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<HTML><!--Distributed by F --><HEAD><TITLE>[Chapter 10] 10.9 Shell Functions </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="1998-08-04T21:35:57Z"><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="ch10_01.htm"TITLE="10. Aliases"><LINKREL="prev"HREF="ch10_08.htm"TITLE="10.8 Fix Quoting in csh Aliases with makealias and quote "><LINKREL="next"HREF="ch10_10.htm"TITLE="10.10 Simulated Bourne Shell Functions and Aliases "></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="ch10_08.htm"TITLE="10.8 Fix Quoting in csh Aliases with makealias and quote "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 10.8 Fix Quoting in csh Aliases with makealias and quote "BORDER="0"></A></TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="171"><B><FONTFACE="ARIEL,HELVETICA,HELV,SANSERIF"SIZE="-1">Chapter 10<BR>Aliases</FONT></B></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch10_10.htm"TITLE="10.10 Simulated Bourne Shell Functions and Aliases "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 10.10 Simulated Bourne Shell Functions and Aliases "BORDER="0"></A></TD></TR></TABLE> <HRALIGN="LEFT"WIDTH="515"TITLE="footer"></DIV><DIVCLASS="SECT1"><H2CLASS="sect1"><ACLASS="title"NAME="UPT-ART-2210">10.9 Shell Functions </A></H2><TABLECLASS="para.programreference"BORDER="1"><TR><THVALIGN="TOP"><ACLASS="programreference"HREF="examples/index.htm"TITLE="sh_init">sh_init</A><BR></TH><TDVALIGN="TOP"><ACLASS="indexterm"NAME="AUTOID-12184"></A><ACLASS="indexterm"NAME="AUTOID-12186"></A><ACLASS="indexterm"NAME="AUTOID-12189"></A>The C shell has<SPANCLASS="link">aliases (<ACLASS="linkend"HREF="ch10_02.htm"TITLE="Aliases for Common Commands ">10.2</A>)</SPAN>.But until System V Release 2, the Bourne Shell had<SPANCLASS="link">almost (<ACLASS="linkend"HREF="ch10_10.htm"TITLE="Simulated Bourne Shell Functions and Aliases ">10.10</A>)</SPAN>no way for users to set up their own built-in commands.Functions are like aliases, but better.For instance, functions can<SPANCLASS="link">return a status (<ACLASS="linkend"HREF="ch44_07.htm"TITLE="Exit Status of UNIX Processes ">44.7</A>)</SPAN>and have<SPANCLASS="link">much more reasonable syntax (<ACLASS="linkend"HREF="ch10_07.htm"TITLE="How to Put if-then-else in a C Shell Alias ">10.7</A>)</SPAN>.<EMCLASS="emphasis">bash</EM> and the Korn Shell have shell functions, too.To find out all about functions, check a shell programming book.There are examples in the <EMCLASS="emphasis">sh_init</EM> file on the CD-ROM.Here are the examples fromarticles<ACLASS="xref"HREF="ch10_02.htm"TITLE="Aliases for Common Commands ">10.2</A>and<ACLASS="xref"HREF="ch10_03.htm"TITLE="C Shell Aliases with Command-Line Arguments ">10.3</A>changed into Bourne shell aliases:</TD></TR></TABLE><ULCLASS="itemizedlist"><LICLASS="listitem"><PCLASS="para"><ACLASS="indexterm"NAME="AUTOID-12205"></A><ACLASS="indexterm"NAME="AUTOID-12208"></A>The <EMCLASS="emphasis">la</EM> function includes "hidden" files in <EMCLASS="emphasis">ls</EM> listings.The <EMCLASS="emphasis">lf</EM> function labels the names as directories, executable files, andso on:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">la () { ls -a "$@"; }lf () { ls -F "$@"; }</PRE></BLOCKQUOTE></P><PCLASS="para"> The spaces and the semicolon (<CODECLASS="literal">;</CODE>) are both important![3]The<SPANCLASS="link"><CODECLASS="literal">"$@"</CODE> (<ACLASS="linkend"HREF="ch44_15.htm"TITLE="Handling Command-Line Arguments in Shell Scripts ">44.15</A>)</SPAN>is replaced by the command-line arguments (other options,or directory and filenames), if you use any:</P><BLOCKQUOTECLASS="footnote"><PCLASS="para">[3] A function is a Bourne shell<SPANCLASS="link">list construct (<ACLASS="linkend"HREF="ch13_08.htm"TITLE="Using {list} to Group Bourne Shell Commands ">13.8</A>)</SPAN>.You can omit the semicolon in <EMCLASS="emphasis">bash</EM>-but, if you do, your functionswon't be portable.</P></BLOCKQUOTE><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">$ <CODECLASS="userinput"><B>la -l somedir</B></CODE> <ICLASS="lineannotation">...runs </I>ls -a -l somedir</PRE></BLOCKQUOTE></P><PCLASS="para"></P></LI><LICLASS="listitem"><PCLASS="para"><ACLASS="indexterm"NAME="AUTOID-12230"></A><ACLASS="indexterm"NAME="AUTOID-12232"></A><ACLASS="indexterm"NAME="AUTOID-12235"></A>This next simple function, <EMCLASS="emphasis">cur</EM>, gives the name of your currentdirectory and then lists it:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">cur(){ pwd ls}</PRE></BLOCKQUOTE></P></LI></UL><PCLASS="para">That example shows how to write a function with more than one line.In that style, with the ending curly brace on its own line,you don't need a semicolon after the last command.</P><DIVCLASS="sect1info"><PCLASS="SECT1INFO">- <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="ch10_08.htm"TITLE="10.8 Fix Quoting in csh Aliases with makealias and quote "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 10.8 Fix Quoting in csh Aliases with makealias and quote "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="ch10_10.htm"TITLE="10.10 Simulated Bourne Shell Functions and Aliases "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 10.10 Simulated Bourne Shell Functions and Aliases "BORDER="0"></A></TD></TR><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="172">10.8 Fix Quoting in csh Aliases with makealias and quote </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">10.10 Simulated Bourne Shell Functions and Aliases </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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