SVIPC(7)                                                                Linux Programmer's Manual                                                               SVIPC(7)

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 messages can have an associated priority, POSIX message queues provide an  al‐
       ternative 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)

Linux                                                                          2020-04-11                                                                       SVIPC(7)