NAME
Time::Local::TZ - time converter functions with localtime-based
interface
SYNOPSIS
use Time::Local::TZ qw/:const :func/;
# get localtime-like result for given timezone and unixtime
($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = tz_localtime("Europe/Moscow" => $epoch);
($asctime) = tz_localtime("Europe/Moscow" => 0); # Thu Jan 1 03:00:00 1970
# get unixtime for given timezone and localtime data
$epoch = tz_timelocal("Europe/Moscow" => $sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst);
$epoch = tz_timelocal("Europe/Moscow" => $sec,$min,$hour,$mday,$mon,$year); # the same
# truncate unixtime to the beginning of minute/hour/day/month/year (of course, in given timezone)
$epoch2 = tz_truncate("Europe/Moscow", $epoch, TM_HOUR());
# get offset (in seconds) between given timezone and UTC (for the given moment)
$tz_offset_seconds = tz_offset("Europe/Moscow" => $epoch);
$tz_offset_seconds = tz_offset("Europe/Moscow");
# convert localtime data from one timezone to another
@localtime_berlin = tz_localtime("Europe/Berlin", tz_timelocal("Europe/Moscow", @localtime_moscow));
# constants to navigate @localtime (and to use with tz_offset function)
@localtime = tz_localtime("UTC", $epoch);
$date_str = sprintf "%04d-%02d-%02d", @localtime[TM_YEAR()+1900, TM_MON()+1, TM_MDAY()]; # 1970-01-01
$time_str = sprintf "%02d:%02d:%02d", @localtime[TM_HOUR(), TM_MIN(), TM_SEC() ]; # 13:25:59
$weekday = $localtime[ TM_WDAY() ];
$yearday = $localtime[ TM_YDAY() ];
$isdst = $localtime[ TM_ISDST() ];
DESCRIPTION
This module provides a set of functions to convert time between
timezones and do some other timezone-dependant operations. Most
functions work with localtime-like arrays, so they can be easily
integrated with other modules supporting this format. Module is written
in XS, so it is fast enough.
FUNCTIONS
@localtime = tz_localtime($timezone_name, $epoch)
Works similar to build-in "localtime" function, but works with
timezone you provide, instead of system timezone. Both arguments are
mandatory.
In scalar context, "tz_localtime" returns the asctime(3) value
(without trailing "\n", like "localtime"):
$date_string = tz_localtime("Europe/Moscow" => time()); # e.g., "Thu Apr 27 15:35:34 2017"
In list context, converts time provided to a 9-element list with the
time analyzed for the given timezone:
# 0 1 2 3 4 5 6 7 8
($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = tz_localtime("Europe/Moscow" => time);
@localtime = tz_localtime("Europe/Moscow" => time);
$date_string = POSIX::strftime("%d %B %Y, %H:%M", @localtime);
Values $mday, $year, $wday, $yday have special format, which can
confuse beginners. See "localtime" function for details.
$epoch = tz_timelocal($timezone_name, @localtime)
Works similar to "timelocal" function from "Time::Local" module, but
works with timezone you provide, instead of system timezone. Returns
unixtime value for the "localtime" data and timezone provided. All
arguments are mandatory, except $wday, $yday, $isdst.
$epoch = tz_timelocal("Europe/Moscow" => $sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst);
$epoch = tz_timelocal("Europe/Moscow" => $sec,$min,$hour,$mday,$mon,$year);
$data_string = "2017-04-27 15:35:34";
@localtime = POSIX::strptime($data_string, "%Y-%m-%d %H:%M:%S");
$epoch = tz_timelocal("Europe/Moscow" => @localtime);
$epoch = tz_truncate($timezone, $epoch, $unit)
This function calculates "tz_localtime" for the timezone and
unixtime provided, resets fields with index smaller than $unit and
calculates unixtime back. This can be useful to get unixtime for
first second of the interval unit (year/month/day/hour/minute) which
$epoch belongs to. All arguments are mandatory. It is recommended to
use "TM_*" constants from this module to specify $unit.
