86 lines
3.9 KiB
Perl
86 lines
3.9 KiB
Perl
.\" $NetBSD: 2.0.t,v 1.2 1998/01/09 06:54:47 perry Exp $
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.\"
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.\" Copyright (c) 1983, 1993, 1994
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)2.0.t 8.4 (Berkeley) 5/26/94
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.\"
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.Sh 1 "System facilities
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.LP
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The system abstractions described are:
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.IP "Directory contexts
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.br
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A directory context is a position in the filesystem name
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space. Operations on files and other named objects in a filesystem are
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always specified relative to such a context.
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.IP "Files
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.br
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Files are used to store uninterpreted sequences of bytes,
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which may be \fIread\fP and \fIwritten\fP randomly.
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Pages from files may also be mapped into the process address space.
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A directory may be read as a file if permitted by the underlying
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storage facility,
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though it is usually accessed using
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.Fn getdirentries
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(see section
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.Xr 2.2.3.1 ).
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(Local filesystems permit directories to be read,
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although most NFS implementations do not allow reading of directories.)
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.IP "Communications domains
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.br
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A communications domain represents
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an interprocess communications environment, such as the communications
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facilities of the 4.4BSD system,
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communications in the INTERNET, or the resource sharing protocols
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and access rights of a resource sharing system on a local network.
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.IP "Sockets
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.br
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A socket is an endpoint of communication and the focal
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point for IPC in a communications domain. Sockets may be created in pairs,
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or given names and used to rendezvous with other sockets
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in a communications domain, accepting connections from these
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sockets or exchanging messages with them. These operations model
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a labeled or unlabeled communications graph, and can be used in a
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wide variety of communications domains. Sockets can have different
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\fItypes\fP\| to provide different semantics of communication,
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increasing the flexibility of the model.
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.IP "Terminals and other devices
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.br
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Devices include terminals (providing input editing, interrupt
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generation, output flow control, and editing), magnetic tapes,
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disks, and other peripherals.
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They normally support the generic
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\fIread\fP and \fIwrite\fP operations as well as a number of \fIioctl\fP\|'s.
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.IP "Processes
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.br
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Process descriptors provide facilities for control and debugging of
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other processes.
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