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diff --git a/doc/gawktexi.in b/doc/gawktexi.in index ade6466f..e360a83b 100644 --- a/doc/gawktexi.in +++ b/doc/gawktexi.in @@ -38702,6 +38702,21 @@ languages. These standards often become international standards as well. See also ``ISO.'' +@item Argument +An argument can be two different things. It can be an option or a +@value{FN} passed to a command while invoking it from the command line, or +it can be something passed to a @dfn{function} inside a program, e.g. +inside @command{awk}. + +In the latter case, an argument can be passed to a function in two ways. +Either it is given to the called function by value, i.e., a copy of the +value of the variable is made available to the called function, but the +original variable cannot be modified by the function itself; or it is +given by reference, i.e., a pointer to the interested variable is passed to +the function, which can then directly modify it. In @command{awk} +scalars are passed by value, and arrays are passed by reference. +See ``Pass By Value/Reference.'' + @item Array A grouping of multiple values under the same name. Most languages just provide sequential arrays. @@ -38743,6 +38758,25 @@ The GNU version of the standard shell @end ifinfo See also ``Bourne Shell.'' +@item Binary +Base-two notation, where the digits are @code{0}--@code{1}. Since +electronic circuitry works ``naturally'' in base 2 (just think of Off/On), +everything inside a computer is calculated using base 2. Each digit +represents the presence (or absence) of a power of 2 and is called a +@dfn{bit}. So, for example, the base-two number @code{10101} is +the same as decimal 21, ((1 x 16) + (1 x 4) + (1 x 1)). + +Since base-two numbers quickly become +very long to read and write, they are usually grouped by 3 (i.e., they are +read as octal numbers), or by 4 (i.e., they are read as hexadecimal +numbers). There is no direct way to insert base 2 numbers in a C program. +If need arises, such numbers are usually inserted as octal or hexadecimal +numbers. The number of base-two digits that fit into registers used for +representing integer numbers in computers is a rough indication of the +computing power of the computer itself. Most computers nowadays use 64 +bits for representing integer numbers in their registers, but 32-bit, +16-bit and 8-bit registers have been widely used in the past. +@xref{Nondecimal-numbers}. @item Bit Short for ``Binary Digit.'' All values in computer memory ultimately reduce to binary digits: values @@ -38774,6 +38808,19 @@ The characters @samp{@{} and @samp{@}}. Braces are used in @command{awk} for delimiting actions, compound statements, and function bodies. +@item Bracket Expression +Inside a @dfn{regular expression}, an expression included in square +brackets, meant to designate a single character as belonging to a +specified character class. A bracket expression can contain a list of one +or more characters, like @samp{[abc]}, a range of characters, like +@samp{[A-Z]}, or a name, delimited by @samp{:}, that designates a known set +of characters, like @samp{[:digit:]}. The form of bracket expression +enclosed between @samp{:} is independent of the underlying representation +of the character themselves, which could utilize the ASCII, ECBDIC, or +Unicode codesets, depending on the architecture of the computer system, and on +localization. +See also ``Regular Expression.'' + @item Built-in Function The @command{awk} language provides built-in functions that perform various numerical, I/O-related, and string computations. Examples are @@ -38827,9 +38874,25 @@ points out similarities between @command{awk} and C when appropriate. In general, @command{gawk} attempts to be as similar to the 1990 version of ISO C as makes sense. +@item C Shell +The C Shell (@command{csh} or its improved version, @command{tcsh}) is a Unix shell that was +created by Bill Joy in the late 1970s. The C shell was differentiated from +other shells by its interactive features and overall style, which +looks more like C. The C Shell is not backward compatible with the Bourne +Shell, so special attention is required when converting scripts +written for other Unix shells to the C shell, especially with regard to the management of +shell variables. +See also ``Bourne Shell.'' + @item C++ A popular object-oriented programming language derived from C. +@item Character Class +See ``Bracket Expression.'' + +@item Character List +See ``Bracket Expression.'' + @cindex ASCII @cindex ISO 8859-1 @cindex ISO Latin-1 @@ -38869,11 +38932,23 @@ machine-executable object code. The object code is then executed directly by the computer. See also ``Interpreter.'' +@item Complemented Bracket Expression +The negation of a @dfn{bracket expression}. All that is @emph{not} +described by a given bracket expression. The symbol @samp{^} precedes +the negated bracket expression. E.g.: @samp{[[^:digit:]} +designates whatever character is not a digit. @samp{[^bad]} +designates whatever character is not one of the letters @samp{b}, @samp{a}, +or @samp{d}. +See ``Bracket Expression.'' + @item Compound Statement A series of @command{awk} statements, enclosed in curly braces. Compound statements may be nested. (@xref{Statements}.) +@item Computed Regexps +See ``Dynamic Regular Expressions.'' + @item Concatenation Concatenating two strings means sticking them together, one after another, producing a new string. For example, the string @samp{foo} concatenated with @@ -38888,6 +38963,13 @@ expression is the value of @var{expr2}; otherwise the value is @var{expr3}. In either case, only one of @var{expr2} and @var{expr3} is evaluated. (@xref{Conditional Exp}.) +@item Control Statement +A control statement is an instruction to perform a given operation or a set +of operations inside an @command{awk} program, if a given condition is +true. Control statements are: @code{if}, @code{for}, @code{while}, and +@code{do} +(@pxref{Statements}). + @cindex McIlroy, Doug @cindex cookie @item Cookie @@ -39042,6 +39124,11 @@ Format strings control the appearance of output in the are controlled by the format strings contained