$data_string = "1970-03-08 05:25:45";
@localtime = POSIX::strptime($data_string, "%Y-%m-%d %H:%M:%S");
$epoch = tz_timelocal("Europe/Moscow" => @localtime); # 5711145
$epoch2 = tz_truncate("Europe/Moscow" => $epoch, TM_HOUR()); # 5709600
print tz_localtime("Europe/Moscow" => $epoch2); # Sun Mar 8 05:00:00 1970
$epoch2 = tz_truncate("Europe/Moscow" => $epoch, TM_YEAR()); # -10800
print tz_localtime("Europe/Moscow" => $epoch2); # Thu Jan 1 00:00:00 1970
# of course, in other timezones this alignment is wrong:
print tz_localtime("Europe/Berlin" => $epoch2); # Wed Dec 31 22:00:00 1969
$offset_seconds = tz_offset($timezone, $epoch)
Calculates offset (in seconds) from UTC to provided timezone, actual
for the given unixtime. Both arguments are mandatory.
print tz_offset("Europe/Moscow", 1293829200); # 10800 (+3 hours for the date 2011-01-01)
print tz_offset("Europe/Moscow", 1309464000); # 14400 (+4 hours for the date 2011-07-01)
CONSTANTS
TM_SEC, TM_MIN, TM_HOUR, TM_MDAY, TM_MON, TM_YEAR, TM_WDAY, TM_YDAY,
TM_ISDST
These constants can be useful to navigate on "localtime" and
"tz_localtime" arrays:
@localtime = tz_localtime("Europe/Moscow" => time);
printf "Time is is %02d:%02d:%02d", @localtime[ TM_HOUR(), TM_MIN(), TM_SEC() ];
It is recommended to use them with "tz_truncate" function:
$epoch2 = tz_truncate("Europe/Moscow" => $epoch, TM_HOUR()); # 5709600
NOTES AND CAVEATS
This module uses your operating system rules to convert time. They are
based on environment variable "TZ" and can differ from OS to OS. Many
modern OSes (including Linux and FreeBSD) support Olson timezone names
(like "Europe/Berlin", "America/New_York" etc.), which is the only
recommended way to use with this module. Other OSes usually know only
POSIX timezone names. You can deal with them too, but the result can be
inconsistent. There is no native Olson db support in Windows, but CYGWIN
solves this.
Please note that set of timezone rules is not something permanent, they
are refreshed up to several times per month. So, to get correct results
from this module you should always have fresh timezone information in
your OS. If you don't want to do this, take a look on
"DateTime::TimeZone", which have its own timezones database inside.
Anyway, you should update it on a regular basis too.
This module works with process environment, so it is not thread-safe.
This module works with mod_perl2 (at least in non-threaded mode).
mod_perl2 has problem with %ENV. Unlike mod_perl1 and usual perl
programs %ENV under mod_perl2 is untied from process environment. So,
even if you change $ENV{TZ}, built-in functions (like "localtime") will
know nothing about it, because real process environment is untouched.
This module works with environment bypassing perl %ENV, so in mod_perl2
prefork mode it works fine.
SEE ALSO
To get more information about "localtime" format, see "localtime" in
perlfunc and "timelocal" in Time::Local.
If you are interested in useful functions to work with "localtime" data,
see "strftime" in POSIX and POSIX::strptime.
If you want to know more on alternative modules to convert time between
timezones, see DateTime and DateTime::TimeZone.
If you want to know more about environment variable "TZ" and it's
formats, you can look at the articles below:
<http://www.gnu.org/software/libc/manual/html_node/TZ-Variable.html>
<https://www.ibm.com/developerworks/aix/library/au-aix-posix/>
SOURCE
The development version is on github at
<https://github.com/bambr/Time-Local-TZ>
AUTHOR
Sergey Panteleev, <bambr@cpan.org>
COPYRIGHT AND LICENSE
Copyright (C) 2017 by Sergey Panteleev
This library is free software; you can redistribute it and/or modify it
under the same terms as Perl itself, either Perl version 5.8.8 or, at
your option, any later version of Perl 5 you may have available.