DIO_FCNTL(3) 1 DIO_FCNTL(3) dio_fcntl - Performs a c library fcntl on fdSYNOPSISmixed dio_fcntl (resource $fd, int $cmd, [mixed $args])DESCRIPTIONThe dio_fcntl(3) function performs the operation specified by $cmd on the file descriptor $fd. Some commands require additional arguments $args to be supplied.PARAMETERSo $fd - The file descriptor returned by dio_open(3). o $cmd - Can be one of the following operations: o F_SETLK - Lock is set or cleared. If the lock is held by someone else dio_fcntl(3) returns -1. o F_SETLKW - like F_SETLK, but in case the lock is held by someone else, dio_fcntl(3) waits until the lock is released. o F_GETLK - dio_fcntl(3) returns an associative array (as described above) if someone else prevents lock. If there is no obstruction key "type" will set to F_UNLCK. o F_DUPFD - finds the lowest numbered available file descriptor greater than or equal to $args and returns them. o F_SETFL - Sets the file descriptors flags to the value specified by $args, which can be O_APPEND, O_NONBLOCK or O_ASYNC. To use O_ASYNC you will need to use the PCNTL extension. o $args -$args is an associative array, when $cmd is F_SETLK or F_SETLLW, with the following keys: o start - offset where lock begins o length - size of locked area. zero means to end of file o whence - Where l_start is relative to: can be SEEK_SET, SEEK_END and SEEK_CUR o type - type of lock: can be F_RDLCK (read lock), F_WRLCK (write lock) or F_UNLCK (unlock)RETURN VALUESReturns the result of the C call.EXAMPLESExample #1 Setting and clearing a lock <?php $fd = dio_open('/dev/ttyS0', O_RDWR); if (dio_fcntl($fd, F_SETLK, Array("type"=>F_WRLCK)) == -1) { // the file descriptor appears locked echo "The lock can not be cleared. It is held by someone else."; } else { echo "Lock successfully set/cleared"; } dio_close($fd); ?>NOTESNote This function is not implemented on Windows platforms. PHP Documentation Group DIO_FCNTL(3)