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<HTML><!--Distributed by F --><HEAD><TITLE>[Chapter 15] 15.6 Maybe You Shouldn't Use Wildcards in Pathnames </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="1998-08-04T21:37:25Z"><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="ch15_01.htm"TITLE="15. Wildcards"><LINKREL="prev"HREF="ch15_05.htm"TITLE='15.5 Matching All "Dot Files" with Wildcards'><LINKREL="next"HREF="ch15_07.htm"TITLE="15.7 Getting a List of Matching Files with grep -l "></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="ch15_05.htm"TITLE='15.5 Matching All "Dot Files" with Wildcards'><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT='Previous: 15.5 Matching All "Dot Files" with Wildcards'BORDER="0"></A></TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="171"><B><FONTFACE="ARIEL,HELVETICA,HELV,SANSERIF"SIZE="-1">Chapter 15<BR>Wildcards</FONT></B></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch15_07.htm"TITLE="15.7 Getting a List of Matching Files with grep -l "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 15.7 Getting a List of Matching Files with grep -l "BORDER="0"></A></TD></TR></TABLE> <HRALIGN="LEFT"WIDTH="515"TITLE="footer"></DIV><DIVCLASS="SECT1"><H2CLASS="sect1"><ACLASS="title"NAME="UPT-ART-0126">15.6 Maybe You Shouldn't Use Wildcards in Pathnames </A></H2><PCLASS="para"><ACLASS="indexterm"NAME="AUTOID-16393"></A><ACLASS="indexterm"NAME="AUTOID-16396"></A>Suppose you're giving a command like the one below (not necessarily <EMCLASS="emphasis">rm</EM>-thisapplies to any UNIX command):</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">% <CODECLASS="userinput"><B>rm /somedir/otherdir/*</B></CODE></PRE></BLOCKQUOTE></P><PCLASS="para">Let's say that matches 100 files.The <EMCLASS="emphasis">rm</EM> command gets 100 complete pathnames from the shell:<EMCLASS="emphasis">/somedir/otherdir/afile</EM>, <EMCLASS="emphasis">/somedir/otherdir/bfile</EM>, and so on.For each of these files, the UNIX kernel has to start at the rootdirectory, then search the <EMCLASS="emphasis">somedir</EM> and <EMCLASS="emphasis">otherdir</EM> directoriesbefore it finds the file to remove.</P><PCLASS="para">That can make a significant difference, especially if your disk isalready busy.It's better to <EMCLASS="emphasis">cd</EM> to the directory first and run the <EMCLASS="emphasis">rm</EM>from there.You can do it in a<SPANCLASS="link">subshell (with parentheses) (<ACLASS="linkend"HREF="ch13_07.htm"TITLE="The () Subshell Operators ">13.7</A>)</SPAN>if you want to,so you won't have to <EMCLASS="emphasis">cd</EM> back to where you started:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">% <CODECLASS="userinput"><B>(cd /somedir/otherdir; rm *)</B></CODE></PRE></BLOCKQUOTE></P><PCLASS="para">There's one more benefit to this second way: you're not as likely toget the error <CODECLASS="literal">Arguments too long</CODE>.(Another way to handle long command lines is with the<SPANCLASS="link"><EMCLASS="emphasis">xargs</EM> (<ACLASS="linkend"HREF="ch09_21.htm"TITLE="Handle Too-Long Command Lines with xargs ">9.21</A>)</SPAN>command.)</P><DIVCLASS="sect1info"><PCLASS="SECT1INFO">- <SPANCLASS="authorinitials">JP</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="ch15_05.htm"TITLE='15.5 Matching All "Dot Files" with Wildcards'><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT='Previous: 15.5 Matching All "Dot Files" with Wildcards'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="ch15_07.htm"TITLE="15.7 Getting a List of Matching Files with grep -l "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 15.7 Getting a List of Matching Files with grep -l "BORDER="0"></A></TD></TR><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="172">15.5 Matching All "Dot Files" with Wildcards</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">15.7 Getting a List of Matching Files with grep -l </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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