The mq_setattr() will set attributes associated with the open message queue description referenced by the message queue descriptor specified by mqdes. The following members of mq_attr will be set to the specified value: mq_flags is the bitwise-logical OR of zero or more of O_NONBLOCK an d any implementation-defined flags. mq_maxmsg, mq_msgsize, and mq_curmsgs memebers of the mq_attr stru cture shall be ignored by mq_setattr(). If omqstat is non-NULL, mq_setattr() will store the previous message queue attributes and the current queue status in the location referenced by omqstat. These values will be the same as would be returned by a call to mq_getattr() at that point. If mq_setattr() is successful, it will return a value of zero and the attributes of the message queue will change as specified. If mq_setattr() is not successful, the message queue attributes will be unchanged, and the function will return a value of -1 and set errno to indicate the error. mq_setattr() fails with EBADF if mqdes argument is not a valid message descriptor.