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anonymous pipe

n. (context computing English) A simplex channel FIFO communication channel that may be used for one-way interprocess communication.

Wikipedia
Anonymous pipe

In computer science, an anonymous pipe is a simplex FIFO communication channel that may be used for one-way interprocess communication (IPC). An implementation is often integrated into the operating system's file IO subsystem. Typically a parent program opens anonymous pipes, and creates a new process that inherits the other ends of the pipes, or creates several new processes and arranges them in a pipeline.

Full-duplex (two-way) communication normally requires two anonymous pipes.

Pipelines are supported in most popular operating systems, from Unix and DOS onwards, and are created using the "|" character.