.TL
PREFACE TO THE TENTH EDITION
.PP
This edition of the 
.I "UNIX Programmer's Manual
appears on the twentieth
anniversary of the original research 
system pioneered by
Ken Thompson and Dennis Ritchie.
It is dedicated to the memory of the late Lee McMahon, whose
influence pervades the system's approaches
to text processing and data networking.
.PP
As with previous editions, the manual 
reports on the system as it exists
in its original home department at AT&T Bell Laboratories.
Although related to the commercial System V and the academic
BSD systems, the research system is just what its title implies.
Some of the facilities 
have long since graduated from the lab into international
commerce; others are experiments in progress.
Their appearance here does not constitute an
announcement of any official product.
.PP
Much has happened between the landmark seventh edition
of 1979, the last edition to be published as trade book,
and today.
The magnitude of the changes may perhaps be most
visible in the papers gathered in Volume 2,
more than half of which are completely new.
Even `old stuff' has been substantially updated.
For example, Volume 2 gives more up-to-date information
about the popular
.I troff
family of typesetting software than does any other published work.
.PP
Careful examination of Volume 1 will also show
enormous changes since the seventh edition.
The distinctive theme is distributed computing.
Ritchie's coroutine `stream' input/output and the
Datakit\(rg virtual circuit switch realization by
Lee McMahon and Bill Marshall provide the basis for 
networking.
Peter Weinberger's network file system makes it painless.
Rob Pike's software for windowed bitmap terminals extends
the system right out to your fingertips, giving
a multiplexed interface to an already multiplexed system.
Dave Presotto's communication software brings
harmony to the Babel of real-world communications.
Norman Wilson's battles with entropy have made
the tenth edition system trimmer
than its less capable predecessors.
.PP
Besides the facilities just listed,
the manual describes dozens of completely new programs
in areas ranging from protocol verification to optical
character recognition.
Practically every page has been improved in
wording if not in function.
Instructive examples, often chosen to suggest nonobvious
uses of the system, have been added.
Sections 4, 5, and 8 have been expanded to
provide more inside wisdom about the system.
.PP
Over the course of years dozens of people at 
Bell Laboratories have contributed
to the software here described.
Their work, acknowledged in previous editions, is their
monument.
Acknowledgement is also made to the Regents of the
University of California for certain portions that
descend from work in the Department of
Electrical Engineering and Computer Science at
Berkeley.
Active contributors to this edition include, besides
those already mentioned,
H. S. Baird,
J. L. Bentley,
S. A. Browning,
L. L. Cherry,
W. R. Cheswick,
M. A. Derr,
T. D. S. Duff,
C. W. Fraser,
D. M. Gay,
P. Glick,
F. T. Grampp,
E. H. Grosse,
D. R. Hanson,
G. J. Holzmann,
A. G. Hume,
B. W. Kernighan,
T. Killian,
A. R. Koenig,
T. J. Kowalski,
W. T. Marshall,
M. D. McIlroy,
S. C. North,
S. Peeters,
R. Pike,
S. A. Rago,
J. A. Reeds,
R. Sethi,
B. Stroustrup,
H. W. Trickey
and others.
Their computing activities have been made possible by the smoothly running
machines and Datakit networks managed by P. Glick,
F. T. Grampp, W. T. Marshall, and E. J. Sitar.
E. H. Carter consulted on book production.
.sp 2
.in 4.5i
A. G. Hume
.br
M. D. McIlroy
.br
October, 1989
.in 0
