How to run eclipse in clean mode? 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