15.1. IntroductionChapter 8, we described the process control primitives and saw how to invoke multiple processes. But the only way for these processes to exchange information is by passing open files across a fork or an exec or through the file system. We'll now describe other techniques for processes to communicate with each other: IPC, or interprocess communication.In the past, UNIX System IPC was a hodgepodge of various approaches, few of which were portable across all UNIX system implementations. Through the POSIX and The Open Group (formerly X/Open) standardization efforts, the situation has improved, but differences still exist. Section 17.3), we show "UDS" in the column. Some implementations support the feature with pipes and UNIX domain sockets, so these entries have both "UDS" and a bullet.As we mentioned in Section 14.4, support for STREAMS is optional in the Single UNIX Specification. Named full-duplex pipes are provided as mounted STREAMS-based pipes and so are also optional in the Single UNIX Specification. On Chapter 17, we take a look at some advanced features of IPC. |