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Top Forums Programming shared memory and message queues Post 302103867 by rvan on Monday 22nd of January 2007 05:18:05 AM
Old 01-22-2007
shared memory and message queues

Hi,

According to my understanding..
When message queues are used, when a process post a message in the queue and if another process reads it from the queue then the queue will be empty unlike shared memory where n number of processess can access the shared memory and still the contents remain there until its deliberately removed.
So when i want to use an IPC between processess and i want the contents to be there until deliberately removed i feel shared memory is the option and not the message queues.. could anyone please clarify me?

Thanks
 

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ipcrm(1)						      General Commands Manual							  ipcrm(1)

NAME
ipcrm - Removes message queue, semaphore set, or shared memory identifiers SYNOPSIS
ipcrm [-m shared_memory] [-M shared_memory_key] [-q message_queue] [-Q message_key] [-s semaphore_ID] [-S semaphore_key] The ipcrm command removes one or more message queue, semaphore set, or shared memory identifiers. STANDARDS
Interfaces documented on this reference page conform to industry standards as follows: ipcrm: XCU5.0 Refer to the standards(5) reference page for more information about industry standards and associated tags. OPTIONS
Removes the shared memory identifier shared_memory. The shared memory segment and data structure associated with shared_memory are also removed after the last detach operation. Removes the shared memory identifier, created with key shared_memory_key. The shared memory seg- ment and data structure associated with it are also removed after the last detach. Removes the message queue identifier message_queue and the message queue and data structure associated with it. Removes the message queue identifier, created with key message_key, and the mes- sage queue and data structure associated with it. Removes the semaphore identifier semaphore_ID and the set of semaphores and data struc- ture associated with it. Removes the semaphore identifier, created with key semaphore_key, and the set of semaphores and data structure associated with it. DESCRIPTION
The details of the remove operations are described in the Section 2 reference pages for msgctl(), shmctl(), and semctl(). The identifiers and keys can be found by using the ipcs command. EXAMPLES
To remove the shared memory segment associated with shared memory identifier 18602, enter: ipcrm -m 18602 SEE ALSO
Commands: ipcs(1) Functions: msgctl(2), msgget(2), semctl(2), semget(2), semop(2), shmctl(2), shmget(2) ipcrm(1)
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