fopen failed to open pipe file in Linux+Apache environment

Hi, I have problem of open named pipe file in linux. Here is my sample code: $fifo_file = "/dev/pmsg"; @ $fp = fopen($fifo_file, 'w+b'); if(!$fp) { echo "open ".$fifo_file." failed"; } else { $msg_cmd = "ttttttt"; fwrite($fp, $msg_cmd, strlen($msg_cmd)); fclose($fp); } There is an other program which is waiting for messages from /dev/pmsg forever. You could also test it by running cat /dev/pmsg in shell console. Every one have permissions of read and write for /dev/pmsg prw-rw-rw- 1 root root 0 12-08 10:13 /dev/pmsg Environment info: php-5.1.2-5, httpd-2.2.0-5.1.2, OS: Redhat FC5 Thanks in advance, Mike