Regedit command-line switches

The syntax of Windows Registry Editor command-line parameters:

To export all registry to file 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