Un outil pour savoir si une commande est posix - retour accueil
git clone git://bebou.netlib.re/isposix
Log | Files | Refs | README |
lex.html (49010B)
1 <!-- Copyright 2001-2024 IEEE and The Open Group, All Rights Reserved -->
2 <!DOCTYPE HTML>
3 <html lang="en">
4 <head>
5 <meta name="generator" content="HTML Tidy for HTML5 for Linux version 5.8.0">
6 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
7 <link type="text/css" rel="stylesheet" href="style.css"><!-- Generated by The Open Group rhtm tool v1.2.4 -->
8 <!-- Copyright (c) 2001-2024 The Open Group, All Rights Reserved -->
9 <title>lex</title>
10 </head>
11 <body bgcolor="white">
12 <div class="NAVHEADER">
13 <table summary="Header navigation table" class="nav" width="100%" border="0" cellpadding="0" cellspacing="0">
14 <tr class="nav">
15 <td class="nav" width="15%" align="left" valign="bottom"><a href="../utilities/kill.html" accesskey="P"><<<
16 Previous</a></td>
17 <td class="nav" width="70%" align="center" valign="bottom"><a href="contents.html">Home</a></td>
18 <td class="nav" width="15%" align="right" valign="bottom"><a href="../utilities/link.html" accesskey="N">Next >>></a></td>
19 </tr>
20 </table>
21 <hr align="left" width="100%"></div>
22 <script language="JavaScript" src="../jscript/codes.js"></script><basefont size="3">
23 <center><font size="2">The Open Group Base Specifications Issue 8<br>
24 IEEE Std 1003.1-2024<br>
25 Copyright © 2001-2024 The IEEE and The Open Group</font></center>
26 <hr size="2" noshade>
27 <a name="top" id="top"></a> <a name="lex" id="lex"></a> <a name="tag_20_65" id="tag_20_65"></a><!-- lex -->
28 <h4 class="mansect"><a name="tag_20_65_01" id="tag_20_65_01"></a>NAME</h4>
29 <blockquote>lex — generate programs for lexical tasks (<b>DEVELOPMENT</b>)</blockquote>
30 <h4 class="mansect"><a name="tag_20_65_02" id="tag_20_65_02"></a>SYNOPSIS</h4>
31 <blockquote class="synopsis">
32 <div class="box"><code><tt><sup>[<a href="javascript:open_code('CD')">CD</a>]</sup> <img src="../images/opt-start.gif" alt=
33 "[Option Start]" border="0"> lex</tt> <b>[</b><tt>-t</tt><b>] [</b><tt>-n|-v</tt><b>] [</b><i>file</i><tt>...</tt><b>]</b>
34 <tt><img src="../images/opt-end.gif" alt="[Option End]" border="0"></tt></code></div>
35 </blockquote>
36 <h4 class="mansect"><a name="tag_20_65_03" id="tag_20_65_03"></a>DESCRIPTION</h4>
37 <blockquote>
38 <p>The <i>lex</i> utility shall generate C programs to be used in lexical processing of character input, and that can be used as an
39 interface to <a href="../utilities/yacc.html"><i>yacc</i></a>. The C programs shall be generated from <i>lex</i> source code and
40 conform to the ISO C standard, without depending on any undefined, unspecified, or implementation-defined behavior, except in
41 cases where the code is copied directly from the supplied source, or in cases that are documented by the implementation. Usually,
42 the <i>lex</i> utility shall write the program it generates to the file <b>lex.yy.c</b>; the state of this file is unspecified if
43 <i>lex</i> exits with a non-zero exit status. See the EXTENDED DESCRIPTION section for a complete description of the <i>lex</i>
44 input language.</p>
45 </blockquote>
46 <h4 class="mansect"><a name="tag_20_65_04" id="tag_20_65_04"></a>OPTIONS</h4>
47 <blockquote>
48 <p>The <i>lex</i> utility shall conform to XBD <a href="../basedefs/V1_chap12.html#tag_12_02"><i>12.2 Utility Syntax
49 Guidelines</i></a> , except for Guideline 9.</p>
50 <p>The following options shall be supported:</p>
51 <dl compact>
52 <dd></dd>
53 <dt><b>-n</b></dt>
54 <dd>Suppress the summary of statistics usually written with the <b>-v</b> option. If no table sizes are specified in the <i>lex</i>
55 source code and the <b>-v</b> option is not specified, then <b>-n</b> is implied.</dd>
56 <dt><b>-t</b></dt>
57 <dd>Write the resulting program to standard output instead of <b>lex.yy.c</b>.</dd>
58 <dt><b>-v</b></dt>
59 <dd>Write a summary of <i>lex</i> statistics to the standard output. (See the discussion of <i>lex</i> table sizes in <a href=
60 "#tag_20_65_13_01">Definitions in lex</a> .) If the <b>-t</b> option is specified and <b>-n</b> is not specified, this report shall
61 be written to standard error. If table sizes are specified in the <i>lex</i> source code, and if the <b>-n</b> option is not
62 specified, the <b>-v</b> option may be enabled.</dd>
63 </dl>
64 </blockquote>
65 <h4 class="mansect"><a name="tag_20_65_05" id="tag_20_65_05"></a>OPERANDS</h4>
66 <blockquote>
67 <p>The following operand shall be supported:</p>
68 <dl compact>
69 <dd></dd>
70 <dt><i>file</i></dt>
71 <dd>A pathname of an input file. If more than one such <i>file</i> is specified, all files shall be concatenated to produce a
72 single <i>lex</i> program. If no <i>file</i> operands are specified, or if a <i>file</i> operand is <tt>'-'</tt>, the standard
73 input shall be used.</dd>
74 </dl>
75 </blockquote>
76 <h4 class="mansect"><a name="tag_20_65_06" id="tag_20_65_06"></a>STDIN</h4>
77 <blockquote>
78 <p>The standard input shall be used if no <i>file</i> operands are specified, or if a <i>file</i> operand is <tt>'-'</tt>. See
79 INPUT FILES.</p>
80 </blockquote>
81 <h4 class="mansect"><a name="tag_20_65_07" id="tag_20_65_07"></a>INPUT FILES</h4>
82 <blockquote>
83 <p>The input files shall be text files containing <i>lex</i> source code, as described in the EXTENDED DESCRIPTION section.</p>
84 </blockquote>
85 <h4 class="mansect"><a name="tag_20_65_08" id="tag_20_65_08"></a>ENVIRONMENT VARIABLES</h4>
86 <blockquote>
87 <p>The following environment variables shall affect the execution of <i>lex</i>:</p>
88 <dl compact>
89 <dd></dd>
90 <dt><i>LANG</i></dt>
91 <dd>Provide a default value for the internationalization variables that are unset or null.</dd>
92 <dt><i>LC_ALL</i></dt>
93 <dd>If set to a non-empty string value, override the values of all the other internationalization variables.</dd>
94 <dt><i>LC_COLLATE</i></dt>
95 <dd><br>
96 Determine the locale for the behavior of ranges, equivalence classes, and multi-character collating elements within regular
97 expressions.</dd>
98 <dt><i>LC_CTYPE</i></dt>
99 <dd>Determine the locale for the interpretation of sequences of bytes of text data as characters (for example, single-byte as
100 opposed to multi-byte characters in arguments and input files), and the behavior of character classes within regular
101 expressions.</dd>
102 <dt><i>LC_MESSAGES</i></dt>
103 <dd><br>
104 Determine the locale that should be used to affect the format and contents of diagnostic messages written to standard error.</dd>
105 <dt><i>NLSPATH</i></dt>
106 <dd><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
107 Determine the location of messages objects and message catalogs. <img src="../images/opt-end.gif" alt="[Option End]" border=
108 "0"></dd>
109 </dl>
110 <p>If the values (if any) of the <i>LANG ,</i> <i>LC_COLLATE ,</i> <i>LC_CTYPE ,</i> and <i>LC_ALL</i> variables result in the
111 locale in effect for the <i>LC_CTYPE</i> or <i>LC_COLLATE</i> category not being the POSIX locale, the behavior is unspecified.
