Timezone manipulation within Perl script

Timezone manipulation within Perl script

[roman.vasicek]

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Hi all,
I want to ask you how convert time between different timezones in perl script running under cygwin. I have an application which store datetime information in Zulu/GMT. I need to provide date in user timezone. How to do the correct conversion? I want to be able to offer Timezone info like 'Europe/Prague'. Following code snippet will provide correct output when running under Active state Perl (time will differ 1 or 2 hours depending on input date), but when running under cygwin perl no conversion will be done. Can anyone help me?

        $ENV{TZ}    = 'Zulu';
        POSIX::tzset();
        $time       = timegm($second, $minute, $hour, $day, $month, $year);

        $ENV{TZ}    = 'Europe/Prague';
        POSIX::tzset();
        ($second, $minute, $hour, $day, $month, $year)   = POSIX::localtime($time);

Attached program will produce under ActiveState PERL

 Winter (delta should be +1 h)
 ZULU : 2007-12-13 11:47:02 Zulu
 LOCAL: 2007-12-13 12:47:02 Europe/Prague

 Summer (delta should be +2 h)
 ZULU : 2007-06-13 11:47:02 Zulu
 LOCAL: 2007-06-13 13:47:02 Europe/Prague

and under CygWin PERL output will be

 Winter (delta should be +1 h)
 ZULU : 2007-12-13 11:47:02 Zulu
 LOCAL: 2007-12-13 11:47:02 Europe/Prague

 Summer (delta should be +2 h)
 ZULU : 2007-06-13 11:47:02 Zulu
 LOCAL: 2007-06-13 11:47:02 Europe/Prague


Best Regards,
Roman

[-- Attachment #2: test-1.pl --]
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#!/usr/bin/perl -w
#

use strict;
use POSIX   qw();
use Time::Local;

my $zulu;
my $local;
my $zone;

sub format_datetime {
    my $datetime    = shift;            # YYYYMMDDhh:mm:ss - Date::Manip compatible format
    my $timezone    = shift || 'GMT';   # expect GMT by default
    my $html_req    = shift || 0;       # output for HTML page? ' ' => ' '
    my $result      = '';

    if ($datetime =~ /^(\d{4})(\d{2})(\d{2})(\d{2}):(\d{2}):(\d{2})$/) {
        my $year    = $1;
        my $month   = $2;
        my $day     = $3;
        my $hour    = $4;
        my $minute  = $5;
        my $second  = $6;

        $result = sprintf("%d-%02d-%02d %02d:%02d:%02d %s", $1, $2, $3, $4, $5, $6, $timezone);
        $result =~ s/ / /g if ($html_req);
    }

    return $result;
}

sub is_zulu {
    my $zulu    = shift;
    my $result  = 0;

    if ($zulu =~ /^(\d{14})Z$/) {
        $result = 1
    }

    return $result;
}

sub zulu_to_datetime {
    my $zulu    = shift;
    my $result  = '';

    if (is_zulu($zulu)) {
        $result = join(':', $zulu =~ /^(\d{10})(\d{2})(\d{2})/);
    }

    return $result;
}

sub zulu_to_local_datetime {
    my $zulu        = shift;
    my $time_zone   = shift || 'Europe/Prague';
    my $result      = '';
    my $time;
    my $year;
    my $month;
    my $day;
    my $hour;
    my $minute;
    my $second;

    if (is_zulu($zulu)) {
        ($year, $month, $day, $hour, $minute, $second)  = $zulu =~ /^(\d+)(\d{2})(\d{2})(\d{2})(\d{2})(\d{2})/;

        # fix offset
        $month--;
        $year   -= 1900;

        my $already = 0;
        my $original_time_zone;

        # save environment settings
        if (exists $ENV{TZ}) {
            $already            = 1;
            $original_time_zone = $ENV{TZ};
        }

        # do datetime conversion dependint to target timezone
        $ENV{TZ}    = 'Zulu';
        POSIX::tzset();
        $time       = timegm($second, $minute, $hour, $day, $month, $year);
        $ENV{TZ}    = $time_zone;
        POSIX::tzset();
        ($second, $minute, $hour, $day, $month, $year)   = POSIX::localtime($time);

        # fix offset
        $month++;
        $year   += 1900;

        # output formating
        $result = sprintf "%d%02d%02d%02d:%02d:%02d", $year, $month, $day, $hour, $minute, $second;

        # revert environment settings back
        if ($already) {
            $ENV{TZ}    = $original_time_zone;
        } else {
            delete $ENV{TZ};
        }
        POSIX::tzset();
    }

    return $result;
}


$zulu   = '20071213114702Z';
$local  = zulu_to_local_datetime($zulu);
$zone   = 'Europe/Prague';

