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23 <script language="JavaScript" src="../jscript/codes.js"></script><basefont size="3">
24 <center><font size="2">The Open Group Base Specifications Issue 8<br>
25 IEEE Std 1003.1-2024<br>
26 Copyright © 2001-2024 The IEEE and The Open Group</font></center>
27 <hr size="2" noshade>
28 <a name="top" id="top"></a> <a name="unexpand" id="unexpand"></a> <a name="tag_20_136" id="tag_20_136"></a><!-- unexpand -->
29 <h4 class="mansect"><a name="tag_20_136_01" id="tag_20_136_01"></a>NAME</h4>
30 <blockquote>unexpand — convert spaces to tabs</blockquote>
31 <h4 class="mansect"><a name="tag_20_136_02" id="tag_20_136_02"></a>SYNOPSIS</h4>
32 <blockquote class="synopsis">
33 <p><code><tt>unexpand</tt> <b>[</b><tt>-a|-t</tt> <i>tablist</i><b>] [</b><i>file</i><tt>...</tt><b>]</b></code></p>
34 </blockquote>
35 <h4 class="mansect"><a name="tag_20_136_03" id="tag_20_136_03"></a>DESCRIPTION</h4>
36 <blockquote>
37 <p>The <i>unexpand</i> utility shall copy files or standard input to standard output, converting <blank> characters at the
38 beginning of each line into the maximum number of <tab> characters followed by the minimum number of <space> characters
39 needed to fill the same column positions originally filled by the translated <blank> characters. By default, tabstops shall
40 be set at every eighth column position. Each <backspace> shall be copied to the output, and shall cause the column position
41 count for tab calculations to be decremented; the count shall never be decremented to a value less than one.</p>
42 </blockquote>
43 <h4 class="mansect"><a name="tag_20_136_04" id="tag_20_136_04"></a>OPTIONS</h4>
44 <blockquote>
45 <p>The <i>unexpand</i> utility shall conform to XBD <a href="../basedefs/V1_chap12.html#tag_12_02"><i>12.2 Utility Syntax
46 Guidelines</i></a> .</p>
47 <p>The following options shall be supported:</p>
48 <dl compact>
49 <dd></dd>
50 <dt><b>-a</b></dt>
51 <dd>In addition to translating <blank> characters at the beginning of each line, translate all sequences of two or more
52 <blank> characters immediately preceding a tab stop to the maximum number of <tab> characters followed by the minimum
53 number of <space> characters needed to fill the same column positions originally filled by the translated <blank>
54 characters.</dd>
55 <dt><b>-t </b><i>tablist</i></dt>
56 <dd>Specify the tab stops. The application shall ensure that the <i>tablist</i> option-argument is a single argument consisting of
57 a single positive decimal integer or multiple positive decimal integers, separated by <blank> or <comma> characters, in
58 ascending order. If a single number is given, tabs shall be set <i>tablist</i> column positions apart instead of the default 8. If
59 multiple numbers are given, the tabs shall be set at those specific column positions.