112 (See XBD <a href="../basedefs/V1_chap08.html#tag_08_02"><i>8.2 Internationalization Variables</i></a> for the precedence of
113 internationalization variables used to determine the values of locale categories.)</p>
114 </blockquote>
115 <h4 class="mansect"><a name="tag_20_65_09" id="tag_20_65_09"></a>ASYNCHRONOUS EVENTS</h4>
116 <blockquote>
117 <p>Default.</p>
118 </blockquote>
119 <h4 class="mansect"><a name="tag_20_65_10" id="tag_20_65_10"></a>STDOUT</h4>
120 <blockquote>
121 <p>If the <b>-t</b> option is specified, the text file of C source code output of <i>lex</i> shall be written to standard
122 output.</p>
123 <p>If the <b>-t</b> option is not specified:</p>
124 <ul>
125 <li>
126 <p>Implementation-defined informational, error, and warning messages concerning the contents of <i>lex</i> source code input shall
127 be written to either the standard output or standard error.</p>
128 </li>
129 <li>
130 <p>If the <b>-v</b> option is specified and the <b>-n</b> option is not specified, <i>lex</i> statistics shall also be written to
131 either the standard output or standard error, in an implementation-defined format. These statistics may also be generated if table
132 sizes are specified with a <tt>'%'</tt> operator in the <i>Definitions</i> section, as long as the <b>-n</b> option is not
133 specified.</p>
134 </li>
135 </ul>
136 </blockquote>
137 <h4 class="mansect"><a name="tag_20_65_11" id="tag_20_65_11"></a>STDERR</h4>
138 <blockquote>
139 <p>If the <b>-t</b> option is specified, implementation-defined informational, error, and warning messages concerning the contents
140 of <i>lex</i> source code input shall be written to the standard error.</p>
141 <p>If the <b>-t</b> option is not specified:</p>
142 <ol>
143 <li>
144 <p>Implementation-defined informational, error, and warning messages concerning the contents of <i>lex</i> source code input shall
145 be written to either the standard output or standard error.</p>
146 </li>
147 <li>
148 <p>If the <b>-v</b> option is specified and the <b>-n</b> option is not specified, <i>lex</i> statistics shall also be written to
149 either the standard output or standard error, in an implementation-defined format. These statistics may also be generated if table
150 sizes are specified with a <tt>'%'</tt> operator in the <i>Definitions</i> section, as long as the <b>-n</b> option is not
151 specified.</p>
152 </li>
153 </ol>
154 </blockquote>
155 <h4 class="mansect"><a name="tag_20_65_12" id="tag_20_65_12"></a>OUTPUT FILES</h4>
156 <blockquote>
157 <p>A text file containing C source code shall be written to <b>lex.yy.c</b>, or to the standard output if the <b>-t</b> option is
158 present.</p>
159 </blockquote>
160 <h4 class="mansect"><a name="tag_20_65_13" id="tag_20_65_13"></a>EXTENDED DESCRIPTION</h4>
161 <blockquote>
162 <p>Each input file shall contain <i>lex</i> source code, which is a table of regular expressions with corresponding actions in the
163 form of C program fragments.</p>
164 <p>When <b>lex.yy.c</b> is compiled and linked with the <i>lex</i> library (using the <b>-l l</b> operand with <a href=
165 "../utilities/c17.html"><i>c17</i></a>), the resulting program shall read character input from the standard input and shall
166 partition it into strings that match the given expressions.<br></p>
167 <p>When an expression is matched, these actions shall occur:</p>
168 <ul>
169 <li>
170 <p>The input string that was matched shall be left in <i>yytext</i> as a null-terminated string; <i>yytext</i> shall either be an
171 external character array or a pointer to a character string. As explained in <a href="#tag_20_65_13_01">Definitions in lex</a> ,
172 the type can be explicitly selected using the <b>%array</b> or <b>%pointer</b> declarations, but the default is
173 implementation-defined.</p>
174 </li>
175 <li>
176 <p>The external <b>int</b> <i>yyleng</i> shall be set to the length of the matching string.</p>
177 </li>
178 <li>
179 <p>The expression's corresponding program fragment, or action, shall be executed.</p>
180 </li>
181 </ul>
182 <p>During pattern matching, <i>lex</i> shall search the set of patterns for the single longest possible match. Among rules that
183 match the same number of characters, the rule given first shall be chosen.</p>
184 <p>The general format of <i>lex</i> source shall be:</p>
185 <blockquote>
186 <pre>
187 <i>Definitions</i>
188 <b>%%</b>
189 <i>Rules</i>
190 <b>%%</b>
191 <i>User</i>Subroutines
192 </pre></blockquote>
193 <p>The first <tt>"%%"</tt> is required to mark the beginning of the rules (regular expressions and actions); the second
194 <tt>"%%"</tt> is required only if user subroutines follow.</p>
195 <p>Any line in the <i>Definitions</i> section beginning with a <blank> shall be assumed to be a C program fragment and shall
196 be copied to the external definition area of the <b>lex.yy.c</b> file. Similarly, anything in the <i>Definitions</i> section
197 included between delimiter lines containing only <tt>"%{"</tt> and <tt>"%}"</tt> shall also be copied unchanged to the external
198 definition area of the <b>lex.yy.c</b> file.</p>
199 <p>Any such input (beginning with a <blank> or within <tt>"%{"</tt> and <tt>"%}"</tt> delimiter lines) appearing at the
200 beginning of the <i>Rules</i> section before any rules are specified shall be written to <b>lex.yy.c</b> after the declarations of
201 variables for the <i>yylex</i>() function and before the first line of code in <i>yylex</i>(). Thus, user variables local to
202 <i>yylex</i>() can be declared here, as well as application code to execute upon entry to <i>yylex</i>().</p>
203 <p>The action taken by <i>lex</i> when encountering any input beginning with a <blank> or within <tt>"%{"</tt> and
204 <tt>"%}"</tt> delimiter lines appearing in the <i>Rules</i> section but coming after one or more rules is undefined. The presence
205 of such input may result in an erroneous definition of the <i>yylex</i>() function.</p>
