File: lmawk.1.html

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libmawk 1.0.5-1
  • links: PTS, VCS
  • area: main
  • in suites: forky, sid
  • size: 3,188 kB
  • sloc: ansic: 27,046; awk: 1,154; yacc: 1,054; makefile: 488; sh: 365
file content (2998 lines) | stat: -rw-r--r-- 80,099 bytes parent folder | download | duplicates (4) 
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<!-- Creator     : groff version 1.22.3 -->
<!-- CreationDate: Sun Nov 11 07:32:01 2018 -->
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
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<title>LMAWK</title>

</head>
<body>

<h1 align="center">LMAWK</h1>

<a href="#NAME">NAME</a><br>
<a href="#SYNOPSIS">SYNOPSIS</a><br>
<a href="#DESCRIPTION">DESCRIPTION</a><br>
<a href="#OPTIONS">OPTIONS</a><br>
<a href="#THE AWK LANGUAGE">THE AWK LANGUAGE</a><br>
<a href="#EXAMPLES">EXAMPLES</a><br>
<a href="#COMPATIBILITY ISSUES">COMPATIBILITY ISSUES</a><br>
<a href="#SEE ALSO">SEE ALSO</a><br>
<a href="#BUGS">BUGS</a><br>
<a href="#AUTHOR">AUTHOR</a><br>

<hr>


<h2>NAME
<a name="NAME"></a>
</h2>


<p style="margin-left:11%; margin-top: 1em">lmawk &minus;
pattern scanning and text processing language</p>

<h2>SYNOPSIS
<a name="SYNOPSIS"></a>
</h2>


<p style="margin-left:11%; margin-top: 1em"><b>lmawk</b>
[&minus;<b>W</b> <i>option</i>] [&minus;<b>F</b>
<i>value</i>] [&minus;<b>v</b> <i>var=value</i>]
[&minus;&minus;] &rsquo;program text&rsquo; [file ...]
<b><br>
lmawk</b> [&minus;<b>W</b> <i>option</i>] [&minus;<b>F</b>
<i>value</i>] [&minus;<b>v</b> <i>var=value</i>]
[&minus;<b>f</b> <i>program-file</i>] [&minus;&minus;] [file
...]</p>

<h2>DESCRIPTION
<a name="DESCRIPTION"></a>
</h2>


<p style="margin-left:11%; margin-top: 1em"><b>lmawk</b> is
an interpreter for the AWK Programming Language derived from
mawk. The AWK language is useful for manipulation of data
files, text retrieval and processing, and for prototyping
and experimenting with algorithms. <b>lmawk</b> is a <i>new
awk</i> meaning it implements the AWK language as defined in
Aho, Kernighan and Weinberger, <i>The AWK Programming
Language,</i> Addison-Wesley Publishing, 1988. (Hereafter
referred to as the AWK book.) <b>mawk</b> conforms to the
Posix 1003.2 (draft 11.3) definition of the AWK language
which contains a few features not described in the AWK book,
and <b>mawk</b> provides a small number of extensions.</p>

<p style="margin-left:11%; margin-top: 1em">An AWK program
is a sequence of <i>pattern {action}</i> pairs and function
definitions. Short programs are entered on the command line
usually enclosed in &rsquo; &rsquo; to avoid shell
interpretation. Longer programs can be read in from a file
with the &minus;f option. Data input is read from the list
of files on the command line or from standard input when the
list is empty. The input is broken into records as
determined by the record separator variable, <b>RS</b>.
Initially, <b>RS</b> = &quot;\n&quot; and records are
synonymous with lines. Each record is compared against each
<i>pattern</i> and if it matches, the program text for
<i>{action}</i> is executed.</p>

<h2>OPTIONS
<a name="OPTIONS"></a>
</h2>


<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="18%">


<p style="margin-top: 1em">&minus;<b>F</b> <i>value</i></p></td>
<td width="5%"></td>
<td width="66%">


<p style="margin-top: 1em">sets the field separator,
<b>FS</b>, to <i>value</i>.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="18%">


<p>&minus;<b>f</b> <i>file</i></p></td>
<td width="5%"></td>
<td width="66%">


<p>Program text is read from <i>file</i> instead of from
the command line. Multiple <b>&minus;f</b> options are
allowed. As a libmawk extension, if file name starts with
plus (&rsquo;+&rsquo;), it is not loaded if the same file
has been loaded already by a previous -f or include from any
of the scripts already loaded.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="18%">


<p>&minus;<b>b</b> <i>file</i></p></td>
<td width="5%"></td>
<td width="66%">


<p>Program bytecode is read from <i>file</i> . Multiple
<b>&minus;b</b> options are allowed. Bytecode can be
generated using -Wcompile. Libmawk may refuse to load
bytecode generated on a different system if byte order, type
sizes or dump version differs.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="18%">


<p>&minus;<b>v</b> <i>var=value</i></p></td>
<td width="5%"></td>
<td width="66%">


<p>assigns <i>value</i> to program variable <i>var</i>.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="18%">


<p>&minus;&minus;</p></td>
<td width="5%"></td>
<td width="66%">


<p>indicates the unambiguous end of options.</p></td></tr>
</table>

<p style="margin-left:11%; margin-top: 1em">The above
options will be available with any Posix compatible
implementation of AWK, and implementation specific options
are prefaced with <b>&minus;W</b>. <b>lmawk</b> provides
six:</p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="21%">


<p style="margin-top: 1em">&minus;<b>W</b> version</p></td>
<td width="2%"></td>
<td width="66%">


<p style="margin-top: 1em"><b>lmawk</b> writes its version
and copyright to stdout and compiled limits to stderr and
exits 0.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="21%">


<p>&minus;<b>W</b> debug</p></td>
<td width="2%"></td>
<td width="66%">


<p>include location info in the compiled code; location
information is visible in the dump and when debugging
libmawk.</p> </td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="21%">


<p>&minus;<b>W</b> dump</p></td>
<td width="2%"></td>
<td width="66%">


<p>writes an assembler like listing of the internal
representation of the program to stdout and exits 0 (on
successful compilation).</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="21%">


<p>&minus;<b>W</b> dumpsym</p></td>
<td width="2%"></td>
<td width="66%">


<p>writes a list of global symbols to stdout and exits 0
(on successful compilation).</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="21%">


<p>&minus;<b>W</b> compile</p></td>
<td width="2%"></td>
<td width="66%">


<p>writes a binary dump of the bytecode to stdout. This
bytecode can be loaded using the &minus;<b>b</b> switch.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="21%">


<p>&minus;<b>W</b> interactive</p></td>
<td width="2%"></td>
<td width="66%">


<p>sets unbuffered writes to stdout and line buffered reads
from stdin. Records from stdin are lines regardless of the
value of <b>RS</b>.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="21%">


<p>&minus;<b>W</b> maxmem=<i>num</i></p></td>
<td width="2%"></td>
<td width="66%">


<p>limit dynamic memory allocation during compilation and
execution to <i>num</i> bytes and exit with
out-of-the-memory error if more memory is to be allocated.
Optional suffixes are k for kilobyte and m for megabyte. 0
means unlimited, which is also the default.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="21%">


<p>&minus;<b>W</b> exec <i>file</i></p></td>
<td width="2%"></td>
<td width="66%">


<p>Program text is read from <i>file</i> and this is the
last option. Useful on systems that support the <b>#!</b>
&quot;magic number&quot; convention for executable
scripts.</p> </td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="21%">


<p>&minus;<b>W</b> sprintf=<i>num</i></p></td>
<td width="2%"></td>
<td width="66%">


<p>adjusts the size of <b>lmawk&rsquo;s</b> internal
sprintf buffer to <i>num</i> bytes. More than rare use of
this option indicates <b>lmawk</b> should be recompiled.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="21%">


<p>&minus;<b>W</b> posix_space</p></td>
<td width="2%"></td>
<td width="66%">


<p>forces <b>lmawk</b> not to consider &rsquo;\n&rsquo; to
be space.</p></td></tr>
</table>

<p style="margin-left:11%; margin-top: 1em">The short forms
<b>&minus;W</b>[vdiesp] are recognized and on some systems
<b>&minus;W</b>e is mandatory to avoid command line length
limitations.</p>

<h2>THE AWK LANGUAGE
<a name="THE AWK LANGUAGE"></a>
</h2>


<p style="margin-left:11%; margin-top: 1em"><b>1. Program
structure</b> <br>
An AWK program is a sequence of <i>pattern {action}</i>
pairs and user function definitions.</p>

<p style="margin-left:11%; margin-top: 1em">A pattern can
be:</p>

<p style="margin-left:22%;"><b>BEGIN <br>
END</b> <br>
expression <br>
expression , expression</p>

<p style="margin-left:11%; margin-top: 1em">One, but not
both, of <i>pattern {action}</i> can be omitted. If
<i>{action}</i> is omitted it is implicitly { print }. If
<i>pattern</i> is omitted, then it is implicitly matched.
<b>BEGIN</b> and <b>END</b> patterns require an action.</p>