60 <p>The application shall ensure that each tab-stop position <i>N</i> is an integer value greater than zero, and the list shall be
61 in strictly ascending order. This is taken to mean that, from the start of a line of output, tabbing to position <i>N</i> shall
62 cause the next character output to be in the (<i>N</i>+1)th column position on that line. When the <b>-t</b> option is not
63 specified, the default shall be the equivalent of specifying <b>-t 8</b> (except for the interaction with <b>-a</b>, described
64 below).</p>
65 <p>No <space>-to-<tab> conversions shall occur for characters at positions beyond the last of those specified in a
66 multiple tab-stop list.</p>
67 <p>When <b>-t</b> is specified, the presence or absence of the <b>-a</b> option shall be ignored; conversion shall not be limited
68 to the processing of leading <blank> characters.</p>
69 </dd>
70 </dl>
71 </blockquote>
72 <h4 class="mansect"><a name="tag_20_136_05" id="tag_20_136_05"></a>OPERANDS</h4>
73 <blockquote>
74 <p>The following operand shall be supported:</p>
75 <dl compact>
76 <dd></dd>
77 <dt><i>file</i></dt>
78 <dd>A pathname of a text file to be used as input.</dd>
79 </dl>
80 </blockquote>
81 <h4 class="mansect"><a name="tag_20_136_06" id="tag_20_136_06"></a>STDIN</h4>
82 <blockquote>
83 <p>See the INPUT FILES section.</p>
84 </blockquote>
85 <h4 class="mansect"><a name="tag_20_136_07" id="tag_20_136_07"></a>INPUT FILES</h4>
86 <blockquote>
87 <p>The input files shall be text files.</p>
88 </blockquote>
89 <h4 class="mansect"><a name="tag_20_136_08" id="tag_20_136_08"></a>ENVIRONMENT VARIABLES</h4>
90 <blockquote>
91 <p>The following environment variables shall affect the execution of <i>unexpand</i>:</p>
92 <dl compact>
93 <dd></dd>
94 <dt><i>LANG</i></dt>
95 <dd>Provide a default value for the internationalization variables that are unset or null. (See XBD <a href=
96 "../basedefs/V1_chap08.html#tag_08_02"><i>8.2 Internationalization Variables</i></a> for the precedence of internationalization
97 variables used to determine the values of locale categories.)</dd>
98 <dt><i>LC_ALL</i></dt>
99 <dd>If set to a non-empty string value, override the values of all the other internationalization variables.</dd>
100 <dt><i>LC_CTYPE</i></dt>
101 <dd>Determine the locale for the interpretation of sequences of bytes of text data as characters (for example, single-byte as
102 opposed to multi-byte characters in arguments and input files), the processing of <tab> and <space> characters, and for
103 the determination of the width in column positions each character would occupy on an output device.</dd>
104 <dt><i>LC_MESSAGES</i></dt>
105 <dd><br>
106 Determine the locale that should be used to affect the format and contents of diagnostic messages written to standard error.</dd>
107 <dt><i>NLSPATH</i></dt>
108 <dd><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
109 Determine the location of messages objects and message catalogs. <img src="../images/opt-end.gif" alt="[Option End]" border=
110 "0"></dd>
111 </dl>
112 </blockquote>
113 <h4 class="mansect"><a name="tag_20_136_09" id="tag_20_136_09"></a>ASYNCHRONOUS EVENTS</h4>
114 <blockquote>
115 <p>Default.</p>
116 </blockquote>
117 <h4 class="mansect"><a name="tag_20_136_10" id="tag_20_136_10"></a>STDOUT</h4>
118 <blockquote>
119 <p>The standard output shall be equivalent to the input files with the specified <space>-to-<tab> conversions.</p>
120 </blockquote>
121 <h4 class="mansect"><a name="tag_20_136_11" id="tag_20_136_11"></a>STDERR</h4>
122 <blockquote>
123 <p>The standard error shall be used only for diagnostic messages.</p>
124 </blockquote>
125 <h4 class="mansect"><a name="tag_20_136_12" id="tag_20_136_12"></a>OUTPUT FILES</h4>
126 <blockquote>
127 <p>None.</p>
128 </blockquote>
129 <h4 class="mansect"><a name="tag_20_136_13" id="tag_20_136_13"></a>EXTENDED DESCRIPTION</h4>
130 <blockquote>
131 <p>None.</p>
132 </blockquote>
133 <h4 class="mansect"><a name="tag_20_136_14" id="tag_20_136_14"></a>EXIT STATUS</h4>
134 <blockquote>
135 <p>The following exit values shall be returned:</p>
136 <dl compact>
