UNIX™ TIME-SHARING SYSTEM: UNIX PROGRAMMER'S MANUAL Seventh Edition. Volume 2A January, 1979 Bell Telephone Laboratories. Incorporated Murray Hill, New Jersey Copyright 191'9" Bell Telepho,ne Laboratories. fncot1)orated. Holders of a UNIX ™ software license are permi ned to c:opy this' document" or any portion of it" as' necessary fo:t-ficensed: use" of the software. pr'ovided tbis copyright, notice atld, sta(,ement of permission are'induded. UNIX Programmer's Manual Volume 2 - Supplementary Documents Seventh Edition January 10, 1979 This volume contains documents which supplement the information contained in Volume 1 of The usut Programmer's ManuaL The documents here are grouped roughly into the areas of basics. editing, language tools, document preparation. and system maintenance. Further general information may be found in the Bell System Technical Journal special issue on UNIX, July-August, 1978. Many of the documents cited within this volume as Bell Laboratories internal memoranda or Computing Science Technical Reports (CSTR) are also contained here. These documents contain occasional localisms, typically references to other operating sys­ tems like GCOS and IBM. In all cases, such references may be safely ignored by UNIX users. General Works 1. 7th Edition UNIX - Summary. A concise summary of the facilities available on UNIX. 2. The UNIX Time-Sharing System. D. M. Ritchie and K. Thompson. The original UNIX paper, reprinted from CACM. Getting Started 3. UNIX for Beginners - Second Edition. B. W. Kernighan. An introduction to the most basic use of the system. 4. A Tutorial Introduction to the UNIX Text Editor. B. W. Kernighan. An easy way to get swted with the editor. S. Advanced Editing on UNIX. B. W. Kernighan. The next step. 6. An Introduction to the UNIX Shell. S. R. Bourne. An introduction to the capabilities of the command interpreter, the shell . ..; 7. Learn - Computer Aided Instruction on UNIX. M. E. Lesk and B. W. Kernighan. Describes a computer-aided instruction program that walks new users through the basics of files, the editor, and document preparation software. Document Preparation 8. Typing Documents on the UNIX. System. M. E. Lesk. Describes the basic use of the formatting tools. Also describes u-ms", a standard­ ized package of formatting requests that can be used to layout most documents (including those in this volume). tUNIX is a Trademark of Bell Laboralories. 9. A System for Typesetting Mathematics. B. W. Kernighan and L. L. Cherry Describes EQN. an easy-to-Iearn language for doing high-quality mathematical typesetting. 10. TBL - A Program to Format Tables. M. E. Lesk. A program to permit easy specification of tabula.r· material for typesetting. Again, easy to learn and use. 11. Some Applications of Inverted Indexes on the UNIX System. M. E. Lesk. Describes. among other things, the program REFER which tnls in bibliographic citations from a data base automatically. 12. NROFF/TROFF User's Manual. J. F. Ossanna. The basic formatting program. 13. A TROFF Tutorial. B. W. Kernighan. An introduction to TROFF for those who really want to know such things. 14. The C Programming Language - Reference Manual. D. M. Ritchie. Official statement of the syntax and semantics of C. Should be sup­ plemented by ThB C Progra.mming Language. B. W. Kernighan and D. M. Ritchie, Prentice-Hall. 1978. which contains a tutorial introduction and many examples. /' 15. Lint. A C Program Checker. S. C. Johnson. Checks C programs for syntax errors, type violations, portability problems, and a variety of probable errors. V1S. Make - A Program for Maintaining Computer Programs. S. I. Feldman. Indespensable tool for making sure that large programs are properly compiled with minimal effort. j 17. UNIX Programming. B. W. Kernighan and D. M. Ritchie. Describes the programmming interface to the operating system and the standard I/O library. .. lB. A Tutorial Inntroduction fo ADB. J.F. Maranzano and S. R. Bourne. How to use the ADB Debugger. Supporting Tools and Languages ( 19. YACC: Yet Another Compiler-Compiler. S. C. Johnson. Converts a BNF specification of a language and semantic actions writ­ ten in C into a compiler of the language. 20. LEX - A lexical Analyzer Generator. M. E. Lesk and E. Schmidt. Creates a recognizer for a set of regular expressions; each regular expression can be followed by arbitrary C code which 'will be executed when the regular expression is found. 21. A Portable Fortran 77 Compiler. S. 1. Feldman and P. J. Weinberger. The first Fortran 77 compiler. and still one of the best. NOTE: This document has been moved to Volume 2c of the UNIX Programmer's Manual. 22. Ratfor - A Preprocessor for a Rational Fortran. B. W. Kernighan. Converts a Fortran with C-like control structures and cosmetics into real. ugly Fortran. 