Good grief. This seems to imply that if you close STDERR then die (and other diagnostics ?) will happily be written to whatever happens to be attached as descriptor 2 ?

If so, then the trick appears to be to open STDERR '>', '/dev/nul', or something else to occupy descriptor 2 to squelch output ? Thinking about a more portable solution I tried:

  use strict ; use warnings ;

  sub die_handler {
    open FH, ">&1";
    print FH "die_handler: ", @_ ;
  } ;

  $SIG{__DIE__} = \&die_handler ;

  close STDERR ;
  open STDERR, '<', \'' ;

  die "Oh shoot !" ;
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which appears to do the trick. Noting that the close STDERR is required.