The syntax of Windows Registry Editor command-line parameters:

I found a very useful link for this :

http://www.eolsoft.com/freeware/registry_jumper/regedit_switches.htm

• c:\all.reg, use the /e switch as follows:
  regedit /E c:\all.reg
• To export a specific registry key to file file.reg, use the /e switch as follows:
  regedit /E file.reg <registry_key>, for example
  regedit /E c:\hklm_run.reg "HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run" will export list of Startup programs from Run section.
• Merge or import file.reg to Registry:
  regedit file.reg
• Create and replace an existing registry from a file file.reg:
  regedit /C file.reg
• For silent execution of Regedit command, use the /s parameter. If /S specified, Regedit will be operate quietly, without asking for confirmation.
• To delete specific registry key from the registry: Win 95,98,ME Regedit has switch /d, use it as follows:
  regedit /D <registry_key>, for example
  regedit /D "HKEY_CLASSES_ROOT\CLSID\{834261E1-DD97-4177-853B-C907E5D5BD6E}" will delete entry of Trojan CWS
  
  Win 2000, XP You can create .reg file and specify in it minus sign before the key name to delete (example - contents of sample file c:\del.reg):
  
  REGEDIT4
  [-HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System]
  Now if Regedit will be launched by command regedit c:\del.reg, the key HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System will be removed from the system registry.
• Win 95,98,ME There are several command line switches for specifying location of User.dat (/L) and user name (/R):
  regedit /L:c:\windows\user.dat /e c:\test.reg