From ea709105b43e6846e6a1e2cfce58ce49038f5338 Mon Sep 17 00:00:00 2001
From: CSRG <csrg@ucbvax.Berkeley.EDU>
Date: Sun, 3 Apr 1983 09:29:59 -0800
Subject: [PATCH] BSD 4_2 development Work on file usr/man/man2/pipe.2

Synthesized-from: CSRG/cd1/4.2
---
 usr/man/man2/pipe.2 | 71 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)
 create mode 100644 usr/man/man2/pipe.2

diff --git a/usr/man/man2/pipe.2 b/usr/man/man2/pipe.2
new file mode 100644
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--- /dev/null
+++ b/usr/man/man2/pipe.2
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+.TH PIPE 2 "12 February 1983"
+.UC 4
+.SH NAME
+pipe \- create an interprocess communication channel
+.SH SYNOPSIS
+.nf
+.ft B
+pipe(fildes)
+int fildes[2];
+.fi
+.ft R
+.SH DESCRIPTION
+The
+.I pipe
+system call
+creates an I/O mechanism called a pipe.
+The file descriptors returned can
+be used in read and write operations.
+When the pipe is written using the descriptor
+.IR fildes [1]
+up to 4096 bytes of data are buffered
+before the writing process is suspended.
+A read using the descriptor
+.IR fildes [0]
+will pick up the data.
+.PP
+It is assumed that after the
+pipe has been set up,
+two (or more)
+cooperating processes
+(created by subsequent
+.I fork
+calls)
+will pass data through the
+pipe with
+.I read
+and
+.I write
+calls.
+.PP
+The shell has a syntax
+to set up a linear array of processes
+connected by pipes.
+.PP
+Read calls on an empty
+pipe (no buffered data) with only one end
+(all write file descriptors closed)
+returns an end-of-file.
+.PP
+Pipes are really a special case of the 
+.IR socketpair (2)
+call and, in fact, are implemented as such in the system.
+.PP
+A signal is generated if a write on a pipe with only one end is attempted.
+.SH "RETURN VALUE
+The function value zero is returned if the
+pipe was created; \-1 if an error occurred.
+.SH ERRORS
+The \fIpipe\fP call will fail if:
+.TP 15
+[EMFILE]
+Too many descriptors are active.
+.TP 15
+[EFAULT]
+The \fIfildes\fP buffer is in an invalid area of the process's address
+space.
+.SH "SEE ALSO"
+sh(1), read(2), write(2), fork(2), socketpair(2)
+.SH BUGS
+Should more than 4096 bytes be necessary in any
+pipe among a loop of processes, deadlock will occur.
-- 
2.20.1