in the predefined variables @code{CONVFMT} and @code{OFMT}. (@xref{Control Letters}.) +@item Fortran +Shorthand for FORmula TRANslator, one of the first programming languages +available for scientific calculations. It was created by John Backus, +and has been available since 1957. It is still in use today. + @item Free Documentation License This document describes the terms under which this @value{DOCUMENT} is published and may be copied. (@xref{GNU Free Documentation License}.) @@ -39059,10 +39146,21 @@ Emacs editor. GNU Emacs is the most widely used version of Emacs today. See ``Free Software Foundation.'' @item Function -A specialized group of statements used to encapsulate general -or program-specific tasks. @command{awk} has a number of built-in -functions, and also allows you to define your own. -(@xref{Functions}.) +A part of an @command{awk} program that can be invoked from every point of +the program, to perform a task. @command{awk} has several built-in +functions. +Users can define their own functions in every part of the program. +Function can be recursive, i.e., they may invoke themselves. +@xref{Functions}. +In @command{gawk} it is also possible to have functions shared +among different programs, and included where required using the +@code{@@include} directive +(@pxref{Include Files}). +In @command{gawk} the name of the function that should be invoked +can be generated at run time, i.e., dynamically. +The @command{gawk} extension API provides constructor functions +(@pxref{Constructor Functions}). + @item @command{gawk} The GNU implementation of @command{awk}. @@ -39186,6 +39284,12 @@ meaning. Keywords are reserved and may not be used as variable names. and @code{while}. +@item Korn Shell +The Korn Shell (@command{ksh}) is a Unix shell which was developed by David Korn at Bell +Laboratories in the early 1980s. The Korn Shell is backward-compatible with the Bourne +shell and includes many features of the C shell. +See also ``Bourne Shell.'' + @cindex LGPL (Lesser General Public License) @cindex Lesser General Public License (LGPL) @cindex GNU Lesser General Public License @@ -39225,6 +39329,14 @@ Characters used within a regexp that do not stand for themselves. Instead, they denote regular expression operations, such as repetition, grouping, or alternation. +@item Nesting +Nesting is where information is organized in layers, or where objects +contain other similar objects. +In @command{gawk} the @code{@@include} +directive can be nested. The ``natural'' nesting of arithmetic and +logical operations can be changed using parentheses +(@pxref{Precedence}). + @item No-op An operation that does nothing. @@ -39245,6 +39357,11 @@ Octal numbers are written in C using a leading @samp{0}, to indicate their base. Thus, @code{013} is 11 ((1 x 8) + 3). @xref{Nondecimal-numbers}. +@item Output Record +A single chunk of data that is written out by @command{awk}. Usually, an +@command{awk} output record consists of one or more lines of text. +@xref{Records}. + @item Pattern Patterns tell @command{awk} which input records are interesting to which rules. @@ -39259,6 +39376,9 @@ An acronym describing what is possibly the most frequent source of computer usage problems. (Problem Exists Between Keyboard And Chair.) +@item Plug-in +See ``Extensions.'' + @item POSIX The name for a series of standards that specify a Portable Operating System interface. The ``IX'' denotes @@ -39283,6 +39403,9 @@ A sequence of consecutive lines from the input file(s). A pattern can specify ranges of input lines for @command{awk} to process or it can specify single lines. (@xref{Pattern Overview}.) +@item Record +See ``Input record'' and ``Output record.'' + @item Recursion When a function calls itself, either directly or indirectly. If this is clear, stop, and proceed to the next entry. @@ -39300,6 +39423,15 @@ operators. (@xref{Getline}, and @ref{Redirection}.) +@item Reference Counts +An internal mechanism in @command{gawk} to minimize the amount of memory +needed to store the value of string variables. If the value assumed by +a variable is used in more than one place, only one copy of the value +itself is kept, and the associated reference count is increased when the +same value is used by an additional variable, and decresed when the related +variable is no longer in use. When the reference count goes to zero, +the memory space used to store the value of the variable is freed. + @item Regexp See ``Regular Expression.'' @@ -39317,6 +39449,15 @@ slashes, such as @code{/foo/}. This regular expression is chosen when you write the @command{awk} program and cannot be changed during its execution. (@xref{Regexp Usage}.) +@item Regular Expression Operators +See ``Metacharacters.'' + +@item Rounding +Rounding the result of an arithmetic operation can be tricky. +More than one way of rounding exists, and in @command{gawk} +it is possible to choose which method should be used in a program. +@xref{Setting the rounding mode}. + @item Rule A segment of an @command{awk} program that specifies how to process single input records. A rule consists of a @dfn{pattern} and an @dfn{action}. @@ -39376,6 +39517,12 @@ A @value{FN} interpreted internally by @command{gawk}, instead of being handed directly to the underlying operating system---for example, @file{/dev/stderr}. (@xref{Special Files}.) +@item Statement +An expression inside an @command{awk} program in the action part +of a pattern--action rule, or inside an +@command{awk} function. A statement can be a variable assignment, +an array operation, a loop, etc. + @item Stream Editor A program that reads records from an input stream and processes them one or more at a time. This is in contrast with batch programs, which may @@ -39426,9 +39573,14 @@ This is standard time in Greenwich, England, which is used as a reference time for day and date calculations. See also ``Epoch'' and ``GMT.'' +@item Variable +A name for a value. In @command{awk}, variables may be either scalars +or arrays. + @item Whitespace A sequence of space, TAB, or newline characters occurring inside an input record or a string. + @end table @end ifclear |