added part on Portable Shell Programming

[[Imported from SVN: r4723]]

doc/devel/portability.wml

@@ -52,6 +52,32 @@ The same problem implies for several _"one big charakter" names.
 So be warned :-)
 </pre>
 
+<h1>Portable Shell Programming</h1>
+<p>
+In the buildsystem quite some shell code is needed. The default
+shell <tt>/bin/sh</tt> is supposed to behave the same, no matter which
+machine you run your script on. Sadly there are some subtile, but
+still important, differences between the different 'bourne shell'
+implementations. Therefore it is important to know about possible caveats.
+</p>
+<ul>
+<li>
+<a href="http://www.newsforge.com/article.pl?sid=04/03/01/1554205">
+What to watch out for when writing portable shell scripts</a>
+(article in newsforge)
+</li>
+<li>
+<a href="http://code.dogmap.org/lintsh/">lintsh</a>: a collection of
+known incompatibilities between different <tt>sh</tt> versions.
+</li>
+<li>
+Autoconf Guide - chapter
+<a
+href="http://www.gnu.org/software/autoconf/manual/autoconf-2.57/html_node/autoconf_114.html">
+Portable Shell Programming</a>
+</li>
+</ul>
+
 <h1>Further information</h1>
 <ul>
 <li><a href="http://predef.sourceforge.net/">http://predef.sourceforge.net/</a>