166 lines
4.1 KiB
HTML
166 lines
4.1 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of TIMEGM</TITLE>
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</HEAD><BODY>
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<H1>TIMEGM</H1>
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Section: Linux Programmer's Manual (3)<BR>Updated: 2016-12-12<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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timegm, timelocal - inverses of gmtime and localtime
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<PRE>
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<B>#include <<A HREF="file:///usr/include/time.h">time.h</A>></B>
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<B>time_t timelocal(struct tm *</B><I>tm</I><B>);</B>
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<B>time_t timegm(struct tm *</B><I>tm</I><B>);</B>
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</PRE>
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Feature Test Macro Requirements for glibc (see
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<B><A HREF="/cgi-bin/man/man2html?7+feature_test_macros">feature_test_macros</A></B>(7)):
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<P>
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<B>timelocal</B>(),
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<B>timegm</B>():
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<BR> Since glibc 2.19:
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<BR> _DEFAULT_SOURCE
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<BR> Glibc 2.19 and earlier:
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<BR> _BSD_SOURCE || _SVID_SOURCE
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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The functions
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<B>timelocal</B>()
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and
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<B>timegm</B>()
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are the inverses of
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<B><A HREF="/cgi-bin/man/man2html?3+localtime">localtime</A></B>(3)
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and
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<B><A HREF="/cgi-bin/man/man2html?3+gmtime">gmtime</A></B>(3).
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Both functions take a broken-down time and convert it to calendar time
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(seconds since the Epoch, 1970-01-01 00:00:00 +0000, UTC).
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The difference between the two functions is that
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<B>timelocal</B>()
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takes the local timezone into account when doing the conversion, while
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<B>timegm</B>()
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takes the input value to be Coordinated Universal Time (UTC).
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<A NAME="lbAE"> </A>
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<H2>RETURN VALUE</H2>
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On success,
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these functions return the calendar time (seconds since the Epoch),
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expressed as a value of type
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<I>time_t</I>.
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On error, they return the value
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<I>(time_t) -1</I>
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and set
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<I>errno</I>
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to indicate the cause of the error.
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<A NAME="lbAF"> </A>
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<H2>ERRORS</H2>
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<DL COMPACT>
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<DT id="1"><B>EOVERFLOW</B>
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<DD>
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The result cannot be represented.
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</DL>
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<A NAME="lbAG"> </A>
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<H2>ATTRIBUTES</H2>
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For an explanation of the terms used in this section, see
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<B><A HREF="/cgi-bin/man/man2html?7+attributes">attributes</A></B>(7).
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<TABLE BORDER>
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<TR VALIGN=top><TD><B>Interface</B></TD><TD><B>Attribute</B></TD><TD><B>Value</B><BR></TD></TR>
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<TR VALIGN=top><TD>
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<B>timelocal</B>(),
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<B>timegm</B>()
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</TD><TD>Thread safety</TD><TD>MT-Safe env locale<BR></TD></TR>
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</TABLE>
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<A NAME="lbAH"> </A>
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<H2>CONFORMING TO</H2>
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These functions are nonstandard GNU extensions
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that are also present on the BSDs.
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Avoid their use.
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<A NAME="lbAI"> </A>
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<H2>NOTES</H2>
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The
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<B>timelocal</B>()
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function is equivalent to the POSIX standard function
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<B><A HREF="/cgi-bin/man/man2html?3+mktime">mktime</A></B>(3).
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There is no reason to ever use it.
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<A NAME="lbAJ"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?3+gmtime">gmtime</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+localtime">localtime</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+mktime">mktime</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+tzset">tzset</A></B>(3)
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<A NAME="lbAK"> </A>
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<H2>COLOPHON</H2>
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This page is part of release 5.05 of the Linux
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<I>man-pages</I>
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project.
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A description of the project,
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information about reporting bugs,
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and the latest version of this page,
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can be found at
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<A HREF="https://www.kernel.org/doc/man-pages/.">https://www.kernel.org/doc/man-pages/.</A>
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="2"><A HREF="#lbAB">NAME</A><DD>
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<DT id="3"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="4"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="5"><A HREF="#lbAE">RETURN VALUE</A><DD>
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<DT id="6"><A HREF="#lbAF">ERRORS</A><DD>
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<DT id="7"><A HREF="#lbAG">ATTRIBUTES</A><DD>
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<DT id="8"><A HREF="#lbAH">CONFORMING TO</A><DD>
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<DT id="9"><A HREF="#lbAI">NOTES</A><DD>
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<DT id="10"><A HREF="#lbAJ">SEE ALSO</A><DD>
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<DT id="11"><A HREF="#lbAK">COLOPHON</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:05:58 GMT, March 31, 2021
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</BODY>
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</HTML>
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