GAWK: Effective AWK Programming

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180 GAWK: Effective AWK Programming-W lint[=fatal]--lint[=fatal]Warns about constructs that are dubious or nonportable to other awk implementations.Some warnings are issued when gawk first reads your program.Others are issued at runtime, as your program executes. With an optionalargument of ‘fatal’, lint warnings become fatal errors. This may be drastic,but its use will certainly encourage the development of cleaner awk programs.With an optional argument of ‘invalid’, only warnings about things that areactually invalid are issued. (This is not fully implemented yet.)Some warnings are only printed once, even if the dubious constructs they warnabout occur multiple times in your awk program. Thus, when eliminating problemspointed out by ‘--lint’, you should take care to search for all occurrencesof each inappropriate construct. As awk programs are usually short, doing sois not burdensome.-W lint-old--lint-oldWarns about constructs that are not available in the original version of awkfrom Version 7 Unix (see Section A.1 [Major Changes Between V7 and SVR3.1],page 257).-W non-decimal-data--non-decimal-dataEnable automatic interpretation of octal and hexadecimal values in input data(see Section 10.1 [Allowing Nondecimal Input Data], page 169).-W posix--posixCaution: This option can severely break old programs. Use with care.Operates in strict POSIX mode. This disables all gawk extensions (just like‘--traditional’) and adds the following additional restrictions:• \x escape sequences are not recognized (see Section 2.2 [Escape Sequences],page 25).• Newlines do not act as whitespace to separate fields when FS is equal to asingle space (see Section 3.2 [Examining Fields], page 39).• Newlines are not allowed after ‘?’ or ‘:’ (see Section 5.12 [ConditionalExpressions], page 92).• The synonym func for the keyword function is not recognized (seeSection 8.2.1 [Function Definition Syntax], page 153).• The ‘**’ and ‘**=’ operators cannot be used in place of ‘^’ and ‘^=’ (seeSection 5.5 [Arithmetic Operators], page 81, and also see Section 5.7 [AssignmentExpressions], page 83).• Specifying ‘-Ft’ on the command-line does not set the value of FS to bea single TAB character (see Section 3.5 [Specifying How Fields Are Separated],page 43).• The locale’s decimal point character is used for parsing input data (seeSection 2.9 [Where You Are Makes A Difference], page 35).
Chapter 11: Running awk and gawk 181• The fflush built-in function is not supported (see Section 8.1.4[Input/Output Functions], page 143).If you supply both ‘--traditional’ and ‘--posix’ on the command line,‘--posix’ takes precedence. gawk also issues a warning if both options aresupplied.-W profile[=file]--profile[=file]Enable profiling of awk programs (see Section 10.5 [Profiling Your awkPrograms], page 173). By default, profiles are created in a file named‘awkprof.out’. The optional file argument allows you to specify a differentfile name for the profile file.When run with gawk, the profile is just a “pretty printed” version of the program.When run with pgawk, the profile contains execution counts for eachstatement in the program in the left margin, and function call counts for eachfunction.-W re-interval--re-intervalAllows interval expressions (see Section 2.3 [Regular Expression Operators],page 27) in regexps. Because interval expressions were traditionally not availablein awk, gawk does not provide them by default. This prevents old awkprograms from breaking.-W source program-text--source program-textAllows you to mix source code in files with source code that you enter on thecommand line. Program source code is taken from the program-text. Thisis particularly useful when you have library functions that you want to usefrom your command-line programs (see Section 11.4 [The AWKPATH EnvironmentVariable], page 183).-W use-lc-numeric--use-lc-numericThis option forces the use of the locale’s decimal point character when parsingnumeric input data (see Section 2.9 [Where You Are Makes A Difference],page 35).-W version--versionPrints version information for this particular copy of gawk. This allows you todetermine if your copy of gawk is up to date with respect to whatever the FreeSoftware Foundation is currently distributing. It is also useful for bug reports(see Section B.5 [Reporting Problems and Bugs], page 280).As long as program text has been supplied, any other options are flagged as invalid witha warning message but are otherwise ignored.In compatibility mode, as a special case, if the value of fs supplied to the ‘-F’ option is‘t’, then FS is set to the TAB character ("\t"). This is true only for ‘--traditional’ andnot for ‘--posix’ (see Section 3.5 [Specifying How Fields Are Separated], page 43).
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