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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: What is Portability?</TITLE><META NAME="description" CONTENT="Autoconf, Automake, and Libtool: What is Portability?"><META NAME="keywords" CONTENT="Autoconf, Automake, and Libtool: What is Portability?"><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; else return false; } if (checkVersion()) { homeon = new Image(); homeon.src = "homeon.png"; homeoff = new Image(); homeoff.src = "home.png"; tocon = new Image(); tocon.src = "tocon.png"; tocoff = new Image(); tocoff.src = "toc.png"; indexon = new Image(); indexon.src = "indexon.png"; indexoff = new Image(); indexoff.src = "index.png"; helpon = new Image(); helpon.src = "helpon.png"; helpoff = new Image(); helpoff.src = "help.png"; backon = new Image(); backon.src = "backon.png"; backoff = new Image(); backoff.src = "back.png"; forwardon = new Image(); forwardon.src = "forwardon.png"; forwardoff = new Image(); forwardoff.src = "forward.png"; prevon = new Image(); prevon.src = "prevon.png"; prevoff = new Image(); prevoff.src = "prev.png"; nexton = new Image(); nexton.src = "nexton.png"; nextoff = new Image(); nextoff.src = "next.png"; upon = new Image(); upon.src = "upon.png"; upoff = new Image(); upoff.src = "up.png"; } function img_act(imgName) { if (checkVersion()) { imgOn = eval(imgName + "on.src"); document [imgName].src = imgOn; } } function img_inact(imgName) { if (checkVersion()) { imgOff = eval(imgName + "off.src"); document [imgName].src = imgOff; } }// --></SCRIPT></HEAD><BODY LANG="EN" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#6688AA" VLINK="#336688" ALINK="#808080"><A NAME="SEC30"></A><TABLE BORDER=0 CELLPADDING=0 CELLSPACING=10><TR VALIGN="TOP"><TD ALIGN="MIDDLE" WIDTH=50 BGCOLOR="#e6e6e6"><TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0><TR VALIGN="TOP" ALIGN="LEFT"><TD VALIGN="MIDDLE" ALIGN="LEFT"><A HREF="autobook_29.html#SEC29" onMouseover="img_act('prev')" onMouseout="img_inact('prev')"><IMG SRC="prev.png" BORDER="0" ALT="Back: Writing configure.in" ALIGN="MIDDLE" NAME="prev"></A></TD></TR><TR VALIGN="TOP" ALIGN="LEFT"><TD VALIGN="MIDDLE" ALIGN="LEFT"><A HREF="autobook_31.html#SEC31" onMouseover="img_act('next')" onMouseout="img_inact('next')"><IMG SRC="next.png" BORDER="0" ALT="Forward: Brief introduction to portable sh" ALIGN="MIDDLE" NAME="next"></A></TD></TR><TR VALIGN="TOP" ALIGN="LEFT"><TD VALIGN="MIDDLE" ALIGN="LEFT"> <TR VALIGN="TOP" ALIGN="LEFT"><TD VALIGN="MIDDLE" ALIGN="LEFT"><A HREF="autobook_29.html#SEC29" onMouseover="img_act('back')" onMouseout="img_inact('back')"><IMG SRC="back.png" BORDER="0" ALT="FastBack: Writing configure.in" ALIGN="MIDDLE" NAME="back"></A></TD></TR><TR VALIGN="TOP" ALIGN="LEFT"><TD VALIGN="MIDDLE" ALIGN="LEFT"><A HREF="autobook_29.html#SEC29" onMouseover="img_act('up')" onMouseout="img_inact('up')"><IMG SRC="up.png" BORDER="0" ALT="Up: Writing configure.in" ALIGN="MIDDLE" NAME="up"></A></TD></TR><TR VALIGN="TOP" ALIGN="LEFT"><TD VALIGN="MIDDLE" ALIGN="LEFT"><A HREF="autobook_35.html#SEC35" onMouseover="img_act('forward')" onMouseout="img_inact('forward')"><IMG SRC="forward.png" BORDER="0" ALT="FastForward: Introducing GNU Automake" ALIGN="MIDDLE" NAME="forward"></A></TD></TR><TR VALIGN="TOP" ALIGN="LEFT"><TD VALIGN="MIDDLE" ALIGN="LEFT"><A HREF="autobook.html#SEC_Top" onMouseover="img_act('home')" onMouseout="img_inact('home')"><IMG