<p style="margin-left:11%; margin-top: 1em">Statements are
terminated by newlines, semi-colons or both. Groups of
statements such as actions or loop bodies are blocked via {
... } as in C. The last statement in a block doesn&rsquo;t
need a terminator. Blank lines have no meaning; an empty
statement is terminated with a semi-colon. Long statements
can be continued with a backslash, \. A statement can be
broken without a backslash after a comma, left brace,
&amp;&amp;, ||, <b>do</b>, <b>else</b>, the right
parenthesis of an <b>if</b>, <b>while</b> or <b>for</b>
statement, and the right parenthesis of a function
definition. A comment starts with # and extends to, but does
not include the end of line.</p>

<p style="margin-left:11%; margin-top: 1em">The following
statements control program flow inside blocks.</p>

<p style="margin-left:22%; margin-top: 1em"><b>if</b> (
<i>expr</i> ) <i>statement</i></p>

<p style="margin-left:22%; margin-top: 1em"><b>if</b> (
<i>expr</i> ) <i>statement</i> <b>else</b>
<i>statement</i></p>

<p style="margin-left:22%; margin-top: 1em"><b>while</b> (
<i>expr</i> ) <i>statement</i></p>

<p style="margin-left:22%; margin-top: 1em"><b>do</b>
<i>statement</i> <b>while</b> ( <i>expr</i> )</p>

<p style="margin-left:22%; margin-top: 1em"><b>for</b> (
<i>opt_expr</i> ; <i>opt_expr</i> ; <i>opt_expr</i> )
<i>statement</i></p>

<p style="margin-left:22%; margin-top: 1em"><b>for</b> (
<i>var</i> <b>in</b> <i>array</i> ) <i>statement</i></p>


<p style="margin-left:22%; margin-top: 1em"><b>continue</b></p>


<p style="margin-left:22%; margin-top: 1em"><b>break</b></p>

<p style="margin-left:11%; margin-top: 1em"><b>2. Data
types, conversion and comparison</b> <br>
There are two basic data types, numeric and string. Numeric
constants can be integer like &minus;2, decimal like 1.08,
or in scientific notation like &minus;1.1e4 or .28E&minus;3.
All numbers are represented internally and all computations
are done in floating point arithmetic. So for example, the
expression 0.2e2 == 20 is true and true is represented as
1.0.</p>

<p style="margin-left:11%; margin-top: 1em">String
constants are enclosed in double quotes.</p>

<p align="center" style="margin-top: 1em">&quot;This is a
string with a newline at the end.\n&quot;</p>

<p style="margin-top: 1em">Strings can be continued across
a line by escaping (\) the newline. The following escape
sequences are recognized.</p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%">
</td>
<td width="8%">


<p>\\</p></td>
<td width="8%">
</td>
<td width="69%">


<p>\</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%">
</td>
<td width="8%">


<p>\&quot;</p></td>
<td width="8%">
</td>
<td width="69%">


<p>&quot;</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%">
</td>
<td width="8%">


<p>\a</p></td>
<td width="8%">
</td>
<td width="69%">


<p>alert, ascii 7</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%">
</td>
<td width="8%">


<p>\b</p></td>
<td width="8%">
</td>
<td width="69%">


<p>backspace, ascii 8</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%">
</td>
<td width="8%">


<p>\t</p></td>
<td width="8%">
</td>
<td width="69%">


<p>tab, ascii 9</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%">
</td>
<td width="8%">


<p>\n</p></td>
<td width="8%">
</td>
<td width="69%">


<p>newline, ascii 10</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%">
</td>
<td width="8%">


<p>\v</p></td>
<td width="8%">
</td>
<td width="69%">


<p>vertical tab, ascii 11</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%">
</td>
<td width="8%">


<p>\f</p></td>
<td width="8%">
</td>
<td width="69%">


<p>formfeed, ascii 12</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%">
</td>
<td width="8%">


<p>\r</p></td>
<td width="8%">
</td>
<td width="69%">


<p>carriage return, ascii 13</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%">
</td>
<td width="8%">


<p>\ddd</p></td>
<td width="8%">
</td>
<td width="69%">


<p>1, 2 or 3 octal digits for ascii ddd</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%">
</td>
<td width="8%">


<p>\xhh</p></td>
<td width="8%">
</td>
<td width="69%">


<p>1 or 2 hex digits for ascii hh</p></td></tr>
</table>

<p style="margin-left:11%; margin-top: 1em">If you escape
any other character \c, you get \c, i.e., <b>lmawk</b>
ignores the escape.</p>

<p style="margin-left:11%; margin-top: 1em">There are
really three basic data types; the third is <i>number and
string</i> which has both a numeric value and a string value
at the same time. User defined variables come into existence
when first referenced and are initialized to <i>null</i>, a
number and string value which has numeric value 0 and string
value &quot;&quot;. Non-trivial number and string typed data
come from input and are typically stored in fields. (See
section 4).</p>

<p style="margin-left:11%; margin-top: 1em">The type of an
expression is determined by its context and automatic type
conversion occurs if needed. For example, to evaluate the
statements</p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>y = x + 2 ; z = x &quot;hello&quot;</p></td></tr>
</table>

<p style="margin-left:11%; margin-top: 1em">The value
stored in variable y will be typed numeric. If x is not
numeric, the value read from x is converted to numeric
before it is added to 2 and stored in y. The value stored in
variable z will be typed string, and the value of x will be
converted to string if necessary and concatenated with
&quot;hello&quot;. (Of course, the value and type stored in
x is not changed by any conversions.) A string expression is
converted to numeric using its longest numeric prefix as
with <i>atof</i>(3). A numeric expression is converted to
string by replacing <i>expr</i> with <b>sprintf(CONVFMT</b>,
<i>expr</i>), unless <i>expr</i> can be represented on the
host machine as an exact integer then it is converted to
<b>sprintf</b>(&quot;%d&quot;, <i>expr</i>).
<b>Sprintf()</b> is an AWK built-in that duplicates the
functionality of <i>sprintf</i>(3), and <b>CONVFMT</b> is a
built-in variable used for internal conversion from number
to string and initialized to &quot;%.6g&quot;. Explicit type
conversions can be forced, <i>expr</i> &quot;&quot; is
string and <i>expr</i>+0 is numeric.</p>

<p style="margin-left:11%; margin-top: 1em">To evaluate,
<i>expr</i>1 <b>rel-op</b> <i>expr</i>2, if both operands
are numeric or number and string then the comparison is
numeric; if both operands are string the comparison is
string; if one operand is string, the non-string operand is
converted and the comparison is string. The result is
numeric, 1 or 0.</p>

<p style="margin-left:11%; margin-top: 1em">In boolean
contexts such as, <b>if</b> ( <i>expr</i> )
<i>statement</i>, a string expression evaluates true if and
only if it is not the empty string &quot;&quot;; numeric
values if and only if not numerically zero.</p>

<p style="margin-left:11%; margin-top: 1em"><b>3. Regular
expressions</b> <br>
In the AWK language, records, fields and strings are often
tested for matching a <i>regular expression</i>. Regular
expressions are enclosed in slashes, and</p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p><i>expr</i> ~ /<i>r</i>/</p></td></tr>
</table>

<p style="margin-left:11%; margin-top: 1em">is an AWK
expression that evaluates to 1 if <i>expr</i>
&quot;matches&quot; <i>r</i>, which means a substring of
<i>expr</i> is in the set of strings defined by <i>r</i>.
With no match the expression evaluates to 0; replacing ~
with the &quot;not match&quot; operator, !~ , reverses the
meaning. As pattern-action pairs,</p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>/<i>r</i>/ { <i>action</i> } and <b>$0</b> ~ /<i>r</i>/
{ <i>action</i> }</p></td></tr>
</table>

<p style="margin-left:11%; margin-top: 1em">are the same,
and for each input record that matches <i>r</i>,
<i>action</i> is executed. In fact, /<i>r</i>/ is an AWK
expression that is equivalent to (<b>$0</b> ~ /<i>r</i>/)
anywhere except when on the right side of a match operator
or passed as an argument to a built-in function that expects
a regular expression argument.</p>

<p style="margin-left:11%; margin-top: 1em">AWK uses
extended regular expressions as with <i>egrep</i>(1). The
regular expression metacharacters, i.e., those with special
meaning in regular expressions are</p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>&nbsp;^ $ . [ ] | ( ) * + ?</p></td></tr>
</table>

<p style="margin-left:11%; margin-top: 1em">Regular
expressions are built up from characters as follows:</p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="22%"></td>
<td width="18%">


<p style="margin-top: 1em"><i>c</i></p></td>
<td width="2%"></td>
<td width="58%">


<p style="margin-top: 1em">matches any non-metacharacter
<i>c</i>.</p> </td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="18%">


