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<HTML><!--Distributed by F --><HEAD><TITLE>[Chapter 50] 50.4 whatis: One-Line Command Summaries </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="1998-08-04T21:56:53Z"><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="ch50_01.htm"TITLE="50. Help--Online Documentation, etc."><LINKREL="prev"HREF="ch50_03.htm"TITLE="50.3 apropos on Systems Without apropos "><LINKREL="next"HREF="ch50_05.htm"TITLE="50.5 whereis: Finding Where a Command Is Located "></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="ch50_03.htm"TITLE="50.3 apropos on Systems Without apropos "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 50.3 apropos on Systems Without apropos "BORDER="0"></A></TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="171"><B><FONTFACE="ARIEL,HELVETICA,HELV,SANSERIF"SIZE="-1">Chapter 50<BR>Help--Online Documentation, etc.</FONT></B></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch50_05.htm"TITLE="50.5 whereis: Finding Where a Command Is Located "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 50.5 whereis: Finding Where a Command Is Located "BORDER="0"></A></TD></TR></TABLE> <HRALIGN="LEFT"WIDTH="515"TITLE="footer"></DIV><DIVCLASS="SECT1"><H2CLASS="sect1"><ACLASS="title"NAME="UPT-ART-2110">50.4 whatis: One-Line Command Summaries </A></H2><PCLASS="para"><ACLASS="indexterm"NAME="AUTOID-59161"></A><ACLASS="indexterm"NAME="AUTOID-59164"></A><ACLASS="indexterm"NAME="AUTOID-59167"></A><ACLASS="indexterm"NAME="AUTOID-59170"></A><ACLASS="indexterm"NAME="AUTOID-59172"></A><EMCLASS="emphasis">whatis</EM> is almost identical to<SPANCLASS="link"><EMCLASS="emphasis">apropos</EM> (<ACLASS="linkend"HREF="ch50_02.htm"TITLE="The apropos Command ">50.2</A>)</SPAN>,but it requires acommand name as an argument - rather than an arbitrary string.Why is this useful?Well, let's say you forget what <EMCLASS="emphasis">cat</EM> does.On my system, <EMCLASS="emphasis">apropos cat</EM> gives you several screenfulsof output.You may not want to read the entire manual page.But <EMCLASS="emphasis">whatis cat</EM> gives you a nice one-line summary:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">% <CODECLASS="userinput"><B>whatis cat</B></CODE>cat (1V) - concatenate and display </PRE></BLOCKQUOTE></P><PCLASS="para">If you're using the <EMCLASS="emphasis">apropos</EM> fake-out we discussed in article <ACLASS="xref"HREF="ch50_03.htm"TITLE="apropos on Systems Without apropos ">50.3</A>,you can simulate <EMCLASS="emphasis">whatis</EM> with an<SPANCLASS="link">alias (<ACLASS="linkend"HREF="ch10_03.htm"TITLE="C Shell Aliases with Command-Line Arguments ">10.3</A>)</SPAN>or<SPANCLASS="link">shell function (<ACLASS="linkend"HREF="ch10_09.htm"TITLE="Shell Functions ">10.9</A>)</SPAN>:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">alias whatis "grep '^ *'\!$ /home/mike/manindex.txt"whatis() { grep "^ *$1" /home/mike/manindex.txt; }</PRE></BLOCKQUOTE></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="ch50_03.htm"TITLE="50.3 apropos on Systems Without apropos "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 50.3 apropos on Systems Without apropos "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="ch50_05.htm"TITLE="50.5 whereis: Finding Where a Command Is Located "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 50.5 whereis: Finding Where a Command Is Located "BORDER="0"></A></TD></TR><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="172">50.3 apropos on Systems Without apropos </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">50.5 whereis: Finding Where a Command Is Located </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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