.TL PREFACE .LP The .UX \s-2/32V\s0 operating system for the VAX*-11 .FS *VAX and PDP are Trademarks of Digital Equipment Corporation. .FE provides substantially the same facilities as the \s-2UNIX\s0 system for the PDP*-11. .LP We acknowledge the work of many who came before us, and particularly thank G. K. Swanson, W. M. Cardoza, D. K. Sharma, and J. F. Jarvis for assistance with the implementation for the VAX-11/780. .sp 2 .in 4i T. B. London .br J. F. Reiser .in 0 .sp 4 .ce \fIPreface to the Seventh Edition\fP .sp 2 .LP Although this Seventh Edition no longer bears their byline, Ken Thompson and Dennis Ritchie remain the fathers and preceptors of the \s-2UNIX\s0 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