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.\" Copyright (C) 2001 Andries Brouwer <aeb@cwi.nl>
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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2007-04-12 22:42:49 +00:00
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.\"
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2004-11-03 13:51:07 +00:00
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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2007-04-12 22:42:49 +00:00
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.\"
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2004-11-03 13:51:07 +00:00
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\"
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2007-07-08 12:11:40 +00:00
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.TH TIMEGM 3 2007-07-26 "GNU" "Linux Programmer's Manual"
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2004-11-03 13:51:07 +00:00
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.SH NAME
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2007-06-12 04:59:43 +00:00
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timegm, timelocal \- inverses of gmtime and localtime
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2004-11-03 13:51:07 +00:00
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.SH SYNOPSIS
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.nf
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.B #include <time.h>
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.sp
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2007-04-03 15:32:52 +00:00
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.BI "time_t timelocal(struct tm *" tm );
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2004-11-03 13:51:07 +00:00
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.sp
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2007-04-03 15:32:52 +00:00
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.BI "time_t timegm(struct tm *" tm );
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2007-07-08 12:11:40 +00:00
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.sp
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.fi
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.in -4n
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Feature Test Macro Requirements for glibc (see
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.BR feature_test_macros (7)):
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.in
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.sp
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.BR timelocal (),
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.BR timegm ():
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_BSD_SOURCE || _SVID_SOURCE
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2004-11-03 13:51:07 +00:00
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.SH DESCRIPTION
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The functions
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2005-10-19 07:07:02 +00:00
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.BR timelocal ()
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and
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.BR timegm ()
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are the inverses of
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2004-11-03 13:51:07 +00:00
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.BR localtime (3)
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and
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.BR gmtime (3).
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2007-05-19 04:30:20 +00:00
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.SH "CONFORMING TO"
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accept.2, execve.2, futimesat.2, getresuid.2, getrlimit.2, madvise.2, mq_getsetattr.2, msgctl.2, nice.2, open.2, poll.2, setresuid.2, shmctl.2, sigaction.2, times.2, utimensat.2, __setfpucw.3, atoi.3, endian.3, err.3, euidaccess.3, fenv.3, fopencookie.3, fpurge.3, getgrouplist.3, getutmp.3, j0.3, lgamma.3, netlink.3, pthread_attr_init.3, pthread_attr_setaffinity_np.3, pthread_cleanup_push_defer_np.3, pthread_getattr_np.3, pthread_kill_other_threads_np.3, pthread_setaffinity_np.3, pthread_tryjoin_np.3, pthread_yield.3, random_r.3, readdir.3, rtnetlink.3, scanf.3, setenv.3, significand.3, sigsetops.3, strerror.3, strstr.3, sysv_signal.3, termios.3, timegm.3, unlocked_stdio.3, y0.3, locale.5, bootparam.7, feature_test_macros.7, ip.7, locale.7, pthreads.7, rtld-audit.7, nscd.8: Global fix: s/non-standard/nonstandard/
The tendency in English, as prescribed in style guides like
Chicago MoS, is towards removing hyphens after prefixes
like "non-" etc.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2010-01-16 16:37:52 +00:00
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These functions are nonstandard GNU extensions
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2007-06-12 04:59:43 +00:00
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that are also present on the BSDs.
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Avoid their use; see NOTES.
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2004-11-03 13:51:07 +00:00
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.SH NOTES
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The
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2005-10-19 07:07:02 +00:00
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.BR timelocal ()
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2004-11-03 13:51:07 +00:00
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function is equivalent to the POSIX standard function
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.BR mktime (3).
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There is no reason to ever use it.
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.LP
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For a portable version of
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2005-10-19 07:07:02 +00:00
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.BR timegm (),
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2004-11-03 13:51:07 +00:00
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set the
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.B TZ
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environment variable to UTC, call
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2007-05-12 00:30:29 +00:00
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.BR mktime (3)
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2004-11-03 13:51:07 +00:00
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and restore the value of
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.BR TZ .
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Something like
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2007-12-19 07:19:23 +00:00
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.in +4n
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2004-11-03 13:51:07 +00:00
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.nf
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#include <time.h>
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#include <stdlib.h>
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2007-04-12 22:42:49 +00:00
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time_t
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my_timegm(struct tm *tm)
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2007-04-05 14:17:54 +00:00
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{
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2004-11-03 13:51:07 +00:00
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time_t ret;
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char *tz;
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tz = getenv("TZ");
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setenv("TZ", "", 1);
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tzset();
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ret = mktime(tm);
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if (tz)
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setenv("TZ", tz, 1);
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else
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unsetenv("TZ");
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tzset();
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return ret;
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}
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.fi
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2007-12-19 07:19:23 +00:00
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.in
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2004-11-03 13:51:07 +00:00
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.SH "SEE ALSO"
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.BR gmtime (3),
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.BR localtime (3),
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.BR mktime (3),
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.BR tzset (3)
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