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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><HTML><HEAD><TITLE>Portability Issues</TITLE><METANAME="GENERATOR"CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+"><LINKREL="HOME"TITLE="Advanced Bash-Scripting Guide"HREF="index.html"><LINKREL="UP"TITLE="Miscellany"HREF="miscellany.html"><LINKREL="PREVIOUS"TITLE="Security Issues"HREF="securityissues.html"><LINKREL="NEXT"TITLE="Shell Scripting Under Windows"HREF="winscript.html"><METAHTTP-EQUIV="Content-Style-Type"CONTENT="text/css"><LINKREL="stylesheet"HREF="common/kde-common.css"TYPE="text/css"><METAHTTP-EQUIV="Content-Type"CONTENT="text/html; charset=iso-8859-1"><METAHTTP-EQUIV="Content-Language"CONTENT="en"><LINKREL="stylesheet"HREF="common/kde-localised.css"TYPE="text/css"TITLE="KDE-English"><LINKREL="stylesheet"HREF="common/kde-default.css"TYPE="text/css"TITLE="KDE-Default"></HEAD><BODYCLASS="SECT1"BGCOLOR="#FFFFFF"TEXT="#000000"LINK="#AA0000"VLINK="#AA0055"ALINK="#AA0000"STYLE="font-family: sans-serif;"><DIVCLASS="NAVHEADER"><TABLESUMMARY="Header navigation table"WIDTH="100%"BORDER="0"CELLPADDING="0"CELLSPACING="0"><TR><THCOLSPAN="3"ALIGN="center">Advanced Bash-Scripting Guide: An in-depth exploration of the art of shell scripting</TH></TR><TR><TDWIDTH="10%"ALIGN="left"VALIGN="bottom"><AHREF="securityissues.html"ACCESSKEY="P">Prev</A></TD><TDWIDTH="80%"ALIGN="center"VALIGN="bottom">Chapter 33. Miscellany</TD><TDWIDTH="10%"ALIGN="right"VALIGN="bottom"><AHREF="winscript.html"ACCESSKEY="N">Next</A></TD></TR></TABLE><HRALIGN="LEFT"WIDTH="100%"></DIV><DIVCLASS="SECT1"><H1CLASS="SECT1"><ANAME="PORTABILITYISSUES"></A>33.10. Portability Issues</H1><P>This book deals specifically with Bash scripting on a GNU/Linux system. All the same, users of <BCLASS="COMMAND">sh</B> and <BCLASS="COMMAND">ksh</B> will find much of value here.</P><P>As it happens, many of the various shells and scripting languages seem to be converging toward the POSIX 1003.2 standard. Invoking Bash with the <TTCLASS="OPTION">--posix</TT> option or inserting a <BCLASS="COMMAND">set -o posix</B> at the head of a script causes Bash to conform very closely to this standard. Another alternative is to use a <ICLASS="FIRSTTERM">#!/bin/sh</I> <AHREF="sha-bang.html#SHABANGREF">sha-bang header</A> in the script, rather than <ICLASS="FIRSTTERM">#!/bin/bash</I>. <ANAME="AEN19186"HREF="#FTN.AEN19186">[1]</A> Note that <TTCLASS="FILENAME">/bin/sh</TT> is a <AHREF="external.html#LINKREF">link</A> to <TTCLASS="FILENAME">/bin/bash</TT> in Linux and certain other flavors of UNIX, and a script invoked this way disables extended Bash functionality.</P><P>Most Bash scripts will run as-is under <BCLASS="COMMAND">ksh</B>, and vice-versa, since Chet Ramey has been busily porting <BCLASS="COMMAND">ksh</B> features to the latest versions of Bash.</P><P>On a commercial UNIX machine, scripts using GNU-specific features of standard commands may not work. This has become less of a problem in the last few years, as the GNU utilities have pretty much displaced their proprietary counterparts even on <SPANCLASS="QUOTE">"big-iron"</SPAN> UNIX. <AHREF="http://linux.oreillynet.com/pub/a/linux/2002/02/28/caldera.html"TARGET="_top">Caldera's release of the source</A> to many of the original UNIX utilities has accelerated the trend.</P><P><ANAME="BASHCOMPAT"></A></P><P>Bash has certain features that the traditional Bourne shell lacks. Among these are: <UL><LI><P>Certain extended <AHREF="options.html#INVOCATIONOPTIONSREF">invocation options</A></P></LI><LI><P><AHREF="commandsub.html#COMMANDSUBREF">Command substitution</A> using <BCLASS="COMMAND">$( )</B> notation</P></LI><LI><P>Certain <AHREF="string-manipulation.html#STRINGMANIP">string manipulation</A> operations</P></LI><LI><P><AHREF="process-sub.html#PROCESSSUBREF">Process substitution</A></P></LI><LI><P>Bash-specific <AHREF="internal.html#BUILTINREF">builtins</A></P></LI></UL> </P><P>See the <AHREF="ftp://ftp.cwru.edu/pub/bash/FAQ"TARGET="_top">Bash F.A.Q.</A> for a complete listing.</P></DIV><H3CLASS="FOOTNOTES">Notes</H3><TABLEBORDER="0"CLASS="FOOTNOTES"WIDTH="100%"><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="5%"><ANAME="FTN.AEN19186"HREF="portabilityissues.html#AEN19186">[1]</A></TD><TDALIGN="LEFT"VALIGN="TOP"WIDTH="95%"><P>Or, better yet, <AHREF="system.html#ENVV2REF">#!/bin/env sh</A>.</P></TD></TR></TABLE><DIVCLASS="NAVFOOTER"><HRALIGN="LEFT"WIDTH="100%"><TABLESUMMARY="Footer navigation table"WIDTH="100%"BORDER="0"CELLPADDING="0"CELLSPACING="0"><TR><TDWIDTH="33%"ALIGN="left"VALIGN="top"><AHREF="securityissues.html"ACCESSKEY="P">Prev</A></TD><TDWIDTH="34%"ALIGN="center"VALIGN="top"><AHREF="index.html"ACCESSKEY="H">Home</A></TD><TDWIDTH="33%"ALIGN="right"VALIGN="top"><AHREF="winscript.html"ACCESSKEY="N">Next</A></TD></TR><TR><TDWIDTH="33%"ALIGN="left"VALIGN="top">Security Issues</TD><TDWIDTH="34%"ALIGN="center"VALIGN="top"><AHREF="miscellany.html"ACCESSKEY="U">Up</A></TD><TDWIDTH="33%"ALIGN="right"VALIGN="top">Shell Scripting Under Windows</TD></TR></TABLE></DIV></BODY></HTML>⌨️ 快捷键说明
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