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) BSD General Commands Manual IPCRM(1)
NAME
ipcrm -- remove the specified message queues, semaphore sets, and shared memory segments
SYNOPSIS
ipcrm [-M shmkey] [-m shmid] [-Q msgkey] [-q msqid] [-S semkey] [-s semid] ...
DESCRIPTION
ipcrm removes the specified message queues, semaphores, and shared memory segments. These System V IPC objects can be specified by their
creation ID or any associated key.
The following options are used to specify which IPC objects will be removed. Any number and combination of these options can be used:
-M shmkey
Mark the shared memory segment associated with key shmkey for removal. This marked segment will be destroyed after the last detach.
-m shmid
Mark the shared memory segment associated with ID shmid for removal. This marked segment will be destroyed after the last detach.
-Q msgkey
Remove the message queue associated with key msgkey from the system.
-q msqid
Remove the message queue associated with the ID msqid from the system.
-S semkey
Remove the semaphore set associated with key semkey from the system.
-s semid
Removes the semaphore set associated with ID semid from the system.
If the id or key argument is ``all'' then all entries of the appropriate type are removed.
The identifiers and keys associated with these System V IPC objects can be determined by using ipcs(1).
SEE ALSO
ipcs(1), shmat(2), shmctl(2), shmdt(2), shmget(2)
BSD
May 31, 2008 BSD