my $SYSOPEN_MODE = O_WRONLY|O_CREAT;
if(exists $Fcntl::{'O_NONBLOCK'}){
    $SYSOPEN_MODE |= &{ $Fcntl::{'O_NONBLOCK'} };
}
if(exists $Fcntl::{'O_NOCTTY'}){
    $SYSOPEN_MODE |= &{ $Fcntl::{'O_NOCTTY'} };
}