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sed & awk describes two text processing programs that are mainstays of the UNIX programmer's toolbox.sed is a "e;stream editor"e; for editing streams of text that might be too large to edit as a single file, or that might be generated on the fly as part of a larger data processing step. The most common operation done with sed is substitution, replacing one block of text with another.awk is a complete programming language. Unlike many conventional languages, awk is "e;data driven"e; -- you specify what kind of data you are interested in and the operations to be performed when that data is found. awk does many things for you, including automatically opening and closing data files, reading records, breaking the records up into fields, and counting the records. While awk provides the features of most conventional programming languages, it also includes some unconventional features, such as extended regular expression matching and associative arrays. sed & awk describes both programs in detail and includes a chapter of example sed and awk scripts.This edition covers features of sed and awk that are mandated by the POSIX standard. This most notably affects awk, where POSIX standardized a new variable, CONVFMT, and new functions, toupper() and tolower(). The CONVFMT variable specifies the conversion format to use when converting numbers to strings (awk used to use OFMT for this purpose). The toupper() and tolower() functions each take a (presumably mixed case) string argument and return a new version of the string with all letters translated to the corresponding case.In addition, this edition covers GNU sed, newly available since the first edition. It also updates the first edition coverage of Bell Labs nawk and GNU awk (gawk), covers mawk, an additional freely available implementation of awk, and briefly discusses three commercial versions of awk, MKS awk, Thompson Automation awk (tawk), and Videosoft (VSAwk).

There are lots of introductory C books, but this is the first one that has the no-nonsense, practical approach that has made Nutshell Handbooks famous.C programming is more than just getting the syntax right. Style and debugging also play a tremendous part in creating programs that run well and are easy to maintain. This book teaches you not only the mechanics of programming, but also describes how to create programs that are easy to read, debug, and update.Practical rules are stressed. For example, there are fifteen precedence rules in C (&& comes before || comes before ?:). The practical programmer reduces these to two:Multiplication and division come before addition and subtraction.Contrary to popular belief, most programmers do not spend most of their time creating code. Most of their time is spent modifying someone else's code. This books shows you how to avoid the all-too-common obfuscated uses of C (and also to recognize these uses when you encounter them in existing programs) and thereby to leave code that the programmer responsible for maintenance does not have to struggle with. Electronic Archaeology, the art of going through someone else's code, is described.This third edition introduces popular Integrated Development Environments on Windows systems, as well as UNIX programming utilities, and features a large statistics-generating program to pull together the concepts and features in the language.

If you use UNIX, you probably use csh to type commands even if you've never heard of it. It's the standard shell (command line) on most UNIX systems. tcsh is an enhanced version that's freely available and highly recommended.Using csh & tcsh describes from the beginning how to use these shells interactively. More important, it shows how to get your work done faster with less typing. Even if you've used UNIX for years, techniques described in this book can make you more efficient.You'll learn how to:Make your prompt tell you where you are (no more pwd)Use what you've typed before (history)Type long command lines with very few keystrokes (command and filename completion)Remind yourself of filenames when in the middle of typing a commandEdit a botched command instead of retyping itThis book does not cover programming or script writing in csh ortcsh because the tasks are better done with a different shell, such as sh (the Bourne shell) or a language like Perl.