SRC="home.png" BORDER="0" ALT="Top: Autoconf, Automake, and Libtool" ALIGN="MIDDLE" NAME="home"></A></TD></TR><TR VALIGN="TOP" ALIGN="LEFT"><TD VALIGN="MIDDLE" ALIGN="LEFT"><A HREF="autobook_toc.html#SEC_Contents" onMouseover="img_act('toc')" onMouseout="img_inact('toc')"><IMG SRC="toc.png" BORDER="0" ALT="Contents: Table of Contents" ALIGN="MIDDLE" NAME="toc"></A></TD></TR><TR VALIGN="TOP" ALIGN="LEFT"><TD VALIGN="MIDDLE" ALIGN="LEFT"><A HREF="autobook_285.html#SEC285" onMouseover="img_act('index')" onMouseout="img_inact('index')"><IMG SRC="index.png" BORDER="0" ALT="Index: Index" ALIGN="MIDDLE" NAME="index"></A></TD></TR><TR VALIGN="TOP" ALIGN="LEFT"><TD VALIGN="MIDDLE" ALIGN="LEFT"><A HREF="autobook_abt.html#SEC_About" onMouseover="img_act('help')" onMouseout="img_inact('help')"><IMG SRC="help.png" BORDER="0" ALT="About: About this document" ALIGN="MIDDLE" NAME="help"></A></TD></TR></TABLE></TD><TD ALIGN="LEFT"><H2> 6.1 What is Portability? </H2><!--docid::SEC30::--><P>Before we talk about the mechanics of deciding what to check for and howto check for it, let's ask ourselves a simple question: what isportability? Portability is a quality of the code that enables it to bebuilt and run on a variety of platforms. In the Autoconf context,portability usually refers to the ability to run on Unix-likesystems--sometimes including Windows.</P><P>When I first started using Autoconf, I had a hard time deciding what tocheck for in my <TT>`configure.in'</TT>. At the time, I was maintaining aproprietary program that ran only on SunOS 4. However, I was interestedin porting it to Solaris, OSF/1, and possibly Irix.</P><P>The approach I took, while workable, was relatively time-consuming andpainful: I wrote a minimal <TT>`configure.in'</TT> and then proceeded tosimply try to build my program on Solaris. Each time I encountered abuild problem, I updated <TT>`configure.in'</TT> and my source and startedagain. Once it built correctly, I started testing to see if there wereruntime problems related to portability.</P><P>Since I didn't start with a relatively portable base, and since I wasunaware of the tools available to help with adding Autoconf support to apackage (see section <A HREF="autobook_237.html#SEC237">24. Migrating an Existing Package to GNU Autotools</A>), it was much moredifficult than it had to be. If at all possible, it is better to writeportable code to begin with.</P><P>There are a large number of Unix-like systems in the world, includingmany systems which, while still running, can only be consideredobsolete. While it is probably possible to port some programs to allsuch systems, typically it isn't useful to even try. Porting toeverything is a difficult process, especially given that it usuallyisn't possible to test on all platforms, and that new operating systems,with their own bugs and idiosyncrasies are released every year.</P><P>We advocate a pragmatic approach to portability: we write our programsto target a fairly large, but also fairly modern, cross-section ofUnix-like systems. As deficiencies are discovered in our portabilityframework, we update <TT>`configure.in'</TT> and our sources, and move on.In practice, this is an effective approach.</P><P><A NAME="Brief introduction to portable sh"></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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