<p>\<i>c</i></p></td>
<td width="2%"></td>
<td width="58%">


<p>matches a character defined by the same escape sequences
used in string constants or the literal character <i>c</i>
if \<i>c</i> is not an escape sequence.</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="18%">


<p>.</p></td>
<td width="2%"></td>
<td width="58%">


<p>matches any character (including newline).</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="18%">


<p>^</p></td>
<td width="2%"></td>
<td width="58%">


<p>matches the front of a string.</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="18%">


<p>$</p></td>
<td width="2%"></td>
<td width="58%">


<p>matches the back of a string.</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="18%">


<p>[c1c2c3...]</p></td>
<td width="2%"></td>
<td width="58%">


<p>matches any character in the class c1c2c3... . An
interval of characters is denoted c1&minus;c2 inside a class
[...].</p> </td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="18%">


<p>[^c1c2c3...]</p></td>
<td width="2%"></td>
<td width="58%">


<p>matches any character not in the class c1c2c3...</p></td></tr>
</table>

<p style="margin-left:11%; margin-top: 1em">Regular
expressions are built up from other regular expressions as
follows:</p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="22%"></td>
<td width="10%">


<p style="margin-top: 1em"><i>r</i>1<i>r</i>2</p></td>
<td width="10%"></td>
<td width="58%">


<p style="margin-top: 1em">matches <i>r</i>1 followed
immediately by <i>r</i>2 (concatenation).</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="10%">


<p><i>r</i>1 | <i>r</i>2</p></td>
<td width="10%"></td>
<td width="58%">


<p>matches <i>r</i>1 or <i>r</i>2 (alternation).</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="10%">


<p><i>r</i>*</p></td>
<td width="10%"></td>
<td width="58%">


<p>matches <i>r</i> repeated zero or more times.</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="10%">


<p><i>r</i>+</p></td>
<td width="10%"></td>
<td width="58%">


<p>matches <i>r</i> repeated one or more times.</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="10%">


<p><i>r</i>?</p></td>
<td width="10%"></td>
<td width="58%">


<p>matches <i>r</i> zero or once.</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="10%">


<p>(<i>r</i>)</p></td>
<td width="10%"></td>
<td width="58%">


<p>matches <i>r</i>, providing grouping.</p></td></tr>
</table>

<p style="margin-left:11%; margin-top: 1em">The increasing
precedence of operators is alternation, concatenation and
unary (*, + or ?).</p>

<p style="margin-left:11%; margin-top: 1em">For
example,</p>


<p style="margin-left:11%; margin-top: 1em">/^[_a&minus;zA-Z][_a&minus;zA&minus;Z0&minus;9]*$/
and</p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">



<p>/^[&minus;+]?([0&minus;9]+\.?|\.[0&minus;9])[0&minus;9]*([eE][&minus;+]?[0&minus;9]+)?$/</p> </td></tr>
</table>

<p style="margin-left:11%; margin-top: 1em">are matched by
AWK identifiers and AWK numeric constants respectively. Note
that . has to be escaped to be recognized as a decimal
point, and that metacharacters are not special inside
character classes.</p>

<p style="margin-left:11%; margin-top: 1em">Any expression
can be used on the right hand side of the ~ or !~ operators
or passed to a built-in that expects a regular expression.
If needed, it is converted to string, and then interpreted
as a regular expression. For example,</p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>BEGIN { identifier =
&quot;[_a&minus;zA&minus;Z][_a&minus;zA&minus;Z0&minus;9]*&quot;
}</p> </td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>$0 ~ &quot;^&quot; identifier</p></td></tr>
</table>

<p style="margin-left:11%; margin-top: 1em">prints all
lines that start with an AWK identifier.</p>

<p style="margin-left:11%; margin-top: 1em"><b>lmawk</b>
recognizes the empty regular expression, //, which matches
the empty string and hence is matched by any string at the
front, back and between every character. For example,</p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>echo abc | lmawk { gsub(//, &quot;X&quot;) ; print }</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>XaXbXcX</p></td></tr>
</table>

<p style="margin-left:11%; margin-top: 1em"><b>4. Records
and fields</b> <br>
Records are read in one at a time, and stored in the
<i>field</i> variable <b>$0</b>. The record is split into
<i>fields</i> which are stored in <b>$1</b>, <b>$2</b>, ...,
<b>$NF</b>. The built-in variable <b>NF</b> is set to the
number of fields, and <b>NR</b> and <b>FNR</b> are
incremented by 1. Fields above <b>$NF</b> are set to
&quot;&quot;.</p>

<p style="margin-left:11%; margin-top: 1em">Assignment to
<b>$0</b> causes the fields and <b>NF</b> to be recomputed.
Assignment to <b>NF</b> or to a field causes <b>$0</b> to be
reconstructed by concatenating the <b>$i&rsquo;s</b>
separated by <b>OFS</b>. Assignment to a field with index
greater than <b>NF</b>, increases <b>NF</b> and causes
<b>$0</b> to be reconstructed.</p>

<p style="margin-left:11%; margin-top: 1em">Data input
stored in fields is string, unless the entire field has
numeric form and then the type is number and string. For
example,</p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>echo 24 24E |</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>lmawk &rsquo;{ print($1&gt;100, $1&gt;&quot;100&quot;,
$2&gt;100, $2&gt;&quot;100&quot;) }&rsquo;</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>0 1 1 1</p></td></tr>
</table>

<p style="margin-left:11%; margin-top: 1em"><b>$0</b> and
<b>$2</b> are string and <b>$1</b> is number and string. The
first comparison is numeric, the second is string, the third
is string (100 is converted to &quot;100&quot;), and the
last is string.</p>

<p style="margin-left:11%; margin-top: 1em"><b>5.
Expressions and operators</b> <br>
The expression syntax is similar to C. Primary expressions
are numeric constants, string constants, variables, fields,
arrays and function calls. The identifier for a variable,
array or function can be a sequence of letters, digits and
underscores, that does not start with a digit. Variables are
not declared; they exist when first referenced and are
initialized to <i>null</i>.</p>

<p style="margin-left:11%; margin-top: 1em">New expressions
are composed with the following operators in order of
increasing precedence.</p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%">


<p><i>assignment</i></p></td>
<td width="8%"></td>
<td width="7%"></td>
<td width="62%">
</td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%"></td>
<td width="8%"></td>
<td width="7%"></td>
<td width="62%">


<p>= += &minus;= *= /= %= ^=</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%">


<p><i>conditional</i></p></td>
<td width="8%"></td>
<td width="7%"></td>
<td width="62%">
</td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%"></td>
<td width="8%"></td>
<td width="7%"></td>
<td width="62%">


<p>? :</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%">


<p><i>logical or</i></p></td>
<td width="8%"></td>
<td width="7%"></td>
<td width="62%">
</td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%"></td>
<td width="8%"></td>
<td width="7%"></td>
<td width="62%">


<p>||</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%">


<p><i>logical and</i></p></td>
<td width="8%"></td>
<td width="7%"></td>
<td width="62%">
</td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%"></td>
<td width="8%"></td>
<td width="7%"></td>
<td width="62%">


<p>&amp;&amp;</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%">


<p><i>array membership</i></p></td>
<td width="8%"></td>
<td width="7%"></td>
<td width="62%">


<p><b>in</b></p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%">


<p><i>matching</i></p></td>
<td width="8%"></td>
<td width="7%">
</td>
<td width="62%">


<p>~ !~</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%">


<p><i>relational</i></p></td>
<td width="8%"></td>
<td width="7%"></td>
<td width="62%">
</td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%"></td>
<td width="8%"></td>
<td width="7%"></td>
<td width="62%">


<p>&lt; &gt; &lt;= &gt;= == !=</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%">


<p><i>concatenation</i></p></td>
<td width="8%"></td>
<td width="7%"></td>
<td width="62%">
</td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%"></td>
<td width="8%"></td>
<td width="7%"></td>
<td width="62%">


<p>(no explicit operator)</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%">


<p><i>add ops</i></p></td>
<td width="8%"></td>
<td width="7%">
</td>
<td width="62%">
</td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%"></td>
<td width="8%"></td>
<td width="7%"></td>
<td width="62%">


<p>+ &minus;</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%">


<p><i>mul ops</i></p></td>
<td width="8%"></td>
<td width="7%">
</td>
<td width="62%">
</td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%"></td>
<td width="8%"></td>
<td width="7%"></td>
<td width="62%">


<p>* / %</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%">


<p><i>unary</i></p></td>
<td width="8%"></td>
<td width="7%">
</td>
<td width="62%">
</td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%"></td>
<td width="8%"></td>
<td width="7%"></td>
<td width="62%">


<p>+ &minus;</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%">


<p><i>logical not</i></p></td>
<td width="8%"></td>
<td width="7%"></td>
<td width="62%">
</td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%"></td>
<td width="8%"></td>
<td width="7%"></td>
<td width="62%">


