbsp;</code><br>
<code>&nbsp;</code><br>
<code>&nbsp;</code><br>
<code>&nbsp;</code><br>
<font size="-1"><code>5</code></font><code>&nbsp;</code><br>
</FONT></TD><TD valign="top" class="source" bgcolor="#FFE0C0"><FONT color=blue>
<code>floppyd&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;mcopy&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;mformat&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;mmount&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;mshowfat</code><br>
<code>mattrib&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;mdel&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;minfo&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;mmove&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;mtoolstest</code><br>
<code>mbadblocks&nbsp;&nbsp;mdeltree&nbsp;&nbsp;mkmanifest&nbsp;&nbsp;mpartition&nbsp;&nbsp;mtype</code><br>
<code>mcat&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;mdir&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;mlabel&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;mrd&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;mzip</code><br>
<code>mcd&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;mdu&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;mmd&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;mren&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;xcopy</code><br>
</FONT></TD></TR></TABLE><P>
Entering <TT>
<FONT COLOR="#0000ff">info mtools</FONT></TT> will give detailed help. In general,
any MS-DOS command, put into lower case with an <TT>
<FONT COLOR="#0000ff">m</FONT></TT> prefixed to it,
gives the corresponding L<SMALL>INUX</SMALL> command.

<P>

<H1><A NAME="SECTION007170000000000000000">
4.17 Archives and Backups</A>
</H1>

<P>
<A NAME="sec:archandback"></A>
<P>
<DIV ALIGN="CENTER">

<TABLE width="100%" border="0" cellspacing="0" cellpadding="0">
<TR><TD bgcolor="#FFE0FF">
<I>Never begin any work before you have a fail-safe method of backing it up.</I>

</TD></TR>
</TABLE>

</DIV>

<P>
One of the primary activities of a system administrator is to make backups.
It is essential never to underestimate the volatility <FONT COLOR="#ffa500">[Ability to evaporate or become chaotic.
]</FONT> of information in a computer. <I>Backups</I> of data are therefore continually made.
A backup is a duplicate of your files that can be used as a replacement
should any or all of the computer be destroyed. The idea is that all of the
data in a directory <FONT COLOR="#ffa500">[As usual, meaning a directory and all its subdirectories and all the files in
those subdirectories, etc.
]</FONT> are stored in a separate place--often compressed--and can be retrieved
in case of an emergency. When we want to store a number of files in this way,
it is useful to be able to pack many files into one file so that we can perform
operations on that single file only. When many files are packed together into
one, this packed file is called an <I>archive</I>. Usually archives have the
extension <TT>
<FONT COLOR="#0000ff">.tar</FONT></TT>, which stands for <I>tape archive</I>.

<P>
To <I>create</I> an archive of a directory, use the <TT>
<FONT COLOR="#0000ff">tar</FONT></TT> command:

<P><TABLE nowrap="1" width="100%" border="0" cellspacing="0" cellpadding="0">
<TR>
<TD valign="top" class="source" width="2%"><FONT color=red>
<code>&nbsp;</code><br>
</FONT></TD><TD valign="top" class="source" bgcolor="#FFE0C0"><FONT color=blue>
<code>tar&nbsp;-c&nbsp;-f&nbsp;&#060;filename&#062;&nbsp;&#060;directory&#062;</code><br>
</FONT></TD></TR></TABLE><P>

<P>
Create a directory with a few files in it, and run the <TT>
<FONT COLOR="#0000ff">tar</FONT></TT> command to
back it up. A file of <TT>
<FONT COLOR="#0000ff">&lt;filename&gt;</FONT></TT> will be created. Take careful note
of any error messages that <TT>
<FONT COLOR="#0000ff">tar</FONT></TT> reports. List the file and check that
its size is appropriate for the size of the directory you are archiving. You
can also use the <I>verify</I> option (see the man page) of the <TT>
<FONT COLOR="#0000ff">tar</FONT></TT>
command to check the integrity of <TT>
<FONT COLOR="#0000ff">&lt;filename&gt;</FONT></TT>. Now remove the directory,
and then restore it with the <I>extract</I> option of the <TT>
<FONT COLOR="#0000ff">tar</FONT></TT> command:

