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26 .TH MQ_SEND 3 2010-02-25 "Linux" "Linux Programmer's Manual"
28 mq_send, mq_timedsend \- send a message to a message queue
31 .B #include <mqueue.h>
33 .BI "mqd_t mq_send(mqd_t " mqdes ", const char *" msg_ptr ,
34 .BI " size_t " msg_len ", unsigned " msg_prio );
36 .B #define _XOPEN_SOURCE 600
38 .B #include <mqueue.h>
40 .BI "mqd_t mq_timedsend(mqd_t " mqdes ", const char *" msg_ptr ,
41 .BI " size_t " msg_len ", unsigned " msg_prio ,
42 .BI " const struct timespec *" abs_timeout );
45 Link with \fI\-lrt\fP.
48 adds the message pointed to by
50 to the message queue referred to by the descriptor
54 argument specifies the length of the message pointed to by
56 this length must be less than or equal to the queue's
59 Zero-length messages are allowed.
63 argument is a nonnegative integer that specifies the priority
65 Messages are placed on the queue in decreasing order of priority,
66 with newer messages of the same priority being placed after
67 older messages with the same priority.
69 If the message queue is already full
70 (i.e., the number of messages on the queue equals the queue's
72 attribute), then, by default,
74 blocks until sufficient space becomes available to allow the message
75 to be queued, or until the call is interrupted by a signal handler.
78 flag is enabled for the message queue description,
79 then the call instead fails immediately with the error
85 except that if the queue is full and the
87 flag is not enabled for the message queue description, then
89 points to a structure which specifies a ceiling on the time for which
91 This ceiling is an absolute timeout in seconds and nanoseconds
92 since the Epoch, 1970-01-01 00:00:00 +0000 (UTC), and it is
93 specified in the following structure:
98 time_t tv_sec; /* seconds */
99 long tv_nsec; /* nanoseconds */
104 If the message queue is full,
105 and the timeout has already expired by the time of the call,
113 return zero; on error, \-1 is returned, with
115 set to indicate the error.
119 The queue was empty, and the
121 flag was set for the message queue description referred to by
125 The descriptor specified in
130 The call was interrupted by a signal handler; see
134 The call would have blocked, and
136 was invalid, either because
138 was less than zero, or because
140 was less than zero or greater than 1000 million.
146 attribute of the message queue.
149 The call timed out before a message could be transferred.
155 is a system call, and
157 is a library function layered on top of that system call.
165 .BR feature_test_macros (7),