<p>!</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%">


<p><i>exponentiation</i></p></td>
<td width="8%"></td>
<td width="7%"></td>
<td width="62%">
</td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%"></td>
<td width="8%"></td>
<td width="7%"></td>
<td width="62%">


<p>^</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%">


<p><i>inc and dec</i></p></td>
<td width="8%"></td>
<td width="7%"></td>
<td width="62%">
</td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%"></td>
<td width="8%"></td>
<td width="7%"></td>
<td width="62%">


<p>++ &minus;&minus; (both post and pre)</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%">


<p><i>field</i></p></td>
<td width="8%"></td>
<td width="7%">
</td>
<td width="62%">
</td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%"></td>
<td width="8%"></td>
<td width="7%"></td>
<td width="62%">


<p>$</p></td></tr>
</table>

<p style="margin-left:11%; margin-top: 1em">Assignment,
conditional and exponentiation associate right to left; the
other operators associate left to right. Any expression can
be parenthesized.</p>

<p style="margin-left:11%; margin-top: 1em"><b>6.
Arrays</b> <br>
Awk provides one-dimensional arrays. Array elements are
expressed as <i>array</i>[<i>expr</i>]. <i>Expr</i> is
internally converted to string type, so, for example, A[1]
and A[&quot;1&quot;] are the same element and the actual
index is &quot;1&quot;. Arrays indexed by strings are called
associative arrays. Initially an array is empty; elements
exist when first accessed. An expression, <i>expr</i>
<b>in</b> <i>array</i> evaluates to 1 if
<i>array</i>[<i>expr</i>] exists, else to 0.</p>

<p style="margin-left:11%; margin-top: 1em">There is a form
of the <b>for</b> statement that loops over each index of an
array.</p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p><b>for</b> ( <i>var</i> <b>in</b> <i>array</i> )
<i>statement</i></p> </td></tr>
</table>

<p style="margin-left:11%; margin-top: 1em">sets <i>var</i>
to each index of <i>array</i> and executes <i>statement</i>.
The order that <i>var</i> transverses the indices of
<i>array</i> is not defined.</p>

<p style="margin-left:11%; margin-top: 1em">The statement,
<b>delete</b> <i>array</i>[<i>expr</i>], causes
<i>array</i>[<i>expr</i>] not to exist. <b>lmawk</b>
supports an extension, <b>delete</b> <i>array</i>, which
deletes all elements of <i>array</i>.</p>


<p style="margin-left:11%; margin-top: 1em">Multidimensional
arrays are synthesized with concatenation using the built-in
variable <b>SUBSEP</b>.
<i>array</i>[<i>expr</i>1,<i>expr</i>2] is equivalent to
<i>array</i>[<i>expr</i>1 <b>SUBSEP</b> <i>expr</i>2].
Testing for a multidimensional element uses a parenthesized
index, such as</p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>if ( (i, j) in A ) print A[i, j]</p></td></tr>
</table>

<p style="margin-left:11%; margin-top: 1em"><b>7.
Builtin-variables</b> <br>
The following variables are built-in and initialized before
program execution.</p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="22%"></td>
<td width="12%">


<p style="margin-top: 1em"><b>ARGC</b></p></td>
<td width="3%"></td>
<td width="63%">


<p style="margin-top: 1em">number of command line
arguments.</p> </td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="12%">


<p><b>ARGV</b></p></td>
<td width="3%"></td>
<td width="63%">


<p>array of command line arguments, 0..ARGC-1.</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="12%">


<p><b>CONVFMT</b></p></td>
<td width="3%"></td>
<td width="63%">


<p>format for internal conversion of numbers to string,
initially = &quot;%.6g&quot;.</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="12%">


<p><b>ENVIRON</b></p></td>
<td width="3%"></td>
<td width="63%">


<p>array indexed by environment variables. An environment
string, <i>var=value</i> is stored as
<b>ENVIRON</b>[<i>var</i>] = <i>value</i>.</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="12%">


<p><b>FILENAME</b></p></td>
<td width="3%"></td>
<td width="63%">


<p>name of the current input file.</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="12%">


<p><b>FNR</b></p></td>
<td width="3%"></td>
<td width="63%">


<p>current record number in <b>FILENAME</b>.</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="12%">


<p><b>FS</b></p></td>
<td width="3%"></td>
<td width="63%">


<p>splits records into fields as a regular expression.</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="12%">


<p><b>NF</b></p></td>
<td width="3%"></td>
<td width="63%">


<p>number of fields in the current record.</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="12%">


<p><b>NR</b></p></td>
<td width="3%"></td>
<td width="63%">


<p>current record number in the total input stream.</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="12%">


<p><b>OFMT</b></p></td>
<td width="3%"></td>
<td width="63%">


<p>format for printing numbers; initially =
&quot;%.6g&quot;.</p> </td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="12%">


<p><b>OFS</b></p></td>
<td width="3%"></td>
<td width="63%">


<p>inserted between fields on output, initially = &quot;
&quot;.</p> </td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="12%">


<p><b>ORS</b></p></td>
<td width="3%"></td>
<td width="63%">


<p>terminates each record on output, initially =
&quot;\n&quot;.</p> </td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="12%">


<p><b>RLENGTH</b></p></td>
<td width="3%"></td>
<td width="63%">


<p>length set by the last call to the built-in function,
<b>match()</b>.</p> </td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="12%">


<p><b>RS</b></p></td>
<td width="3%"></td>
<td width="63%">


<p>input record separator, initially = &quot;\n&quot;.</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="12%">


<p><b>RSTART</b></p></td>
<td width="3%"></td>
<td width="63%">


<p>index set by the last call to <b>match()</b>.</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="12%">


<p><b>SUBSEP</b></p></td>
<td width="3%"></td>
<td width="63%">


<p>used to build multiple array subscripts, initially =
&quot;\034&quot;.</p> </td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="12%">


<p><b>ERRNO</b></p></td>
<td width="3%"></td>
<td width="63%">


<p>misc built-in functions (libmawk extensions) use this
variable to rerport error. All extension calls will set this
variable before returning, therefor ERRNO holds the result
of the last call. An empty string value means no error.
Error messages are formatted in a way that the first word is
an unique integer, followed by a human readable error
message from the second word. int(ERRNO) can be used to
acquire the error code, which then can be used as a
secondary output from the extension function. For example,
an awk program can use valueof() to determine if a global
symbol exists and is a function or a variable or anything
else.</p> </td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="12%">


<p><b>LIBPATH</b></p></td>
<td width="3%"></td>
<td width="63%">


<p>is a semicolon separated list of search paths. When
loading an awk script by file name (-f command line argument
or include from another awk script) these paths are inserted
before the file name, in order, one by one, until the first
path that allows opening the file. An empty path is
equivalent to the current working directory. LIBPATH can be
modified from the command line using -v, as arguments are
scanned before loading the scripts. Setting LIBPATH to empty
string results in the original behaviour of mawk. LIBPATH is
ignored for script file names starting with slash
(&rsquo;/&rsquo;) as those are assumed to be absolute
paths.</p> </td></tr>
</table>

<p style="margin-left:11%; margin-top: 1em"><b>8. Built-in
functions</b> <br>
String functions</p>

<p style="margin-left:22%;">gsub(<i>r,s,t</i>)
gsub(<i>r,s</i>)</p>

<p style="margin-left:32%;">Global substitution, every
match of regular expression <i>r</i> in variable <i>t</i> is
replaced by string <i>s</i>. The number of replacements is
returned. If <i>t</i> is omitted, <b>$0</b> is used. An
&amp; in the replacement string <i>s</i> is replaced by the
matched substring of <i>t</i>. \&amp; and \\ put literal
&amp; and \, respectively, in the replacement string.</p>

<p style="margin-left:22%;">index(<i>s,t</i>)</p>

<p style="margin-left:32%;">If <i>t</i> is a substring of
<i>s</i>, then the position where <i>t</i> starts is
returned, else 0 is returned. The first character of
<i>s</i> is in position 1.</p>

<p style="margin-left:22%;">length(<i>s</i>)</p>

<p style="margin-left:32%;">Returns the length of string
<i>s</i>.</p>

<p style="margin-left:22%;">match(<i>s,r</i>)</p>

<p style="margin-left:32%;">Returns the index of the first
longest match of regular expression <i>r</i> in string
<i>s</i>. Returns 0 if no match. As a side effect,
<b>RSTART</b> is set to the return value. <b>RLENGTH</b> is
set to the length of the match or &minus;1 if no match. If
the empty string is matched, <b>RLENGTH</b> is set to 0, and
1 is returned if the match is at the front, and
length(<i>s</i>)+1 is returned if the match is at the
back.</p>

<p style="margin-left:22%;">split(<i>s,A,r</i>)
split(<i>s,A</i>)</p>

<p style="margin-left:32%;">String <i>s</i> is split into
fields by regular expression <i>r</i> and the fields are
loaded into array <i>A</i>. The number of fields is
returned. See section 11 below for more detail. If <i>r</i>
is omitted, <b>FS</b> is used.</p>


