447 lines
7.0 KiB
HTML
447 lines
7.0 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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>Text Viewing Tools </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="GNU/Linux Command-Line Tools Summary"
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HREF="index.html"><LINK
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REL="UP"
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TITLE="Text Related Tools"
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HREF="text-related-tools.html"><LINK
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REL="PREVIOUS"
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TITLE="Text Editors"
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HREF="text-editors.html"><LINK
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REL="NEXT"
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TITLE="Text Information Tools"
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HREF="text-information-tools.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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>GNU/Linux Command-Line Tools Summary</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="text-editors.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 11. Text Related Tools</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="text-information-tools.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="TEXT-VIEWING-TOOLS"
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></A
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>11.2. Text Viewing Tools</H1
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><P
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></P
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><DIV
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CLASS="VARIABLELIST"
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><DL
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><DT
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>head</DT
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><DD
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><P
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>With no options it shows the first ten lines of a text file. </P
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><P
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>Use<EM
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> head -n x </EM
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>(where “x” is a number) to display the first x<EM
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> </EM
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>lines. </P
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><P
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>Try <EM
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> head -F </EM
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>to use a continually updated version of <EM
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>head</EM
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> (if the file changes it will be reloaded and displayed), please note that using this option will run <EM
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>head</EM
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> is a continuous loop so you'll need to use
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<B
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CLASS="KEYCAP"
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>CTRL</B
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>-<B
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CLASS="KEYCAP"
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>C</B
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>
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to exit.</P
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><P
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>For example:</P
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><TABLE
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BORDER="1"
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BGCOLOR="#E0E0E0"
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WIDTH="90%"
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><TR
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><TD
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><FONT
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COLOR="#000000"
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><PRE
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CLASS="SCREEN"
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>head -n 20 somelog.txt </PRE
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></FONT
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></TD
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></TR
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></TABLE
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><P
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>Will display the top 20 entries of the file “somelog.txt”.</P
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></DD
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><DT
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>tail</DT
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><DD
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><P
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>With no options it shows the last ten lines of a file. </P
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><P
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>Use<EM
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> tail -n x </EM
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>(where “x” is a number) to display the last <EM
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>x </EM
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>lines. </P
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><P
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>Try<EM
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> tail -F </EM
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>to use a continually updated version of <EM
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>tail</EM
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> (if the file changes it will be reloaded and displayed), please note that using this option will run <EM
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>tail</EM
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> is a continuous loop so you'll need to use
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<B
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CLASS="KEYCAP"
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>CTRL</B
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>-<B
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CLASS="KEYCAP"
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>C</B
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>
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to exit.</P
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><P
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>For example:</P
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><TABLE
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BORDER="1"
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BGCOLOR="#E0E0E0"
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WIDTH="90%"
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><TR
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><TD
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><FONT
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COLOR="#000000"
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><PRE
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CLASS="SCREEN"
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>tail -n 20 somelog.txt</PRE
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></FONT
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></TD
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></TR
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></TABLE
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><P
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>Will display the last 20 entries of the file “somelog.txt”.</P
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></DD
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><DT
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>less</DT
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><DD
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><P
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>Views text, can scroll backwards and forwards. Has many different options which are all described in the manual page. </P
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><P
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>When <EM
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>less</EM
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> is already running, use :n and :p (type a colon then the character) to move to the next and previous files (when there are multiple open files).</P
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><P
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>Command syntax:</P
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><TABLE
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BORDER="1"
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BGCOLOR="#E0E0E0"
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WIDTH="90%"
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><TR
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><TD
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><FONT
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COLOR="#000000"
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><PRE
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CLASS="SCREEN"
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>less filename.txt</PRE
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></FONT
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></TD
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></TR
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></TABLE
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><P
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>Or using a tool (in this example <EM
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>cat</EM
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>):</P
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><TABLE
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BORDER="1"
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BGCOLOR="#E0E0E0"
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WIDTH="90%"
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><TR
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><TD
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><FONT
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COLOR="#000000"
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><PRE
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CLASS="SCREEN"
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>cat file.txt | less</PRE
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></FONT
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></TD
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></TR
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></TABLE
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></DD
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><DT
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>more</DT
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><DD
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><P
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>Displays text, one page full at a time, more limited than <EM
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>less</EM
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>. In this case <EM
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>less</EM
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> is better than <EM
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>more</EM
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>.</P
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><TABLE
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BORDER="1"
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BGCOLOR="#E0E0E0"
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WIDTH="90%"
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><TR
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><TD
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><FONT
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COLOR="#000000"
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><PRE
