/share/doc/psd/05.sysman/2.0.t

https://bitbucket.org/freebsd/freebsd-head/ · Raku · 83 lines · 83 code · 0 blank · 0 comment · 8 complexity · 80e4e3f3e7f406b2ab4a5b85876a2183 MD5 · raw file

  1. .\" Copyright (c) 1983, 1993
  2. .\" The Regents of the University of California. All rights reserved.
  3. .\"
  4. .\" Redistribution and use in source and binary forms, with or without
  5. .\" modification, are permitted provided that the following conditions
  6. .\" are met:
  7. .\" 1. Redistributions of source code must retain the above copyright
  8. .\" notice, this list of conditions and the following disclaimer.
  9. .\" 2. Redistributions in binary form must reproduce the above copyright
  10. .\" notice, this list of conditions and the following disclaimer in the
  11. .\" documentation and/or other materials provided with the distribution.
  12. .\" 3. All advertising materials mentioning features or use of this software
  13. .\" must display the following acknowledgement:
  14. .\" This product includes software developed by the University of
  15. .\" California, Berkeley and its contributors.
  16. .\" 4. Neither the name of the University nor the names of its contributors
  17. .\" may be used to endorse or promote products derived from this software
  18. .\" without specific prior written permission.
  19. .\"
  20. .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21. .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22. .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23. .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24. .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25. .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26. .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27. .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28. .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29. .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30. .\" SUCH DAMAGE.
  31. .\"
  32. .\" @(#)2.0.t 8.1 (Berkeley) 6/8/93
  33. .\"
  34. .ds ss 1
  35. .sh "System facilities
  36. This section discusses the system facilities that
  37. are not considered part of the kernel.
  38. .PP
  39. The system abstractions described are:
  40. .IP "Directory contexts
  41. .br
  42. A directory context is a position in the UNIX file system name
  43. space. Operations on files and other named objects in a file system are
  44. always specified relative to such a context.
  45. .IP "Files
  46. .br
  47. Files are used to store uninterpreted sequence of bytes on which
  48. random access \fIreads\fP and \fIwrites\fP may occur.
  49. Pages from files may also be mapped into process address space.\(dg
  50. A directory may be read as a file.
  51. .FS
  52. \(dg Support for mapping files is not included in the 4.3 release.
  53. .FE
  54. .IP "Communications domains
  55. .br
  56. A communications domain represents
  57. an interprocess communications environment, such as the communications
  58. facilities of the UNIX system,
  59. communications in the INTERNET, or the resource sharing protocols
  60. and access rights of a resource sharing system on a local network.
  61. .IP "Sockets
  62. .br
  63. A socket is an endpoint of communication and the focal
  64. point for IPC in a communications domain. Sockets may be created in pairs,
  65. or given names and used to rendezvous with other sockets
  66. in a communications domain, accepting connections from these
  67. sockets or exchanging messages with them. These operations model
  68. a labeled or unlabeled communications graph, and can be used in a
  69. wide variety of communications domains. Sockets can have different
  70. \fItypes\fP\| to provide different semantics of communication,
  71. increasing the flexibility of the model.
  72. .IP "Terminals and other devices
  73. .br
  74. Devices include
  75. terminals, providing input editing and interrupt generation
  76. and output flow control and editing, magnetic tapes,
  77. disks and other peripherals. They often support the generic
  78. \fIread\fP and \fIwrite\fP operations as well as a number of \fIioctl\fP\|s.
  79. .IP "Processes
  80. .br
  81. Process descriptors provide facilities for control and debugging of
  82. other processes.
  83. .ds ss 2