# phpman > info > sysvipc

[SVIPC(7)](https://www.chedong.com/phpMan.php/man/SVIPC/7/markdown)                   Linux Programmer's Manual                  [SVIPC(7)](https://www.chedong.com/phpMan.php/man/SVIPC/7/markdown)

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 mes-
       sages.  Each messages can have an associated  priority,  POSIX  message
       queues  provide  an  alternative API for achieving the same result; see
       [mq_overview(7)](https://www.chedong.com/phpMan.php/man/mqoverview/7/markdown).

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

       [msgget(2)](https://www.chedong.com/phpMan.php/man/msgget/2/markdown)
              Create a new message queue or obtain the ID of an existing  mes-
              sage queue.  This call returns an identifier that is used in the
              remaining APIs.

       [msgsnd(2)](https://www.chedong.com/phpMan.php/man/msgsnd/2/markdown)
              Add a message to a queue.

       [msgrcv(2)](https://www.chedong.com/phpMan.php/man/msgrcv/2/markdown)
              Remove a message from a queue.

       [msgctl(2)](https://www.chedong.com/phpMan.php/man/msgctl/2/markdown)
              Perform various control operations on a queue,  including  dele-
              tion.

   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)](https://www.chedong.com/phpMan.php/man/semoverview/7/markdown).

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

       [semget(2)](https://www.chedong.com/phpMan.php/man/semget/2/markdown)
              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)](https://www.chedong.com/phpMan.php/man/semop/2/markdown)
              Perform operations on the semaphores in a set.

       [semctl(2)](https://www.chedong.com/phpMan.php/man/semctl/2/markdown)
              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)](https://www.chedong.com/phpMan.php/man/shmoverview/7/markdown).

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

       [shmget(2)](https://www.chedong.com/phpMan.php/man/shmget/2/markdown)
              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)](https://www.chedong.com/phpMan.php/man/shmat/2/markdown)
              Attach  an  existing  shared  memory  object  into  the  calling
              process's address space.

       [shmdt(2)](https://www.chedong.com/phpMan.php/man/shmdt/2/markdown)
              Detach a segment from the calling process's address space.

       [shmctl(2)](https://www.chedong.com/phpMan.php/man/shmctl/2/markdown)
              Perform various control operations on a segment, including dele-
              tion.

   IPC namespaces
       For  a  discussion  of  the interaction of System V IPC objects and IPC
       namespaces, see [ipc_namespaces(7)](https://www.chedong.com/phpMan.php/man/ipcnamespaces/7/markdown).

SEE ALSO
       [ipcmk(1)](https://www.chedong.com/phpMan.php/man/ipcmk/1/markdown), [ipcrm(1)](https://www.chedong.com/phpMan.php/man/ipcrm/1/markdown), [ipcs(1)](https://www.chedong.com/phpMan.php/man/ipcs/1/markdown), [lsipc(1)](https://www.chedong.com/phpMan.php/man/lsipc/1/markdown),  [ipc(2)](https://www.chedong.com/phpMan.php/man/ipc/2/markdown),  [msgctl(2)](https://www.chedong.com/phpMan.php/man/msgctl/2/markdown),  [msgget(2)](https://www.chedong.com/phpMan.php/man/msgget/2/markdown),
       [msgrcv(2)](https://www.chedong.com/phpMan.php/man/msgrcv/2/markdown),  [msgsnd(2)](https://www.chedong.com/phpMan.php/man/msgsnd/2/markdown),  [semctl(2)](https://www.chedong.com/phpMan.php/man/semctl/2/markdown),  [semget(2)](https://www.chedong.com/phpMan.php/man/semget/2/markdown), [semop(2)](https://www.chedong.com/phpMan.php/man/semop/2/markdown), [shmat(2)](https://www.chedong.com/phpMan.php/man/shmat/2/markdown), shm-
       [ctl(2)](https://www.chedong.com/phpMan.php/man/ctl/2/markdown), [shmdt(2)](https://www.chedong.com/phpMan.php/man/shmdt/2/markdown), [shmget(2)](https://www.chedong.com/phpMan.php/man/shmget/2/markdown), [ftok(3)](https://www.chedong.com/phpMan.php/man/ftok/3/markdown), [ipc_namespaces(7)](https://www.chedong.com/phpMan.php/man/ipcnamespaces/7/markdown)

COLOPHON
       This page is part of release 5.10 of the Linux  man-pages  project.   A
       description  of  the project, information about reporting bugs, and the
       latest    version    of    this    page,    can     be     found     at
       <https://www.kernel.org/doc/man-pages/>.

Linux                             2020-04-11                          [SVIPC(7)](https://www.chedong.com/phpMan.php/man/SVIPC/7/markdown)