When all you have is a hammer everything looks like a nail :-D. Except of course having a swiss army chainsaw there is more than a hammer at our disposal. However, it surely cannot be too difficult to later clean and pass other environment variables as needed. Else one could say not clearing %ENV will eventually bite you in the butt because you have no idea what some clever author of an external program will rely upon and do with an environment variable ;-).

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perl -p -e "s/(?:\w);([st])/'\$1/mg"