is_file returns TRUE but include fails on same file
<p>When I run the following script:</p>

<pre><code>&lt;html&gt;
&lt;head&gt;
&lt;title&gt;Example&lt;/title&gt;
&lt;/head&gt;
&lt;?php
echo get_include_path(), "\n";

var_dump(is_file('/usr/lib/php/HTTP/OAuth.php'));
?&gt;
&lt;body&gt;
&lt;/body&gt;
&lt;/html&gt;
</code></pre>

<p>I get the following output on the rendered page:</p>

<pre><code>.:/php/includes:/usr/lib/php:/usr/lib/php/PEAR bool(true)
</code></pre>

<p>However, if I run this script:</p>

<pre><code>&lt;html&gt;
&lt;head&gt;
&lt;title&gt;Example&lt;/title&gt;
&lt;/head&gt;
&lt;?php
echo get_include_path(), "\n";

var_dump(is_file('/usr/lib/php/HTTP/OAuth.php'));

#### NEW SECTION ####

if (include(''/usr/lib/php/HTTP/OAuth.php'') == 'OK') {
echo 'INCLUDE OK, "\n"';
} else { echo 'INCLUDE FAILED \n' ; }

#### END NEW SECTION ####

?&gt;
&lt;body&gt;
&lt;/body&gt;
&lt;/html&gt;
</code></pre>

<p>I get the following output:</p>

<pre><code>.:/php/includes:/usr/lib/php:/usr/lib/php/PEAR bool(true) INCLUDE FAILED \n
</code></pre>

<p>Why would the include fail if the file is said to exist already?  </p>

<p>uname output in case it is helpful:</p>

<pre><code>Darwin 70cd606c7510 10.8.0 Darwin Kernel Version 10.8.0: Tue Jun  7 16:33:36 PDT 2011; root:xnu-1504.15.3~1/RELEASE_I386 i386
</code></pre>

<p>Thank you for your help.</p>

<p>John</p>
