893 lines
11 KiB
HTML
893 lines
11 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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<HTML
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><HEAD
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><TITLE
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>Summary</TITLE
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><META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK
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REL="HOME"
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TITLE="Introduction to Linux"
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HREF="index.html"><LINK
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REL="UP"
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TITLE="About files and the file system"
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HREF="chap_03.html"><LINK
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REL="PREVIOUS"
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TITLE="File security"
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HREF="sect_03_04.html"><LINK
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REL="NEXT"
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TITLE="Exercises"
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HREF="sect_03_06.html"></HEAD
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><BODY
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CLASS="sect1"
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BGCOLOR="#FFFFFF"
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TEXT="#000000"
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LINK="#0000FF"
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VLINK="#840084"
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ALINK="#0000FF"
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><DIV
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CLASS="NAVHEADER"
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><TABLE
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SUMMARY="Header navigation table"
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WIDTH="100%"
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BORDER="0"
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CELLPADDING="0"
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CELLSPACING="0"
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><TR
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><TH
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COLSPAN="3"
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ALIGN="center"
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>Introduction to Linux: </TH
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></TR
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><TR
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><TD
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WIDTH="10%"
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ALIGN="left"
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VALIGN="bottom"
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><A
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HREF="sect_03_04.html"
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ACCESSKEY="P"
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>Prev</A
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></TD
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><TD
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WIDTH="80%"
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ALIGN="center"
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VALIGN="bottom"
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>Chapter 3. About files and the file system</TD
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><TD
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WIDTH="10%"
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ALIGN="right"
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VALIGN="bottom"
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><A
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HREF="sect_03_06.html"
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ACCESSKEY="N"
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>Next</A
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></TD
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></TR
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></TABLE
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><HR
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ALIGN="LEFT"
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WIDTH="100%"></DIV
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><DIV
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CLASS="sect1"
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><H1
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CLASS="sect1"
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><A
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NAME="sect_03_05"
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></A
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>3.5. Summary</H1
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><P
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>On UNIX, as on Linux, all entities are in some way or another presented to the system as files with the appropriate file properties. Use of (predefined) paths allows the users and the system admin to find, read and manipulate files.</P
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><P
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>We've made our first steps toward becoming an expert: we discussed the real and the fake structure of the file system, and we know about the Linux file security model, as well as several other security precautions that are taken on every system by default.</P
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><P
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>The shell is the most important tool for interaction with the system. We learned several shell commands in this chapter, which are listed in the table below.</P
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><DIV
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CLASS="table"
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><A
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NAME="AEN4247"
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></A
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><P
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><B
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>Table 3-10. New commands in chapter 3: Files and the file system</B
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></P
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><TABLE
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BORDER="1"
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CLASS="CALSTABLE"
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><THEAD
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><TR
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><TH
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Command</TH
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><TH
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Meaning</TH
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></TR
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></THEAD
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><TBODY
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
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CLASS="command"
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>bash</B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>GNU shell program.</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
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CLASS="command"
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>cat <TT
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CLASS="filename"
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>file(s)</TT
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></B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Send content of file(s) to standard output.</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
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CLASS="command"
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>cd <TT
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CLASS="filename"
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>directory</TT
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></B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Enter <TT
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CLASS="filename"
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>directory</TT
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>. <B
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CLASS="command"
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>cd</B
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> is a <B
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CLASS="command"
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>bash</B
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> built-in command.</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
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CLASS="command"
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>chgrp <TT
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CLASS="parameter"
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><I
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>newgroup</I
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></TT
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> <TT
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CLASS="filename"
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>file(s)</TT
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></B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Change the group ownership of <TT
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CLASS="filename"
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>file(s)</TT
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> to <EM
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>newgroup</EM
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></TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
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CLASS="command"
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>chmod <TT
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CLASS="parameter"
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><I
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>mode</I
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></TT
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> <TT
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CLASS="filename"
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>file(s)</TT
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></B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Change access permissions on <TT
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CLASS="filename"
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>file(s)</TT
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></TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
