Plot's a bit dry.

This book, copyright 1984, is not one's typical software read. Typical books on software deal with the latest and greatest that's coming down the pike. Instead, this book is a reminder of what is great in the UNIX operating system. It harkens back to the days when assembly coding was common and programming in C was considered more cutting edge.

So why is this worth a programmer's time to read over thirty years later in an era of object-orientation and machine-learning? The answer to this question is not vexing; indeed, it is simple. Great ideas transformed into great inventions deserve great study.

This book's epilog sums up this advice in describing four elements of UNIX's style:

1. "Let the machine do the work."
2. "Let other people do the work. Use programs that already exist as building blocks in your programs..."
3. "Do the job in stages. Build the simplest thing that will be useful, and let your experience with that determine what (if anything) is worth doing next."
4. "Build tools. Write programs that mesh with the existing environment, enhancing it rather than merely adding to it." ( )

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Before there was bash, before Ruby or PHP or Python or Perl, before X Windows, there was The Shell. ( )

Indeholder "Preface", "1. UNIX for Beginners", " 1.1 Getting started", " 1.2 Day-to-day use: files and common commands", " 1.3 More about files: directories", " 1.4 The shell", " 1.5 The rest of the UNIX system", "2. The File System", " 2.1 The basics of files", " 2.2 What's in a file?", " 2.3 Directories and filenames", " 2.4 Permissions", " 2.5 Inodes", " 2.6 The directory hierarchy", " 2.7 Devices", "3. Using the Shell", " 3.1 Command line structure", " 3.2 Metacharacters", " 3.3 Creating new commands", " 3.4 Command arguments and parameters", " 3.5 Program output as arguments", " 3.6 Shell variables", " 3.7 More on I/O redirection", " 3.8 Looping in shell programs", " 3.9 bundle: putting it all together", " 3.10 Why a programmable shell?", "4. Filters ", " 4.1 The grep family", " 4.2 Other filters", " 4.3 The stream editor sed", " 4.4 The awk pattern scanning and processing language", " 4.5 Good files and good filters", "5. Shell Programming", " 5.1 Customizing the cal command", " 5.2 Which command is which?", " 5.3 While and until loops: watching for things", " 5.4 Traps: catching interrupts", " 5.5 Replacing a file: overwrite", " 5.6 Zap: killing processes by name", " 5.7 The pick command: blanks vs. arguments", " 5.8 The news command: community service messages", " 5.9 Get and put: tracking file changes", " 5.10 A look back", "6. Programming with Standard I/O", " 6.1 Standard input and output: vis", " 6.2 Program arguments: vis version 2", " 6.3 File access: vis version 3", " 6.4 A screen-at-a-time printer: p", " 6.5 An example: pick", " 6.6 On bugs and debugging", " 6.7 An example: zap", " 6.8 An interactive file comparison program: idiff", " 6.9 Accessing the environment", "7. UNIX System Calls", " 7.1 Low-level I/O", " 7.2 File system: directories", " 7.3 File system: inodes", " 7.4 Processes", " 7.5 Signals and interrupts", "8. Program Development", " 8.1 Stage 1: A four-function calculator", " 8.2 Stage 2: Variables and error recovery", " 8.3 Stage 3: Arbitrary variable names; built-in functions", " 8.4 Stage 4: Compilation into a machine", " 8.5 Stage 5: Control flow and relational operators", " 8.6 Stage 6: Functions and procedures; input/output", " 8.7 Performance evaluation", " 8.8 A look back", "9. Document Preparation", " 9.1 The ms macro package", " 9.2 The troff level", " 9.3 The tbl and eqn preprocessors", " 9.4 The manual page", " 9.5 Other document preparation tools", "10. Epilog", " Appendix 1. Editor Summary", " Appendix 2. hoc Manual", " Appendix 3. hoc Listing", "Index".

Aldeles glimrende introduktion til diverse værktøjer i unix værktøjskassen. Overraskende aktuel selv om den snakker om halv og fuld duplex et par steder. Kapitel 8 handler om udvikling af en floating-point lommeregner som et program. Der er gode overvejelser, men når man kigger nøjere på den skæbne selve programmet hoc (high-order calculator) har fået, så får man hurtigt den ide at det er et mareridt at lave portable programmer til at håndtere floating point aritmetik.
bc og dc overlevede. Det gjorde hoc ikke. (Det er ikke en del af standardpakker til fx ubuntu og jeg kan heller ikke få det til at compilere på ubuntu 20.04 (sikkert min fejl)).
http://nadav.harel.org.il/homepage/hoc/ har en hoc version 9.2 der faktisk kan installeres. ( )