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NAME | DESCRIPTION | NOTES | SEE ALSO | COLOPHON |
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fifo(7) Miscellaneous Information Manual fifo(7)
fifo - first-in first-out special file, named pipe
A FIFO special file (a named pipe) is similar to a pipe, except
that it is accessed as part of the filesystem. It can be opened
by multiple processes for reading or writing. When processes are
exchanging data via the FIFO, the kernel passes all data
internally without writing it to the filesystem. Thus, the FIFO
special file has no contents on the filesystem; the filesystem
entry merely serves as a reference point so that processes can
access the pipe using a name in the filesystem.
The kernel maintains exactly one pipe object for each FIFO
special file that is opened by at least one process. The FIFO
must be opened on both ends (reading and writing) before data can
be passed. Normally, opening the FIFO blocks until the other end
is opened also.
A process can open a FIFO in nonblocking mode. In this case,
opening for read-only succeeds even if no one has opened on the
write side yet and opening for write-only fails with ENXIO (no
such device or address) unless the other end has already been
opened.
Under Linux, opening a FIFO for read and write will succeed both
in blocking and nonblocking mode. POSIX leaves this behavior
undefined. This can be used to open a FIFO for writing while
there are no readers available. A process that uses both ends of
the connection in order to communicate with itself should be very
careful to avoid deadlocks.
For details of the semantics of I/O on FIFOs, see pipe(7).
When a process tries to write to a FIFO that is not opened for
read on the other side, the process is sent a SIGPIPE signal.
FIFO special files can be created by mkfifo(3), and are indicated
by ls -l with the file type 'p'.
mkfifo(1), open(2), pipe(2), sigaction(2), signal(2),
socketpair(2), mkfifo(3), pipe(7)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.9.1.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2024-06-26. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
[email protected]
Linux man-pages 6.9.1 2024-05-02 fifo(7)
Pages that refer to this page: open(2), mkfifo(3), sd_is_fifo(3), systemd.socket(5), pipe(7), signal(7)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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