<p style="margin-left:22%;">sprintf(<i>format,expr-list</i>)</p>

<p style="margin-left:32%;">Returns a string constructed
from <i>expr-list</i> according to <i>format</i>. See the
description of printf() below.</p>

<p style="margin-left:22%;">sub(<i>r,s,t</i>)
sub(<i>r,s</i>)</p>

<p style="margin-left:32%;">Single substitution, same as
gsub() except at most one substitution.</p>

<p style="margin-left:22%;">substr(<i>s,i,n</i>)
substr(<i>s,i</i>)</p>

<p style="margin-left:32%;">Returns the substring of string
<i>s</i>, starting at index <i>i</i>, of length <i>n</i>. If
<i>n</i> is omitted, the suffix of <i>s</i>, starting at
<i>i</i> is returned.</p>

<p style="margin-left:22%;">tolower(<i>s</i>)</p>

<p style="margin-left:32%;">Returns a copy of <i>s</i> with
all upper case characters converted to lower case.</p>

<p style="margin-left:22%;">toupper(<i>s</i>)</p>

<p style="margin-left:32%;">Returns a copy of <i>s</i> with
all lower case characters converted to upper case.</p>

<p style="margin-left:11%; margin-top: 1em">Arithmetic
functions</p>


<p style="margin-left:22%; margin-top: 1em">atan2(<i>y,x</i>)
Arctan of <i>y</i>/<i>x</i> between -PI and PI.</p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%">


<p>cos(<i>x</i>)</p></td>
<td width="8%"></td>
<td width="69%">
</td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%"></td>
<td width="8%"></td>
<td width="69%">


<p>Cosine function, <i>x</i> in radians.</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%">


<p>exp(<i>x</i>)</p></td>
<td width="8%"></td>
<td width="69%">
</td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%"></td>
<td width="8%"></td>
<td width="69%">


<p>Exponential function.</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%">


<p>int(<i>x</i>)</p></td>
<td width="8%"></td>
<td width="69%">
</td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%"></td>
<td width="8%"></td>
<td width="69%">


<p>Returns <i>x</i> truncated towards zero.</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%">


<p>log(<i>x</i>)</p></td>
<td width="8%"></td>
<td width="69%">
</td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%"></td>
<td width="8%"></td>
<td width="69%">


<p>Natural logarithm.</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%">


<p>rand()</p></td>
<td width="8%"></td>
<td width="69%">
</td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%"></td>
<td width="8%"></td>
<td width="69%">


<p>Returns a random number between zero and one.</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%">


<p>sin(<i>x</i>)</p></td>
<td width="8%"></td>
<td width="69%">
</td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%"></td>
<td width="8%"></td>
<td width="69%">


<p>Sine function, <i>x</i> in radians.</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%">


<p>sqrt(<i>x</i>)</p></td>
<td width="8%"></td>
<td width="69%">
</td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="-14%"></td>
<td width="7%"></td>
<td width="8%"></td>
<td width="8%"></td>
<td width="69%">


<p>Returns square root of <i>x</i>.</p></td></tr>
</table>

<p style="margin-left:22%;">srand(<i>expr</i>) srand()</p>

<p style="margin-left:32%;">Seeds the random number
generator, using the clock if <i>expr</i> is omitted, and
returns the value of the previous seed. <b>lmawk</b> seeds
the random number generator from the clock at startup so
there is no real need to call srand(). Srand(<i>expr</i>) is
useful for repeating pseudo random sequences.</p>

<p style="margin-left:11%; margin-top: 1em">Misc functions
(libmawk extensions)</p>


<p style="margin-left:22%;">call(<i>fname,arg1,arg2,...</i>)</p>

<p style="margin-left:32%;">Call awk function <i>fname</i>
with the supplied arguments. If the call fails, empty value,
else the return value of the callee is returned. Built-in
variable ERRNO is always set.</p>


<p style="margin-left:22%;">acall(<i>fname,arrname</i>)</p>

<p style="margin-left:32%;">Call awk function <i>fname</i>
with arguments supplied in array named <i>arrname</i> (both
arguments are strings naming an existing object). The array
should be indexed from 1. Number of arguments is determined
by looking for the first empty (non-existing) index in the
array. If the call fails, empty value, else the return value
of the callee is returned. Built-in variable ERRNO is always
set.</p>

<p style="margin-left:22%;">valueof(<i>vname
[,idx]</i>)</p>

<p style="margin-left:32%;">Return the value of variable
<i>fname</i>; if the variable is an array, return the
element indexed by <i>idx</i> (which must be present in this
case). If index is not present or is empty (&quot;&quot;),
the variable is expected to be scalar. Built-in variable
ERRNO is always set. NOTE: valueof() has access to the
global symbol table only. It will fail to resolve anything
else than global objects; most notably it will fail on local
variables, $ arguments and on most of the built-in
variables.</p>

<p style="margin-left:11%; margin-top: 1em"><b>9. Input and
output</b> <br>
There are two output statements, <b>print</b> and
<b>printf</b>.</p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="22%"></td>
<td width="7%">


<p>print</p></td>
<td width="3%"></td>
<td width="53%">


<p>writes <b>$0 ORS</b> to standard output.</p></td>
<td width="15%">
</td></tr>
</table>

<p style="margin-left:22%;">print <i>expr</i>1,
<i>expr</i>2, ..., <i>expr</i>n</p>

<p style="margin-left:32%;">writes <i>expr</i>1 <b>OFS</b>
<i>expr</i>2 <b>OFS</b> ... <i>expr</i>n <b>ORS</b> to
standard output. Numeric expressions are converted to string
with <b>OFMT</b>.</p>

<p style="margin-left:22%;">printf <i>format,
expr-list</i></p>

<p style="margin-left:32%;">duplicates the printf C library
function writing to standard output. The complete ANSI C
format specifications are recognized with conversions %c,
%d, %e, %E, %f, %g, %G, %i, %o, %s, %u, %x, %X and %%, and
conversion qualifiers h and l.</p>

<p style="margin-left:11%; margin-top: 1em">The argument
list to print or printf can optionally be enclosed in
parentheses. Print formats numbers using <b>OFMT</b> or
&quot;%d&quot; for exact integers. &quot;%c&quot; with a
numeric argument prints the corresponding 8 bit character,
with a string argument it prints the first character of the
string. The output of print and printf can be redirected to
a file or command by appending &gt; <i>file</i>, &gt;&gt;
<i>file</i> or | <i>command</i> to the end of the print
statement. Redirection opens <i>file</i> or <i>command</i>
only once, subsequent redirections append to the already
open stream. By convention, <b>lmawk</b> associates the
filename &quot;/dev/stderr&quot; with stderr which allows
print and printf to be redirected to stderr. <b>lmawk</b>
also associates &quot;&minus;&quot; and
&quot;/dev/stdout&quot; with stdin and stdout which allows
these streams to be passed to functions. Opening /dev/fd/N
will do an fdopen() on file descriptor N, where N is an
integer - this is a libmawk extension. If any of the /dev
heuristics needs to be bypassed (i.e. the script wants to
open the real /dev/stdout or the real /dev/fd/5), the
leading slash should be doubled (e.g. //dev/fd/5).</p>

<p style="margin-left:11%; margin-top: 1em">The input
function <b>getline</b> has the following variations.</p>

<p style="margin-left:22%;">getline</p>

<p style="margin-left:32%;">reads into <b>$0</b>, updates
the fields, <b>NF</b>, <b>NR</b> and <b>FNR</b>.</p>

<p style="margin-left:22%;">getline &lt; <i>file</i></p>

<p style="margin-left:32%;">reads into <b>$0</b> from
<i>file</i>, updates the fields and <b>NF</b>.</p>

<p style="margin-left:22%;">getline <i>var</i></p>

<p style="margin-left:32%;">reads the next record into
<i>var</i>, updates <b>NR</b> and <b>FNR</b>.</p>

<p style="margin-left:22%;">getline <i>var</i> &lt;
<i>file</i></p>

<p style="margin-left:32%;">reads the next record of
<i>file</i> into <i>var</i>.</p>

<p style="margin-left:22%;"><i>command</i> | getline</p>

<p style="margin-left:32%;">pipes a record from
<i>command</i> into <b>$0</b> and updates the fields and
<b>NF</b>.</p>

<p style="margin-left:22%;"><i>command</i> | getline
<i>var</i></p>

<p style="margin-left:32%;">pipes a record from
<i>command</i> into <i>var</i>.</p>

<p style="margin-left:11%; margin-top: 1em">Getline returns
0 on end-of-file, &minus;1 on error, otherwise 1.</p>

<p style="margin-left:11%; margin-top: 1em">Commands on the
end of pipes are executed by /bin/sh.</p>

