$flags = fcntl( FH, F_GETFL, 0 );
$rc = fcntl( FH, F_SETFL, $flags );

##</code><code>##

$flags = fcntl( FH, F_GETFL, 0 );
print "current flags -> $flags\n";  ## now we've got trouble
$rc = fcntl( FH, F_SETFL, $flags );