regeditx V 1.0, by forxm@21cn.com, 2006-12.
Work with/like regedit.exe, but firstly check if a Registry-Key exist.

regeditx.exe /T[-|+]:RegistryKey [*]

/T              Test the existence of a registry-key.
                RegistryKey must be started with:
                HKEY_CLASSES_ROOT   HKEY_CURRENT_CONFIG   HKEY_CURRENT_USER
                HKEY_LOCAL_MACHINE  HKEY_USERS            HKEY_PERFORMANCE_DATA
                HKEY_DYN_DATA
[-|+]           -: (default) if not exist, continue to call regedit.exe.
                +: if exist, continue.
[*]             Other parameters will transfer to regedit.exe.

Example, if a key not exist, combine a specified *.reg file:
regeditx.exe /T:"HKEY_CURRENT_USER\Software\ODBC\ODBC.INI\MS Access Database" /S RegAccessDsn.reg