Redirection for a command in Registry

Question

I'm trying to add a right click option to every file so that it executes a command. Seemed simple enough at first glance.

Right click option

By going in the registry editor, specifically HKCR\*\shell (which represents the context menu options that appear for every file type, hence the "*"), I added my own key as such :

HKEY_CLASSES_ROOT
    *
        shell
            my_right_click_option
            (Default) = "Click me!"
                command
                    (Default) = my_command

Command

After this, the clickable entry appeared in the context menu instantly. In my case, the key is called "checkmd5" and the command key's "Default" value stores the command 'my_command' to execute when clicked. The command is :

"C:\Quite_a_long_path\md5\md5.exe" -n "%1" | clip

The -n option (an md5.exe switch) is just to remove the name of the program that gets displayed after the hash. The %1 will be replaced by the right clicked program's path, and the double quotes are used in case any of the paths contain some whitespaces. Sadly, all I've managed to do is execute the command (a cmd window appears and disappears, which means that the cmd has been executed) and also, just to be sure, I checked with Process Monitor (from the SysInternals Suite) the command line being executed in the small cmd window that appears and disappears and it looks like the command I put is being executed exactly as I wanted. Nonetheless, even after appending to the command either "| clip" (to redirect output to clipboard) or "> file.txt" (to a file) [I tried using an absolute path for file too], the clipboard doesn't update, nor the file.txt gets created with the output of the command..

I can't seem to understand how to make it work.. Any help from you windows savvy will be greatly appreciated.

Thank you again for your patience, especially after getting to the end of this long post.

Answer 1

Turns out the only way to use the re-directions is by adding the cmd.exe /C before the command to be executed so that the command interpreter (cmd.exe) understands the redirection and not the program to be executed (aprogram.exe).

e.g:

aprogram.exe -param0 string > C:\temp\file.txt
wouldn't work, because aprogram.exe doesn't know how to manipulate redirections.
Instead it should be :
cmd.exe /C aprogram.exe -param0 string > C:\temp\file.txt