# should be +1 hour
print "\n", "Winter (delta should be +1 h)", "\n";
print "ZULU : ", format_datetime(zulu_to_datetime($zulu), 'Zulu'), "\n";
print "LOCAL: ", format_datetime($local, $zone), "\n";

$zulu = '20070613114702Z';
$local = zulu_to_local_datetime($zulu, $zone);

# should be +2 hour
print "\n", "Summer (delta should be +2 h)", "\n";
print "ZULU : ", format_datetime(zulu_to_datetime($zulu), 'Zulu'), "\n";
print "LOCAL: ", format_datetime($local, $zone), "\n";


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Re: Timezone manipulation within Perl script

[Reini Urban]

2007/12/14, roman.vasicek@email.cz <roman.vasicek@email.cz>:
> Hi all,
> I want to ask you how convert time between different timezones in perl script running under cygwin. I have an application which store datetime information in Zulu/GMT. I need to provide date in user timezone. How to do the correct conversion? I want to be able to offer Timezone info like 'Europe/Prague'. Following code snippet will provide correct output when running under Active state Perl (time will differ 1 or 2 hours depending on input date), but when running under cygwin perl no conversion will be done. Can anyone help me?
>
>         $ENV{TZ}    = 'Zulu';
>         POSIX::tzset();
>         $time       = timegm($second, $minute, $hour, $day, $month, $year);
>
>         $ENV{TZ}    = 'Europe/Prague';
>         POSIX::tzset();
>         ($second, $minute, $hour, $day, $month, $year)   = POSIX::localtime($time);
>
> Attached program will produce under ActiveState PERL
>
>  Winter (delta should be +1 h)
>  ZULU : 2007-12-13 11:47:02 Zulu
>  LOCAL: 2007-12-13 12:47:02 Europe/Prague
>
>  Summer (delta should be +2 h)
>  ZULU : 2007-06-13 11:47:02 Zulu
>  LOCAL: 2007-06-13 13:47:02 Europe/Prague
>
> and under CygWin PERL output will be
>
>  Winter (delta should be +1 h)
>  ZULU : 2007-12-13 11:47:02 Zulu
>  LOCAL: 2007-12-13 11:47:02 Europe/Prague
>
>  Summer (delta should be +2 h)
>  ZULU : 2007-06-13 11:47:02 Zulu
>  LOCAL: 2007-06-13 11:47:02 Europe/Prague

Interesting. For me the standard cygwin perl works okay.

$ perl test-1.pl

Winter (delta should be +1 h)
ZULU : 2007-12-13 11:47:02 Zulu
LOCAL: 2007-12-13 12:47:02 Europe/Prague

Summer (delta should be +2 h)
ZULU : 2007-06-13 11:47:02 Zulu
LOCAL: 2007-06-13 13:47:02 Europe/Prague

$ printenv TZ

Windows XP, currently in the GMT-5 timezone
-- 
Reini Urban

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Re: Timezone manipulation within Perl script

[Brian Dessent]

roman.vasicek@email.cz wrote:

> I want to ask you how convert time between different timezones in perl script running under cygwin. I have an application which store datetime information in Zulu/GMT. I need to provide date in user timezone. How to do the correct conversion? I want to be able to offer Timezone info like 'Europe/Prague'. Following code snippet will provide correct output when running under Active state Perl (time will differ 1 or 2 hours depending on input date), but when running under cygwin perl no conversion will be done. Can anyone help me?

The testcase works fine for me as well.  You didn't include cygcheck
output, so do you have the tzcode package installed?  If not, try
installing it.  It should be part of Base now so you should get it
automatically the next time you run setup.

Brian

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Re: Timezone manipulation within Perl script

[roman.vasicek]

You are right. Package tzcode was missing. After installing it, timezone conversion script works ok. Output is the the same when running under cygwin and ActiveState perl. Thank you for your help.

BTW How should I detect that there is another package required/missing?

Roman

> ------------ Původní zpráva ------------
> Od: Brian Dessent <brian@dessent.net>
> Předmět: Re: Timezone manipulation within Perl script
> Datum: 15.12.2007 02:05:28
> ----------------------------------------
> roman.vasicek@email.cz wrote:
>
> > I want to ask you how convert time between different timezones in perl script
> running under cygwin. I have an application which store datetime information in
> Zulu/GMT. I need to provide date in user timezone. How to do the correct
> conversion? I want to be able to offer Timezone info like 'Europe/Prague'.
> Following code snippet will provide correct output when running under Active
> state Perl (time will differ 1 or 2 hours depending on input date), but when
> running under cygwin perl no conversion will be done. Can anyone help me?
>
> The testcase works fine for me as well.  You didn't include cygcheck
> output, so do you have the tzcode package installed?  If not, try
> installing it.  It should be part of Base now so you should get it
> automatically the next time you run setup.
>
> Brian
>
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>
>
>
>

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