[[Solved]] - How to Update Eclipse from Terminal or IDE in Ubuntu 12.04, 14.04, 15.04, 16.04

Since I had installed Eclipse manually under '/opt/eclipse/' directory and not from the Ubuntu Software Centre, I couldn't update it from the terminal. Trying to Update Eclipse from the Terminal or within the IDE was giving me several errors such as these:

 Error 1:  
 An error occurred while uninstalling  
 session context was:(profile=epp.package.cpp, phase=org.eclipse.equinox.internal.p2.engine.phases.Uninstall, operand=[R]org.eclipse.platform_root 4.5.1.v20150904-0015 --> null, action=org.eclipse.equinox.internal.p2.touchpoint.natives.actions.CleanupzipAction).  
 Backup of file /opt/eclipse/.eclipseproduct failed.  
 File that was copied to backup could not be deleted: /opt/eclipse/.eclipseproduct 

 Error 2:  
 An error occurred while uninstalling  
 session context was:(profile=epp.package.cpp, phase=org.eclipse.equinox.internal.p2.engine.phases.Uninstall, operand=[R]org.eclipse.rcp_root 4.5.1.v20150904-0015 --> null, action=org.eclipse.equinox.internal.p2.touchpoint.natives.actions.CleanupzipAction).  
 Backup of file /opt/eclipse/readme/readme_eclipse.html failed.  
 File that was copied to backup could not be deleted: /opt/eclipse/readme/readme_eclipse.html 

 Error 3:  
 An error occurred while uninstalling  
 session context was:(profile=epp.package.cpp, phase=org.eclipse.equinox.internal.p2.engine.phases.Uninstall, operand=[R]org.eclipse.rcp_root 4.5.1.v20150904-0015 --> null, action=org.eclipse.equinox.internal.p2.touchpoint.natives.actions.CleanupzipAction).  
 Backup of file /opt/eclipse/readme failed.  
 Permission denied  

Update Eclipse

Looking at the above errors I figured out one of the possible cause was that Eclipse did not have SU (Super User) privilege. So, I executed Eclipse from the terminal giving it Super User privilege. And once in the IDE ran and update from within it. (Look image below)

To run Eclipse with Super User Permission from within the terminal. Launch your terminal with CTRL + ALT + T:

 cd /opt/eclipse  
 sudo ./eclipse  

Updating Eclipse from IDE

Once in Eclipse go to Help > Check for Updates. Now the Eclipse should be updated without any error.