206 <p>C-language code in the input shall not contain C-language trigraphs. The C-language code within <tt>"%{"</tt> and <tt>"%}"</tt>
207 delimiter lines shall not contain any lines consisting only of <tt>"%}"</tt>, or only of <tt>"%%"</tt>.</p>
208 <h5><a name="tag_20_65_13_01" id="tag_20_65_13_01"></a>Definitions in lex</h5>
209 <p><i>Definitions</i> appear before the first <tt>"%%"</tt> delimiter. Any line in this section not contained between <tt>"%{"</tt>
210 and <tt>"%}"</tt> lines and not beginning with a <blank> shall be assumed to define a <i>lex</i> substitution string. The
211 format of these lines shall be:</p>
212 <pre>
213 <i>name substitute</i><tt>
214 </tt></pre>
215 <p>If a <i>name</i> does not meet the requirements for identifiers in the ISO C standard, the result is undefined. The string
216 <i>substitute</i> shall replace the string {<i>name</i>} when it is used in a rule. The <i>name</i> string shall be recognized in
217 this context only when the braces are provided and when it does not appear within a bracket expression or within double-quotes.</p>
218 <p>In the <i>Definitions</i> section, any line beginning with a <percent-sign> (<tt>'%'</tt>) character and followed by an
219 alphanumeric word beginning with either <tt>'s'</tt> or <tt>'S'</tt> shall define a set of start conditions. Any line beginning
220 with a <tt>'%'</tt> followed by a word beginning with either <tt>'x'</tt> or <tt>'X'</tt> shall define a set of exclusive start
221 conditions. When the generated scanner is in a <tt>%s</tt> state, patterns with no state specified shall be also active; in a
222 <tt>%x</tt> state, such patterns shall not be active. The rest of the line, after the first word, shall be considered to be one or
223 more <blank>-separated names of start conditions. Start condition names shall be constructed in the same way as definition
224 names. Start conditions can be used to restrict the matching of regular expressions to one or more states as described in <a href=
225 "#tag_20_65_13_04">Regular Expressions in lex</a> .</p>
226 <p>Implementations shall accept either of the following two mutually-exclusive declarations in the <i>Definitions</i> section:</p>
227 <dl compact>
228 <dd></dd>
229 <dt><b>%array</b></dt>
230 <dd>Declare the type of <i>yytext</i> to be a null-terminated character array.</dd>
231 <dt><b>%pointer</b></dt>
232 <dd>Declare the type of <i>yytext</i> to be a pointer to a null-terminated character string.</dd>
233 </dl>
234 <p>The default type of <i>yytext</i> is implementation-defined. If an application refers to <i>yytext</i> outside of the scanner
235 source file (that is, via an <b>extern</b>), the application shall include the appropriate <b>%array</b> or <b>%pointer</b>
236 declaration in the scanner source file.</p>
237 <p>Implementations shall accept declarations in the <i>Definitions</i> section for setting certain internal table sizes. The
238 declarations are shown in the following table.</p>
239 <p class="caption">Table: Table Size Declarations in <i>lex</i></p>
240 <center>
241 <table border="1" cellpadding="3" align="center">
242 <tr valign="top">
243 <th align="center">
244 <p class="tent"><b>Declaration</b></p>
245 </th>
246 <th align="center">
247 <p class="tent"><b>Description</b></p>
248 </th>
249 <th align="center">
250 <p class="tent"><b>Minimum Value</b></p>
251 </th>
252 </tr>
253 <tr valign="top">
254 <td align="left">
255 <p class="tent">%<b>p</b> <i>n</i></p>
256 </td>
257 <td align="left">
258 <p class="tent">Number of positions</p>
259 </td>
260 <td align="left">
261 <p class="tent">2500</p>
262 </td>
263 </tr>
264 <tr valign="top">
265 <td align="left">
266 <p class="tent">%<b>n</b> <i>n</i></p>
267 </td>
268 <td align="left">
269 <p class="tent">Number of states</p>
270 </td>
271 <td align="left">
272 <p class="tent">500</p>
273 </td>
274 </tr>
275 <tr valign="top">
276 <td align="left">
277 <p class="tent">%<b>a</b> <i>n</i></p>
278 </td>
279 <td align="left">
280 <p class="tent">Number of transitions</p>
281 </td>
282 <td align="left">
283 <p class="tent">2000</p>
284 </td>
285 </tr>
286 <tr valign="top">
287 <td align="left">
288 <p class="tent">%<b>e</b> <i>n</i></p>
289 </td>
290 <td align="left">
291 <p class="tent">Number of parse tree nodes</p>
292 </td>
293 <td align="left">
294 <p class="tent">1000</p>
295 </td>
296 </tr>
297 <tr valign="top">
298 <td align="left">
299 <p class="tent">%<b>k</b> <i>n</i></p>
300 </td>
301 <td align="left">
302 <p class="tent">Number of packed character classes</p>
303 </td>
304 <td align="left">
305 <p class="tent">1000</p>
306 </td>
307 </tr>
308 <tr valign="top">
309 <td align="left">
310 <p class="tent">%<b>o</b> <i>n</i></p>
311 </td>
312 <td align="left">
313 <p class="tent">Size of the output array</p>
314 </td>
315 <td align="left">
316 <p class="tent">3000</p>
317 </td>
318 </tr>
319 </table>
320 </center>
321 <p class="tent">In the table, <i>n</i> represents a positive decimal integer, preceded by one or more <blank> characters. The
322 exact meaning of these table size numbers is implementation-defined. The implementation shall document how these numbers affect the
323 <i>lex</i> utility and how they are related to any output that may be generated by the implementation should limitations be
324 encountered during the execution of <i>lex</i>. It shall be possible to determine from this output which of the table size values
325 needs to be modified to permit <i>lex</i> to successfully generate tables for the input language. The values in the column Minimum
326 Value represent the lowest values conforming implementations shall provide.</p>
327 <h5><a name="tag_20_65_13_02" id="tag_20_65_13_02"></a>Rules in lex</h5>
328 <p class="tent">The rules in <i>lex</i> source files are a table in which the left column contains regular expressions and the
329 right column contains actions (C program fragments) to be executed when the expressions are recognized.</p>
330 <pre>
331 <i>ERE action
332 ERE action</i><tt>
333 ...
