How to run eclipse in clean mode? and what happens if we do so?

What it does:

if set to "true", any cached data used by the OSGi framework and eclipse runtime will be wiped clean. This will clean the caches used to store bundle dependency resolution and eclipse extension registry data. Using this option will force eclipse to reinitialize these caches.

How to use it:

• Edit the eclipse.ini file located in your Eclipse install directory and insert -clean as the first line.
• Or edit the shortcut you use to start Eclipse and add -clean as the first argument.
• Or create a batch or shell script that calls the Eclipse executable with the -clean argument. The advantage to this step is you can keep the script around and use it each time you want to clean out the workspace. You can name it something like eclipse-clean.bat (or eclipse-clean.sh).

(From: http://www.eclipsezone.com/eclipse/forums/t61566.html)

Other eclipse command line options: http://help.eclipse.org/indigo/index.jsp?topic=%2Forg.eclipse.platform.doc.isv%2Freference%2Fmisc%2Fruntime-options.html

or

You can start Eclipse in clean mode from the command line:

eclipse -clean