% perl
close STDERR;
die "ZOMG, infinite loop!";
__END__
 % 

##</code><code>##

 % perl
close STDOUT;
print "Generate error!\n";
__END__
 % 

##</code><code>##

 % perl -w
close STDOUT;
print "Generate error!\n";
__END__
print() on closed filehandle STDOUT at - line 2.
 % 

##</code><code>##

 % perl -w
close STDOUT; close STDERR;
print "Generate error!\n";
__END__
 % 

##</code><code>##

 % perl -w
my $loop; $SIG{__WARN__}= $loop= sub {
    $SIG{__WARN__}= $loop;
    print STDERR "Got: ", @_;
    print "Warn: ", @_;
};
close STDOUT;
print "Generate warning!\n";
die "Done.\n";
__END__
Got: print() on closed filehandle STDOUT at - line 7.
print() on closed filehandle STDOUT at - line 4.
Done.
 %