namedFIFO

A namedFIFO, commonly called a named pipe, is a special file in Unix-like operating systems that represents a unidirectional data channel for interprocess communication. It exists as an ordinary file in the filesystem and can be accessed by unrelated processes via its path. Data written to a namedFIFO by one process can be read by another process in a first-in-first-out order, though the channel itself is not message-oriented; it is a byte stream.

A namedFIFO is created with the mkfifo command or the equivalent system call, which creates a special file with the FIFO type and assigns permission bits. The name of the FIFO serves as a persistent handle in the filesystem, allowing processes to locate and use it by path. Permissions control which users or groups may open the FIFO for reading or writing.

When a process opens a namedFIFO, behavior depends on the end being opened. Opening for reading blocks until a writer opens, and opening for writing blocks until a reader opens, unless non-blocking mode (O_NONBLOCK) is specified. Once data flow begins, writes append to the FIFO’s internal buffer and reads retrieve data in the same order it was written. The kernel imposes a finite pipe buffer; writers block when the buffer is full and readers block when the buffer is empty.

A namedFIFO remains in the filesystem after processes terminate, unless it is explicitly removed with unlink. This persistence allows decoupled processes to coordinate over time. Security is governed by standard filesystem permissions, which restrict access to the FIFO file.

Common use cases include simple producer–consumer pipelines, decoupled components in a software system, and situations requiring IPC between unrelated processes. Limitations include reliance on correct synchronization for message boundaries and the potential for blocking behavior if readers or writers are absent.