23. The M4 Macro Processor. B. W. Kernighan and D. M. Ritchie. M4 is a macro processor useful as a front end for C, Ratfor. Cobol. and in its own right. "'- 3 - ../ 24. SED - A Non-interactive Text Editor. L. E. McMahon. A variant of the editor for processing large inputs. ~ 25. AWK - A Pattern Scanning and Processing Language. A. V. Aho, B. W. Kernighan and P. J. Weinberger. Makes it easy to specify many data transformation and selection operations. 26. DC - An Interactive Desk Calculator. R. H. Morris and L. L. Cherry. A super HP calculator, if you don't need floating point. 27. BC - An Arbitrary Precision Desk-Calculator Language. L. L. Cherry and R. H. Morris. A front end for DC that provides infix notation, control now, and built-in functions. 28. UNIX Assembler Reference Manual. D. M. Ritchie. The ultimate dead language. Implementation. Maintenance, and Misc:ellaneous 29. Setting Up UNIX - Seventh Edition. C. B. Haley and D. M. Ritchie. How to configure and get your system running. 30. Regenerating System Software. C. B. Haley and D. M. Ritchie. Whal do do when you have to change things. 31. UNIX Implementation. .K. Thompson. How the system actually works inside. 32. The UNIX 110 System. D. M. Ritchie. How the 110 system really works. 33. A Tour Through the UNIX C Compiler. D. M. Ritchie. How the PDP-II compiler works inside. 34. A Tour Through the Portable C Compiler. S. C. Johnson. How the portable C compiler works inside. 35. A Dial-Up Network of UNIX Systems. D. A. Nowitz and M. E. Lesk. Describes UUCP t a program for communicating files between UNIX systems. 36. UUCP Implementation Description. D. A. Nowitz. How UUCP works., and how to administer iL 37. On the Security of UNIX. D. M. Ritchie. Hints on how to break UNIX, and how to avoid doing so. 38. Password Security: A Case History. R. H. Morris and K. Thompson. How the bad guys used to be able to break the password algorithm, and why they can't now, alleast not so easily. LEARN - Computer-Aided Instruction on UNIX (Second Edition) Brian W. Kernighan Michael E. Lesk Bell Laboratories Murray Hill, New Jersey 07974 ABSTRACT This paper describes the second version of the learn program for interpret­ ing CAl scripts on the U~lxt operating system, and a set of scripts that provide a computerized introduction to the system. Six current scripts cover basic commands and file handling, the editor, additional file handling commands, the eqn program for mathematical typing, the H -ms" package of formatting macros, and an introduction to the C pro­ gramming language. These scripts now include a total of about 530 lessons. Many users from a wide variety of backgrounds have used learn to acquire basic UNIX skills. Most usage involves the first two scripts, an introduc­ tion to files and commands, and the text editor. The second version of learn is about four times faster than the previous one in CPU utilization, and much faster in perceived time because of better overlap of computing and printing. It also requires less file space than the first version. Many of the lessons have been revised; new material has been added to reflect changes and enhancements in the UNIX system itself. Script-writing is also easier because of revisions to the script language. January 30, 1979 tUNIX is a Trademark o( Bell Laboratories. LEARN - Computer~Aided Instruction on UNIX (Second Edition) Brian ~V. Kernighan il-lichael E. Lesk Bell Laboratories Murray Hill, New Jersey 07974 1. Introduction. Learn is a driver for CAl scripts. It is intended to permit the easy composition of lessons and lesson fragments to teach people computer skills. Since it is teaching the same system on which it is implemented, it makes direct use of UNIxt facilities to create a controlled UNIX environment. The system includes two main parts: (1) a driver that interprets the lesson scripts; and (2) the lesson scripts themselves. At present there are six scripts: basic file handling commands the UNIX text editor ed advanced file handling the "eqn language for typing mathematics the U-mS" macro package for document formatting the C programming language The purported advantages of CAl scripts for training in computer skills include the follow ... ing: (a) students are forced to perform the exercises that ;.re in fact the basis of training in any case~ (b) students receive immediate feedback and confirmation of progress~ (c) students may progress at their own rate; . (d) no schedule requirements are imposed; students may study at any time convenient for them; (e) the lessons may be improved individually and the improvements are immediately available to new users; (f) since the student has access to a computer for the CAl script there is a place to do exercises; (g) the use of high technology will improve student motivation and the interest of their management.