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Diffstat (limited to 'doc/gawk.texi')
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1 files changed, 150 insertions, 13 deletions
diff --git a/doc/gawk.texi b/doc/gawk.texi index 093c776b..7f85c13c 100644 --- a/doc/gawk.texi +++ b/doc/gawk.texi @@ -471,8 +471,8 @@ particular records in a file and perform operations upon them. includes command-line syntax. * One-shot:: Running a short throwaway @command{awk} program. -* Read Terminal:: Using no input files (input from - the keyboard instead). +* Read Terminal:: Using no input files (input from the + keyboard instead). * Long:: Putting permanent @command{awk} programs in files. * Executable Scripts:: Making self-contained @command{awk} @@ -494,6 +494,7 @@ particular records in a file and perform operations upon them. * Other Features:: Other Features of @command{awk}. * When:: When to use @command{gawk} and when to use other things. +* Intro Summary:: Summary of the introduction. * Command Line:: How to run @command{awk}. * Options:: Command-line options and their meanings. @@ -515,6 +516,7 @@ particular records in a file and perform operations upon them. program. * Obsolete:: Obsolete Options and/or features. * Undocumented:: Undocumented Options and Features. +* Invoking Summary:: Invocation summary. * Regexp Usage:: How to Use Regular Expressions. * Escape Sequences:: How to write nonprinting characters. * Regexp Operators:: Regular Expression Operators. @@ -523,8 +525,12 @@ particular records in a file and perform operations upon them. * Case-sensitivity:: How to do case-insensitive matching. * Leftmost Longest:: How much text matches. * Computed Regexps:: Using Dynamic Regexps. +* Regexp Summary:: Regular expressions summary. * Records:: Controlling how data is split into records. +* awk split records:: How standard @command{awk} splits + records. +* gawk split records:: How @command{gawk} splits records. * Fields:: An introduction to fields. * Nonconstant Fields:: Nonconstant Field Numbers. * Changing Fields:: Changing the Contents of a Field. @@ -981,8 +987,8 @@ particular records in a file and perform operations upon them. @command{gawk}. * New Ports:: Porting @command{gawk} to a new operating system. -* Derived Files:: Why derived files are kept in the - Git repository. +* Derived Files:: Why derived files are kept in the Git + repository. * Future Extensions:: New features that may be implemented one day. * Implementation Limitations:: Some limitations of the @@ -1300,9 +1306,6 @@ has been removed.) * Conventions:: Typographical Conventions. * Manual History:: Brief history of the GNU project and this @value{DOCUMENT}. -@ifset FOR_PRINT -* Staying current:: How to keep up. -@end ifset * How To Contribute:: Helping to save the world. * Acknowledgments:: Acknowledgments. @end menu @@ -1861,7 +1864,7 @@ find an error in this @value{DOCUMENT}, please report it! @xref{Bugs}, for information on submitting problem reports electronically. @ifset FOR_PRINT -@node Staying current +@c fakenode --- for prepinfo @unnumberedsec How to Stay Current It may be you have a version of @command{gawk} which is newer than the @@ -2178,6 +2181,7 @@ program looks like this: * Other Features:: Other Features of @command{awk}. * When:: When to use @command{gawk} and when to use other things. +* Intro Summary:: Summary of the introduction. @end menu @node Running gawk @@ -3369,6 +3373,39 @@ Programs in these languages may require more lines of source code than the equivalent @command{awk} programs, but they are easier to maintain and usually run more efficiently. +@node Intro Summary +@section Summary + +@itemize @value{BULLET} +@item +Programs in @command{awk} consist of @var{pattern}-@var{action} pairs. + +@item +Use either +@samp{awk '@var{program}' @var{files}} +or +@samp{awk -f @var{program-file} @var{files}} +to run @command{awk}. + +@item +You may use the special @samp{#!} header line to create @command{awk} +programs that are directly executable. + +@item +Comments in @command{awk} programs start with @samp{#} and continue to +the end of the same line. + +@item +Be aware of quoting issues when writing @command{awk} programs as +part of a larger shell script (or MS-Windows batch file). + +@item +You may use backslash continuation to continue a source line. +Lines are automatically continued after +a comma, open brace, question mark, colon, +@samp{||}, @samp{&&}, @code{do} and @code{else}. +@end itemize + @node Invoking Gawk @chapter Running @command{awk} and @command{gawk} @@ -3397,6 +3434,7 @@ things in this @value{CHAPTER} that don't interest you right now. * Loading Shared Libraries:: Loading shared libraries into your program. * Obsolete:: Obsolete Options and/or features. * Undocumented:: Undocumented Options and Features. +* Invoking Summary:: Invocation summary. @end menu @node Command Line @@ -4566,6 +4604,58 @@ long-undocumented ``feature'' of Unix @code{awk}. @end ignore +@node Invoking Summary +@section Summary + +@itemize @value{BULLET} +@item +Use either +@samp{awk '@var{program}' @var{files}} +or +@samp{awk -f @var{program-file} @var{files}} +to run @command{awk}. + +@item +The three standard @command{awk} options are @option{-f}, @option{-F} +and @option{-v}. @command{gawk} supplies these and many others, as well +as corresponding GNU-style long options. + +@item +Non-option command-line arguments are usually treated as @value{FN}s, +unless they have the form @samp{@var{var}=@var{value}}, in which case +they are taken as variable assignments to be performed at that point +in processing the input. + +@item +All non-option command-line arguments, excluding the program text, +are placed in the @code{ARGV} array. Adjusting @code{ARGC} and @code{ARGV} +affects how @command{awk} processes input. + +@item +You can use a single minus sign (@samp{-}) to refer to standard input +on the command line. + +@item +@command{gawk} pays attention to a number of environment variables. +@env{AWKPATH}, @env{AWKLIBPATH}, and @env{POSIXLY_CORRECT} are the +most important ones. + +@item +@command{gawk}'s exit status conveys information to the program +that invoked it. Use the @code{exit} statement from within +an @command{awk} program to set the exit status. + +@item +@command{gawk} allows you to include other @command{awk} source files into +your program using the @code{@@include} statement and/or the @option{-i} +and @option{-f} command-line options. + +@item +@command{gawk} allows you to load additional functions written in C +or C++ using the @code{@@load} statement and/or the @option{-l} option. +(This advanced feature is described later on in @ref{Dynamic Extensions}.) +@end itemize + @node Regexp @chapter Regular Expressions @cindex regexp @@ -4604,6 +4694,7 @@ regular expressions work, we present more complicated instances. * Case-sensitivity:: How to do case-insensitive matching. * Leftmost Longest:: How much text matches. * Computed Regexps:: Using Dynamic Regexps. +* Regexp Summary:: Regular expressions summary. @end menu @node Regexp Usage @@ -5841,6 +5932,52 @@ occur often in practice, but it's worth noting for future reference. @end ifnotdocbook @c ENDOFRANGE dregexp @c ENDOFRANGE regexpd + +@node Regexp Summary +@section Summary + +@itemize @value{BULLET} +@item +Regular expressions describe sets of strings to be matched. +In @command{awk}, regular expression constants are written enclosed +between slashes: @code{/}@dots{}@code{/}. + +@item +Regexp constants may be used by standalone in patterns and +in conditional expressions, or as part of matching expressions +using the @samp{~} and @samp{!~} operators. + +@item +Escape sequences let you represent non-printable characters and +also let you represent regexp metacharacters as literal characters +to be matched. + +@item +Regexp operators provide grouping, alternation and repetition. + +@item +Bracket expressions give you a shorthand for specifyings sets +of characters that can match at a particular point in a regexp. +Within bracket expressions, POSIX character classes let you specify +certain groups of characters in a locale-independent fashion. + +@item +@command{gawk}'s @code{IGNORECASE} variable lets you control the +case sensitivity of regexp matching. In other @command{awk} +versions, use @code{tolower()} or @code{toupper()}. + +@item +Regular expressions match the leftmost longest text in the string being +matched. This matters for cases where you need to know the extent of +the match, such as for text substitution and when the record separator +is a regexp. + +@item +Matching expressions may use dynamic regexps; that is string values +treated as regular expressions. + +@end itemize + @c ENDOFRANGE regexp @node Reading Files @@ -5913,8 +6050,8 @@ number of input records read so far from all @value{DF}s. It starts at zero, but is never automatically reset to zero. @menu -* awk split records:: How standard @command{awk} splits records. -* gawk split records:: How @command{gawk} splits records. +* awk split records:: How standard @command{awk} splits records. +* gawk split records:: How @command{gawk} splits records. @end menu @node awk split records @@ -11723,7 +11860,7 @@ has the value one if @code{x} contains @samp{foo}, such as @cindex @code{!} (exclamation point), @code{!~} operator @cindex exclamation point (@code{!}), @code{!~} operator The righthand operand of the @samp{~} and @samp{!~} operators may be -either a regexp constant (@code{/@dots{}/}) or an ordinary +either a regexp constant (@code{/}@dots{}@code{/}) or an ordinary expression. In the latter case, the value of the expression as a string is used as a dynamic regexp (@pxref{Regexp Usage}; also @pxref{Computed Regexps}). @@ -37286,8 +37423,8 @@ as well as any considerations you should bear in mind. @command{gawk}. * New Ports:: Porting @command{gawk} to a new operating system. -* Derived Files:: Why derived files are kept in the - Git repository. +* Derived Files:: Why derived files are kept in the Git + repository. @end menu @node Accessing The Source |