convert the systemdate in iso 8601 format in perl

Question

I want the system date to be converted to ISO 8601 format. code:

my $now = time();
my $tz = strftime("%z", localtime($now));
$tz =~ s/(\d{2})(\d{2})/$1:$2/;
print "Time zone *******-> \"$tz\"\n";
# ISO8601
my $currentDate =  strftime("%Y-%m-%dT%H:%M:%S", localtime($now)) . $tz;
print "Current date *******-> \"$currentDate\"\n";

Current output is:

Time zone *******-> "-04:00"
Current date *******-> "2014-06-03T03:46:07-04:00"

I want the current date to be in format "2014-07-02T10:48:07.124Z", So that I can compute the difference between the two.

Answer 1

You should use gmtime() instead of localtime() to get the broken-down time values in UTC.

use POSIX qw(strftime);
my $now = time();
print strftime('%Y-%m-%dT%H:%M:%SZ', gmtime($now)), "\n";

output:

2014-06-04T10:17:17Z

Answer 2

Time::Piece and Time::Seconds have been included as a standard part of Perl since 2007.

#!/usr/bin/perl
use strict;
use warnings;
use 5.010;
use Time::Piece;

my $time = localtime;
say $time->datetime; # Time in ISO8601 format
say $time->tzoffset; # Time zone offset in seconds

# But tzoffset actually returns a Time::Seconds object
say $time->tzoffset->hours; # Time zone offset in hours (for example)

Answer 3

Perl's DateTime package (on CPAN) can produce ISO8601 dates for you very easily, but, with one caveat.

The string returned by DateTime will be in UTC, but, without a timezone specifier. This SHOULD be fine, because according to the ISO8601 spec, if no timezone is specified, then UTC should be assumed. However, not all parsers obey the spec perfectly. To make my dates more robust I append a Z to the end of the string I get from DateTime, so this is the code I recommend:

use DateTime;
my $now = DateTime->now()->iso8601().'Z';