[unix-history] / usr / src / lib / libc / sys / pipe.2

.\" Copyright (c) 1980 Regents of the University of California.
.\" All rights reserved.  The Berkeley software License Agreement
.\" specifies the terms and conditions for redistribution.
.\"
.\"	@(#)pipe.2	4.1 (Berkeley) %G%
.\"
.TH PIPE 2 
.UC 4
.SH NAME
pipe \- create an interprocess channel
.SH SYNOPSIS
.nf
.B pipe(fildes)
.B int fildes[2];
.fi
.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.
.SH "SEE ALSO"
sh(1), read(2), write(2), fork(2)
.SH DIAGNOSTICS
The function value zero is returned if the
pipe was created; \-1 if
too many files are already open.
A signal is generated if a write on a pipe with only one end is attempted.
.SH BUGS
Should more than 4096 bytes be necessary in any
pipe among a loop of processes, deadlock will occur.
.SH "ASSEMBLER (PDP-11)"
(pipe = 42.)
.br
.B sys pipe
.br
(read file descriptor in r0)
.br
(write file descriptor in r1)
Commit	Line	Data
c15b236d KM	1	.\" Copyright (c) 1980 Regents of the University of California.
	2	.\" All rights reserved. The Berkeley software License Agreement
	3	.\" specifies the terms and conditions for redistribution.
	4	.\"
	5	.\" @(#)pipe.2 4.1 (Berkeley) %G%
	6	.\"
	7	.TH PIPE 2
	8	.UC 4
	9	.SH NAME
	10	pipe \- create an interprocess channel
	11	.SH SYNOPSIS
	12	.nf
	13	.B pipe(fildes)
	14	.B int fildes[2];
	15	.fi
	16	.SH DESCRIPTION
	17	The
	18	.I pipe
	19	system call
	20	creates an I/O mechanism called a pipe.
	21	The file descriptors returned can
	22	be used in read and write operations.
	23	When the pipe is written using the descriptor
	24	.IR fildes [1]
	25	up to 4096 bytes of data are buffered
	26	before the writing process is suspended.
	27	A read using the descriptor
	28	.IR fildes [0]
	29	will pick up the data.
	30	.PP
	31	It is assumed that after the
	32	pipe has been set up,
	33	two (or more)
	34	cooperating processes
	35	(created by subsequent
	36	.I fork
	37	calls)
	38	will pass data through the
	39	pipe with
	40	.I read
	41	and
	42	.I write
	43	calls.
	44	.PP
	45	The Shell has a syntax
	46	to set up a linear array of processes
	47	connected by pipes.
	48	.PP
	49	Read calls on an empty
	50	pipe (no buffered data) with only one end
	51	(all write file descriptors closed)
	52	returns an end-of-file.
	53	.SH "SEE ALSO"
	54	sh(1), read(2), write(2), fork(2)
	55	.SH DIAGNOSTICS
	56	The function value zero is returned if the
	57	pipe was created; \-1 if
	58	too many files are already open.
	59	A signal is generated if a write on a pipe with only one end is attempted.
	60	.SH BUGS
	61	Should more than 4096 bytes be necessary in any
	62	pipe among a loop of processes, deadlock will occur.
	63	.SH "ASSEMBLER (PDP-11)"
	64	(pipe = 42.)
65	.br
66	.B sys pipe
67	.br
68	(read file descriptor in r0)
69	.br
70	(write file descriptor in r1)