212 lines
6.1 KiB
HTML
212 lines
6.1 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>tzset</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="tzset"></a> <a name="tag_03_795"></a><!-- tzset -->
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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_795_01"></a>NAME</h4>
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<blockquote>daylight, timezone, tzname, tzset - set timezone conversion information</blockquote>
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<h4><a name="tag_03_795_02"></a>SYNOPSIS</h4>
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<blockquote class="synopsis">
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<p><code><tt>#include <<a href="../basedefs/time.h.html">time.h</a>><br>
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<br>
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</tt></code></p>
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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"> extern int daylight;<br>
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extern long timezone;<br>
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<img src="../images/opt-end.gif" alt="[Option End]" border="0"></tt></code></div>
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<div class="box"><code><tt><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt=
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"[Option Start]" border="0"> extern char *tzname[2];<br>
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void tzset(void); <img src="../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_795_03"></a>DESCRIPTION</h4>
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<blockquote>
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<p>The <i>tzset</i>() function shall use the value of the environment variable <i>TZ</i> to set time conversion information used by
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<a href="ctime.html"><i>ctime</i>()</a> , <a href="localtime.html"><i>localtime</i>()</a> , <a href=
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"mktime.html"><i>mktime</i>()</a> , and <a href="strftime.html"><i>strftime</i>()</a> . If <i>TZ</i> is absent from the
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environment, implementation-defined default timezone information shall be used.</p>
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<p>The <i>tzset</i>() function shall set the external variable <i>tzname</i> as follows:</p>
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<pre>
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<tt>tzname[0] = "</tt><i>std</i><tt>";
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tzname[1] = "</tt><i>dst</i><tt>";
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</tt>
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</pre>
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<p>where <i>std</i> and <i>dst</i> are as described in the Base Definitions volume of IEEE Std 1003.1-2001, <a href=
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"../basedefs/xbd_chap08.html">Chapter 8, Environment Variables</a>.</p>
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<p><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
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The <i>tzset</i>() function also shall set the external variable <i>daylight</i> to 0 if Daylight Savings Time conversions should
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never be applied for the timezone in use; otherwise, non-zero. The external variable <i>timezone</i> shall be set to the
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difference, in seconds, between Coordinated Universal Time (UTC) and local standard time. <img src="../images/opt-end.gif" alt=
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"[Option End]" border="0"></p>
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</blockquote>
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<h4><a name="tag_03_795_04"></a>RETURN VALUE</h4>
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<blockquote>
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<p>The <i>tzset</i>() function shall not return a value.</p>
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</blockquote>
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<h4><a name="tag_03_795_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_795_06"></a>EXAMPLES</h4>
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<blockquote>
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<p>Example <i>TZ</i> variables and their timezone differences are given in the table below:</p>
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<table border="1" cellpadding="3">
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<tr valign="top">
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<th align="center">
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<p class="tent">TZ</p>
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</th>
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<th align="center">
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<p class="tent">timezone</p>
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</th>
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</tr>
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<tr valign="top">
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<td align="left">
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<p class="tent">EST5EDT</p>
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</td>
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<td align="left">
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<p class="tent">5*60*60</p>
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</td>
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</tr>
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<tr valign="top">
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<td align="left">
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<p class="tent">GMT0</p>
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</td>
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<td align="left">
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<p class="tent">0*60*60</p>
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</td>
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</tr>
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<tr valign="top">
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<td align="left">
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<p class="tent">JST-9</p>
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</td>
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<td align="left">
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<p class="tent">-9*60*60</p>
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</td>
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</tr>
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<tr valign="top">
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<td align="left">
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<p class="tent">MET-1MEST</p>
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</td>
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<td align="left">
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<p class="tent">-1*60*60</p>
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</td>
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</tr>
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<tr valign="top">
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<td align="left">
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<p class="tent">MST7MDT</p>
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</td>
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<td align="left">
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<p class="tent">7*60*60</p>
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</td>
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</tr>
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<tr valign="top">
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<td align="left">
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<p class="tent">PST8PDT</p>
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</td>
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<td align="left">
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<p class="tent">8*60*60</p>
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</td>
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</tr>
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</table>
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</blockquote>
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<h4><a name="tag_03_795_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_795_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_795_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_795_10"></a>SEE ALSO</h4>
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<blockquote>
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<p><a href="ctime.html"><i>ctime</i>()</a> , <a href="localtime.html"><i>localtime</i>()</a> , <a href=
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"mktime.html"><i>mktime</i>()</a> , <a href="strftime.html"><i>strftime</i>()</a> , the Base Definitions volume of
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IEEE Std 1003.1-2001, <a href="../basedefs/xbd_chap08.html">Chapter 8, Environment Variables</a>, <a href=
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"../basedefs/time.h.html"><i><time.h></i></a></p>
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</blockquote>
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<h4><a name="tag_03_795_11"></a>CHANGE HISTORY</h4>
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<blockquote>
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<p>First released in Issue 1. Derived from Issue 1 of the SVID.</p>
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</blockquote>
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<h4><a name="tag_03_795_12"></a>Issue 6</h4>
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<blockquote>
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<p>The example is corrected.</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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