Thanks for this handy hack!
Unfortunately, I already have an open EmEditor instance most of the time when working (also with many active tabs in it, so it cannot be easily closed either), but perhaps this could in turn be worked-around by adding the “/sp” parameter, thus forcing the creation of a new EmEditor process? I will try.
It would be great though with an “official” confirmation from Mr Emura, that this environment variable hack is the only way to provide parameters to macros from the command line (in which case I would like to submit a feature suggestion for a new method to provide such parameters to macros directly on the command-line when starting EmEditor). Mr Emura?