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CLASS="SCREEN"
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>more filename.txt</PRE
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></FONT
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></TD
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></TR
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></TABLE
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><P
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>Or using a tool (is this example cat):</P
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><TABLE
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BORDER="1"
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BGCOLOR="#E0E0E0"
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WIDTH="90%"
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><TR
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><TD
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><FONT
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COLOR="#000000"
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><PRE
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CLASS="SCREEN"
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>cat file.txt | more</PRE
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></FONT
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></TD
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></TR
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></TABLE
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></DD
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><DT
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>cat<A
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NAME="CAT"
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></A
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></DT
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><DD
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><P
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>Combines (concatenates) multiple documents into one document. Can be used on individual files as well.</P
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><P
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>Some useful options:</P
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><P
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></P
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><UL
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><LI
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><P
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><EM
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>-b</EM
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> --- number all non-blank lines</P
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></LI
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><LI
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><P
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><EM
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>-n</EM
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> --- number all lines. </P
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></LI
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></UL
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><P
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>Also try using <EM
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>nl</EM
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> to number lines (it can do more complex numbering), you will find it under under this section, <A
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HREF="text-manipulation-tools.html"
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>Section 11.4</A
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></P
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><P
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>Example:</P
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><TABLE
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BORDER="1"
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BGCOLOR="#E0E0E0"
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WIDTH="90%"
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><TR
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><TD
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><FONT
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COLOR="#000000"
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><PRE
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CLASS="SCREEN"
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>cat filepart1 filepart2 filepart3 > wholefile.txt</PRE
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></FONT
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></TD
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></TR
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></TABLE
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><P
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>This will combine (concatenate) filepart1, filepart2 and filepart3 into the single file “wholefile.txt”.</P
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></DD
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><DT
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>tac</DT
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><DD
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><P
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>Combines (concatenates) multiple documents into one document and outputs them in reverse order. Can also be used on individual files. Notice that <EM
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>tac</EM
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> is <EM
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>cat</EM
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> written backwards. </P
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><P
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>Example:</P
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><TABLE
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BORDER="1"
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BGCOLOR="#E0E0E0"
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WIDTH="90%"
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><TR
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><TD
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><FONT
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COLOR="#000000"
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><PRE
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CLASS="SCREEN"
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>tac filepart1 filepart2 filepart3 > wholefile.txt</PRE
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></FONT
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></TD
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></TR
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></TABLE
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><P
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>This will combine (concatenate) filepart1, filepart2 and filepart3 into the single file but have each of the files written in reverse.</P
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></DD
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><DT
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>z*<2A>commands</DT
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><DD
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><P
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>Many commands can be prefixed with a “z” to read/work within a gzip compressed file. </P
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><P
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>Some examples are <EM
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>zcat, zless, zmore, zgrep, zcmp, zdiff</EM
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>. </P
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><P
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>There are many utilities for working with text within compressed files without trying to manually de-compress them somewhere first...most begin with a “z”. You will find some of them mentioned over here, <A
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HREF="compression.html"
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>Section 15.3</A
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>.</P
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></DD
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><DT
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>bz*<2A>commands</DT
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><DD
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><P
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>There are also a few commands that prefixed with a “bz” to read/work within a file compressed with bzip2. </P
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><P
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>The tools are <EM
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>bzcat, bzless, bzgrep.</EM
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> You will find some of them mentioned over here, <A
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HREF="compression.html"
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>Section 15.3</A
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>.</P
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></DD
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></DL
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></DIV
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></DIV
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><DIV
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CLASS="NAVFOOTER"
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><HR
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ALIGN="LEFT"
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WIDTH="100%"><TABLE
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SUMMARY="Footer 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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><TD
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WIDTH="33%"
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ALIGN="left"
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VALIGN="top"
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><A
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HREF="text-editors.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="34%"
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||
ALIGN="center"
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VALIGN="top"
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><A
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||
HREF="index.html"
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ACCESSKEY="H"
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>Home</A
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></TD
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><TD
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WIDTH="33%"
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ALIGN="right"
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VALIGN="top"
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><A
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HREF="text-information-tools.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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><TR
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><TD
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WIDTH="33%"
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ALIGN="left"
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VALIGN="top"
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>Text Editors</TD
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><TD
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WIDTH="34%"
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ALIGN="center"
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VALIGN="top"
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><A
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HREF="text-related-tools.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"
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VALIGN="top"
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>Text Information Tools</TD
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||
></TR
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||
></TABLE
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||
></DIV
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||
></BODY
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></HTML
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> |