334 </tt></pre>
335 <p class="tent">The extended regular expression (ERE) portion of a row shall be separated from <i>action</i> by one or more
336 <blank> characters. A regular expression containing <blank> characters shall be recognized under one of the following
337 conditions:</p>
338 <ul>
339 <li class="tent">The entire expression appears within double-quotes.</li>
340 <li class="tent">The <blank> characters appear within double-quotes or square brackets.</li>
341 <li class="tent">Each <blank> is preceded by a <backslash> character.</li>
342 </ul>
343 <h5><a name="tag_20_65_13_03" id="tag_20_65_13_03"></a>User Subroutines in lex</h5>
344 <p class="tent">Anything in the user subroutines section shall be copied to <b>lex.yy.c</b> following <i>yylex</i>().</p>
345 <h5><a name="tag_20_65_13_04" id="tag_20_65_13_04"></a>Regular Expressions in lex</h5>
346 <p class="tent">The <i>lex</i> utility shall support the set of extended regular expressions (see XBD <a href=
347 "../basedefs/V1_chap09.html#tag_09_04"><i>9.4 Extended Regular Expressions</i></a> ), with the following additions and exceptions
348 to the syntax:</p>
349 <dl compact>
350 <dd></dd>
351 <dt><tt>"..."</tt></dt>
352 <dd>Any string enclosed in double-quotes shall represent the characters within the double-quotes as themselves, except that
353 <backslash>-escapes (which appear in the following table) shall be recognized. Any <backslash>-escape sequence shall be
354 terminated by the closing quote. For example, <tt>"\01"</tt><tt>"1"</tt> represents a single string: the octal value 1 followed by
355 the character <tt>'1'</tt>.</dd>
356 <dt><<i>state</i>><i>r</i>, <<i>state1,state2,</i>...><i>r</i></dt>
357 <dd><br>
358 The regular expression <i>r</i> shall be matched only when the program is in one of the start conditions indicated by <i>state</i>,
359 <i>state1</i>, and so on; see <a href="#tag_20_65_13_05">Actions in lex</a> . (As an exception to the typographical conventions of
360 the rest of this volume of POSIX.1-2024, in this case <<i>state</i>> does not represent a metavariable, but the literal
361 angle-bracket characters surrounding a symbol.) The start condition shall be recognized as such only at the beginning of a regular
362 expression.</dd>
363 <dt><i>r</i>/<i>x</i></dt>
364 <dd>The regular expression <i>r</i> shall be matched only if it is followed by an occurrence of regular expression <i>x</i>
365 (<i>x</i> is the instance of trailing context, further defined below). The token returned in <i>yytext</i> shall only match
366 <i>r</i>. If the trailing portion of <i>r</i> matches the beginning of <i>x</i>, the result is unspecified. The <i>r</i> expression
367 cannot include further trailing context or the <tt>'$'</tt> (match-end-of-line) operator; <i>x</i> cannot include the <tt>'^'</tt>
368 (match-beginning-of-line) operator, nor trailing context, nor the <tt>'$'</tt> operator. That is, only one occurrence of trailing
369 context is allowed in a <i>lex</i> regular expression, and the <tt>'^'</tt> operator only can be used at the beginning of such an
370 expression.</dd>
371 <dt>{<i>name</i>}</dt>
372 <dd>When <i>name</i> is one of the substitution symbols from the <i>Definitions</i> section, the string, including the enclosing
373 braces, shall be replaced by the <i>substitute</i> value. The <i>substitute</i> value shall be treated in the extended regular
374 expression as if it were enclosed in parentheses. No substitution shall occur if {<i>name</i>} occurs within a bracket expression
375 or within double-quotes.</dd>
376 </dl>
377 <p class="tent">Within an ERE, a <backslash> character shall be considered to begin an escape sequence as specified in the
378 table in XBD <a href="../basedefs/V1_chap05.html#tag_05"><i>5. File Format Notation</i></a> (<tt>'\\'</tt>, <tt>'\a'</tt>,
379 <tt>'\b'</tt>, <tt>'\f'</tt>, <tt>'\n'</tt>, <tt>'\r'</tt>, <tt>'\t'</tt>, <tt>'\v'</tt>). In addition, the escape sequences in the
380 following table shall be recognized.</p>
381 <p class="tent">A literal <newline> cannot occur within an ERE; the escape sequence <tt>'\n'</tt> can be used to represent a
382 <newline>. A <newline> shall not be matched by a period operator.<br></p>
383 <p class="caption">Table: Escape Sequences in <i>lex</i></p>
384 <center>
385 <table border="1" cellpadding="3" align="center">
386 <tr valign="top">
387 <th align="center">
388 <p class="tent"><b>Escape Sequence</b></p>
389 </th>
390 <th align="center">
391 <p class="tent"><b>Description</b></p>
392 </th>
393 <th align="center">
394 <p class="tent"><b>Meaning</b></p>
395 </th>
396 </tr>
397 <tr valign="top">
398 <td align="left">
399 <p class="tent">\<i>digits</i></p>
400 </td>
401 <td align="left">
402 <p class="tent">A <backslash> character followed by the longest sequence of one, two, or three octal-digit characters
403 (01234567). If all of the digits are 0 (that is, representation of the NUL character), the behavior is undefined.</p>
404 </td>
405 <td align="left">
406 <p class="tent">The character whose encoding is represented by the one, two, or three-digit octal integer. Multi-byte characters
407 require multiple, concatenated escape sequences of this type, including the leading <backslash> for each byte.</p>
408 </td>
409 </tr>
410 <tr valign="top">
411 <td align="left">
412 <p class="tent">\x<i>digits</i></p>
413 </td>
414 <td align="left">
415 <p class="tent">A <backslash> character followed by the longest sequence of hexadecimal-digit characters
416 (01234567abcdefABCDEF). If all of the digits are 0 (that is, representation of the NUL character), the behavior is undefined.</p>
417 </td>
418 <td align="left">
419 <p class="tent">The character whose encoding is represented by the hexadecimal integer.</p>
420 </td>
421 </tr>
422 <tr valign="top">
423 <td align="left">
424 <p class="tent">\c</p>
425 </td>
426 <td align="left">
427 <p class="tent">A <backslash> character followed by any character not described in this table or in the table in XBD <a href=
428 "../basedefs/V1_chap05.html#tag_05"><i>5. File Format Notation</i></a> (<tt>'\\'</tt>, <tt>'\a'</tt>, <tt>'\b'</tt>, <tt>'\f'</tt>,
429 <tt>'\n'</tt>, <tt>'\r'</tt>, <tt>'\t'</tt>, <tt>'\v'</tt>).</p>
430 </td>
431 <td align="left">
432 <p class="tent">The character <tt>'c'</tt>, unchanged.</p>
433 </td>
434 </tr>
435 </table>
436 </center>
437 <basefont size="2">
438 <dl>
439 <dt><b>Note:</b></dt>
440 <dd>If a <tt>'\x'</tt> sequence needs to be immediately followed by a hexadecimal digit character, a sequence such as
441 <tt>"\x1"</tt><tt>"1"</tt> can be used, which represents a character containing the value 1, followed by the character
442 <tt>'1'</tt>.</dd>
443 </dl>
444 <basefont size="3">
445 <p class="tent">The order of precedence given to extended regular expressions for <i>lex</i> differs from that specified in XBD
446 <a href="../basedefs/V1_chap09.html#tag_09_04"><i>9.4 Extended Regular Expressions</i></a> . The order of precedence for <i>lex</i>
447 shall be as shown in the following table, from high to low. <basefont size="2"></p>
448 <dl>
