mirror of https://github.com/mkerrisk/man-pages
102 lines
2.4 KiB
Groff
102 lines
2.4 KiB
Groff
.\" Copyright (C) 2001 Andries Brouwer <aeb@cwi.nl>
|
|
.\"
|
|
.\" Permission is granted to make and distribute verbatim copies of this
|
|
.\" manual provided the copyright notice and this permission notice are
|
|
.\" preserved on all copies.
|
|
.\"
|
|
.\" Permission is granted to copy and distribute modified versions of this
|
|
.\" manual under the conditions for verbatim copying, provided that the
|
|
.\" entire resulting derived work is distributed under the terms of a
|
|
.\" permission notice identical to this one.
|
|
.\"
|
|
.\" Since the Linux kernel and libraries are constantly changing, this
|
|
.\" manual page may be incorrect or out-of-date. The author(s) assume no
|
|
.\" responsibility for errors or omissions, or for damages resulting from
|
|
.\" the use of the information contained herein. The author(s) may not
|
|
.\" have taken the same level of care in the production of this manual,
|
|
.\" which is licensed free of charge, as they might when working
|
|
.\" professionally.
|
|
.\"
|
|
.\" Formatted or processed versions of this manual, if unaccompanied by
|
|
.\" the source, must acknowledge the copyright and authors of this work.
|
|
.\"
|
|
.TH TIMEGM 3 2007-07-26 "GNU" "Linux Programmer's Manual"
|
|
.SH NAME
|
|
timegm, timelocal \- inverses of gmtime and localtime
|
|
.SH SYNOPSIS
|
|
.nf
|
|
.B #include <time.h>
|
|
.sp
|
|
.BI "time_t timelocal(struct tm *" tm );
|
|
.sp
|
|
.BI "time_t timegm(struct tm *" tm );
|
|
.sp
|
|
.fi
|
|
.in -4n
|
|
Feature Test Macro Requirements for glibc (see
|
|
.BR feature_test_macros (7)):
|
|
.in
|
|
.sp
|
|
.BR timelocal (),
|
|
.BR timegm ():
|
|
_BSD_SOURCE || _SVID_SOURCE
|
|
.SH DESCRIPTION
|
|
The functions
|
|
.BR timelocal ()
|
|
and
|
|
.BR timegm ()
|
|
are the inverses of
|
|
.BR localtime (3)
|
|
and
|
|
.BR gmtime (3).
|
|
.SH "CONFORMING TO"
|
|
These functions are non-standard GNU extensions
|
|
that are also present on the BSDs.
|
|
Avoid their use; see NOTES.
|
|
.SH NOTES
|
|
The
|
|
.BR timelocal ()
|
|
function is equivalent to the POSIX standard function
|
|
.BR mktime (3).
|
|
There is no reason to ever use it.
|
|
.LP
|
|
For a portable version of
|
|
.BR timegm (),
|
|
set the
|
|
.B TZ
|
|
environment variable to UTC, call
|
|
.BR mktime (3)
|
|
and restore the value of
|
|
.BR TZ .
|
|
Something like
|
|
|
|
.in +4n
|
|
.nf
|
|
#include <time.h>
|
|
#include <stdlib.h>
|
|
|
|
time_t
|
|
my_timegm(struct tm *tm)
|
|
{
|
|
time_t ret;
|
|
char *tz;
|
|
|
|
tz = getenv("TZ");
|
|
setenv("TZ", "", 1);
|
|
tzset();
|
|
ret = mktime(tm);
|
|
if (tz)
|
|
setenv("TZ", tz, 1);
|
|
else
|
|
unsetenv("TZ");
|
|
tzset();
|
|
return ret;
|
|
}
|
|
.fi
|
|
.in
|
|
.SH "SEE ALSO"
|
|
.BR gmtime (3),
|
|
.BR localtime (3),
|
|
.BR mktime (3),
|
|
.BR tzset (3)
|