<P><TABLE nowrap="1" width="100%" border="0" cellspacing="0" cellpadding="0">
<TR>
<TD valign="top" class="source" width="2%"><FONT color=red>
<code>&nbsp;</code><br>
</FONT></TD><TD valign="top" class="source" bgcolor="#FFE0C0"><FONT color=blue>
<code>tar&nbsp;-x&nbsp;-f&nbsp;&#060;filename&#062;</code><br>
</FONT></TD></TR></TABLE><P>
You should see your directory recreated with all its files intact. A nice option
to give to tar is <TT>
<FONT COLOR="#0000ff">-v</FONT></TT>. This option lists all the files that are being added
to or extracted from the archive as they are processed, and is useful for monitoring
the progress of archiving. It is obvious that you can call your archive anything
you like, however; the common practice is to call it <TT>
<FONT COLOR="#0000ff">&lt;directory&gt;.tar</FONT></TT>,
which makes it clear to all exactly what it is. Another important option is
<TT>
<FONT COLOR="#0000ff">-p</FONT></TT> which preserves detailed attribute information of files.

<P>
Once you have your <TT>
<FONT COLOR="#0000ff">.tar</FONT></TT> file, you would probably want to compress it with <TT>
<FONT COLOR="#0000ff">gzip</FONT></TT>.
This will create a file <TT>
<FONT COLOR="#0000ff">&lt;directory&gt;.tar.gz</FONT></TT>, which is sometimes
called <TT>
<FONT COLOR="#0000ff">&lt;directory&gt;.tgz</FONT></TT> for brevity.

<P>
A second kind of archiving utility is <TT>
<FONT COLOR="#0000ff">cpio</FONT></TT>. <TT>
<FONT COLOR="#0000ff">cpio</FONT></TT> is actually
more powerful than tar, but is considered to be more cryptic to use. The principles
of <TT>
<FONT COLOR="#0000ff">cpio</FONT></TT> are quite similar and its use is left as an exercise.

<P>

<H1><A NAME="SECTION007180000000000000000">
4.18 The <TT>
<FONT COLOR="#0000ff">PATH</FONT></TT> Where Commands Are Searched For</A>
</H1>

<P>
When you type a command at the shell prompt, it has to be read off disk
out of one or other directory. On U<SMALL>NIX</SMALL>, all such <I>executable
commands</I> are located in one of about four directories. A file is
located in the directory tree according to its type, rather than
according to what software package it belongs to. For
example, a word processor may have its actual executable stored
in a directory with all other executables, while its font files
are stored in a directory with other fonts from all other packages.

<P>
The shell has a procedure for searching for executables when you type
them in. If you type in a command with slashes, like <TT>
<FONT COLOR="#0000ff">/bin/cp</FONT></TT>,
then the shell tries to run the named program, <TT>
<FONT COLOR="#0000ff">cp</FONT></TT>, out of the
<TT>
<FONT COLOR="#0000ff">/bin</FONT></TT> directory. If you just type <TT>
<FONT COLOR="#0000ff">cp</FONT></TT> on its own,
then it tries to find the <TT>
<FONT COLOR="#0000ff">cp</FONT></TT> command in each of the
subdirectories of your <TT>
<FONT COLOR="#0000ff">PATH</FONT></TT>. To see what your <TT>
<FONT COLOR="#0000ff">PATH</FONT></TT>
is, just type

<P><TABLE nowrap="1" width="100%" border="0" cellspacing="0" cellpadding="0">
<TR>
<TD valign="top" class="source" width="2%"><FONT color=red>
<code>&nbsp;</code><br>
</FONT></TD><TD valign="top" class="source" bgcolor="#FFE0C0"><FONT color=blue>
<code>echo&nbsp;$PATH</code><br>
</FONT></TD></TR></TABLE><P>

<P>
You will see a colon separated list of four or more directories. Note that
the current directory <TT>
<FONT COLOR="#0000ff">&nbsp;.&nbsp;</FONT></TT> is not
listed. It is important that the current directory
<I>not</I> be listed for reasons of security. Hence, to execute a command
in the current directory, we hence always <TT>
<FONT COLOR="#0000ff">./&lt;command&gt;</FONT></TT>.