449 <dt><b>Note:</b></dt>
450 <dd>The escaped characters entry is not meant to imply that these are operators, but they are included in the table to show their
451 relationships to the true operators. The start condition, trailing context, and anchoring notations have been omitted from the
452 table because of the placement restrictions described in this section; they can only appear at the beginning or ending of an
453 ERE.</dd>
454 </dl>
455 <basefont size="3"><br>
456 <p class="caption">Table: ERE Precedence in <i>lex</i></p>
457 <center>
458 <table border="1" cellpadding="3" align="center">
459 <tr valign="top">
460 <th align="center">
461 <p class="tent"><b>Extended Regular Expression</b></p>
462 </th>
463 <th align="center">
464 <p class="tent"><b>Precedence</b></p>
465 </th>
466 </tr>
467 <tr valign="top">
468 <td align="left">
469 <p class="tent">collation-related bracket symbols</p>
470 </td>
471 <td align="left">
472 <p class="tent">[= =] [: :] [. .]</p>
473 </td>
474 </tr>
475 <tr valign="top">
476 <td align="left">
477 <p class="tent">escaped characters</p>
478 </td>
479 <td align="left">
480 <p class="tent">\<<i>special character</i>></p>
481 </td>
482 </tr>
483 <tr valign="top">
484 <td align="left">
485 <p class="tent">bracket expression</p>
486 </td>
487 <td align="left">
488 <p class="tent">[ ]</p>
489 </td>
490 </tr>
491 <tr valign="top">
492 <td align="left">
493 <p class="tent">quoting</p>
494 </td>
495 <td align="left">
496 <p class="tent">"..."</p>
497 </td>
498 </tr>
499 <tr valign="top">
500 <td align="left">
501 <p class="tent">grouping</p>
502 </td>
503 <td align="left">
504 <p class="tent">( )</p>
505 </td>
506 </tr>
507 <tr valign="top">
508 <td align="left">
509 <p class="tent">definition</p>
510 </td>
511 <td align="left">
512 <p class="tent">{<i>name</i>}</p>
513 </td>
514 </tr>
515 <tr valign="top">
516 <td align="left">
517 <p class="tent">single-character RE duplication</p>
518 </td>
519 <td align="left">
520 <p class="tent">* + ?</p>
521 </td>
522 </tr>
523 <tr valign="top">
524 <td align="left">
525 <p class="tent">concatenation</p>
526 </td>
527 <td align="left">
528 <p class="tent"> </p>
529 </td>
530 </tr>
531 <tr valign="top">
532 <td align="left">
533 <p class="tent">interval expression</p>
534 </td>
535 <td align="left">
536 <p class="tent">{m,n}</p>
537 </td>
538 </tr>
539 <tr valign="top">
540 <td align="left">
541 <p class="tent">alternation</p>
542 </td>
543 <td align="left">
544 <p class="tent">|</p>
545 </td>
546 </tr>
547 </table>
548 </center>
549 <p class="tent">The ERE anchoring operators <tt>'^'</tt> and <tt>'$'</tt> do not appear in the table. With <i>lex</i> regular
550 expressions, these operators are restricted in their use: the <tt>'^'</tt> operator can only be used at the beginning of an entire
551 regular expression, and the <tt>'$'</tt> operator only at the end. The operators apply to the entire regular expression. Thus, for
552 example, the pattern <tt>"(^abc)|(def$)"</tt> is undefined; it can instead be written as two separate rules, one with the regular
553 expression <tt>"^abc"</tt> and one with <tt>"def$"</tt>, which share a common action via the special <tt>'|'</tt> action (see
554 below). If the pattern were written <tt>"^abc|def$"</tt>, it would match either <tt>"abc"</tt> or <tt>"def"</tt> on a line by
555 itself.</p>
556 <p class="tent">Unlike the general ERE rules, embedded anchoring is not allowed by most historical <i>lex</i> implementations. An
557 example of embedded anchoring would be for patterns such as <tt>"(^| )foo( |$)"</tt> to match <tt>"foo"</tt> when it
558 exists as a complete word. This functionality can be obtained using existing <i>lex</i> features:</p>
559 <pre>
560 <tt>^foo/[ \n] |
561 " foo"/[ \n] /* Found foo as a separate word. */
562 </tt></pre>
563 <p class="tent">Note also that <tt>'$'</tt> is a form of trailing context (it is equivalent to <tt>"/\n"</tt>) and as such cannot
564 be used with regular expressions containing another instance of the operator (see the preceding discussion of trailing
565 context).</p>
566 <p class="tent">The additional regular expressions trailing-context operator <tt>'/'</tt> can be used as an ordinary character if
567 presented within double-quotes, <tt>"/"</tt>; preceded by a <backslash>, <tt>"\/"</tt>; or within a bracket expression,
568 <tt>"[/]"</tt>. The start-condition <tt>'<'</tt> and <tt>'>'</tt> operators shall be special only in a start condition at the
569 beginning of a regular expression; elsewhere in the regular expression they shall be treated as ordinary characters.</p>
570 <h5><a name="tag_20_65_13_05" id="tag_20_65_13_05"></a>Actions in lex</h5>
571 <p class="tent">The action to be taken when an ERE is matched can be a C program fragment or the special actions described below;
572 the program fragment can contain one or more C statements, and can also include special actions. The empty C statement <tt>';'</tt>
573 shall be a valid action; any string in the <b>lex.yy.c</b> input that matches the pattern portion of such a rule is effectively
574 ignored or skipped. However, the absence of an action shall not be valid, and the action <i>lex</i> takes in such a condition is
575 undefined.</p>
576 <p class="tent">The specification for an action, including C statements and special actions, can extend across several lines if
577 enclosed in braces:</p>
578 <pre>
579 <i>ERE</i><tt> <</tt><i>one or more blanks</i><tt>> { </tt><i>program statement
580 program statement</i><tt> }
581 </tt></pre>
582 <p class="tent">The program statements shall not contain unbalanced curly brace preprocessing tokens.</p>
583 <p class="tent">The default action when a string in the input to a <b>lex.yy.c</b> program is not matched by any expression shall
584 be to copy the string to the output. Because the default behavior of a program generated by <i>lex</i> is to read the input and
585 copy it to the output, a minimal <i>lex</i> source program that has just <tt>"%%"</tt> shall generate a C program that simply
586 copies the input to the output unchanged.</p>
587 <p class="tent">Four special actions shall be available:</p>
588 <pre>
589 <tt>| ECHO; REJECT; BEGIN
590 </tt></pre>
591 <dl compact>
592 <dd></dd>
593 <dt><tt>|</tt></dt>
594 <dd>The action <tt>'|'</tt> means that the action for the next rule is the action for this rule. Unlike the other three actions,
595 <tt>'|'</tt> cannot be enclosed in braces or be <semicolon>-terminated; the application shall ensure that it is specified
596 alone, with no other actions.</dd>
597 <dt><b>ECHO;</b></dt>
598 <dd>Write the contents of the string <i>yytext</i> on the output.</dd>
599 <dt><b>REJECT;</b></dt>
600 <dd>Usually only a single expression is matched by a given string in the input. <b>REJECT</b> means "continue to the next
601 expression that matches the current input", and shall cause whatever rule was the second choice after the current rule to be
602 executed for the same input. Thus, multiple rules can be matched and executed for one input string or overlapping input strings.
