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<HTML><!--Distributed by F --><HEAD><TITLE>[Chapter 17] 17.9 Problems with -newer </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="1998-08-04T21:38:22Z"><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="ch17_01.htm"TITLE="17. Finding Files with find"><LINKREL="prev"HREF="ch17_08.htm"TITLE="17.8 Exact File Time Comparisons "><LINKREL="next"HREF="ch17_10.htm"TITLE="17.10 Running Commands on What You Find "></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="ch17_08.htm"TITLE="17.8 Exact File Time Comparisons "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 17.8 Exact File Time Comparisons "BORDER="0"></A></TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="171"><B><FONTFACE="ARIEL,HELVETICA,HELV,SANSERIF"SIZE="-1">Chapter 17<BR>Finding Files with find</FONT></B></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch17_10.htm"TITLE="17.10 Running Commands on What You Find "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 17.10 Running Commands on What You Find "BORDER="0"></A></TD></TR></TABLE> <HRALIGN="LEFT"WIDTH="515"TITLE="footer"></DIV><DIVCLASS="SECT1"><H2CLASS="sect1"><ACLASS="title"NAME="UPT-ART-0291">17.9 Problems with -newer </A></H2><PCLASS="para">You may run into problems with the<SPANCLASS="link"><EMCLASS="emphasis">-newer</EM> (<ACLASS="linkend"HREF="ch17_08.htm"TITLE="Exact File Time Comparisons ">17.8</A>)</SPAN>operator if you try touse it twice in the same command. Let's say that you want to find allfiles that are newer than <EMCLASS="emphasis">filea</EM> but older than <EMCLASS="emphasis">fileb</EM>. Theobvious way to do this would be with the command:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">% <CODECLASS="userinput"><B>find . -newer filea ! -newer fileb -print</B></CODE></PRE></BLOCKQUOTE></P><PCLASS="para">However, most versions of <EMCLASS="emphasis">find</EM> can only work with one date at atime.When <EMCLASS="emphasis">find</EM> reads the date of <EMCLASS="emphasis">fileb</EM>, it discardsthe date of <EMCLASS="emphasis">filea</EM>, and uses <EMCLASS="emphasis">fileb</EM>'s date in both places.So it's really trying to find files that are newer than <EMCLASS="emphasis">fileb</EM>but older than <EMCLASS="emphasis">fileb</EM>, and will (obviously) find nothing at all.</P><PCLASS="para">You can work around this by figuring out the number of days since<EMCLASS="emphasis">filea</EM> and <EMCLASS="emphasis">fileb</EM> were modified, and rewriting the commandusing two <EMCLASS="emphasis">-mtime</EM> operators. <EMCLASS="emphasis">-mtime</EM> isn't afflicted by thesame bug.</P><PCLASS="para">As with all bugs (or "features"), some vendors may havefixed it. So your system may not be afflicted with the problem. A <EMCLASS="emphasis">find</EM>expression with two <EMCLASS="emphasis">-newer</EM> operators apparently works under SunOS 4.1, but not under previous SunOSreleases. It also seems to work under SVR4. The GNU version(on the CD-ROM) doesn't have the bug.<ACLASS="indexterm"NAME="AUTOID-18844"></A></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="ch17_08.htm"TITLE="17.8 Exact File Time Comparisons "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 17.8 Exact File Time Comparisons "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="ch17_10.htm"TITLE="17.10 Running Commands on What You Find "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 17.10 Running Commands on What You Find "BORDER="0"></A></TD></TR><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="172">17.8 Exact File Time Comparisons </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">17.10 Running Commands on What You Find </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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