Update soffice documentation

documentation/installation_guide.html

@@ -796,13 +796,20 @@ Provider</a> for) include a full review of the full-text search feature.
 <h2><a name="11._Chamilo_rapid_ppt_conversion"></a>Chamilo Rapid - PPT conversion system</h2>
 <p>
 <em>Note</em>: This step will require a dedicated server or a virtual dedicated server as the packages involved are not available on most shared hosting solutions.<br />
-On Debian or Ubuntu 11.10 and superior, install LibreOffice.org v3 and start it as a headless server:
+On Debian or Ubuntu 11.10 and superior, install LibreOffice v3 (or v4) and start it as a headless server:
 <pre>
-sudo apt-get install libreoffice
-sudo soffice --accept="socket,host=127.0.0.1,port=2002,tcpNoDelay=1;urp;" --headless --nodefault --nofirststartwizard --nolockcheck --nologo --norestore &amp;
+sudo apt-get install libreoffice screen
+sudo screen
+su - www-data
+soffice --accept="socket,host=127.0.0.1,port=2002,tcpNoDelay=1;urp;" --headless --nodefault --nofirststartwizard --nolockcheck --nologo --norestore
+CTRL+a, CTRL+d
 </pre>
-Then go to your administration page -&gt; <i>Chamilo Rapid</i> and set the host to "localhost" and the port to "2002". Save. Go to your course, learning path tool and see the new icon appeared. Import your PPT. This should work.
-<em>Note</em>: Sometimes, this doesn't work out so easily. You can probably ask for the assistance of any system administrator around with a bit of Java and PHP experience, or you can always ask one of the Chamilo's Official Providers for assistance (ask for a guaranteed commercial contract). One other possibility is to launch soffice from a "screen" instance, without the &amp; at the end.
+Please note that this will effectively launch LibreOffice in a "headless" mode (thanks to the --headless option), in a "headless" terminal (thanks to screen). You can later get back into your "headless" terminal by launching:
+<pre>
+sudo screen -r
+</pre>
+You can then go to your administration page -&gt; <i>Chamilo Rapid</i> and set the host to "localhost" and the port to "2002". Save. Go to your course, learning path tool and see the new icon appeared. Import your PPT. This should work.
+<em>Note</em>: Sometimes, this doesn't work out so easily. You can probably ask for the assistance of any system administrator around with a bit of Java and PHP experience, or you can always ask one of the Chamilo's Official Providers for assistance (ask for a guaranteed commercial contract). The above is *not* meant for production servers with a high load. You should get a real system administrator to look at it and develop init scripts, in a way that makes monitoring and relaunching feasable. If any sysadmin wants to contribute this, feel free to contribute it to Chamilo: send us an e-mail at info@chamilo.org.
 <em>Note</em>: If you use LibreOffice 4, please note that version 4.2 (available in Ubuntu 14.04) has demonstrated to be more successfull at converting documents than version 4.1, which tended to crash when sending a document for conversion.
 </p>