Exploring the Perl DateTime module
COUNTING OUT TIME
Because calendar rules are influenced by historical and political decisions, date manipulations are riddled with pitfalls. Perl’s DateTime module knows all the tricks.
If a backup script launches at 10 pm and quits at 4 am, how long did it take to run? Six hours? Well, it depends. Just think about a process that ran between March 26 and 27 in 2005 somewhere in the UK. The clocks were put forward by one hour at 1 am, and that would make five hours the right answer. If the same process had run at the same time in the USA, the answer would have been six hours, as summer time starts a week later in the US. But not in Indiana, which had not yet introduced summer time in 2005. In fact, Indiana is introducing summer time this year (2006, [2]). Fortunately, the DateTime module ([5]) from CPAN knows all these historical and future rules and provides an easy interface to even the most complex date calculations. What if you wanted to know how long the current summer time rules have been in use in the UK? Listing 1 (dsthist) discovers this by looking back from the year 2006 and checking through the month of March to find out if there is a day where you end up at 5 a.m. when adding three hours and one second to 00:59:59. If this happens, summer time was used during this year, and the script stops when it discovers that’s not the case. The display shows that 1972 was the first year with today’s summertime rules:
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Find SysAdmin Jobs
News
-
Escuelas Linux 8.0 is Now Available
Just in time for its 25th anniversary, the developers of Escuelas Linux have released the latest version.
-
LibreOffice 7.5 has Arrived Loaded with New Features and Improvements
The favorite office suite of the Linux community has a new release that includes some visual refreshing and new features across all modules.
-
The Next Major Release of Elementary OS Has Arrived
It's been over a year since the developers of elementary OS released version 6.1 (Jólnir) but they've finally made their latest release (Horus) available with a renewed focus on the user.
-
KDE Plasma 5.27 Beta Is Ready for Testing
The latest beta iteration of the KDE Plasma desktop is now available and includes some important additions and fixes.
-
Netrunner OS 23 Is Now Available
The latest version of this Linux distribution is now based on Debian Bullseye and is ready for installation and finally hits the KDE 5.20 branch of the desktop.
-
New Linux Distribution Built for Gamers
With a Gnome desktop that offers different layouts and a custom kernel, PikaOS is a great option for gamers of all types.
-
System76 Beefs Up Popular Pangolin Laptop
The darling of open-source-powered laptops and desktops will soon drop a new AMD Ryzen 7-powered version of their popular Pangolin laptop.
-
Nobara Project Is a Modified Version of Fedora with User-Friendly Fixes
If you're looking for a version of Fedora that includes third-party and proprietary packages, look no further than the Nobara Project.
-
Gnome 44 Now Has a Release Date
Gnome 44 will be officially released on March 22, 2023.
-
Nitrux 2.6 Available with Kernel 6.1 and a Major Change
The developers of Nitrux have officially released version 2.6 of their Linux distribution with plenty of new features to excite users.