137 <dd></dd>
138 <dt> 0</dt>
139 <dd>Successful completion.</dd>
140 <dt>>0</dt>
141 <dd>An error occurred.</dd>
142 </dl>
143 </blockquote>
144 <h4 class="mansect"><a name="tag_20_136_15" id="tag_20_136_15"></a>CONSEQUENCES OF ERRORS</h4>
145 <blockquote>
146 <p>Default.</p>
147 </blockquote>
148 <hr>
149 <div class="box"><em>The following sections are informative.</em></div>
150 <h4 class="mansect"><a name="tag_20_136_16" id="tag_20_136_16"></a>APPLICATION USAGE</h4>
151 <blockquote>
152 <p>One non-intuitive aspect of <i>unexpand</i> is its restriction to leading <space> characters when neither <b>-a</b> nor
153 <b>-t</b> is specified. Users who always want to convert all <space> characters in a file can easily alias <i>unexpand</i> to
154 use the <b>-a</b> or <b>-t 8</b> option.</p>
155 </blockquote>
156 <h4 class="mansect"><a name="tag_20_136_17" id="tag_20_136_17"></a>EXAMPLES</h4>
157 <blockquote>
158 <p>None.</p>
159 </blockquote>
160 <h4 class="mansect"><a name="tag_20_136_18" id="tag_20_136_18"></a>RATIONALE</h4>
161 <blockquote>
162 <p>On several occasions, consideration was given to adding a <b>-t</b> option to the <i>unexpand</i> utility to complement the
163 <b>-t</b> in <a href="../utilities/expand.html"><i>expand</i></a> (see <a href="../utilities/expand.html#"><i>expand</i></a> ). The
164 historical intent of <i>unexpand</i> was to translate multiple <blank> characters into tab stops, where tab stops were a
165 multiple of eight column positions on most UNIX systems. An early proposal omitted <b>-t</b> because it seemed outside the scope of
166 the User Portability Utilities option; it was not described in any of the base documents for IEEE Std 1003.2-1992.
167 However, hard-coding tab stops every eight columns was not suitable for the international community and broke historical precedents
168 for some vendors in the FORTRAN community, so <b>-t</b> was restored in conjunction with the list of valid extension categories
169 considered by the standard developers. Thus, <i>unexpand</i> is now the logical converse of <a href=
170 "../utilities/expand.html"><i>expand</i></a>.</p>
171 </blockquote>
172 <h4 class="mansect"><a name="tag_20_136_19" id="tag_20_136_19"></a>FUTURE DIRECTIONS</h4>
173 <blockquote>
174 <p>None.</p>
175 </blockquote>
176 <h4 class="mansect"><a name="tag_20_136_20" id="tag_20_136_20"></a>SEE ALSO</h4>
177 <blockquote>
178 <p><a href="../utilities/expand.html#"><i>expand</i></a> , <a href="../utilities/tabs.html#"><i>tabs</i></a></p>
179 <p>XBD <a href="../basedefs/V1_chap08.html#tag_08"><i>8. Environment Variables</i></a> , <a href=
180 "../basedefs/V1_chap12.html#tag_12_02"><i>12.2 Utility Syntax Guidelines</i></a></p>
181 </blockquote>
182 <h4 class="mansect"><a name="tag_20_136_21" id="tag_20_136_21"></a>CHANGE HISTORY</h4>
183 <blockquote>
184 <p>First released in Issue 4.</p>
185 </blockquote>
186 <h4 class="mansect"><a name="tag_20_136_22" id="tag_20_136_22"></a>Issue 6</h4>
187 <blockquote>
188 <p>This utility is marked as part of the User Portability Utilities option.</p>
189 <p>The definition of the <i>LC_CTYPE</i> environment variable is changed to align with the IEEE P1003.2b draft standard.</p>
190 <p>The normative text is reworded to avoid use of the term "must" for application requirements.</p>
191 </blockquote>
192 <h4 class="mansect"><a name="tag_20_136_23" id="tag_20_136_23"></a>Issue 7</h4>
193 <blockquote>
194 <p>The <i>unexpand</i> utility is moved from the User Portability Utilities option to the Base. User Portability Utilities is now
195 an option for interactive utilities.</p>
196 <p>SD5-XCU-ERN-97 is applied, updating the SYNOPSIS.</p>
197 <p>POSIX.1-2008, Technical Corrigendum 2, XCU/TC2-2008/0198 [885] is applied.</p>
198 </blockquote>
199 <h4 class="mansect"><a name="tag_20_136_24" id="tag_20_136_24"></a>Issue 8</h4>
200 <blockquote>
201 <p>Austin Group Defect 1122 is applied, changing the description of <i>NLSPATH .</i></p>
202 </blockquote>
203 <div class="box"><em>End of informative text.</em></div>
204 <hr>
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