1sysvipc(7)             Miscellaneous Information Manual             sysvipc(7)
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NAME

6       sysvipc - System V interprocess communication mechanisms
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DESCRIPTION

9       System  V  IPC  is  the  name given to three interprocess communication
10       mechanisms that are widely available on UNIX systems:  message  queues,
11       semaphore, and shared memory.
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13   Message queues
14       System V message queues allow data to be exchanged in units called mes‐
15       sages.  Each message can have an associated  priority.   POSIX  message
16       queues  provide  an  alternative API for achieving the same result; see
17       mq_overview(7).
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19       The System V message queue API consists of the following system calls:
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21       msgget(2)
22              Create a new message queue or obtain the ID of an existing  mes‐
23              sage queue.  This call returns an identifier that is used in the
24              remaining APIs.
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26       msgsnd(2)
27              Add a message to a queue.
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29       msgrcv(2)
30              Remove a message from a queue.
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32       msgctl(2)
33              Perform various control operations on a queue,  including  dele‐
34              tion.
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36   Semaphore sets
37       System V semaphores allow processes to synchronize their actions.  Sys‐
38       tem V semaphores are allocated in groups called sets; each semaphore in
39       a set is a counting semaphore.  POSIX semaphores provide an alternative
40       API for achieving the same result; see sem_overview(7).
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42       The System V semaphore API consists of the following system calls:
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44       semget(2)
45              Create a new set or obtain the ID of an existing set.  This call
46              returns an identifier that is used in the remaining APIs.
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48       semop(2)
49              Perform operations on the semaphores in a set.
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51       semctl(2)
52              Perform various control operations on a set, including deletion.
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54   Shared memory segments
55       System  V  shared memory allows processes to share a region a memory (a
56       "segment").  POSIX shared memory is an alternative  API  for  achieving
57       the same result; see shm_overview(7).
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59       The System V shared memory API consists of the following system calls:
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61       shmget(2)
62              Create  a  new  segment or obtain the ID of an existing segment.
63              This call returns an identifier that is used  in  the  remaining
64              APIs.
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66       shmat(2)
67              Attach  an  existing  shared  memory  object  into  the  calling
68              process's address space.
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70       shmdt(2)
71              Detach a segment from the calling process's address space.
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73       shmctl(2)
74              Perform various control operations on a segment, including dele‐
75              tion.
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77   IPC namespaces
78       For  a  discussion  of  the interaction of System V IPC objects and IPC
79       namespaces, see ipc_namespaces(7).
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SEE ALSO

82       ipcmk(1), ipcrm(1), ipcs(1), lsipc(1),  ipc(2),  msgctl(2),  msgget(2),
83       msgrcv(2),  msgsnd(2),  semctl(2),  semget(2), semop(2), shmat(2), shm‐
84       ctl(2), shmdt(2), shmget(2), ftok(3), ipc_namespaces(7)
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88Linux man-pages 6.04              2022-10-30                        sysvipc(7)