Sistemas

UNIXTM TIME-SHARING SYSTEM:

UNIX PROGRAMMER’S MANUAL
Seventh Edition, Volume 1 January, 1979

Bell Telephone Laboratories, Incorporated Murray Hill, New Jersey

PREFACE

Although this Seventh Edition no longer bears their byline, Ken Thompson and Dennis Ritchie remain the fathers and preceptors of the UNIX† 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 UNIX, 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 andcriticism 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.

B. W. Kernighan M. D. McIlroy

__________________ †UNIX is a Trademark of Bell Laboratories.

INTRODUCTION TO VOLUME 1

This volume gives descriptions of the publicly available features of the UNIX† system. It does not attempt to provide perspectiveor tutorial information upon the UNIX operating system, its facilities, or its implementation. Various documents on those topics are contained in Volume 2. In particular, for an overview see ‘The UNIX Time-Sharing System’ by Ritchie and Thompson; for a tutorial see ‘UNIX for Beginners’ by Kernighan. Within the area it surveys, this volume attempts to be timely, complete and concise. Where thelatter two objectives conflict, the obvious is often left unsaid in favor of brevity. It is intended that each program be described as it is, not as it should be. Inevitably, this means that various sections will soon be out of date. The volume is divided into eight sections: 1. 2. 3. 4. 5. 6. 7. 8. Commands System calls Subroutines Special files File formats and conventions Games Macro packages andlanguage conventions Maintenance

Commands are programs intended to be invoked directly by the user, in contradistinction to subroutines, which are intended to be called by the user’s programs. Commands generally reside in directory /bin (for bin ary programs). Some programs also reside in / usr/ bin, to save space in /bin. These directories are searched automatically by the command interpreter.System calls are entries into the UNIX supervisor. Every system call has one or more C language interfaces described in section 2. The underlying assembly language interface, coded with opcode sys, a synonym for trap, is given as well. An assortment of subroutines is available; they are described in section 3. The primary libraries in which they are kept are described in intro(3). The functions aredescribed in terms of C, but most will work with Fortran as well. The special files section 4 discusses the characteristics of each system ‘file’ that actually refers to an I/O device. The names in this section refer to the DEC device names for the hardware, instead of the names of the special files themselves. The file formats and conventions section 5 documents the structure of particular kinds offiles; for example, the form of the output of the loader and assembler is given. Excluded are files used by only one command, for example the assembler’s intermediate files. Games have been relegated to section 6 to keep them from contaminating the more staid information of section 1. Section 7 is a miscellaneous collection of information necessary to writing in various specialized languages: charactercodes, macro packages for typesetting, etc. The maintenance section 8 discusses procedures not intended for use by the ordinary user. These procedures often involve use of commands of section 1, where an attempt has been made to single out
__________________ †UNIX is a Trademark of Bell Laboratories.

- iii peculiarly maintenance-flavored commands by marking them 1M. Each section consists...