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<HTML><!--Distributed by F --><HEAD><TITLE>[Chapter 36] 36.5 Alphabetic and Numeric Sorting </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="1998-08-04T21:48:41Z"><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="ch36_01.htm"TITLE="36. Sorting"><LINKREL="prev"HREF="ch36_04.htm"TITLE="36.4 Confusion with White Space Field Delimiters "><LINKREL="next"HREF="ch36_06.htm"TITLE="36.6 Miscellaneous sort Hints "></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="ch36_04.htm"TITLE="36.4 Confusion with White Space Field Delimiters "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 36.4 Confusion with White Space Field Delimiters "BORDER="0"></A></TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="171"><B><FONTFACE="ARIEL,HELVETICA,HELV,SANSERIF"SIZE="-1">Chapter 36<BR>Sorting</FONT></B></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch36_06.htm"TITLE="36.6 Miscellaneous sort Hints "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 36.6 Miscellaneous sort Hints "BORDER="0"></A></TD></TR></TABLE> <HRALIGN="LEFT"WIDTH="515"TITLE="footer"></DIV><DIVCLASS="SECT1"><H2CLASS="sect1"><ACLASS="title"NAME="UPT-ART-2923">36.5 Alphabetic and Numeric Sorting </A></H2><PCLASS="para"><ACLASS="indexterm"NAME="AUTOID-41675"></A><EMCLASS="emphasis">sort</EM> performs two fundamentally different kinds of sorting operations:alphabetic sorts and numeric sorts.An alphabetic sort isperformed according to the traditional "dictionary order," using the<SPANCLASS="link">ASCII (<ACLASS="linkend"HREF="ch51_03.htm"TITLE="ASCII Characters: Listing and Getting Values ">51.3</A>)</SPAN>collating sequence.Uppercase letters come before lowercase letters (unlessyou specify the <EMCLASS="emphasis">-f</EM> option, which "folds" uppercase andlowercase together), with numerals and punctuation interspersed.</P><PCLASS="para">This is all fairly trivial and common sense.However, it's worthbelaboring the difference, because it's a frequent source of bugs inshell scripts.Say you sort the numbers 1 through 12.A numeric sortgives you these numbers "in order," just like you'd expect.Analphabetic sort gives you:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">111122...</PRE></BLOCKQUOTE></P><PCLASS="para">Of course, this is how you'd sort the numbers if you applieddictionary rules to the list.Numeric sorts can handle decimalnumbers (for example, numbers like 123.44565778); they can't handlefloating-point numbers (for example, 1.2344565778E+02).</P><PCLASS="para">What happens if you include alphabeticcharacters in a numeric sort?Although the results arepredictable, I would prefer to say that they're "undefined."Including alphabetic characters in a numeric sort is a mistake, andthere's no guarantee that different versions of <EMCLASS="emphasis">sort</EM> will handlethem the same way.As far as I know, there is no provision forsorting hexadecimal numbers.</P><PCLASS="para">One final note: Under System V, the numeric sort treats initialblanks as significant - so numbers with additional spaces before themwill be sorted ahead of numbers without the additional spaces.Thisis an incredibly stupid misfeature.There is a workaround; use the<EMCLASS="emphasis">-b</EM> (ignore leading blanks) and always specify a sort field.[2]That is: <CODECLASS="literal">sort -nb +0</CODE> will do what you expect; <CODECLASS="literal">sort -n</CODE>won't.<ACLASS="indexterm"NAME="AUTOID-41695"></A></P><BLOCKQUOTECLASS="footnote"><PCLASS="para">[2] Stupid misfeature number 2: <EMCLASS="emphasis">-b</EM> doesn't work unless youspecify a sort field explicitly, with a <EMCLASS="emphasis">+n</EM> option.</P></BLOCKQUOTE><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="ch36_04.htm"TITLE="36.4 Confusion with White Space Field Delimiters "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 36.4 Confusion with White Space Field Delimiters "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="ch36_06.htm"TITLE="36.6 Miscellaneous sort Hints "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 36.6 Miscellaneous sort Hints "BORDER="0"></A></TD></TR><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="172">36.4 Confusion with White Space Field Delimiters </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">36.6 Miscellaneous sort Hints </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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