249 lines
8.1 KiB
HTML
249 lines
8.1 KiB
HTML
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<link type="text/css" rel="stylesheet" href="style.css"><!-- Generated by The Open Group's rhtm tool v1.2.1 -->
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<!-- Copyright (c) 2001 The Open Group, All Rights Reserved -->
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<title>getsubopt</title>
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</head>
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<body bgcolor="white">
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<script type="text/javascript" language="JavaScript" src="../jscript/codes.js">
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<basefont size="3"> <a name="getsubopt"></a> <a name="tag_03_253"></a><!-- getsubopt -->
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<!--header start-->
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<center><font size="2">The Open Group Base Specifications Issue 6<br>
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IEEE Std 1003.1-2001<br>
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Copyright © 2001 The IEEE and The Open Group, All Rights reserved.</font></center>
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<!--header end-->
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<hr size="2" noshade>
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<h4><a name="tag_03_253_01"></a>NAME</h4>
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<blockquote>getsubopt - parse suboption arguments from a string</blockquote>
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<h4><a name="tag_03_253_02"></a>SYNOPSIS</h4>
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<blockquote class="synopsis">
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<div class="box"><code><tt><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt=
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"[Option Start]" border="0"> #include <<a href="../basedefs/stdlib.h.html">stdlib.h</a>><br>
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<br>
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int getsubopt(char **</tt><i>optionp</i><tt>, char * const *</tt><i>tokens</i><tt>, char **</tt><i>valuep</i><tt>); <img src=
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"../images/opt-end.gif" alt="[Option End]" border="0"></tt></code></div>
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<tt><br>
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</tt></blockquote>
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<h4><a name="tag_03_253_03"></a>DESCRIPTION</h4>
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<blockquote>
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<p>The <i>getsubopt</i>() function shall parse suboption arguments in a flag argument. Such options often result from the use of <a
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href="../functions/getopt.html"><i>getopt</i>()</a>.</p>
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<p>The <i>getsubopt</i>() argument <i>optionp</i> is a pointer to a pointer to the option argument string. The suboption arguments
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shall be separated by commas and each may consist of either a single token, or a token-value pair separated by an equal sign.</p>
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<p>The <i>keylistp</i> argument shall be a pointer to a vector of strings. The end of the vector is identified by a null pointer.
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Each entry in the vector is one of the possible tokens that might be found in *<i>optionp</i>. Since commas delimit suboption
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arguments in <i>optionp</i>, they should not appear in any of the strings pointed to by <i>keylistp</i>. Similarly, because an
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equal sign separates a token from its value, the application should not include an equal sign in any of the strings pointed to by
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<i>keylistp</i>.</p>
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<p>The <i>valuep</i> argument is the address of a value string pointer.</p>
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<p>If a comma appears in <i>optionp</i>, it shall be interpreted as a suboption separator. After commas have been processed, if
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there are one or more equal signs in a suboption string, the first equal sign in any suboption string shall be interpreted as a
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separator between a token and a value. Subsequent equal signs in a suboption string shall be interpreted as part of the value.</p>
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<p>If the string at *<i>optionp</i> contains only one suboption argument (equivalently, no commas), <i>getsubopt</i>() shall update
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*<i>optionp</i> to point to the null character at the end of the string. Otherwise, it shall isolate the suboption argument by
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replacing the comma separator with a null character, and shall update *<i>optionp</i> to point to the start of the next suboption
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argument. If the suboption argument has an associated value (equivalently, contains an equal sign), <i>getsubopt</i>() shall update
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*<i>valuep</i> to point to the value's first character. Otherwise, it shall set *<i>valuep</i> to a null pointer. The calling
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application may use this information to determine whether the presence or absence of a value for the suboption is an error.</p>
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<p>Additionally, when <i>getsubopt</i>() fails to match the suboption argument with a token in the <i>keylistp</i> array, the
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calling application should decide if this is an error, or if the unrecognized option should be processed in another way.</p>
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</blockquote>
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<h4><a name="tag_03_253_04"></a>RETURN VALUE</h4>
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<blockquote>
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<p>The <i>getsubopt</i>() function shall return the index of the matched token string, or -1 if no token strings were matched.</p>
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</blockquote>
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<h4><a name="tag_03_253_05"></a>ERRORS</h4>
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<blockquote>
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<p>No errors are defined.</p>
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</blockquote>
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<hr>
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<div class="box"><em>The following sections are informative.</em></div>
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<h4><a name="tag_03_253_06"></a>EXAMPLES</h4>
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<blockquote>
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<pre>
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<tt>#include <stdio.h>
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#include <stdlib.h>
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<br>
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int do_all;
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const char *type;
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int read_size;
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int write_size;
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int read_only;
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<br>
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enum
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{
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RO_OPTION = 0,
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RW_OPTION,
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READ_SIZE_OPTION,
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WRITE_SIZE_OPTION
