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<HTML><!--Distributed by F --><HEAD><TITLE>[Chapter 25] 25.14 How to Look at the End of a File: tail </TITLE><METANAME="DC.title"CONTENT="UNIX Power Tools"><METANAME="DC.creator"CONTENT="Jerry Peek, Tim O'Reilly & Mike Loukides"><METANAME="DC.publisher"CONTENT="O'Reilly & Associates, Inc."><METANAME="DC.date"CONTENT="1998-08-04T21:43:27Z"><METANAME="DC.type"CONTENT="Text.Monograph"><METANAME="DC.format"CONTENT="text/html"SCHEME="MIME"><METANAME="DC.source"CONTENT="1-56592-260-3"SCHEME="ISBN"><METANAME="DC.language"CONTENT="en-US"><METANAME="generator"CONTENT="Jade 1.1/O'Reilly DocBook 3.0 to HTML 4.0"><LINKREV="made"HREF="mailto:online-books@oreilly.com"TITLE="Online Books Comments"><LINKREL="up"HREF="ch25_01.htm"TITLE="25. Showing What's in a File"><LINKREL="prev"HREF="ch25_13.htm"TITLE="25.13 pushin: Squeeze Out Extra White Space "><LINKREL="next"HREF="ch25_15.htm"TITLE="25.15 Finer Control on tail "></HEAD><BODYBGCOLOR="#FFFFFF"TEXT="#000000"><DIVCLASS="htmlnav"><H1><IMGSRC="gifs/smbanner.gif"ALT="UNIX Power Tools"USEMAP="#srchmap"BORDER="0"></H1><MAPNAME="srchmap"><AREASHAPE="RECT"COORDS="0,0,466,58"HREF="index.htm"ALT="UNIX Power Tools"><AREASHAPE="RECT"COORDS="467,0,514,18"HREF="jobjects/fsearch.htm"ALT="Search this book"></MAP><TABLEWIDTH="515"BORDER="0"CELLSPACING="0"CELLPADDING="0"><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch25_13.htm"TITLE="25.13 pushin: Squeeze Out Extra White Space "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 25.13 pushin: Squeeze Out Extra White Space "BORDER="0"></A></TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="171"><B><FONTFACE="ARIEL,HELVETICA,HELV,SANSERIF"SIZE="-1">Chapter 25<BR>Showing What's in a File</FONT></B></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch25_15.htm"TITLE="25.15 Finer Control on tail "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 25.15 Finer Control on tail "BORDER="0"></A></TD></TR></TABLE> <HRALIGN="LEFT"WIDTH="515"TITLE="footer"></DIV><DIVCLASS="SECT1"><H2CLASS="sect1"><ACLASS="title"NAME="UPT-ART-0014">25.14 How to Look at the End of a File: tail </A></H2><PCLASS="para">' TIM SAYS "SUBSECTIONS DON'T WORK"<ACLASS="indexterm"NAME="UPT-ART-14-IX-TAIL-COMMAND"></A><ACLASS="indexterm"NAME="UPT-ART-14-IX-DISPLAYING-BEGINNING-END-ONLY"></A>Let's say that you want to look at the end of some large file. Forexample, you've just sent some<SPANCLASS="link">mail via UUCP (<ACLASS="linkend"HREF="ch01_33.htm"TITLE="UNIX Networking and Communications ">1.33</A>)</SPAN>and want to find outwhether it was handled correctly. But when you give the<EMCLASS="emphasis">uulog</EM> command, you find out that the UUCP log file is30 or 40 KB long, and you don't care about the whole thing - youcertainly don't want to page through it until you get to the end.How do you handle this?</P><PCLASS="para">The <EMCLASS="emphasis">tail</EM> command is just what you need in this situation.<EMCLASS="emphasis">tail</EM> reads its input and discards everything except for the lastten lines (by default). Therefore, if you're pretty sure that theinformation you want is at the end of the file, you can use <EMCLASS="emphasis">tail</EM>to get rid of the junk that you don't want. To use the <EMCLASS="emphasis">uulog</EM>example:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">% <CODECLASS="userinput"><B>uulog | tail</B></CODE></PRE></BLOCKQUOTE></P><PCLASS="para">This will give you the last ten lines of the UUCP log.If you need more or less than ten lines, look at article<ACLASS="xref"HREF="ch25_15.htm"TITLE="Finer Control on tail ">25.15</A>.</P><PCLASS="para">You can give <EMCLASS="emphasis">tail</EM> one (and <EMCLASS="emphasis">only</EM> one!) filename:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">% <CODECLASS="userinput"><B>tail </B></CODE><CODECLASS="replaceable"><I>somefile</I></CODE></PRE></BLOCKQUOTE></P><PCLASS="para">There are many other situations in which <EMCLASS="emphasis">tail</EM> is useful: I'veused it to make sure that a job that produces a big output file hasfinished correctly, to remind me what the last piece of mail in mymailbox was about, and so on. You'll find <EMCLASS="emphasis">tail</EM> importantwhenever you're interested only in the end of something.</P><DIVCLASS="sect1info"><PCLASS="SECT1INFO">- <SPANCLASS="authorinitials">ML</SPAN></P></DIV></DIV><DIVCLASS="htmlnav"><P></P><HRALIGN="LEFT"WIDTH="515"TITLE="footer"><TABLEWIDTH="515"BORDER="0"CELLSPACING="0"CELLPADDING="0"><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch25_13.htm"TITLE="25.13 pushin: Squeeze Out Extra White Space "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 25.13 pushin: Squeeze Out Extra White Space "BORDER="0"></A></TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="171"><ACLASS="book"HREF="index.htm"TITLE="UNIX Power Tools"><IMGSRC="gifs/txthome.gif"SRC="gifs/txthome.gif"ALT="UNIX Power Tools"BORDER="0"></A></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch25_15.htm"TITLE="25.15 Finer Control on tail "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 25.15 Finer Control on tail "BORDER="0"></A></TD></TR><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="172">25.13 pushin: Squeeze Out Extra White Space </TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="171"><ACLASS="index"HREF="index/idx_0.htm"TITLE="Book Index"><IMGSRC="gifs/index.gif"SRC="gifs/index.gif"ALT="Book Index"BORDER="0"></A></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="172">25.15 Finer Control on tail </TD></TR></TABLE><HRALIGN="LEFT"WIDTH="515"TITLE="footer"><IMGSRC="gifs/smnavbar.gif"SRC="gifs/smnavbar.gif"USEMAP="#map"BORDER="0"ALT="The UNIX CD Bookshelf Navigation"><MAPNAME="map"><AREASHAPE="RECT"COORDS="0,0,73,21"HREF="../index.htm"ALT="The UNIX CD Bookshelf"><AREASHAPE="RECT"COORDS="74,0,163,21"HREF="index.htm"ALT="UNIX Power Tools"><AREASHAPE="RECT"COORDS="164,0,257,21"HREF="../unixnut/index.htm"ALT="UNIX in a Nutshell"><AREASHAPE="RECT"COORDS="258,0,321,21"HREF="../vi/index.htm"ALT="Learning the vi Editor"><AREASHAPE="RECT"COORDS="322,0,378,21"HREF="../sedawk/index.htm"ALT="sed & awk"><AREASHAPE="RECT"COORDS="379,0,438,21"HREF="../ksh/index.htm"ALT="Learning the Korn Shell"><AREASHAPE="RECT"COORDS="439,0,514,21"HREF="../lrnunix/index.htm"ALT="Learning the UNIX Operating System"></MAP></DIV></BODY></HTML>⌨️ 快捷键说明
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