<p style="margin-left:11%; margin-top: 1em">The function
<b>close</b>(<i>expr</i>) closes the file or pipe associated
with <i>expr</i>. Close returns 0 if <i>expr</i> is an open
file, the exit status if <i>expr</i> is a piped command, and
&minus;1 otherwise. Close is used to reread a file or
command, make sure the other end of an output pipe is
finished or conserve file resources.</p>

<p style="margin-left:11%; margin-top: 1em">The function
<b>fflush</b>(<i>expr</i>) flushes the output file or pipe
associated with <i>expr</i>. Fflush returns 0 if <i>expr</i>
is an open output stream else &minus;1. Fflush without an
argument flushes stdout. Fflush with an empty argument
(&quot;&quot;) flushes all open output.</p>

<p style="margin-left:11%; margin-top: 1em">The function
<b>system</b>(<i>expr</i>) uses /bin/sh to execute
<i>expr</i> and returns the exit status of the command
<i>expr</i>. Changes made to the <b>ENVIRON</b> array are
not passed to commands executed with <b>system</b> or
pipes.</p>

<p style="margin-left:11%; margin-top: 1em"><b>10. User
defined functions</b> <br>
The syntax for a user defined function is</p>


<p style="margin-left:11%; margin-top: 1em"><b>function</b>
name( <i>args</i> ) { <i>statements</i> }</p>

<p style="margin-left:11%; margin-top: 1em">The function
body can contain a return statement</p>

<p style="margin-left:11%; margin-top: 1em"><b>return</b>
<i>opt_expr</i></p>

<p style="margin-left:11%; margin-top: 1em">A return
statement is not required. Function calls may be nested or
recursive. Functions are passed expressions by value and
arrays by reference. Extra arguments serve as local
variables and are initialized to <i>null</i>. For example,
csplit(<i>s,A</i>) puts each character of <i>s</i> into
array <i>A</i> and returns the length of <i>s</i>.</p>

<p style="margin-left:11%; margin-top: 1em">function
csplit(s, A, n, i)</p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%"></td>
<td width="85%">


<p>{</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%"></td>
<td width="85%">


<p>n = length(s)</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%"></td>
<td width="85%">


<p>for( i = 1 ; i &lt;= n ; i++ ) A[i] = substr(s, i,
1)</p> </td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%"></td>
<td width="85%">


<p>return n</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%"></td>
<td width="85%">


<p>}</p></td></tr>
</table>

<p style="margin-left:11%; margin-top: 1em">Putting extra
space between passed arguments and local variables is
conventional. Functions can be referenced before they are
defined, but the function name and the &rsquo;(&rsquo; of
the arguments must touch to avoid confusion with
concatenation.</p>

<p style="margin-left:11%; margin-top: 1em"><b>11.
Splitting strings, records and files</b> <br>
Awk programs use the same algorithm to split strings into
arrays with split(), and records into fields on <b>FS</b>.
<b>lmawk</b> uses essentially the same algorithm to split
files into records on <b>RS</b>.</p>


<p style="margin-left:11%; margin-top: 1em">Split(<i>expr,A,sep</i>)
works as follows:</p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="22%"></td>
<td width="4%">


<p>(1)</p></td>
<td width="6%"></td>
<td width="68%">


<p>If <i>sep</i> is omitted, it is replaced by <b>FS</b>.
<i>Sep</i> can be an expression or regular expression. If it
is an expression of non-string type, it is converted to
string.</p> </td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="4%">


<p>(2)</p></td>
<td width="6%"></td>
<td width="68%">


<p>If <i>sep</i> = &quot; &quot; (a single space), then
&lt;SPACE&gt; is trimmed from the front and back of
<i>expr</i>, and <i>sep</i> becomes &lt;SPACE&gt;.
<b>lmawk</b> defines &lt;SPACE&gt; as the regular expression
/[&nbsp;\t\n]+/. Otherwise <i>sep</i> is treated as a
regular expression, except that meta-characters are ignored
for a string of length 1, e.g., split(x, A, &quot;*&quot;)
and split(x, A, /\*/) are the same.</p></td></tr>
<tr valign="top" align="left">
<td width="22%"></td>
<td width="4%">


<p>(3)</p></td>
<td width="6%"></td>
<td width="68%">


<p>If <i>expr</i> is not string, it is converted to string.
If <i>expr</i> is then the empty string &quot;&quot;,
split() returns 0 and <i>A</i> is set empty. Otherwise, all
non-overlapping, non-null and longest matches of <i>sep</i>
in <i>expr</i>, separate <i>expr</i> into fields which are
loaded into <i>A</i>. The fields are placed in A[1], A[2],
..., A[n] and split() returns n, the number of fields which
is the number of matches plus one. Data placed in <i>A</i>
that looks numeric is typed number and string.</p></td></tr>
</table>

<p style="margin-left:11%; margin-top: 1em">Splitting
records into fields works the same except the pieces are
loaded into <b>$1</b>, <b>$2</b>,..., <b>$NF</b>. If
<b>$0</b> is empty, <b>NF</b> is set to 0 and all <b>$i</b>
to &quot;&quot;.</p>

<p style="margin-left:11%; margin-top: 1em"><b>lmawk</b>
splits files into records by the same algorithm, but with
the slight difference that <b>RS</b> is really a terminator
instead of a separator. (<b>ORS</b> is really a terminator
too).</p>

<p style="margin-left:22%; margin-top: 1em">E.g., if
<b>FS</b> = &quot;:+&quot; and <b>$0</b> = &quot;a::b:&quot;
, then <b>NF</b> = 3 and <b>$1</b> = &quot;a&quot;,
<b>$2</b> = &quot;b&quot; and <b>$3</b> = &quot;&quot;, but
if &quot;a::b:&quot; is the contents of an input file and
<b>RS</b> = &quot;:+&quot;, then there are two records
&quot;a&quot; and &quot;b&quot;.</p>

<p style="margin-left:11%; margin-top: 1em"><b>RS</b> =
&quot; &quot; is not special.</p>

<p style="margin-left:11%; margin-top: 1em">If <b>FS</b> =
&quot;&quot;, then <b>lmawk</b> breaks the record into
individual characters, and, similarly,
split(<i>s,A,</i>&quot;&quot;) places the individual
characters of <i>s</i> into <i>A</i>.</p>

<p style="margin-left:11%; margin-top: 1em"><b>12.
Multi-line records</b> <br>
Since <b>lmawk</b> interprets <b>RS</b> as a regular
expression, multi-line records are easy. Setting <b>RS</b> =
&quot;\n\n+&quot;, makes one or more blank lines separate
records. If <b>FS</b> = &quot; &quot; (the default), then
single newlines, by the rules for &lt;SPACE&gt; above,
become space and single newlines are field separators.</p>

<p style="margin-left:22%; margin-top: 1em">For example, if
a file is &quot;a&nbsp;b\nc\n\n&quot;, <b>RS</b> =
&quot;\n\n+&quot; and <b>FS</b> = &quot;&nbsp;&quot;, then
there is one record &quot;a&nbsp;b\nc&quot; with three
fields &quot;a&quot;, &quot;b&quot; and &quot;c&quot;.
Changing <b>FS</b> = &quot;\n&quot;, gives two fields
&quot;a b&quot; and &quot;c&quot;; changing <b>FS</b> =
&quot;&quot;, gives one field identical to the record.</p>

<p style="margin-left:11%; margin-top: 1em">If you want
lines with spaces or tabs to be considered blank, set
<b>RS</b> = &quot;\n([&nbsp;\t]*\n)+&quot;. For
compatibility with other awks, setting <b>RS</b> =
&quot;&quot; has the same effect as if blank lines are
stripped from the front and back of files and then records
are determined as if <b>RS</b> = &quot;\n\n+&quot;. Posix
requires that &quot;\n&quot; always separates records when
<b>RS</b> = &quot;&quot; regardless of the value of
<b>FS</b>. <b>lmawk</b> does not support this convention,
because defining &quot;\n&quot; as &lt;SPACE&gt; makes it
unnecessary.</p>

<p style="margin-left:11%; margin-top: 1em">Most of the
time when you change <b>RS</b> for multi-line records, you
will also want to change <b>ORS</b> to &quot;\n\n&quot; so
the record spacing is preserved on output.</p>

<p style="margin-left:11%; margin-top: 1em"><b>13. Program
execution</b> <br>
This section describes the order of program execution. First
<b>ARGC</b> is set to the total number of command line
arguments passed to the execution phase of the program.
<b>ARGV[0]</b> is set the name of the AWK interpreter and
<b>ARGV[1]</b> ... <b>ARGV[ARGC-1]</b> holds the remaining
command line arguments exclusive of options and program
source. For example with</p>

<p style="margin-left:11%; margin-top: 1em">lmawk &minus;f
prog v=1 A t=hello B</p>

