Invalid syntax error passing argument to reg.exe in .LNK (same command succeeds in CMD, PS, and as a .BAT)

Question

I am trying to create a shortcut to add create a registry key named after an arbitrary file. The idea is to put this shortcut in the shell:Sendto menu, so the filename is passed to the command as an argument.

reg add "HKCU\SOFTWARE\MICROSOFT\WINDOWS NT\CURRENTVERSION\AppCompatFlags\Layers" /v %1 /t REG_SZ /d ~HIGHDPIAWARE /f

When I created a shortcut (.lnk) with the above code as the target, it returns Error: invalid syntax.

Pasting the same code into a CMD or Powershell window (and substituting in a file pathname for the %1) succeeds. Pasting the original code directly into a batch file, then pointing the shortcut at that .BAT, also succeeds. (This is what I'm currently doing as my workaround. Ideally though, I would prefer to just have the shortcut and not need an extra .BAT file lying around).

When troubleshooting the syntax in the original shortcut, I tried every permutation of wrapping %1 and ~HIGHDPIAWARE in quotation marks, with no change. I thought maybe reg.exe simply does not use the %1 argument variables, so I tried putting making the shortcut target CMD with this code:

cmd.exe /k reg add "HKCU\SOFTWARE\MICROSOFT\WINDOWS NT\CURRENTVERSION\AppCompatFlags\Layers" /v %1 /t REG_SZ /d ~HIGHDPIAWARE /f

but it still returned an invalid syntax error. And yet, as I mentioned above, when I stopped trying to put everything in the shortcut target and instead put the exact same code into a batch file, it worked.

Is there a reason why shortcut files cannot process the syntax the same way?

Answer 1

Windows Shortcuts in the shell:Sendto folder (aka %AppData%\Microsoft\Windows\SendTo) are passed the calling file as an argument implicitly; it is not necessary to specify %n parameters. The following code will succeed as the target of a shortcut:

reg add "HKCU\SOFTWARE\MICROSOFT\WINDOWS NT\CURRENTVERSION\AppCompatFlags\Layers" /t REG_SZ /d ~HIGHDPIAWARE /f /v

Since shortcuts assume the target is the name of an executable, the calling file is passed how an argument normally would be, i.e. after the executable. As a result, the calling file name is passed directly after the /v parameter in the above code, effectively "filling in" the missing argument. Fortunately, reg.exe parameters are order-agnostic. This would likely not be possible if the parameters could not be rewritten to place the "%1" term at the very end.