GAWK: Effective AWK Programming

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234 GAWK: Effective AWK ProgrammingBEGIN {# let getopt print a message about# invalid options. we ignore themwhile ((c = getopt(ARGC, ARGV, "lwc")) != -1) {if (c == "l")do_lines = 1else if (c == "w")do_words = 1else if (c == "c")do_chars = 1}for (i = 1; i < Optind; i++)ARGV[i] = ""}# if no options, do allif (! do_lines && ! do_words && ! do_chars)do_lines = do_words = do_chars = 1print_total = (ARGC - i > 2)The beginfile function is simple; it just resets the counts of lines, words, and charactersto zero, and saves the current file name in fname:function beginfile(file){chars = lines = words = 0fname = FILENAME}The endfile function adds the current file’s numbers to the running totals of lines,words, and characters. 2 It then prints out those numbers for the file that was just read. Itrelies on beginfile to reset the numbers for the following data file:function endfile(file){tchars += charstlines += linestwords += wordsif (do_lines)printf "\t%d", linesif (do_words)printf "\t%d", wordsif (do_chars)printf "\t%d", charsprintf "\t%s\n", fname2 wc can’t just use the value of FNR in endfile. If you examine the code in Section 12.3.1 [Noting DataFile Boundaries], page 197, you will see that FNR has already been reset by the time endfile is called.
Chapter 13: Practical awk Programs 235}There is one rule that is executed for each line. It adds the length of the record, plusone, to chars. Adding one plus the record length is needed because the newline characterseparating records (the value of RS) is not part of the record itself, and thus not includedin its length. Next, lines is incremented for each line read, and words is incremented bythe value of NF, which is the number of “words” on this line:# do per line{chars += length($0) + 1lines++words += NF}# get newlineFinally, the END rule simply prints the totals for all the files:END {if (print_total) {if (do_lines)printf "\t%d", tlinesif (do_words)printf "\t%d", twordsif (do_chars)printf "\t%d", tcharsprint "\ttotal"}}13.3 A Grab Bag of awk ProgramsThis section is a large “grab bag” of miscellaneous programs. We hope you find them bothinteresting and enjoyable.13.3.1 Finding Duplicated Words in a DocumentA common error when writing large amounts of prose is to accidentally duplicate words.Typically you will see this in text as something like “the the program does the following. . .”When the text is online, often the duplicated words occur at the end of one line and thebeginning of another, making them very difficult to spot.This program, ‘dupword.awk’, scans through a file one line at a time and looks foradjacent occurrences of the same word. It also saves the last word on a line (in the variableprev) for comparison with the first word on the next line.The first two statements make sure that the line is all lowercase, so that, for example,“The” and “the” compare equal to each other. The next statement replaces nonalphanumericand nonwhitespace characters with spaces, so that punctuation does not affect thecomparison either. The characters are replaced with spaces so that formatting controlsdon’t create nonsense words (e.g., the Texinfo ‘@code{NF}’ becomes ‘codeNF’ if punctuationis simply deleted). The record is then resplit into fields, yielding just the actual wordson the line, and ensuring that there are no empty fields.
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