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(libc.info)Pipes and FIFOs

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Pipes and FIFOs
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   A "pipe" is a mechanism for interprocess communication; data written
to the pipe by one process can be read by another process.  The data is
handled in a first-in, first-out (FIFO) order.  The pipe has no name; it
is created for one use and both ends must be inherited from the single
process which created the pipe.

   A "FIFO special file" is similar to a pipe, but instead of being an
anonymous, temporary connection, a FIFO has a name or names like any
other file.  Processes open the FIFO by name in order to communicate
through it.

   A pipe or FIFO has to be open at both ends simultaneously.  If you
read from a pipe or FIFO file that doesn't have any processes writing
to it (perhaps because they have all closed the file, or exited), the
read returns end-of-file.  Writing to a pipe or FIFO that doesn't have a
reading process is treated as an error condition; it generates a
`SIGPIPE' signal, and fails with error code `EPIPE' if the signal is
handled or blocked.

   Neither pipes nor FIFO special files allow file positioning.  Both
reading and writing operations happen sequentially; reading from the
beginning of the file and writing at the end.

Creating a Pipe

Making a pipe with the `pipe' function.

Pipe to a Subprocess

Using a pipe to communicate with a

child process.

FIFO Special Files

Making a FIFO special file.

Pipe Atomicity

When pipe (or FIFO) I/O is atomic.