IPC_NAMESPACES(7)         (2019-08-02)          IPC_NAMESPACES(7)

     NAME
          ipc_namespaces - overview of Linux IPC namespaces

     DESCRIPTION
          IPC namespaces isolate certain IPC resources, namely, System
          V IPC objects (see sysvipc(7)) and (since Linux 2.6.30)
          POSIX message queues (see mq_overview(7)).  The common char-
          acteristic of these IPC mechanisms is that IPC objects are
          identified by mechanisms other than filesystem pathnames.

          Each IPC namespace has its own set of System V IPC identi-
          fiers and its own POSIX message queue filesystem.  Objects
          created in an IPC namespace are visible to all other pro-
          cesses that are members of that namespace, but are not visi-
          ble to processes in other IPC namespaces.

          The following /proc interfaces are distinct in each IPC
          namespace:

          *  The POSIX message queue interfaces in
             /proc/sys/fs/mqueue.

          *  The System V IPC interfaces in /proc/sys/kernel, namely:
             msgmax, msgmnb, msgmni, sem, shmall, shmmax, shmmni, and
             shm_rmid_forced.

          *  The System V IPC interfaces in /proc/sysvipc.

          When an IPC namespace is destroyed (i.e., when the last pro-
          cess that is a member of the namespace terminates), all IPC
          objects in the namespace are automatically destroyed.

          Use of IPC namespaces requires a kernel that is configured
          with the CONFIG_IPC_NS option.

     SEE ALSO
          nsenter(1), unshare(1), clone(2), setns(2), unshare(2),
          mq_overview(7), namespaces(7), sysvipc(7)

     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/.

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