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CLASS="command"
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>chown <TT
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CLASS="parameter"
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><I
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>newowner</I
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></TT
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>[<SPAN
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CLASS="optional"
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>:[<SPAN
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CLASS="optional"
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>newgroup</SPAN
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>]</SPAN
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>] <TT
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CLASS="filename"
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>file(s)</TT
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> </B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Change file owner and group ownership.</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
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CLASS="command"
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>cp <TT
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CLASS="filename"
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>sourcefile</TT
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> <TT
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CLASS="filename"
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>targetfile</TT
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></B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Copy <TT
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CLASS="filename"
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>sourcefile</TT
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> to <TT
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CLASS="filename"
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>targetfile</TT
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>.</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
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CLASS="command"
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>df <TT
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CLASS="filename"
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>file</TT
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></B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Reports on used disk space on the partition containing <TT
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CLASS="filename"
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>file</TT
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>.</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
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CLASS="command"
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>echo <TT
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CLASS="parameter"
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><I
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>string</I
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></TT
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></B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Display a line of text</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
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CLASS="command"
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>export</B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Part of <B
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CLASS="command"
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>bash</B
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> that announces variables and their values to the system.</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
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CLASS="command"
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>file <TT
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CLASS="filename"
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>filename</TT
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></B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Determine file type of <TT
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CLASS="filename"
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>filename</TT
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>.</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
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CLASS="command"
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>find <TT
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CLASS="parameter"
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><I
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>path</I
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></TT
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> <TT
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CLASS="parameter"
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><I
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>expression</I
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></TT
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></B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Find files in the file system hierarchy</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
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CLASS="command"
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>grep <TT
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CLASS="parameter"
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><I
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>PATTERN</I
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></TT
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> <TT
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CLASS="filename"
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>file</TT
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></B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Print lines in <TT
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CLASS="filename"
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>file</TT
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> containing the search pattern.</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
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CLASS="command"
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>head <TT
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CLASS="filename"
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>file</TT
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></B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Send the first part of <TT
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CLASS="filename"
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>file</TT
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> to standard output</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
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CLASS="command"
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>id</B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Prints real and effective user name and groups.</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
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CLASS="command"
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>info <TT
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CLASS="parameter"
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><I
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>command</I
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></TT
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></B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Read documentation about <B
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CLASS="command"
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>command</B
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>.</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
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CLASS="command"
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>less <TT
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CLASS="filename"
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>file</TT
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></B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>View <TT
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CLASS="filename"
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>file</TT
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> with a powerful viewer.</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
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CLASS="command"
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>ln <TT
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CLASS="filename"
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>targetfile</TT
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> <TT
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CLASS="filename"
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>linkname</TT
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></B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Make a link with name <TT
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CLASS="filename"
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>linkname</TT
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> to <TT
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CLASS="filename"
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>targetfile</TT
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>.</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
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CLASS="command"
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>locate <TT
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CLASS="parameter"
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><I
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>searchstring</I
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></TT
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></B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Print all accessible files matching the search pattern.</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
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CLASS="command"
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>ls <TT
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CLASS="filename"
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>file(s)</TT
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></B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Prints directory content.</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
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CLASS="command"
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>man <TT
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CLASS="parameter"
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><I
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>command</I
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></TT
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></B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Format and display online (system) manual pages for <B
