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<HTML><!--Distributed by F --><HEAD><TITLE>[Chapter 25] 25.18 Watching Several Files Grow </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="1998-08-04T21:43:30Z"><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_17.htm"TITLE="25.17 An Alias in Case You Don't Have tail "><LINKREL="next"HREF="ch25_19.htm"TITLE="25.19 Reverse Lines in Long Files with flip "></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_17.htm"TITLE="25.17 An Alias in Case You Don't Have tail "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 25.17 An Alias in Case You Don't Have tail "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_19.htm"TITLE="25.19 Reverse Lines in Long Files with flip "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 25.19 Reverse Lines in Long Files with flip "BORDER="0"></A></TD></TR></TABLE> <HRALIGN="LEFT"WIDTH="515"TITLE="footer"></DIV><DIVCLASS="SECT1"><H2CLASS="sect1"><ACLASS="title"NAME="UPT-ART-9032">25.18 Watching Several Files Grow </A></H2><PCLASS="para"><ACLASS="indexterm"NAME="AUTOID-28100"></A>Now here's a useful tool: suppose you want to monitor severalfiles at once.Administrators, for example, might want to keep trackof several log files, such as <EMCLASS="emphasis">/usr/adm/messages</EM>,<EMCLASS="emphasis">/usr/adm/lpd-errs</EM>, UUCP error files, etc.</P><TABLECLASS="para.programreference"BORDER="1"><TR><THVALIGN="TOP"><ACLASS="programreference"HREF="examples/index.htm"TITLE="xtail">xtail</A><BR></TH><TDVALIGN="TOP"><ACLASS="indexterm"NAME="AUTOID-28106"></A>The <EMCLASS="emphasis">xtail</EM> program comes in useful for keeping an eyeon several administrative log files at once.But it also comes in useful for non-administrators.It's sort of a <EMCLASS="emphasis">tail -f</EM> forseveral files as once.</TD></TR></TABLE><PCLASS="para">For example, suppose you want to perform several <EMCLASS="emphasis">grep</EM>s through many files, saving the output in different files.You can then monitor the files using <EMCLASS="emphasis">xtail</EM>.For example:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">% <CODECLASS="userinput"><B>grep Berkeley ch?? > Berkeley.grep &</B></CODE>% <CODECLASS="userinput"><B>grep BSD ch?? > BSD.grep &</B></CODE>% <CODECLASS="userinput"><B>grep "System V" ch?? > SystemV.grep &</B></CODE>% <CODECLASS="userinput"><B>grep SysV ch?? > SysV.grep &</B></CODE>% <CODECLASS="userinput"><B>xtail Berkeley.grep BSD.grep SystemV.grep SysV.grep</B></CODE></PRE></BLOCKQUOTE></P><PCLASS="para"> When new text appears in the files called with <EMCLASS="emphasis">xtail</EM>,it also appears on the screen:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">*** SysV.grep ***ch01:using a SysV-based UNIX system, you must*** Berkeley.grep ***ch01:at the University of California at Berkeley, where*** BSD.grep ***ch03:prefer BSD UNIX systems because they are less likely toch04:who use a BSD-based UNIX systems must run the*** SysV.grep ***ch04:is a SysV derivative sold by Acme Products Inc.</PRE></BLOCKQUOTE></P><PCLASS="para">(When text is written to a new file, the filename is printedsurrounded by <CODECLASS="literal">***</CODE>.)</P><PCLASS="para">If you press your<SPANCLASS="link">interrupt key (<ACLASS="linkend"HREF="ch05_09.htm"TITLE="Setting Your Erase, Kill, and Interrupt Characters ">5.9</A>)</SPAN>(usually CTRL-c or DEL), <EMCLASS="emphasis">xtail</EM>will tell you which files have been modified most recently:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen"><KBDCLASS="keycap">[CTRL-c]</KBD>*** recently changed files *** 1 4-Nov-92 18:21:12 BSD.grep 2 4-Nov-92 18:19:52 Berkeley.grep 3 4-Nov-92 17:42:45 SysV.grep</PRE></BLOCKQUOTE></P><PCLASS="para">To exit <EMCLASS="emphasis">xtail</EM>, you must send the <EMCLASS="emphasis">QUIT</EM> signal(usually CTRL-\, control-backslash).</P><PCLASS="para">If an argument given to <EMCLASS="emphasis">xtail</EM> is a directory name and not a filename, then <EMCLASS="emphasis">xtail</EM> monitors all files in that directory.For administrators, this comes in very useful for monitoring the<SPANCLASS="link">UUCP (<ACLASS="linkend"HREF="ch01_33.htm"TITLE="UNIX Networking and Communications ">1.33</A>)</SPAN>log files in all the subdirectories of <EMCLASS="emphasis">/usr/spool/uucp/.Log</EM>:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">% <CODECLASS="userinput"><B>xtail /usr/spool/uucp/.Log/*</B></CODE></PRE></BLOCKQUOTE></P><DIVCLASS="sect1info"><PCLASS="SECT1INFO">- <SPANCLASS="authorinitials">LM</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_17.htm"TITLE="25.17 An Alias in Case You Don't Have tail "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 25.17 An Alias in Case You Don't Have tail "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_19.htm"TITLE="25.19 Reverse Lines in Long Files with flip "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 25.19 Reverse Lines in Long Files with flip "BORDER="0"></A></TD></TR><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="172">25.17 An Alias in Case You Don't Have tail </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">25.19 Reverse Lines in Long Files with flip </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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