Thanks choroba, but I don't think that article is on point for my problem. Let me state it again but more precisely. Every one of my Perl scripts has these two opening lines:
#!/usr/bin/env perl -w
##!/usr/bin/env perl -wd
I switch between these two lines, the first for ordinary runs, the second for debug runs. When I wish to debug I invert the lines, comment out the second, uncomment the first and proceed. Both these shebang lines fail in debian but work correctly in macOS. In debian I cannot have any argument to perl from an /usr/bin/env shebang despite rtfm. That page says the command can take an argument. True, if the argument was an argument list I would certainly quote it so that it appears as a single argument. In both of those example shebangs, I cannot have any arguments no matter how I quote them, and I've tried every quote option there is.