POSIX interprocess communication (IPC) is a variation of System V interprocess communication. Like System V objects, POSIX IPC objects have read and write, but not execute, permissions for the owner, the owner's group, and for others. There is no way for the owner of a POSIX IPC object to assign a different owner. POSIX IPC includes the following features:
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Messages allow processes to send formatted data streams to arbitrary processes.
Semaphores allow processes to synchronize execution.
Shared memory allows processes to share parts of their virtual address space.
Unlike the System V IPC interfaces, the POSIX IPC interfaces are all multithread safe.