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<HTML><!--Distributed by F --><HEAD><TITLE>[Chapter 13] 13.11 tpipe-Redirecting stdout to More than One Place </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="1998-08-04T21:36:49Z"><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="ch13_01.htm"TITLE="13. Redirecting Input and Output"><LINKREL="prev"HREF="ch13_10.htm"TITLE="13.10 How to tee Several Commands Into One File "><LINKREL="next"HREF="ch13_12.htm"TITLE="13.12 Writing to Multiple Terminals for Demonstrations "></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="ch13_10.htm"TITLE="13.10 How to tee Several Commands Into One File "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 13.10 How to tee Several Commands Into One File "BORDER="0"></A></TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="171"><B><FONTFACE="ARIEL,HELVETICA,HELV,SANSERIF"SIZE="-1">Chapter 13<BR>Redirecting Input and Output</FONT></B></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch13_12.htm"TITLE="13.12 Writing to Multiple Terminals for Demonstrations "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 13.12 Writing to Multiple Terminals for Demonstrations "BORDER="0"></A></TD></TR></TABLE> <HRALIGN="LEFT"WIDTH="515"TITLE="footer"></DIV><DIVCLASS="SECT1"><H2CLASS="sect1"><ACLASS="title"NAME="UPT-ART-9018">13.11 tpipe-Redirecting stdout to More than One Place </A></H2><TABLECLASS="para.programreference"BORDER="1"><TR><THVALIGN="TOP"><ACLASS="programreference"HREF="examples/index.htm"TITLE="tpipe">tpipe</A><BR></TH><TDVALIGN="TOP"><ACLASS="indexterm"NAME="AUTOID-14668"></A><ACLASS="indexterm"NAME="AUTOID-14670"></A><ACLASS="indexterm"NAME="AUTOID-14673"></A><ACLASS="indexterm"NAME="AUTOID-14676"></A><ACLASS="indexterm"NAME="AUTOID-14680"></A>What if you want to use the output of a program twice,and you don't want to deal with an intermediary file?Try the <EMCLASS="emphasis">tpipe</EM> program. </TD></TR></TABLE><PCLASS="para"><EMCLASS="emphasis">tpipe</EM> is similar to<SPANCLASS="link"><EMCLASS="emphasis">tee</EM> (<ACLASS="linkend"HREF="ch13_09.htm"TITLE="Send Output Two or More Places with tee ">13.9</A>)</SPAN>,but instead of putting a copy of standard input in a file,it passes the input to a new pipe.You couldsimulate <EMCLASS="emphasis">tpipe</EM> by using <EMCLASS="emphasis">tee</EM> and runningthe commands on the <EMCLASS="emphasis">tee</EM> file, but there areinstances when you don't want to clutter up your diskwith files.</P><PCLASS="para">For example, suppose I have some large, compressed PostScript files.I want to print the files, but I also want to know how many pages they are.I know that the number of pagesappears on a line following <CODECLASS="literal">%%Pages:</CODE> at the end of the file.Using<SPANCLASS="link"><EMCLASS="emphasis">gzcat</EM> (<ACLASS="linkend"HREF="ch24_07.htm"TITLE="Compressing Files to Save Space ">24.7</A>)</SPAN>to uncompress the fileto standard output, I can type the following commands into a<SPANCLASS="link"><EMCLASS="emphasis">for</EM> loop (<ACLASS="linkend"HREF="ch09_12.htm"TITLE="The Bourne Shell for Loop ">9.12</A>)</SPAN>(or put them into a shell script).This loop sends eachfile to the printer and uses <EMCLASS="emphasis">sed</EM> to capture the correct line:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">for fdo gzcat $f | lpr gzcat $f | sed -n "s/^%%Pages: \([0-9][0-9]*\)/$f: \1 pages/p"done</PRE></BLOCKQUOTE></P><PCLASS="para">But this ends up running <EMCLASS="emphasis">gzcat</EM> twice, which takes some time.I can <EMCLASS="emphasis">gunzip</EM> the file first, but frankly I'm not sure I havethe disk space for that.</P><PCLASS="para">Using <EMCLASS="emphasis">tpipe</EM>, I can do it in one line, without wasting processesand without eating disk space:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">for fdo gzcat $f | tpipe lpr | sed -n "s/^%%Pages: \([0-9][0-9]*\)/$f: \1 pages/p"done</PRE></BLOCKQUOTE></P><PCLASS="para">From running this script, as each file is sent to the printer Ireceive the following messages on my screen:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">ch01.ps.gz: 44 pagesch02.ps.gz: 51 pagesch03.ps.gz: 23 pages ...</PRE></BLOCKQUOTE></P><PCLASS="para"> If you don't have <EMCLASS="emphasis">tpipe</EM>, you can also simulate itusing<SPANCLASS="link"><EMCLASS="emphasis">awk</EM> (<ACLASS="linkend"HREF="ch33_11.htm"TITLE="Quick Reference: awk ">33.11</A>)</SPAN>:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">gzcat $f | awk "{ print | \"lpr\" ; print }" | \ sed -n "s/^%%Pages: \([0-9][0-9]*\)/$f: \1 pages/p"</PRE></BLOCKQUOTE></P><PCLASS="para">This is much slower and only works on text files, but it does the job.</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="ch13_10.htm"TITLE="13.10 How to tee Several Commands Into One File "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 13.10 How to tee Several Commands Into One File "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="ch13_12.htm"TITLE="13.12 Writing to Multiple Terminals for Demonstrations "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 13.12 Writing to Multiple Terminals for Demonstrations "BORDER="0"></A></TD></TR><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="172">13.10 How to tee Several Commands Into One File </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">13.12 Writing to Multiple Terminals for Demonstrations </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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