You can enable or disable file name completion for a particular invocation of CMD.EXE with the /F:ON or /F:OFF switch. You ...

You can enable or disable file name completion for a particular
invocation of CMD.EXE with the /F:ON or /F:OFF switch.  You can enable
or disable completion for all invocations of CMD.EXE on a machine and/or
user logon session by setting either or both of the following REG_DWORD
values in the registry using REGEDIT.EXE:

    HKEY_LOCAL_MACHINE\Software\Microsoft\Command Processor\CompletionChar
    HKEY_LOCAL_MACHINE\Software\Microsoft\Command Processor\PathCompletionChar

        and/or

    HKEY_CURRENT_USER\Software\Microsoft\Command Processor\CompletionChar
    HKEY_CURRENT_USER\Software\Microsoft\Command Processor\PathCompletionChar

with the hex value of a control character to use for a particular
function (e.g.  0x4 is Ctrl-D and 0x6 is Ctrl-F).  The user specific
settings take precedence over the machine settings.  The command line
switches take precedence over the registry settings.

If completion is enabled with the /F:ON switch, the two control
characters used are Ctrl-D for directory name completion and Ctrl-F for
file name completion.  To disable a particular completion character in
the registry, use the value for space (0x20) as it is not a valid
control character.