10 More Discussions You Might Find Interesting
1. Ubuntu
Hello
How can I see the created message queues in the system? (4 Replies)
Discussion started by: xyzt
4 Replies
2. Programming
Hi all,
I need help about message queues, i have a server-client program that communicates each other via msg queue, firstly server opens its msg queue and waits for msg then client opens server msg queue and its own msg queue(for receiving msg from server,clients sends msg to server msg... (7 Replies)
Discussion started by: SaTYR
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3. Programming
Hii can anyone pls tell how to limit the max no of message in a posix message queue. I have made changes in proc/sys/fs/mqueue/msg_max
But still whenever i try to read the value of max. message in the queue using attr.mq_curmsgs (where struct mq_attr attr) its giving the default value as 10.... (0 Replies)
Discussion started by: mohit3884
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4. Programming
Hello,
i need to write a message queue "chat server", that should work only localy.
Can anyone please help me with some ideas and peshaps code. I'm studying the UNIX IPC mechanisms right now. So far, i understand how it works but i still cannot get an idea how to write a chat programm...
... (2 Replies)
Discussion started by: etenv
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5. Programming
hi all...
ive been trying this program where i spawn 4 threads... and i am trying to use message queue to send msgs from 3 of the threads to the parent thread... but it doent seem to be working... ive almost pulled out my hair tryin to fix the prob :confused:
another wierd thing... (1 Reply)
Discussion started by: strider
1 Replies
6. IP Networking
I am sending and retriving the message to the queue
the problem is
after retrieving the message can i see what is there in my message queue.
(actually in my application i am encountring some garbage value)
so i want to retieve this garbage value and also want to know its size
how... (0 Replies)
Discussion started by: ramneek
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7. Programming
Is there any way one can delete , say , a particular message from a message queue on system V? (2 Replies)
Discussion started by: satansfury
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8. Programming
hi all,
I'm working on this problem for 2 days. Can somebody tell me that how to delete all message queues from the system ?
Since "ipcs -q" gives the list of all existing message queue, then there must be a system call and data stucture where from I can fetch the data about all existing... (2 Replies)
Discussion started by: v_rathor
2 Replies
9. HP-UX
Hello,
J work on a HP.
I want to create message queue by using mq_open with this parameters:
mq_open(p,O_CREAT|O_WRONLY|O_EXCL|0_NONBLOCK,0600,&queue_attr)
with p char
and the function returns the value -1 and errno equal 2.
can you help me ?
Thank. (3 Replies)
Discussion started by: AUBERT
3 Replies
10. Programming
Hi there:
Thanks first. When I use a message queue amony severl processes, will I have to synchronize the queue? I don't think I would have to because a message queue is implemented in a link listed. Correct me If I am wrong... (0 Replies)
Discussion started by: yanhu
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mq_receive(2) System Calls Manual mq_receive(2)
NAME
mq_receive - receive a message from a message queue
SYNOPSIS
DESCRIPTION
The system call receives the oldest of the highest priority message from the message queue specified by mqdes. The selected message is
removed from the queue and copied to the buffer pointed to by the msg_ptr argument. The argument, msg_len, specifies the size of the buffer
in bytes. The value of msg_len should be greater than or equal to the mq_msgsize attribute of the message queue, or will fail.
If the argument msg_prio is not NULL, the priority of the message removed from the queue is stored in the location pointed to by msg_prio.
If the specified message queue is empty and the flag is not set in the message queue blocking status associated with mqdes, will block in
priority order, until it can receive a message from the queue, or until is interrupted by a signal. If the specified message queue is empty
and the flag is set in the message queue blocking status associated with mqdes, will not wait for a message to arrive on the queue and
will return with an error.
To use this function, link in the realtime library by specifying on the compiler or linker command line.
RETURN VALUE
returns the following values:
n Successful completion. n is the size of the selected message in bytes and the message is removed from the queue.
Failure.
is set to indicate the error and no message is removed from the queue.
ERRORS
If fails, is set to one of the following values:
[EAGAIN] The flag is set in the message queue blocking status associated with mqdes, and the message queue is empty.
[EBADF] mqdes is not a valid message queue descriptor open for reading.
[EINTR] A signal interrupted the call to
[EINVAL] msg_ptr points to an invalid address.
[EMSGSIZE] The specified message buffer size, msg_len, is less than the message size attribute of the message queue.
[ENOSYS] is not supported by the implementation.
SEE ALSO
mq_send(2).
STANDARDS CONFORMANCE
mq_receive(2)