NAME

       sysvipc - System V interprocess communication mechanisms

DESCRIPTION

       System  V  IPC  is  the name given to three interprocess communication mechanisms that are
       widely available on UNIX systems: message queues, semaphore, and shared memory.

   Message queues
       System V message queues allow data to be exchanged in units called messages.  Each message
       can  have  an  associated  priority.   POSIX message queues provide an alternative API for
       achieving the same result; see mq_overview(7).

       The System V message queue API consists of the following system calls:

       msgget(2)
              Create a new message queue or obtain the ID of an  existing  message  queue.   This
              call returns an identifier that is used in the remaining APIs.

       msgsnd(2)
              Add a message to a queue.

       msgrcv(2)
              Remove a message from a queue.

       msgctl(2)
              Perform various control operations on a queue, including deletion.

   Semaphore sets
       System V semaphores allow processes to synchronize their actions.  System V semaphores are
       allocated in groups called sets; each semaphore in a set is a counting  semaphore.   POSIX
       semaphores provide an alternative API for achieving the same result; see sem_overview(7).

       The System V semaphore API consists of the following system calls:

       semget(2)
              Create  a  new  set  or  obtain  the  ID  of an existing set.  This call returns an
              identifier that is used in the remaining APIs.

       semop(2)
              Perform operations on the semaphores in a set.

       semctl(2)
              Perform various control operations on a set, including deletion.

   Shared memory segments
       System V shared memory allows processes to share a region a memory (a  "segment").   POSIX
       shared memory is an alternative API for achieving the same result; see shm_overview(7).

       The System V shared memory API consists of the following system calls:

       shmget(2)
              Create a new segment or obtain the ID of an existing segment.  This call returns an
              identifier that is used in the remaining APIs.

       shmat(2)
              Attach an existing shared memory object into the calling process's address space.

       shmdt(2)
              Detach a segment from the calling process's address space.

       shmctl(2)
              Perform various control operations on a segment, including deletion.

   IPC namespaces
       For a discussion of the interaction of System  V  IPC  objects  and  IPC  namespaces,  see
       ipc_namespaces(7).

SEE ALSO

       ipcmk(1), ipcrm(1), ipcs(1), lsipc(1), ipc(2), msgctl(2), msgget(2), msgrcv(2), msgsnd(2),
       semctl(2),  semget(2),  semop(2),  shmat(2),  shmctl(2),  shmdt(2),  shmget(2),   ftok(3),
       ipc_namespaces(7)