 Hi there, welcome back to my YouTube channel. This is Daniel Rosal here. I want to do a video today about the TZ database system. The TZ database system is a way of conveniently referencing time zones. Now, if you've spent the last year trying to organize meetings on Zoom, then you don't need me telling you that there are lots and lots of time zones in the world. And time zones are complicated. There is daylight saving time and universal time coordinated, which is not the same thing as GMT exactly. And lots and lots of kind of finicky detail that sometimes you do need to know to put those into programs in order that you can know what time it is. So I wanted to just show why you might want to assist an instance where you might want to know this and where you can sort of get this data from. Now, the easiest place is there is a good Wikipedia article that is well updated because this is such a sort of low level in the computing sense of the word. This is such a low level and essential database for pulling in time zone data to different programs and operating systems. So this is just kind of a quick and dirty reference, if you will, that just gives you a chart here listing out the different longitude and latitude, the TZ database name. This is basically fine. That's what you need for most programs. As well as very importantly, the status. And that's divided into you have some deprecated entries here and you have aliases and canonicals. UTC offsets given as well. That's the offset as an integer positive or negative against universal time coordinated, also known as Zulu time. And there's also a UTC DST offset for daylight saving times, daylight saving time. So that's a Wikipedia source, but naturally you might want to sort of dig a little bit further and get data always, always better if you really needed to be robust to get data from the original source and the maintainers of that data. So in order to track down where I could find this, I plugged TZ database into the Google machine and I quickly chanced upon the second entry here that came up in Google was from IANA. This is all kind of oddly fascinating stuff. Like who are these people? The International Assign Numbers Authority. It's fascinating. What's actually more fascinating or most fascinating is the fact that there is like a guy, there is a guy who's responsible for maintaining the time zone database. I don't know, I find that kind of hilarious. It was founded by, there is another Wikipedia entry called TZ database in which you can actually read the history of the database as opposed to just the list. And it will tell you that Paul Eger is its current editor and maintainer. Like there is a guy out there, Paul Eger. And he's like the world time zone computer guy. A lot of weight on his shoulders. So, but getting back to this, so you can click into the IANA website. And they have the time zone database. And it looks like your average tech, something like a GitHub site where you can see the latest version and the previous versions. And they have them packaged up as tar.gz, which as anyone who uses Linux knows is pretty easy to work with. So that is that. Now, just to show you, bring this down to a more practical level when you might need to know these time zone entries. So I just installed G world clock, which is a multiple time zone editing program in Ubuntu. And this is why I always say that when your computer, this is why I love taking backups. Because when your computer, if your computer ever vanishes or breaks and you lose two years worth of data, these are all the tiny little things you lose. So it must be many years since I last used this program because it wasn't there. So I just put it on to my new computer. And I know in the process of setting up something that is vaguely useful. So I'm going to refer to the Wikipedia chart here. And just to show you how this works very simply, G world clocks has a system where you can search your way through countries and regions. But you can also just plug in the tz value. So the tz value, well, I'm going to go for Jerusalem as one. And the tz value for this is Asia. Now there's no leading trail. There is a trail after the continent. So Asia for its last Jerusalem is the current canonical time zone denotation for this time zone. So what I can do is say Jerusalem. And I can say Asia Jerusalem. And I can go add zone. And now I have Jerusalem. If you want to watch my last video on how to use this notation system, you can also watch that. So OK, we've got going. Now Zulu time, or GMT is available. You can also have notations for GMT and for GMT offsets. You can actually add those manually to a program as well if instead of adding a particular geographical entity, you can actually add any offset positive or negative. But the one I would always want to add is UTC. And you can see UTC is listed here as the canonical. And Zulu's deprecated. So I'm going to go into my world clock program here again on Ubuntu. And I'm going to just add this and call it UTC. And I'm going to say ETC forward slash UTC in capital. Now, this is pretty easy to work with. But it's a really nice standardized system for referring to time zones. Now, because I am a finicky person and I like to remember that ETC and UTC and GMT are not always equal, I'm going to throw in GMT in there as well. So that's ETC forward slash GMT. So I'm going to put in also GMT at that time zone. And I always put in Cork, which is where I'm originally from in the world. But sorry, I mean, it focuses on major cities. So it's going to be Dublin. And you can see that is Europe Dublin. So I'm going to add, I'm going to just call it Cork. But I'm going to, it's always, there's no, there's only one time zone in Ireland. So it's the same thing effectively. So Europe Dublin. So we have Cork Dublin. Where else would be useful? I mean, think, where do I currently have people I'm talking to in the world? Well, you know, I'm not going to do all of these. It'd be interesting to see if they have one for Eastern time. EST as a whole, EST, New York with an underscore. So America. So these are quite specific. So I'm just going to call that in my system EST. And I'm going to go for America forward slash New underscore York. Instead of CST, I'm going to put in, I'm going to put in Dallas as well. What else is on CST? Central Standard Time. Central, I just saw it come up there, Chicago. So anyway, this is a really, really big database. So I'm not going to bore, make this video super long by going through everything I want to add. What I do want to show is the original data what that looks like, just in case anyone watching this has become curious. So this is that tar.gz that I downloaded there from the website of the International Assigned Numbers Authority. I'm so curious about these people. It feels like the matrix or something. There's all these kind of vague entities and vague people like Paul Egger controlling all these things about the internet. So, Lea, let me just jump back here. So this is the source data coming from the IANA, the maintainer of this data. And you can see the way it's batched. I've just downloaded this. They have it batched by continent. So let's jump into Europe, which was modified on the 29th of September. Ah, because it just opened on my machine. So I'm just going to, sorry for these technical mishaps here, let us take a look into, I looked at Antarctica because I was curious, but let's look at Europe. Here we go. So this is the real hardcore source data as such, right? So it looks like kind of more like a program file where you're going to have tons and tons of stuff commented off at the start, talking about the originator of this project, talking about who's currently maintaining it. But let me show you some of the actual information. And this is actually, this is quite entertaining stuff. There's these little kind of historical notes added by the maintainers of this document, time zone trivia. There is, this is kind of a combination of a text file and sort of a, look the Irish statute book, incredible. Anyway, skip through all the comments and you'll get to the actual things in this document. You can see just look at the uncommitted lines and you'll see where the data is. There was ones that were more useful. There is 11 mentions of Dublin in this document, but let's jump to the actual Dublin, the actual data entry because this is just so, so long. Here we go. So you can see the formats use zone and the official name being Europe forward slash Dublin. And that's basically most of what there is to be found in this document. So just out of curiosity, I find this kind of interesting because it's just so essential to the operation of not just the internet, but operating systems and computing in general. Hope that video was interesting and if you would like to get more videos about everything related to Linux, Ubuntu, time zones, technology, feel free to hit the subscribe button.