Just create a batch file in a folder in your Path. In my case I named it zero.cmd.
type nul > "%1"
To "zero" all .txt files in the current folder you can use a command prompt:
for %s in (*.txt) do zero %s
or you can make a .cmd file that uses shift to go through the command line args.
Linux shell stuff is generally better about command line globbing than Windows though.
You could probably do it with gnu win32 utilities using find.