Thanks. I was too lazy to specify what went wrong when I replaced the bash "exec" script (meant to be /usr/bin/perl; let's call it "mywrapper") with a perl "exec" script. Here's what happened.

"mywrapper -v" produced the desired output, showing that the correct perl binary was invoked (perlY if perlY available, else perlX).

helloworld.pl is this:

#!/path/to/mywrapper

use strict;

print "Hello World!";
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"/path/to/mywrapper helloworld.pl" caused helloworld.pl to run properly.

But executing helloworld.pl yields

 line 3: use: command not found
 line 5: print: command not found
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