noble (7) sysvipc.7.gz

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)