open(SAVE,">&STDOUT")
  or die "Couldn't save STDOUT: $!\n";
open(NULL,"> /dev/null")
  or die "Couldn't open /dev/null: $!\n";
open(STDOUT,">&NULL")
  or die "Couldn't dup NULL to STDOUT: $!\n";
# Do validation
open(STDOUT,">&SAVE")
  or die "Couldn't restore STDOUT: $!\n";