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Classic Shell Scripting

This might be a great second book on shell scripting., June 5, 2005

This might be a great second book on shell scripting. Can serve as a valuable add on to "Learning Korn shell" from O'Reilly -- also a very strong book on shell scripting.

The authors provide a lot of interesting and useful information that is difficult to find in other books. They devoted Ch 5 to piping and in 5.4 "Word List" they discuss famous Doug McIlroy alternative solution to Donald Knuth program of creating the list of the n most-frequent words, with counts of their frequency of occurrence, sorted by descending count from an arbitrary text file.

The authors discuss many Unix tools that are used with shell (Unix toolbox). They provide a very good (but too brief) discussion of grep and find. Discussion of xargs (which is usually a sign on a good book on scripting) includes /dev/null trick, but unfortunately they do not mention an option -0n with which this trick makes the most sense.

One of the best chapters of the book is Ch. 13 devoted to process control. Also good is Chapter 11 that provides a solution to pretty complex and practically important for many system administrators task of merging passwd files in Unix. It provides a perfect insight into solving real sysadmins problems using AWK and shell.
Shortcomings are few. in "5.2. Structured Data for the Web" the authors should probably list AWK instead of SED. Also XML processing generally requires using a lexical analyzer, not regular expressions. Therefore a tag list example would be better converted to something simpler, for example generating C-tags for vi.