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CLASS="command"
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>command</B
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>.</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
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CLASS="command"
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>mkdir <TT
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CLASS="filename"
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>newdir</TT
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></B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Make a new empty directory.</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
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CLASS="command"
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>mv <TT
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CLASS="filename"
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>oldfile</TT
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> <TT
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CLASS="filename"
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>newfile</TT
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></B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Rename or move <TT
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CLASS="filename"
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>oldfile</TT
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>.</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
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CLASS="command"
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>newgrp <TT
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CLASS="parameter"
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><I
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>groupname</I
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></TT
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></B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Log in to a new group.</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
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CLASS="command"
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>pwd</B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Print the present or current working directory.</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
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CLASS="command"
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>quota</B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Show disk usage and limits.</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
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CLASS="command"
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>rm <TT
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CLASS="filename"
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>file</TT
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></B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Removes files and directories.</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
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CLASS="command"
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>rmdir <TT
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CLASS="filename"
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>file</TT
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></B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Removes directories.</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
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CLASS="command"
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>tail <TT
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CLASS="filename"
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>file</TT
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></B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Print the last part of <TT
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CLASS="filename"
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>file</TT
|
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>.</TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
|
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CLASS="command"
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>umask [<SPAN
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CLASS="optional"
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><TT
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CLASS="parameter"
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><I
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>value</I
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></TT
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></SPAN
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>]</B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Show or change new file creation mode.</TD
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></TR
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><TR
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><TD
|
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
|
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CLASS="command"
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>wc <TT
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CLASS="filename"
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>file</TT
|
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></B
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Counts lines, words and characters in <TT
|
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CLASS="filename"
|
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>file</TT
|
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>.</TD
|
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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><B
|
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CLASS="command"
|
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>which <TT
|
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CLASS="parameter"
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><I
|
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>command</I
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></TT
|
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></B
|
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="MIDDLE"
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>Shows the full path to <B
|
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CLASS="command"
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>command</B
|
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>.</TD
|
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></TR
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></TBODY
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></TABLE
|
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></DIV
|
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><P
|
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>We also stressed the fact that you should READ THE MAN PAGES. This documentation is your first-aid kit and contains the answers to many questions. The above list contains the basic commands that you will use on a daily basis, but they can do much more than the tasks we've discussed here. Reading the documentation will give you the control you need.</P
|
|
><P
|
|
>Last but not least, a handy overview of file permissions:</P
|
|
><DIV
|
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CLASS="table"
|
|
><A
|
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NAME="AEN4445"
|
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></A
|
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><P
|
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><B
|
|
>Table 3-11. File permissions</B
|
|
></P
|
|
><TABLE
|
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BORDER="1"
|
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CLASS="CALSTABLE"
|
|
><THEAD
|
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><TR
|
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><TH
|
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ALIGN="LEFT"
|
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VALIGN="MIDDLE"
|
|
>Who\What</TH
|
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><TH
|
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ALIGN="LEFT"
|
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VALIGN="MIDDLE"
|
|
>r(ead)</TH
|
|
><TH
|
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ALIGN="LEFT"
|
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VALIGN="MIDDLE"
|
|
>w(rite)</TH
|
|
><TH
|
|
ALIGN="LEFT"
|
|
VALIGN="MIDDLE"
|
|
>(e)x(ecute)</TH
|
|
></TR
|
|
></THEAD
|
|
><TBODY
|
|
><TR
|
|
><TD
|
|
ALIGN="LEFT"
|
|
VALIGN="MIDDLE"
|
|
>u(ser)</TD
|
|
><TD
|
|
ALIGN="LEFT"
|
|
VALIGN="MIDDLE"
|
|
>4</TD
|
|
><TD
|
|
ALIGN="LEFT"
|
|
VALIGN="MIDDLE"
|
|
>2</TD
|
|
><TD
|
|
ALIGN="LEFT"
|
|
VALIGN="MIDDLE"
|
|
>1</TD
|
|
></TR
|
|
><TR
|
|
><TD
|
|
ALIGN="LEFT"
|
|
VALIGN="MIDDLE"
|
|
>g(roup)</TD
|
|
><TD
|
|
ALIGN="LEFT"
|
|
VALIGN="MIDDLE"
|
|
>4</TD
|
|
><TD
|
|
ALIGN="LEFT"
|
|
VALIGN="MIDDLE"
|
|
>2</TD
|
|
><TD
|
|
ALIGN="LEFT"
|
|
VALIGN="MIDDLE"
|
|
>1</TD
|
|
></TR
|
|
><TR
|
|
><TD
|
|
ALIGN="LEFT"
|
|
VALIGN="MIDDLE"
|
|
>o(ther)</TD
|
|
><TD
|
|
ALIGN="LEFT"
|
|
VALIGN="MIDDLE"
|
|
>4</TD
|
|
><TD
|
|
ALIGN="LEFT"
|
|
VALIGN="MIDDLE"
|
|
>2</TD
|
|
><TD
|
|
ALIGN="LEFT"
|
|
VALIGN="MIDDLE"
|
|
>1</TD
|
|
></TR
|
|
></TBODY
|
|
></TABLE
|
|
></DIV
|
|
></DIV
|
|
><DIV
|
|
CLASS="NAVFOOTER"
|
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><HR
|
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ALIGN="LEFT"
|
|
WIDTH="100%"><TABLE
|
|
SUMMARY="Footer navigation table"
|
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WIDTH="100%"
|
|
BORDER="0"
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CELLPADDING="0"
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CELLSPACING="0"
|
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><TR
|
|
><TD
|
|
WIDTH="33%"
|
|
ALIGN="left"
|
|
VALIGN="top"
|
|
><A
|
|
HREF="sect_03_04.html"
|
|
ACCESSKEY="P"
|
|
>Prev</A
|
|
></TD
|
|
><TD
|
|
WIDTH="34%"
|
|
ALIGN="center"
|
|
VALIGN="top"
|
|
><A
|
|
HREF="index.html"
|
|
ACCESSKEY="H"
|
|
>Home</A
|
|
></TD
|
|
><TD
|
|
WIDTH="33%"
|
|
ALIGN="right"
|
|
VALIGN="top"
|
|
><A
|
|
HREF="sect_03_06.html"
|
|
ACCESSKEY="N"
|
|
>Next</A
|
|
></TD
|
|
></TR
|
|
><TR
|
|
><TD
|
|
WIDTH="33%"
|
|
ALIGN="left"
|
|
VALIGN="top"
|
|
>File security</TD
|
|
><TD
|
|
WIDTH="34%"
|
|
ALIGN="center"
|
|
VALIGN="top"
|
|
><A
|
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HREF="chap_03.html"
|
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ACCESSKEY="U"
|
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>Up</A
|
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></TD
|
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><TD
|
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WIDTH="33%"
|
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ALIGN="right"
|
|
VALIGN="top"
|
|
>Exercises</TD
|
|
></TR
|
|
></TABLE
|
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></DIV
|
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> |