Adding upstream version 6.05.01.upstream/6.05.01

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 70 insertions, 0 deletions

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+.\" SPDX-License-Identifier: Linux-man-pages-1-para
+.\"
+.\" This man page is Copyright (C) 1999 Claus Fischer.
+.\"
+.\" 990620 - page created - aeb@cwi.nl
+.\"
+.TH fifo 7 2023-07-15 "Linux man-pages 6.05.01"
+.SH NAME
+fifo \- first-in first-out special file, named pipe
+.SH DESCRIPTION
+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.
+.PP
+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.
+.PP
+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
+.B ENXIO
+(no such device or address) unless the other
+end has already been opened.
+.PP
+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.
+.SH NOTES
+For details of the semantics of I/O on FIFOs, see
+.BR pipe (7).
+.PP
+When a process tries to write to a FIFO that is not opened
+for read on the other side, the process is sent a
+.B SIGPIPE
+signal.
+.PP
+FIFO special files can be created by
+.BR mkfifo (3),
+and are indicated by
+.I ls\~\-l
+with the file type \[aq]p\[aq].
+.SH SEE ALSO
+.BR mkfifo (1),
+.BR open (2),
+.BR pipe (2),
+.BR sigaction (2),
+.BR signal (2),
+.BR socketpair (2),
+.BR mkfifo (3),
+.BR pipe (7)