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};
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<br>
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const char *mount_opts[] =
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{
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[RO_OPTION] = "ro",
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[RW_OPTION] = "rw",
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[READ_SIZE_OPTION] = "rsize",
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[WRITE_SIZE_OPTION] = "wsize",
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NULL
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};
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<br>
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int
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main(int argc, char *argv[])
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{
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char *subopts, *value;
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int opt;
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<br>
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while ((opt = getopt(argc, argv, "at:o:")) != -1)
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switch(opt)
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{
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case 'a':
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do_all = 1;
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break;
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case 't':
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type = optarg;
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break;
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case 'o':
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subopts = optarg;
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while (*subopts != '\0')
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switch(getsubopt(&subopts, mount_opts, &value))
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{
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case RO_OPTION:
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read_only = 1;
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break;
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case RW_OPTION:
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read_only = 0;
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break;
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case READ_SIZE_OPTION:
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if (value == NULL)
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abort();
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read_size = atoi(value);
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break;
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case WRITE_SIZE_OPTION:
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if (value == NULL)
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abort();
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write_size = atoi(value);
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break;
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default:
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/* Unknown suboption. */
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printf("Unknown suboption `%s'\n", value);
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break;
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}
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break;
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default:
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abort();
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}
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<br>
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/* Do the real work. */
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<br>
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return 0;
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}
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</tt>
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</pre>
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<h5><a name="tag_03_253_06_01"></a>Parsing Suboptions</h5>
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<p>The following example uses the <i>getsubopt</i>() function to parse a <i>value</i> argument in the <i>optarg</i> external
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variable returned by a call to <a href="../functions/getopt.html"><i>getopt</i>()</a>.</p>
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<pre>
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<tt>#include <stdlib.h>
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...
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char *tokens[] = {"HOME", "PATH", "LOGNAME", (char *) NULL };
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char *value;
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int opt, index;
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<br>
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while ((opt = getopt(argc, argv, "e:")) != -1) {
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switch(opt) {
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case 'e' :
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while ((index = getsubopt(&optarg, tokens, &value)) != -1) {
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switch(index) {
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...
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}
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break;
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...
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}
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}
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...
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</tt>
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</pre>
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</blockquote>
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<h4><a name="tag_03_253_07"></a>APPLICATION USAGE</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_253_08"></a>RATIONALE</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_253_09"></a>FUTURE DIRECTIONS</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_253_10"></a>SEE ALSO</h4>
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<blockquote>
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<p><a href="getopt.html"><i>getopt</i>()</a> , the Base Definitions volume of IEEE Std 1003.1-2001, <a href=
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"../basedefs/stdlib.h.html"><i><stdlib.h></i></a></p>
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</blockquote>
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<h4><a name="tag_03_253_11"></a>CHANGE HISTORY</h4>
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<blockquote>
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<p>First released in Issue 4, Version 2.</p>
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</blockquote>
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<h4><a name="tag_03_253_12"></a>Issue 5</h4>
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<blockquote>
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<p>Moved from X/OPEN UNIX extension to BASE.</p>
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</blockquote>
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<div class="box"><em>End of informative text.</em></div>
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<hr>
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<hr size="2" noshade>
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<center><font size="2"><!--footer start-->
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UNIX ® is a registered Trademark of The Open Group.<br>
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POSIX ® is a registered Trademark of The IEEE.<br>
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[ <a href="../mindex.html">Main Index</a> | <a href="../basedefs/contents.html">XBD</a> | <a href=
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"../utilities/contents.html">XCU</a> | <a href="../functions/contents.html">XSH</a> | <a href="../xrat/contents.html">XRAT</a>
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]</font></center>
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