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<HTML><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><!-- Created on September, 12 2004 by texi2html 1.64 --><!-- Written by: Lionel Cons <Lionel.Cons@cern.ch> (original author) Karl Berry <karl@freefriends.org> Olaf Bachmann <obachman@mathematik.uni-kl.de> and many others.Maintained by: Olaf Bachmann <obachman@mathematik.uni-kl.de>Send bugs and suggestions to <texi2html@mathematik.uni-kl.de> --><HEAD><TITLE>Autoconf, Automake, and Libtool: Why Use the Bourne Shell?</TITLE><META NAME="description" CONTENT="Autoconf, Automake, and Libtool: Why Use the Bourne Shell?"><META NAME="keywords" CONTENT="Autoconf, Automake, and Libtool: Why Use the Bourne Shell?"><META NAME="resource-type" CONTENT="document"><META NAME="distribution" CONTENT="global"><META NAME="Generator" CONTENT="texi2html 1.64"><script language="Javascript"><!-- // Check the browser version. function checkVersion() { if (navigator.appVersion.charAt(0)>=3) return true; if (navigator.appVersion.charAt(0)>=4) return true; 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Much of the subject matter of this book isconcerned with how best to approach writing programs which will work onas many of these variants as possible. One of the few programming toolsthat is absolutely guaranteed to be present on every flavour of Unix inuse today is Steve Bourne's original shell, <CODE>sh</CODE> -- the BourneShell. That is why Libtool is written as a Bourne Shell script, and whythe <CODE>configure</CODE> files generated by Autoconf are Bourne Shellscripts: they can be executed on all known Unix flavours, and as a bonuson most POSIX based non-Unix operating systems too.</P><P>However, there are complications. Over the years, <FONT SIZE="-1">OS</FONT> vendorshave improved Steve Bourne's original shell or have reimplemented it inan almost, but not quite, compatible way. There also a great number ofBourne compatible shells which are often used as a system's default<SAMP>`/bin/sh'</SAMP>: <CODE>ash</CODE>, <CODE>bash</CODE>, <CODE>bsh</CODE>,<CODE>ksh</CODE>, <CODE>sh5</CODE> and <CODE>zsh</CODE> are some that you maycome across. For the rest of this chapter, when I say `shell', I meana Bourne compatible shell.</P><P>This leads us to the black art known as <EM>portable shellprogramming</EM>, the art of writing a single script which will runcorrectly through all of these varying implementations of<SAMP>`/bin/sh'</SAMP>. Of course, Unix systems are constantly evolving and newvariations are being introduced all the time (and very old systems whichhave fallen into disuse can perhaps be ignored by the pragmatic). Theamount of system knowledge required to write a truly portable shellscript is vast, and a great deal of the information that sets aprecedent for a given idiom is necessarily second or third (or tenth)hand. Practically, this means that some of the knowledge accumulated inpopular portable shell scripts is very probably folklore -- but thatdoesn't really matter too much, the important thing is that if youadhere to these idioms, you shouldn't have any problems from people whocan't run your program on their system.</P><P><A NAME="Sh Implementation"></A></TR></TABLE><BR> <FONT SIZE="-1">This document was generatedby <I>Gary V. Vaughan</I> on <I>September, 12 2004</I>using <A HREF="http://www.mathematik.uni-kl.de/~obachman/Texi2html"><I>texi2html</I></A></BODY></HTML>⌨️ 快捷键说明
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