<P>
To append, for example, a new directory <TT>
<FONT COLOR="#0000ff">/opt/gnome/bin</FONT></TT>
to your <TT>
<FONT COLOR="#0000ff">PATH</FONT></TT>, do

<P><TABLE nowrap="1" width="100%" border="0" cellspacing="0" cellpadding="0">
<TR>
<TD valign="top" class="source" width="2%"><FONT color=red>
<code>&nbsp;</code><br>
<code>&nbsp;</code><br>
</FONT></TD><TD valign="top" class="source" bgcolor="#FFE0C0"><FONT color=blue>
<code>PATH="$PATH:/opt/gnome/bin"</code><br>
<code>export&nbsp;PATH</code><br>
</FONT></TD></TR></TABLE><P>
L<SMALL>INUX</SMALL> supports the convenience of doing this in one line:

<P><TABLE nowrap="1" width="100%" border="0" cellspacing="0" cellpadding="0">
<TR>
<TD valign="top" class="source" width="2%"><FONT color=red>
<code>&nbsp;</code><br>
</FONT></TD><TD valign="top" class="source" bgcolor="#FFE0C0"><FONT color=blue>
<code>export&nbsp;PATH="$PATH:/opt/gnome/bin"</code><br>
</FONT></TD></TR></TABLE><P>

<P>
There is a further command, <TT>
<FONT COLOR="#0000ff">which</FONT></TT>, to check whether a command is
locatable from the <TT>
<FONT COLOR="#0000ff">PATH</FONT></TT>. Sometimes there are two commands of the same
name in different directories of the <TT>
<FONT COLOR="#0000ff">PATH</FONT></TT>. <FONT COLOR="#ffa500">[This is
more often true of Solaris systems than L<SMALL>INUX</SMALL>.]</FONT> Typing
<TT>
<FONT COLOR="#0000ff">which &lt;command&gt;</FONT></TT> locates the one that your shell
would execute. Try:

<P><TABLE nowrap="1" width="100%" border="0" cellspacing="0" cellpadding="0">
<TR>
<TD valign="top" class="source" width="2%"><FONT color=red>
<code>&nbsp;</code><br>
<code>&nbsp;</code><br>
<code>&nbsp;</code><br>
<code>&nbsp;</code><br>
</FONT></TD><TD valign="top" class="source" bgcolor="#FFE0C0"><FONT color=blue>
<code>which&nbsp;ls</code><br>
<code>which&nbsp;cp&nbsp;mv&nbsp;rm</code><br>
<code>which&nbsp;which</code><br>
<code>which&nbsp;cranzgots</code><br>
</FONT></TD></TR></TABLE><P>

<P>
<TT>
<FONT COLOR="#0000ff">which</FONT></TT> is also useful in shell scripts to tell if
there is a command at all, and hence check whether a particular package
is installed, for example, <TT>
<FONT COLOR="#0000ff">which netscape</FONT></TT>.

<P>

<H1><A NAME="SECTION007190000000000000000">
4.19 The <TT>
<FONT COLOR="#0000ff">&#45;&#45;</FONT></TT> Option</A>
</H1>

<P>
If a file name happens to begin with a <TT>
<FONT COLOR="#0000ff">-</FONT></TT> then it would be impossible
to use that file name as an argument to a command. To overcome this circumstance,
most commands take an option <TT>
<FONT COLOR="#0000ff">&#45;&#45;</FONT></TT>. This option specifies that no more
options follow on the command-line--everything else must be treated as
a literal file name. For instance

<P><TABLE nowrap="1" width="100%" border="0" cellspacing="0" cellpadding="0">
<TR>
<TD valign="top" class="source" width="2%"><FONT color=red>
<code>&nbsp;</code><br>
<code>&nbsp;</code><br>
</FONT></TD><TD valign="top" class="source" bgcolor="#FFE0C0"><FONT color=blue>
<code>touch&nbsp;--&nbsp;-stupid_file_name</code><br>
<code>rm&nbsp;--&nbsp;-stupid_file_name</code><br>
</FONT></TD></TR></TABLE><P>

<P>

<P>
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