603 For example, given the regular expressions <tt>"xyz"</tt> and <tt>"xy"</tt> and the input <tt>"xyz"</tt>, usually only the regular
604 expression <tt>"xyz"</tt> would match. The next attempted match would start after <b>z.</b> If the last action in the
605 <tt>"xyz"</tt> rule is <b>REJECT</b>, both this rule and the <tt>"xy"</tt> rule would be executed. The <b>REJECT</b> action may be
606 implemented in such a fashion that flow of control does not continue after it, as if it were equivalent to a <b>goto</b> to another
607 part of <i>yylex</i>(). The use of <b>REJECT</b> may result in somewhat larger and slower scanners.</dd>
608 <dt><b>BEGIN</b></dt>
609 <dd>The action:
610 <pre>
611 <tt>BEGIN </tt><i>newstate</i><tt>;
612 </tt></pre>
613 <p class="tent">switches the state (start condition) to <i>newstate</i>. If the string <i>newstate</i> has not been declared
614 previously as a start condition in the <i>Definitions</i> section, the results are unspecified. The initial state is indicated by
615 the digit <tt>'0'</tt> or the token <b>INITIAL</b>.</p>
616 </dd>
617 </dl>
618 <p class="tent">The functions or macros described below are accessible to user code included in the <i>lex</i> input. It is
619 unspecified whether they appear in the C code output of <i>lex</i>, or are accessible only through the <b>-l l</b> operand to
620 <a href="../utilities/c17.html"><i>c17</i></a> (the <i>lex</i> library).</p>
621 <dl compact>
622 <dd></dd>
623 <dt><b>int </b><i>yylex</i>(<b>void</b>)</dt>
624 <dd><br>
625 Performs lexical analysis on the input; this is the primary function generated by the <i>lex</i> utility. The function shall return
626 zero when the end of input is reached; otherwise, it shall return non-zero values (tokens) determined by the actions that are
627 selected.</dd>
628 <dt><b>int </b><i>yymore</i>(<b>void</b>)</dt>
629 <dd><br>
630 When called, indicates that when the next input string is recognized, it is to be appended to the current value of <i>yytext</i>
631 rather than replacing it; the value in <i>yyleng</i> shall be adjusted accordingly.</dd>
632 <dt><b>int </b><i>yyless</i>(<b>int </b><i>n</i>)</dt>
633 <dd><br>
634 Retains <i>n</i> initial characters in <i>yytext</i>, NUL-terminated, and treats the remaining characters as if they had not been
635 read; the value in <i>yyleng</i> shall be adjusted accordingly.</dd>
636 <dt><b>int </b><i>input</i>(<b>void</b>)</dt>
637 <dd><br>
638 Returns the next character from the input, or zero on end-of-file. It shall obtain input from the stream pointer <i>yyin</i>,
639 although possibly via an intermediate buffer. Thus, once scanning has begun, the effect of altering the value of <i>yyin</i> is
640 undefined. The character read shall be removed from the input stream of the scanner without any processing by the scanner.</dd>
641 <dt><b>int </b><i>unput</i>(<b>int </b><i>c</i>)</dt>
642 <dd><br>
643 Returns the character <tt>'c'</tt> to the input; <i>yytext</i> and <i>yyleng</i> are undefined until the next expression is
644 matched. The result of using <i>unput</i>() for more characters than have been input is unspecified.</dd>
645 </dl>
646 <p class="tent">The following functions shall appear only in the <i>lex</i> library accessible through the <b>-l l</b>
647 operand; they can therefore be redefined by a conforming application:</p>
648 <dl compact>
649 <dd></dd>
650 <dt><b>int </b><i>yywrap</i>(<b>void</b>)</dt>
651 <dd><br>
652 Called by <i>yylex</i>() at end-of-file; the default <i>yywrap</i>() shall always return 1. If the application requires
653 <i>yylex</i>() to continue processing with another source of input, then the application can include a function <i>yywrap</i>(),
654 which associates another file with the external variable <b>FILE *</b> <i>yyin</i> and shall return a value of zero.</dd>
655 <dt><b>int </b><i>main</i>(<b>int </b><i>argc</i>, <b>char *</b><i>argv</i>[])</dt>
656 <dd><br>
657 Calls <i>yylex</i>() to perform lexical analysis, then exits. The user code can contain <i>main</i>() to perform
658 application-specific operations, calling <i>yylex</i>() as applicable.</dd>
659 </dl>
660 <p class="tent">Except for <i>input</i>(), <i>unput</i>(), and <i>main</i>(), all external and static names generated by <i>lex</i>
661 shall begin with the prefix <b>yy</b> or <b>YY</b>.</p>
662 </blockquote>
663 <h4 class="mansect"><a name="tag_20_65_14" id="tag_20_65_14"></a>EXIT STATUS</h4>
664 <blockquote>
665 <p>The following exit values shall be returned:</p>
666 <dl compact>
667 <dd></dd>
668 <dt> 0</dt>
669 <dd>Successful completion.</dd>
670 <dt>>0</dt>
671 <dd>An error occurred.</dd>
672 </dl>
673 </blockquote>
674 <h4 class="mansect"><a name="tag_20_65_15" id="tag_20_65_15"></a>CONSEQUENCES OF ERRORS</h4>
675 <blockquote>
676 <p>Default.</p>
677 </blockquote>
678 <hr>
679 <div class="box"><em>The following sections are informative.</em></div>
680 <h4 class="mansect"><a name="tag_20_65_16" id="tag_20_65_16"></a>APPLICATION USAGE</h4>
681 <blockquote>
682 <p>Conforming applications are warned that in the <i>Rules</i> section, an ERE without an action is not acceptable, but need not be
683 detected as erroneous by <i>lex</i>. This may result in compilation or runtime errors.</p>
684 <p class="tent">The purpose of <i>input</i>() is to take characters off the input stream and discard them as far as the lexical
685 analysis is concerned. A common use is to discard the body of a comment once the beginning of a comment is recognized.</p>
686 <p class="tent">The <i>lex</i> utility is not fully internationalized in its treatment of regular expressions in the <i>lex</i>
687 source code or generated lexical analyzer. It would seem desirable to have the lexical analyzer interpret the regular expressions
688 given in the <i>lex</i> source according to the environment specified when the lexical analyzer is executed, but this is not
689 possible with the current <i>lex</i> technology. Furthermore, the very nature of the lexical analyzers produced by <i>lex</i> must
690 be closely tied to the lexical requirements of the input language being described, which is frequently locale-specific anyway. (For