<p style="margin-left:11%; margin-top: 1em"><b>ARGC</b> = 5
with <b>ARGV[0]</b> = &quot;lmawk&quot;, <b>ARGV[1]</b> =
&quot;v=1&quot;, <b>ARGV[2]</b> = &quot;A&quot;,
<b>ARGV[3]</b> = &quot;t=hello&quot; and <b>ARGV[4]</b> =
&quot;B&quot;.</p>

<p style="margin-left:11%; margin-top: 1em">Next, each
<b>BEGIN</b> block is executed in order. If the program
consists entirely of <b>BEGIN</b> blocks, then execution
terminates, else an input stream is opened and execution
continues. If <b>ARGC</b> equals 1, the input stream is set
to stdin, else the command line arguments <b>ARGV[1]</b> ...
<b>ARGV[ARGC-1]</b> are examined for a file argument.</p>

<p style="margin-left:11%; margin-top: 1em">The command
line arguments divide into three sets: file arguments,
assignment arguments and empty strings &quot;&quot;. An
assignment has the form <i>var</i>=<i>string</i>. When an
<b>ARGV[i]</b> is examined as a possible file argument, if
it is empty it is skipped; if it is an assignment argument,
the assignment to <i>var</i> takes place and <b>i</b> skips
to the next argument; else <b>ARGV[i]</b> is opened for
input. If it fails to open, execution terminates with exit
code 2. If no command line argument is a file argument, then
input comes from stdin. Getline in a <b>BEGIN</b> action
opens input. &quot;&minus;&quot; as a file argument denotes
stdin.</p>

<p style="margin-left:11%; margin-top: 1em">Once an input
stream is open, each input record is tested against each
<i>pattern</i>, and if it matches, the associated
<i>action</i> is executed. An expression pattern matches if
it is boolean true (see the end of section 2). A
<b>BEGIN</b> pattern matches before any input has been read,
and an <b>END</b> pattern matches after all input has been
read. A range pattern, <i>expr</i>1,<i>expr</i>2 , matches
every record between the match of <i>expr</i>1 and the match
<i>expr</i>2 inclusively.</p>

<p style="margin-left:11%; margin-top: 1em">When end of
file occurs on the input stream, the remaining command line
arguments are examined for a file argument, and if there is
one it is opened, else the <b>END</b> <i>pattern</i> is
considered matched and all <b>END</b> <i>actions</i> are
executed.</p>

<p style="margin-left:11%; margin-top: 1em">In the example,
the assignment v=1 takes place after the <b>BEGIN</b>
<i>actions</i> are executed, and the data placed in v is
typed number and string. Input is then read from file A. On
end of file A, t is set to the string &quot;hello&quot;, and
B is opened for input. On end of file B, the <b>END</b>
<i>actions</i> are executed.</p>

<p style="margin-left:11%; margin-top: 1em">Program flow at
the <i>pattern {action}</i> level can be changed with
the</p>


<p style="margin-left:11%; margin-top: 1em"><b>next</b></p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p><b>exit</b> <i>opt_expr</i></p></td></tr>
</table>

<p style="margin-left:11%; margin-top: 1em">statements. A
<b>next</b> statement causes the next input record to be
read and pattern testing to restart with the first
<i>pattern {action}</i> pair in the program. An <b>exit</b>
statement causes immediate execution of the <b>END</b>
actions or program termination if there are none or if the
<b>exit</b> occurs in an <b>END</b> action. The
<i>opt_expr</i> sets the exit value of the program unless
overridden by a later <b>exit</b> or subsequent error.</p>

<p style="margin-left:11%; margin-top: 1em"><b>14.
include</b> <br>
libmawk introduces source inclusion feature. Syntax is:</p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>include &quot;filename&quot;</p></td></tr>
</table>

<p style="margin-left:11%; margin-top: 1em">Include
statements must be on top level (outside of blocks). If file
name <br>
starts with a plus sign (&rsquo;+&rsquo;), the script file
is not loaded if it has <br>
been already loaded (by another include or -f command line
argument).</p>

<h2>EXAMPLES
<a name="EXAMPLES"></a>
</h2>


<p style="margin-left:11%; margin-top: 1em">1. emulate
cat.</p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>{ print }</p></td></tr>
</table>

<p style="margin-left:11%; margin-top: 1em">2. emulate
wc.</p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>{ chars += length($0) + 1 # add one for the \n</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>words += NF</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>}</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>END{ print NR, words, chars }</p></td></tr>
</table>

<p style="margin-left:11%; margin-top: 1em">3. count the
number of unique &quot;real words&quot;.</p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>BEGIN { FS = &quot;[^A-Za-z]+&quot; }</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>{ for(i = 1 ; i &lt;= NF ; i++) word[$i] = &quot;&quot;
}</p> </td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>END { delete word[&quot;&quot;]</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>for ( i in word ) cnt++</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>print cnt</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>}</p></td></tr>
</table>

<p style="margin-left:11%; margin-top: 1em">4. sum the
second field of every record based on the first field.</p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>$1 ~ /credit|gain/ { sum += $2 }</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>$1 ~ /debit|loss/ { sum &minus;= $2 }</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>END { print sum }</p></td></tr>
</table>

<p style="margin-left:11%; margin-top: 1em">5. sort a file,
comparing as string</p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%"></td>
<td width="8%">


<p>{ line[NR] = $0 &quot;&quot; } # make sure of comparison
type</p> </td>
<td width="8%"></td>
<td width="15%"></td>
<td width="8%"></td>
<td width="46%">
</td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%">
</td>
<td width="8%">
</td>
<td width="8%">
</td>
<td width="15%"></td>
<td width="8%"></td>
<td width="46%">
</td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%"></td>
<td width="8%"></td>
<td width="8%">


<p># in case some lines look numeric</p></td>
<td width="15%"></td>
<td width="8%"></td>
<td width="46%">
</td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%"></td>
<td width="8%">


<p>END { isort(line, NR)</p></td>
<td width="8%"></td>
<td width="15%"></td>
<td width="8%"></td>
<td width="46%">
</td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%"></td>
<td width="8%">


<p>for(i = 1 ; i &lt;= NR ; i++) print line[i]</p></td>
<td width="8%"></td>
<td width="15%"></td>
<td width="8%"></td>
<td width="46%">
</td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%"></td>
<td width="8%">


<p>}</p></td>
<td width="8%"></td>
<td width="15%"></td>
<td width="8%"></td>
<td width="46%">
</td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%"></td>
<td width="8%">


<p>#insertion sort of A[1..n]</p></td>
<td width="8%"></td>
<td width="15%"></td>
<td width="8%"></td>
<td width="46%">
</td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%">
</td>
<td width="8%">


<p>function isort( A, n,</p></td>
<td width="8%"></td>
<td width="15%"></td>
<td width="8%"></td>
<td width="46%">


<p>i, j, hold)</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%"></td>
<td width="8%">


<p>{</p></td>
<td width="8%"></td>
<td width="15%"></td>
<td width="8%"></td>
<td width="46%">
</td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%"></td>
<td width="8%">


<p>for( i = 2 ; i &lt;= n ; i++)</p></td>
<td width="8%"></td>
<td width="15%"></td>
<td width="8%"></td>
<td width="46%">
</td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%"></td>
<td width="8%">


<p>{</p></td>
<td width="8%"></td>
<td width="15%"></td>
<td width="8%"></td>
<td width="46%">
</td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%"></td>
<td width="8%">


<p>hold = A[j = i]</p></td>
<td width="8%"></td>
<td width="15%"></td>
<td width="8%"></td>
<td width="46%">
</td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%"></td>
<td width="8%">


<p>while ( A[j&minus;1] &gt; hold )</p></td>
<td width="8%"></td>
<td width="15%"></td>
<td width="8%"></td>
<td width="46%">
</td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%"></td>
<td width="8%">


<p>{ j&minus;&minus; ; A[j+1] = A[j] }</p></td>
<td width="8%"></td>
<td width="15%"></td>
<td width="8%"></td>
<td width="46%">
</td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%"></td>
<td width="8%">


<p>A[j] = hold</p></td>
<td width="8%"></td>
<td width="15%"></td>
<td width="8%"></td>
<td width="46%">
</td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%"></td>
<td width="8%">


<p>}</p></td>
<td width="8%"></td>
<td width="15%"></td>
<td width="8%"></td>
<td width="46%">
</td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%"></td>
<td width="8%">


<p># sentinel A[0] = &quot;&quot; will be created if
needed</p> </td>
<td width="8%"></td>
<td width="15%"></td>
<td width="8%"></td>
<td width="46%">
</td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%"></td>
<td width="8%">


<p>}</p></td>
<td width="8%"></td>
<td width="15%"></td>
<td width="8%"></td>
<td width="46%">
</td></tr>
</table>

<h2>COMPATIBILITY ISSUES
<a name="COMPATIBILITY ISSUES"></a>
</h2>


<p style="margin-left:11%; margin-top: 1em">The Posix
1003.2(draft 11.3) definition of the AWK language is AWK as
described in the AWK book with a few extensions that
appeared in SystemVR4 nawk. The extensions are:</p>

