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<HTML><!--Distributed by F --><HEAD><TITLE>[Chapter 34] 34.12 Transformations on Text </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="1998-08-04T21:47:19Z"><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="ch34_01.htm"TITLE="34. The sed Stream Editor"><LINKREL="prev"HREF="ch34_11.htm"TITLE="34.11 Search & Replacement: One Match Among Many "><LINKREL="next"HREF="ch34_13.htm"TITLE="34.13 Hold Space: The Set-Aside Buffer "></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="ch34_11.htm"TITLE="34.11 Search & Replacement: One Match Among Many "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 34.11 Search & Replacement: One Match Among Many "BORDER="0"></A></TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="171"><B><FONTFACE="ARIEL,HELVETICA,HELV,SANSERIF"SIZE="-1">Chapter 34<BR>The sed Stream Editor</FONT></B></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch34_13.htm"TITLE="34.13 Hold Space: The Set-Aside Buffer "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 34.13 Hold Space: The Set-Aside Buffer "BORDER="0"></A></TD></TR></TABLE> <HRALIGN="LEFT"WIDTH="515"TITLE="footer"></DIV><DIVCLASS="SECT1"><H2CLASS="sect1"><ACLASS="title"NAME="UPT-ART-8001">34.12 Transformations on Text </A></H2><PCLASS="para"><ACLASS="indexterm"NAME="AUTOID-38712"></A>The transform command (<EMCLASS="emphasis">y</EM>) is useful forexchanging lowercase letters for uppercase letters on a line.Effectively, it performs a similar function to<SPANCLASS="link"><EMCLASS="emphasis">tr</EM> (<ACLASS="linkend"HREF="ch35_11.htm"TITLE="Hacking on Characters with tr ">35.11</A>)</SPAN>.It replaces any character found in the first string withthe equivalent character in the second string. The command:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">y/abcdefghijklmnopqrstuvwxyz/ABCDEFGHIJKLMNOPQRSTUVWXYZ/</PRE></BLOCKQUOTE></P><PCLASS="para">will convert any lowercase letter into the corresponding uppercaseletter. The following: </P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">y/abcdefghijklmnopqrstuvwxyz/nopqrstuvwxyzabcdefghijklm/</PRE></BLOCKQUOTE></P><PCLASS="para">would perform a <EMCLASS="emphasis">rot13</EM> transformation - a simple form ofencryption in which each alphabetic character is replaced by thecharacter halfway through the alphabet. (<EMCLASS="emphasis">rot13</EM> encryption issometimes used to keep offensive<SPANCLASS="link">news postings (<ACLASS="linkend"HREF="ch01_33.htm"TITLE="UNIX Networking and Communications ">1.33</A>)</SPAN>from beingread except by someone who really means to. Encryption anddecryption are automatically supported by most news readers, but it'sfun to see how simple the encryption is. By the way, the commandabove handles only lowercase letters; if we'd shown uppercase aswell, the command would have run past the margins!)</P><DIVCLASS="sect1info"><PCLASS="SECT1INFO">- <SPANCLASS="authorinitials">TOR</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="ch34_11.htm"TITLE="34.11 Search & Replacement: One Match Among Many "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 34.11 Search & Replacement: One Match Among Many "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="ch34_13.htm"TITLE="34.13 Hold Space: The Set-Aside Buffer "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 34.13 Hold Space: The Set-Aside Buffer "BORDER="0"></A></TD></TR><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="172">34.11 Search & Replacement: One Match Among Many </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">34.13 Hold Space: The Set-Aside Buffer </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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