691 example, writing an analyzer that is used for French text is not automatically useful for processing other languages.)</p>
692 </blockquote>
693 <h4 class="mansect"><a name="tag_20_65_17" id="tag_20_65_17"></a>EXAMPLES</h4>
694 <blockquote>
695 <p>The following is an example of a <i>lex</i> program that implements a rudimentary scanner for a Pascal-like syntax:</p>
696 <pre>
697 <tt>%{
698 /* Need this for the call to atof() below. */
699 #include <math.h>
700 /* Need this for printf(), fopen(), and stdin below. */
701 #include <stdio.h>
702 %}
703 DIGIT [0-9]
704 ID [a-z][a-z0-9]*
705 %%
706 {DIGIT}+ {
707 printf("An integer: %s (%d)\n", yytext,
708 atoi(yytext));
709 }
710 {DIGIT}+"."{DIGIT}* {
711 printf("A float: %s (%g)\n", yytext,
712 atof(yytext));
713 }
714 if|then|begin|end|procedure|function {
715 printf("A keyword: %s\n", yytext);
716 }
717 {ID} printf("An identifier: %s\n", yytext);
718 "+"|"-"|"*"|"/" printf("An operator: %s\n", yytext);
719 "{"[^}\n]*"}" /* Eat up one-line comments. */
720 [ \t\n]+ /* Eat up white space. */
721 . printf("Unrecognized character: %s\n", yytext);
722 %%
723 int main(int argc, char *argv[])
724 {
725 ++argv, --argc; /* Skip over program name. */
726 if (argc > 0)
727 yyin = fopen(argv[0], "r");
728 else
729 yyin = stdin;
730 yylex();
731 }
732 </tt></pre></blockquote>
733 <h4 class="mansect"><a name="tag_20_65_18" id="tag_20_65_18"></a>RATIONALE</h4>
734 <blockquote>
735 <p>Even though references to the C language are retained in this description, <i>lex</i> may be generalized to other languages, as
736 was done at one time for EFL, the Extended FORTRAN Language. Since the <i>lex</i> input specification is essentially
737 language-independent, versions of this utility could be written to produce Ada, Modula-2, or Pascal code, and there are known
738 historical implementations that do so.</p>
739 <p class="tent">The current description of <i>lex</i> bypasses the issue of dealing with internationalized EREs in the <i>lex</i>
740 source code or generated lexical analyzer. If it follows the model used by <a href="../utilities/awk.html"><i>awk</i></a> (the
741 source code is assumed to be presented in the POSIX locale, but input and output are in the locale specified by the environment
742 variables), then the tables in the lexical analyzer produced by <i>lex</i> would interpret EREs specified in the <i>lex</i> source
743 in terms of the environment variables specified when <i>lex</i> was executed. The desired effect would be to have the lexical
744 analyzer interpret the EREs given in the <i>lex</i> source according to the environment specified when the lexical analyzer is
745 executed, but this is not possible with the current <i>lex</i> technology.</p>
746 <p class="tent">The description of octal and hexadecimal-digit escape sequences agrees with the ISO C standard use of escape
747 sequences.</p>
748 <p class="tent">Earlier versions of this standard allowed for implementations with bytes other than eight bits, but this has been
749 modified in this version.</p>
750 <p class="tent">There is no detailed output format specification. The observed behavior of <i>lex</i> under four different
751 historical implementations was that none of these implementations consistently reported the line numbers for error and warning
752 messages. Furthermore, there was a desire that <i>lex</i> be allowed to output additional diagnostic messages. Leaving message
753 formats unspecified avoids these formatting questions and problems with internationalization.</p>
754 <p class="tent">Although the <tt>%x</tt> specifier for <i>exclusive</i> start conditions is not historical practice, it is believed
755 to be a minor change to historical implementations and greatly enhances the usability of <i>lex</i> programs since it permits an
756 application to obtain the expected functionality with fewer statements.</p>
757 <p class="tent">The <b>%array</b> and <b>%pointer</b> declarations were added as a compromise between historical systems. The
758 System V-based <i>lex</i> copies the matched text to a <i>yytext</i> array. The <i>flex</i> program, supported in BSD and GNU
759 systems, uses a pointer. In the latter case, significant performance improvements are available for some scanners. Most historical
760 programs should require no change in porting from one system to another because the string being referenced is null-terminated in
761 both cases. (The method used by <i>flex</i> in its case is to null-terminate the token in place by remembering the character that
762 used to come right after the token and replacing it before continuing on to the next scan.) Multi-file programs with external
763 references to <i>yytext</i> outside the scanner source file should continue to operate on their historical systems, but would
764 require one of the new declarations to be considered strictly portable.</p>
765 <p class="tent">The description of EREs avoids unnecessary duplication of ERE details because their meanings within a <i>lex</i>
766 ERE are the same as that for the ERE in this volume of POSIX.1-2024.</p>
767 <p class="tent">The reason for the undefined condition associated with text beginning with a <blank> or within <tt>"%{"</tt>
768 and <tt>"%}"</tt> delimiter lines appearing in the <i>Rules</i> section is historical practice. Both the BSD and System V
769 <i>lex</i> copy the indented (or enclosed) input in the <i>Rules</i> section (except at the beginning) to unreachable areas of the
770 <i>yylex</i>() function (the code is written directly after a <a href="../utilities/V3_chap02.html#break"><i>break</i></a>
771 statement). In some cases, the System V <i>lex</i> generates an error message or a syntax error, depending on the form of indented
772 input.</p>
773 <p class="tent">The intention in breaking the list of functions into those that may appear in <b>lex.yy.c</b> <i>versus</i> those
774 that only appear in <b>libl.a</b> is that only those functions in <b>libl.a</b> can be reliably redefined by a conforming
775 application.</p>
776 <p class="tent">The descriptions of standard output and standard error are somewhat complicated because historical <i>lex</i>
