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Annotation of 43BSDReno/lib/libc/sys/pipe.2, revision 1.1

1.1     ! root        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      6.2 (Berkeley) 8/26/85
        !             6: .\"
        !             7: .TH PIPE 2 "August 26, 1985"
        !             8: .UC 4
        !             9: .SH NAME
        !            10: pipe \- create an interprocess communication channel
        !            11: .SH SYNOPSIS
        !            12: .nf
        !            13: .ft B
        !            14: pipe(fildes)
        !            15: int fildes[2];
        !            16: .fi
        !            17: .ft R
        !            18: .SH DESCRIPTION
        !            19: The
        !            20: .I pipe
        !            21: system call
        !            22: creates an I/O mechanism called a pipe.
        !            23: The file descriptors returned can
        !            24: be used in read and write operations.
        !            25: When the pipe is written using the descriptor
        !            26: .IR fildes [1]
        !            27: up to 4096 bytes of data are buffered
        !            28: before the writing process is suspended.
        !            29: A read using the descriptor
        !            30: .IR fildes [0]
        !            31: will pick up the data.
        !            32: .PP
        !            33: It is assumed that after the
        !            34: pipe has been set up,
        !            35: two (or more)
        !            36: cooperating processes
        !            37: (created by subsequent
        !            38: .I fork
        !            39: calls)
        !            40: will pass data through the
        !            41: pipe with
        !            42: .I read
        !            43: and
        !            44: .I write
        !            45: calls.
        !            46: .PP
        !            47: The shell has a syntax
        !            48: to set up a linear array of processes
        !            49: connected by pipes.
        !            50: .PP
        !            51: Read calls on an empty
        !            52: pipe (no buffered data) with only one end
        !            53: (all write file descriptors closed)
        !            54: returns an end-of-file.
        !            55: .PP
        !            56: Pipes are really a special case of the 
        !            57: .IR socketpair (2)
        !            58: call and, in fact, are implemented as such in the system.
        !            59: .PP
        !            60: A signal is generated if a write on a pipe with only one end is attempted.
        !            61: .SH "RETURN VALUE
        !            62: The function value zero is returned if the
        !            63: pipe was created; \-1 if an error occurred.
        !            64: .SH ERRORS
        !            65: The \fIpipe\fP call will fail if:
        !            66: .TP 15
        !            67: [EMFILE]
        !            68: Too many descriptors are active.
        !            69: .TP 15
        !            70: [ENFILE]
        !            71: The system file table is full.
        !            72: .TP 15
        !            73: [EFAULT]
        !            74: The \fIfildes\fP buffer is in an invalid area of the process's address
        !            75: space.
        !            76: .SH "SEE ALSO"
        !            77: sh(1), read(2), write(2), fork(2), socketpair(2)
        !            78: .SH BUGS
        !            79: Should more than 4096 bytes be necessary in any
        !            80: pipe among a loop of processes, deadlock will occur.

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