<p style="margin-left:22%; margin-top: 1em">New functions:
toupper() and tolower(); libmawk extensions: call(),
acall(), valueof().</p>

<p style="margin-left:22%; margin-top: 1em">New variables:
ENVIRON[] and CONVFMT; libmawk extension: ERRNO, LIBPATH. As
a libmawk extension, ENVIRON affects the environment of
children processes.</p>

<p style="margin-left:22%; margin-top: 1em">As a libmawk
extension, new built-in variable LIBPATH is used as a list
of search paths while loading scripts from the command line
or from include.</p>

<p style="margin-left:22%; margin-top: 1em">If a script
name starts with plus (&rsquo;+&rsquo;), the file is not
loaded if it has been loaded earlier (to avoid double
loading libs trough -f and/or include). This is a libmawk
extension.</p>

<p style="margin-left:22%; margin-top: 1em">It is possible
to include a script from another script using keyword
include &quot;scriptname.awk&quot; (libmawk extension).</p>

<p style="margin-left:22%; margin-top: 1em">ANSI C
conversion specifications for printf() and sprintf().</p>

<p style="margin-left:22%; margin-top: 1em">New command
options: &minus;v var=value, multiple -f options and
implementation options as arguments to &minus;W.</p>

<p style="margin-left:11%; margin-top: 1em">Posix AWK is
oriented to operate on files a line at a time. <b>RS</b> can
be changed from &quot;\n&quot; to another single character,
but it is hard to find any use for this &mdash; there are no
examples in the AWK book. By convention, <b>RS</b> =
&quot;&quot;, makes one or more blank lines separate
records, allowing multi-line records. When <b>RS</b> =
&quot;&quot;, &quot;\n&quot; is always a field separator
regardless of the value in <b>FS</b>.</p>

<p style="margin-left:11%; margin-top: 1em"><b>lmawk</b>,
on the other hand, allows <b>RS</b> to be a regular
expression. When &quot;\n&quot; appears in records, it is
treated as space, and <b>FS</b> always determines
fields.</p>

<p style="margin-left:11%; margin-top: 1em">Removing the
line at a time paradigm can make some programs simpler and
can often improve performance. For example, redoing example
3 from above,</p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>BEGIN { RS = &quot;[^A-Za-z]+&quot; }</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>{ word[ $0 ] = &quot;&quot; }</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>END { delete word[ &quot;&quot; ]</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>for( i in word ) cnt++</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>print cnt</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>}</p></td></tr>
</table>

<p style="margin-left:11%; margin-top: 1em">counts the
number of unique words by making each word a record. On
moderate size files, <b>lmawk</b> executes twice as fast,
because of the simplified inner loop.</p>

<p style="margin-left:11%; margin-top: 1em">The following
program replaces each comment by a single space in a C
program file,</p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%"></td>
<td width="8%">


<p>BEGIN {</p></td>
<td width="77%">
</td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%"></td>
<td width="8%">


<p>RS = &quot;/\*([^*]|\*+[^/*])*\*+/&quot;</p></td>
<td width="77%">
</td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%">
</td>
<td width="8%">
</td>
<td width="77%">


<p># comment is record separator</p></td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%"></td>
<td width="8%">


<p>ORS = &quot; &quot;</p></td>
<td width="77%">
</td></tr>
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%"></td>
<td width="8%">


<p>getline hold</p></td>
<td width="77%">
</td></tr>
</table>

<p style="margin-left:11%;">}</p>

<p style="margin-left:11%; margin-top: 1em">{ print hold ;
hold = $0 }</p>

<p style="margin-left:11%; margin-top: 1em">END { printf
&quot;%s&quot; , hold }</p>

<p style="margin-left:11%; margin-top: 1em">Buffering one
record is needed to avoid terminating the last record with a
space.</p>

<p style="margin-left:11%; margin-top: 1em">With
<b>lmawk</b>, the following are all equivalent,</p>

<table width="100%" border="0" rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="92%">


<p>x ~ /a\+b/ x ~ &quot;a\+b&quot; x ~
&quot;a\\+b&quot;</p> </td></tr>
</table>

<p style="margin-left:11%; margin-top: 1em">The strings get
scanned twice, once as string and once as regular
expression. On the string scan, <b>lmawk</b> ignores the
escape on non-escape characters while the AWK book advocates
<i>\c</i> be recognized as <i>c</i> which necessitates the
double escaping of meta-characters in strings. Posix
explicitly declines to define the behavior which passively
forces programs that must run under a variety of awks to use
the more portable but less readable, double escape.</p>

<p style="margin-left:11%; margin-top: 1em">Posix AWK does
not recognize &quot;/dev/std{out,err}&quot; or \x hex escape
sequences in strings. Unlike ANSI C, <b>lmawk</b> limits the
number of digits that follows \x to two as the current
implementation only supports 8 bit characters. The built-in
<b>fflush</b> first appeared in a recent (1993) AT&amp;T awk
released to netlib, and is not part of the posix standard.
Aggregate deletion with <b>delete</b> <i>array</i> is not
part of the posix standard.</p>

<p style="margin-left:11%; margin-top: 1em">Posix
explicitly leaves the behavior of <b>FS</b> = &quot;&quot;
undefined, and mentions splitting the record into characters
as a possible interpretation, but currently this use is not
portable across implementations.</p>

<p style="margin-left:11%; margin-top: 1em">Finally, here
is how <b>lmawk</b> handles exceptional cases not discussed
in the AWK book or the Posix draft. It is unsafe to assume
consistency across awks and safe to skip to the next
section.</p>

<p style="margin-left:22%; margin-top: 1em">substr(s, i, n)
returns the characters of s in the intersection of the
closed interval [1, length(s)] and the half-open interval
[i, i+n). When this intersection is empty, the empty string
is returned; so substr(&quot;ABC&quot;, 1, 0) = &quot;&quot;
and substr(&quot;ABC&quot;, &minus;4, 6) =
&quot;A&quot;.</p>

<p style="margin-left:22%; margin-top: 1em">Every string,
including the empty string, matches the empty string at the
front so, s ~ // and s ~ &quot;&quot;, are always 1 as is
match(s, //) and match(s, &quot;&quot;). The last two set
<b>RLENGTH</b> to 0.</p>

<p style="margin-left:22%; margin-top: 1em">index(s, t) is
always the same as match(s, t1) where t1 is the same as t
with metacharacters escaped. Hence consistency with match
requires that index(s, &quot;&quot;) always returns 1. Also
the condition, index(s,t) != 0 if and only t is a substring
of s, requires index(&quot;&quot;,&quot;&quot;) = 1.</p>

<p style="margin-left:22%; margin-top: 1em">If getline
encounters end of file, getline var, leaves var unchanged.
Similarly, on entry to the <b>END</b> actions, <b>$0</b>,
the fields and <b>NF</b> have their value unaltered from the
last record.</p>

<h2>SEE ALSO
<a name="SEE ALSO"></a>
</h2>



<p style="margin-left:11%; margin-top: 1em"><i>egrep</i>(1),
<i>mawk</i>(1)</p>

<p style="margin-left:11%; margin-top: 1em">Aho, Kernighan
and Weinberger, <i>The AWK Programming Language</i>,
Addison-Wesley Publishing, 1988, (the AWK book), defines the
language, opening with a tutorial and advancing to many
interesting programs that delve into issues of software
design and analysis relevant to programming in any
language.</p>

<p style="margin-left:11%; margin-top: 1em"><i>The GAWK
Manual</i>, The Free Software Foundation, 1991, is a
tutorial and language reference that does not attempt the
depth of the AWK book and assumes the reader may be a novice
programmer. The section on AWK arrays is excellent. It also
discusses Posix requirements for AWK.</p>

<h2>BUGS
<a name="BUGS"></a>
</h2>


<p style="margin-left:11%; margin-top: 1em"><b>lmawk</b>
cannot handle ascii NUL \0 in the source or data files. You
can output NUL using printf with %c, and any other 8 bit
character is acceptable input.</p>

<p style="margin-left:11%; margin-top: 1em"><b>lmawk</b>
implements printf() and sprintf() using the C library
functions, printf and sprintf, so full ANSI compatibility
requires an ANSI C library. In practice this means the h
conversion qualifier may not be available. Also <b>lmawk</b>
inherits any bugs or limitations of the library
functions.</p>

<p style="margin-left:11%; margin-top: 1em">Implementors of
the AWK language have shown a consistent lack of imagination
when naming their programs.</p>

<h2>AUTHOR
<a name="AUTHOR"></a>
</h2>


<p style="margin-left:11%; margin-top: 1em"><b>mawk:</b>
Mike Brennan (brennan@whidbey.com).</p>

<p style="margin-left:11%; margin-top: 1em"><b>libmawk
extensions:</b> Tibor Palinkas (libmawk@igor2.repo.hu).</p>
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