There’s a command called fhmanagew.exe that comes with Windows 10 (not sure about Windows 8.1, but I assume so). The full path is c:\windows\system32\fhmanagew.exe. This tool is used for managing certain aspects of File History, and contains a few undocumented features.
From what I can tell, Microsoft has only mentioned the -cleanup argument which is used like: fhmanagew.exe -cleanup <# days> [-quiet]
A couple examples:
fhmanagew.exe -cleanup 365
fhmanagew.exe -cleanup 30 -quiet
I used strings.exe by sysinternals (a Windows port of a handy *nix tool for extracting raw strings from a binary file) to analyze fhmanagew.exe and found the following arguments are available:
|-autoplay||Bring up the File History UI|
|-cleanup <days> [-quiet]||Cleanup files older than a certain number of days on your File History destination drive.|
|-migrate <path>||Seems to be used for migrating your file history to a new destination. Destination must be added to File History first.|
|-stop||Stop File History|
This blog post over at winhelponline.com mentions a few of the args I’ve discovered with a short description of them. It doesn’t seem to mention the -migrate command, however.