.TL
PREFACE
.LP
Although this Seventh Edition no longer bears their byline,
Ken Thompson and Dennis Ritchie remain the fathers
and preceptors of the
.UX
time-sharing system.
Many of the improvements here described bear their mark.
Among many, many other people who have contributed to
the further flowering of
\s-2UNIX\s0,
we wish especially to
acknowledge the contributions of
A. V. Aho,
S. R. Bourne,
L. L. Cherry,
G. L. Chesson,
S. I. Feldman,
C. B. Haley,
R. C. Haight,
S. C. Johnson,
M. E. Lesk,
T. L. Lyon,
L. E. McMahon,
R. Morris,
R. Muha,
D. A. Nowitz,
L. Wehr,
and
P. J. Weinberger.
We appreciate also 
the effective advice and criticism of
T. A. Dolotta,
A. G. Fraser,
J. F. Maranzano,
and
J. R. Mashey;
and we remember the important work of
the late Joseph F. Ossanna.
.sp 2
.in 4i
B. W. Kernighan
.br
M. D. McIlroy
.in 0