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<HTML><!--Distributed by F --><HEAD><TITLE>[Chapter 19] 19.7 Extracting Files from a Compressed Archive </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="1998-08-04T21:39:29Z"><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="ch19_01.htm"TITLE="19. Creating and Reading Archives"><LINKREL="prev"HREF="ch19_06.htm"TITLE="19.6 GNU tar Sampler "><LINKREL="next"HREF="ch19_08.htm"TITLE="19.8 Problems with Verbose tar "></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="ch19_06.htm"TITLE="19.6 GNU tar Sampler "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 19.6 GNU tar Sampler "BORDER="0"></A></TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="171"><B><FONTFACE="ARIEL,HELVETICA,HELV,SANSERIF"SIZE="-1">Chapter 19<BR>Creating and Reading Archives</FONT></B></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch19_08.htm"TITLE="19.8 Problems with Verbose tar "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 19.8 Problems with Verbose tar "BORDER="0"></A></TD></TR></TABLE> <HRALIGN="LEFT"WIDTH="515"TITLE="footer"></DIV><DIVCLASS="SECT1"><H2CLASS="sect1"><ACLASS="title"NAME="UPT-ART-0398">19.7 Extracting Files from a Compressed Archive </A></H2><PCLASS="para"><ACLASS="indexterm"NAME="AUTOID-21502"></A><ACLASS="indexterm"NAME="AUTOID-21504"></A><ACLASS="indexterm"NAME="AUTOID-21508"></A><ACLASS="indexterm"NAME="AUTOID-21511"></A>Article<ACLASS="xref"HREF="ch19_05.htm"TITLE="Using tar to Create and Unpack Archives ">19.5</A>,discussed creating and unpacking compressed <EMCLASS="emphasis">tar</EM> archives with<SPANCLASS="link"><EMCLASS="emphasis">gzip</EM>, <EMCLASS="emphasis">gunzip</EM> (<ACLASS="linkend"HREF="ch24_07.htm"TITLE="Compressing Files to Save Space ">24.7</A>)</SPAN>,and <EMCLASS="emphasis">tar</EM>.This article explains how to simplify those two-step processes.The first command line below creates a <EMCLASS="emphasis">gzip</EM>ped archive;the second extracts it:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">% <CODECLASS="userinput"><B>tar cf - </B></CODE><CODECLASS="replaceable"><I>pathnames </I></CODE><CODECLASS="userinput"><B>| gzip > archive.tar.gz</B></CODE>% <CODECLASS="userinput"><B>gzcat archive.tar.gz | tar xf - </B></CODE><CODECLASS="replaceable"><I>pathnames</I></CODE></PRE></BLOCKQUOTE></P><PCLASS="para"><EMCLASS="emphasis">gzcat</EM> uncompresses a file (the <EMCLASS="emphasis">gzip</EM> format, aswell as older <EMCLASS="emphasis">compress</EM> and <EMCLASS="emphasis">pack</EM> formats), sending the result tostandard output. With the <EMCLASS="emphasis">f</EM> option, and<ACLASS="indexterm"NAME="AUTOID-21533"></A><SPANCLASS="link"><CODECLASS="literal">-</CODE> (<ACLASS="linkend"HREF="ch13_13.htm"TITLE='The "Filename" - '>13.13</A>)</SPAN>listed as a filename, <EMCLASS="emphasis">tar</EM> writes to standard output whencreating an archive and reads from standard input when extracting.You don't need to create the larger, uncompressed file; you canstore the archive permanently in its compressed form.To extract only some of the files in the archive, give the<CODECLASS="replaceable"><I>pathnames</I></CODE> on the command line <EMCLASS="emphasis">exactly</EM> as they're stored inthe archive.Otherwise, <EMCLASS="emphasis">tar</EM> will extract all the files.(For a list of the exact pathnames, use <CODECLASS="literal">tar tf -</CODE>.)</P><PCLASS="para">GNU <EMCLASS="emphasis">tar</EM> makes this even easier.As article<ACLASS="xref"HREF="ch19_06.htm"TITLE="GNU tar Sampler ">19.6</A>shows, the GNU <EMCLASS="emphasis">z</EM> option creates or extracts a <EMCLASS="emphasis">gzip</EM>pedarchive directly.Here are the two examples above using the <EMCLASS="emphasis">z</EM> option:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">% <CODECLASS="userinput"><B>tar czf archive.tar.gz </B></CODE><CODECLASS="replaceable"><I>pathnames</I></CODE>% <CODECLASS="userinput"><B>tar xzf archive.tar.gz </B></CODE><CODECLASS="replaceable"><I>pathnames</I></CODE></PRE></BLOCKQUOTE></P><TABLECLASS="para.programreference"BORDER="1"><TR><THVALIGN="TOP"><ACLASS="xref.warning"HREF="ch19_08.htm"TITLE="19.8 Problems with Verbose tar ">Warning!</A> </TH><TDVALIGN="TOP"> Instead of <CODECLASS="literal">cf</CODE>, you can use <CODECLASS="literal">cvf</CODE> so <EMCLASS="emphasis">tar</EM>will list each file as it's processed.</TD></TR></TABLE><BLOCKQUOTECLASS="note"><PCLASS="para"><STRONG>NOTE:</STRONG> If you extract files from an archive that you didn't create, thefiles you extract may not belong to you.Here's why.On many non-BSD systems, when <EMCLASS="emphasis">tar</EM> extracts a file,the file will be owned by the same<SPANCLASS="link">UID (<ACLASS="linkend"HREF="ch38_03.htm"TITLE="Managing Processes: Overall Concepts ">38.3</A>)</SPAN>that owned the file when the archive was created.If that UID isn't yours, <EMCLASS="emphasis">tar</EM> may extract directoriesyou can't modify and files you can't edit.<ACLASS="indexterm"NAME="AUTOID-21565"></A>On systems with that problem, you can add the <EMCLASS="emphasis">o</EM> option(for example, <CODECLASS="literal">tar</CODE> <CODECLASS="literal">xof</CODE>) to be sure that filesextracted will belong to you.</P></BLOCKQUOTE><DIVCLASS="sect1info"><PCLASS="SECT1INFO">- <SPANCLASS="authorinitials">ML</SPAN>, <SPANCLASS="authorinitials">JIK</SPAN>, <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="ch19_06.htm"TITLE="19.6 GNU tar Sampler "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 19.6 GNU tar Sampler "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="ch19_08.htm"TITLE="19.8 Problems with Verbose tar "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 19.8 Problems with Verbose tar "BORDER="0"></A></TD></TR><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="172">19.6 GNU tar Sampler </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">19.8 Problems with Verbose tar </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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