777 implementations chose to issue diagnostic messages to standard output (unless <b>-t</b> was given). POSIX.1-2024 allows this
778 behavior, but leaves an opening for the more expected behavior of using standard error for diagnostics. Also, the System V behavior
779 of writing the statistics when any table sizes are given is allowed, while BSD-derived systems can avoid it. The programmer can
780 always precisely obtain the desired results by using either the <b>-t</b> or <b>-n</b> options.</p>
781 <p class="tent">The OPERANDS section does not mention the use of <b>-</b> as a synonym for standard input; not all historical
782 implementations support such usage for any of the <i>file</i> operands.</p>
783 <p class="tent">A description of the <i>translation table</i> was deleted from early proposals because of its relatively low usage
784 in historical applications.</p>
785 <p class="tent">The change to the definition of the <i>input</i>() function that allows buffering of input presents the opportunity
786 for major performance gains in some applications.</p>
787 <p class="tent">The following examples clarify the differences between <i>lex</i> regular expressions and regular expressions
788 appearing elsewhere in this volume of POSIX.1-2024. For regular expressions of the form <tt>"r/x"</tt>, the string matching
789 <i>r</i> is always returned; confusion may arise when the beginning of <i>x</i> matches the trailing portion of <i>r</i>. For
790 example, given the regular expression <tt>"a*b/cc"</tt> and the input <tt>"aaabcc"</tt>, <i>yytext</i> would contain the string
791 <tt>"aaab"</tt> on this match. But given the regular expression <tt>"x*/xy"</tt> and the input <tt>"xxxy"</tt>, the token
792 <b>xxx</b>, not <b>xx</b>, is returned by some implementations because <b>xxx</b> matches <tt>"x*"</tt>.</p>
793 <p class="tent">In the rule <tt>"ab*/bc"</tt>, the <tt>"b*"</tt> at the end of <i>r</i> extends <i>r</i>'s match into the beginning
794 of the trailing context, so the result is unspecified. If this rule were <tt>"ab/bc"</tt>, however, the rule matches the text
795 <tt>"ab"</tt> when it is followed by the text <tt>"bc"</tt>. In this latter case, the matching of <i>r</i> cannot extend into the
796 beginning of <i>x</i>, so the result is specified.</p>
797 </blockquote>
798 <h4 class="mansect"><a name="tag_20_65_19" id="tag_20_65_19"></a>FUTURE DIRECTIONS</h4>
799 <blockquote>
800 <p>None.</p>
801 </blockquote>
802 <h4 class="mansect"><a name="tag_20_65_20" id="tag_20_65_20"></a>SEE ALSO</h4>
803 <blockquote>
804 <p><a href="../utilities/c17.html#"><i>c17</i></a> , <a href="../utilities/ed.html#"><i>ed</i></a> , <a href=
805 "../utilities/yacc.html#"><i>yacc</i></a></p>
806 <p class="tent">XBD <a href="../basedefs/V1_chap05.html#tag_05"><i>5. File Format Notation</i></a> , <a href=
807 "../basedefs/V1_chap08.html#tag_08"><i>8. Environment Variables</i></a> , <a href="../basedefs/V1_chap09.html#tag_09"><i>9. Regular
808 Expressions</i></a> , <a href="../basedefs/V1_chap12.html#tag_12_02"><i>12.2 Utility Syntax Guidelines</i></a></p>
809 </blockquote>
810 <h4 class="mansect"><a name="tag_20_65_21" id="tag_20_65_21"></a>CHANGE HISTORY</h4>
811 <blockquote>
812 <p>First released in Issue 2.</p>
813 </blockquote>
814 <h4 class="mansect"><a name="tag_20_65_22" id="tag_20_65_22"></a>Issue 6</h4>
815 <blockquote>
816 <p>This utility is marked as part of the C-Language Development Utilities option.</p>
817 <p class="tent">The obsolescent <b>-c</b> option is removed.</p>
818 <p class="tent">The normative text is reworded to avoid use of the term "must" for application requirements.</p>
819 <p class="tent">IEEE Std 1003.1-2001/Cor 2-2004, item XCU/TC2/D6/14 is applied, removing text describing behavior on
820 systems with bytes consisting of more than eight bits.</p>
821 </blockquote>
822 <h4 class="mansect"><a name="tag_20_65_23" id="tag_20_65_23"></a>Issue 7</h4>
823 <blockquote>
824 <p>Austin Group Interpretation 1003.1-2001 #190 is applied, clarifying the requirements for generated code to conform to the
825 ISO C standard.</p>
826 <p class="tent">Austin Group Interpretation 1003.1-2001 #191 is applied, clarifying the handling of C-language trigraphs and curly
827 brace preprocessing tokens.</p>
828 <p class="tent">SD5-XCU-ERN-6 is applied, clarifying that Guideline 9 of the Utility Syntax Guidelines does not apply.</p>
829 <p class="tent">SD5-XCU-ERN-97 is applied, updating the SYNOPSIS.</p>
830 </blockquote>
831 <h4 class="mansect"><a name="tag_20_65_24" id="tag_20_65_24"></a>Issue 8</h4>
832 <blockquote>
833 <p>Austin Group Defect 1122 is applied, changing the description of <i>NLSPATH .</i></p>
834 <p class="tent">Austin Group Defect 1453 is applied, changing the ENVIRONMENT VARIABLES section.</p>
835 <p class="tent">Austin Group Defect 1517 is applied, removing a reference to the <b>-c</b> option from the RATIONALE section.</p>
836 </blockquote>
837 <div class="box"><em>End of informative text.</em></div>
838 <hr>
839 <p> </p>
840 <a href="#top"><span class="topOfPage">return to top of page</span></a><br>
841 <hr size="2" noshade>
842 <center><font size="2">UNIX® is a registered Trademark of The Open Group.<br>
843 POSIX™ is a Trademark of The IEEE.<br>
844 Copyright © 2001-2024 The IEEE and The Open Group, All Rights Reserved<br>
845 [ <a href="../mindex.html">Main Index</a> | <a href="../basedefs/contents.html">XBD</a> | <a href=
846 "../functions/contents.html">XSH</a> | <a href="../utilities/contents.html">XCU</a> | <a href="../xrat/contents.html">XRAT</a>
847 ]</font></center>
848 <hr size="2" noshade>
849 <div class="NAVHEADER">
850 <table summary="Header navigation table" class="nav" width="100%" border="0" cellpadding="0" cellspacing="0">
851 <tr class="nav">
852 <td class="nav" width="15%" align="left" valign="bottom"><a href="../utilities/kill.html" accesskey="P"><<<
853 Previous</a></td>
854 <td class="nav" width="70%" align="center" valign="bottom"><a href="contents.html">Home</a></td>
855 <td class="nav" width="15%" align="right" valign="bottom"><a href="../utilities/link.html" accesskey="N">Next >>></a></td>
856 </tr>
857 </table>
858 <hr align="left" width="100%"></div>
859 </body>
860 </html>