Tutorials Archives • Page 16 of 31 • Linux Tips

Let’s Learn To Remove A Directory

Today’s article is going to teach you how to remove a directory. This being Linux and rmdir, you can only remove empty directories. That’s okay, that’s still what we’re going to use. I’m pretty sure I’ve explained how to remove files before and, if not, that’s a pretty simple task.

This article is going to be light on details and pretty short. I popped positive on one COVID test and negative on another. I could take a third test, but I really just feel crappy and not all that bad. Still, it’s an excuse to have a nice and easy article! I like those sometimes! My proofreading may be sub-par.

Like I said, we’ll be using ‘rmdir’ and that only works on EMPTY directories. I can’t stress this enough! If there’s a file in the directory, any file, it will not delete the directory.

Umm…

I do not know the design reason for making ‘rmdir’ (a standard tool in every Linux) only remove empty directories – but I suspect it’s a protection method. It’s protecting itself from you – meaning you must go in and confirm that it is empty and that there are no files remaining that you’d like to keep. After that, you can delete the directory.

That stands to reason and, frankly, it’s the only reason I can think of. If anyone knows the real reason, assuming I am wrong, please feel free to let me know in a comment. I’m quite curious. Ah well… Onto the article!

Remove A Directory:

This article requires an open terminal, like many other articles on this site. If you don’t know how to open the terminal, you can do so with your keyboard – just press CTRL + ALT + T and your default terminal should open.

Now, with your terminal open, let’s use ‘rmdir‘ and learn how to remove a directory. In its basic form, the command is:

rmdir <directory>

1	rmdir <directory>

This works if it’s a path you want to specify:

rmdir /path/to/dir

1	rmdir /path/to/dir

If you want, you can use the -v switch and get a verbose output, telling you what is being deleted. This is probably for the best. So, it’d look like:

rmdir -v /path/to/dir

1	rmdir -v /path/to/dir

But wait, there’s more! What if you wanted to remove all of that, you want to remove /path /path/to and /path/to/dir? Well, you can do that:

rmdir -p /path/to/dir

1	rmdir -p /path/to/dir

Of course, if you want confirmation of what’s being deleted, try:

rmdir -p -v /path/to/dir

1	rmdir -p -v /path/to/dir

Assuming all those directories are empty, the command will complete itself and remove all the directories in that path. Those are basically all the rmdir commands you’re likely to need, but you can check man rmdir for more information.

Closure:

See? Nice and easy. See? You even get an article when I’m dying from the plague! Don’t worry, I’m sure I’ll be just fine. Statistics are my friend at times like this, so my worry level is exactly 0%. The odds of it incapacitating me are negligible and I’m a pretty big fan of math.

I’m vaxxed to the max and even boosted – which only lessens your chance. I’ll be fine. After all, only the good die young! (I am not young, now that I think about it!) I’ll quarantine at home and hope for the best, while monitoring for degradation.

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How To: Add Ubuntu’s Default Repositories

The headline is correct that, in today’s article, I’ll explain how to add Ubuntu’s default repositories – in the terminal. Seeing as I’m doing so, I’ll tell you about each repository as we go along. They exist for different reasons, so we might as well know how and why.

This article is probably only interesting to new Ubuntu users who want to learn to do things in the terminal. That’s a lofty goal, though I’ve already explained how to reset Ubuntu’s default repositories – but that’s graphical. It’s also likely quicker to do this in a GUI. Still, we might as well cover this.

I see no reason to make the intro section very long. The article will be plenty long. So, onto the article!

Add Ubuntu’s Default Repositories:

Yup. You guessed it. You’re going to need an open terminal. Many of my articles do. If you don’t know how to open the terminal, you can do so with your keyboard – just press CTRL + ALT + T and your default terminal should open.

You’re also going to need Ubuntu, or an official Ubuntu flavor. I can’t recommend trying this will all Ubuntu derivatives, as I have not ever tested this in all Ubuntu derivative. So, only do this if you are using Ubuntu or an official flavor of Ubuntu – or it may mess up your system. You have been warned.

About Repositories:

If we’re going to be writing about repositories, allow me to explain what those are. They’re central points from which you download software and software upgrades. They are there to provide the software you need, though not all software is included.

There’s generally a lot of software in them and some folks will only install software included in their default repositories. (Some folks will refuse even some software in the available repos, as the repositories may vary based on the licenses used by the software within.)

Ubuntu’s Main Repository:

Inside this repository, you’ll come across all the software the system needs to have a running system and a bunch of applications. All the software in this repository is FOSS (Free Open Source Software).

You already have this repository enabled, but stuff happens. If you’ve somehow disabled it (don’t do that) you can add it back with:

sudo add-apt-repository main

1	sudo add-apt-repository main

Ubuntu’s Universe Repository:

This repository contains software that is also FOSS – but Ubuntu can’t vouch for the update state or software inside the Universe repository. They are packages managed by the community, not by Ubuntu themselves.

It’s software you can install and doesn’t really come with all that many risks as the above may sound. Stuff tends to get updated pretty well. There are a lot of diligent people who tend to this sort of stuff. Upgrades are usually fairly rapid. To enable Ubuntu’s Universe repository, you’d run this command:

sudo add-apt-repository universe

1	sudo add-apt-repository universe

Ubuntu’s Multiverse Repository:

In Ubuntu’s Multiverse repository, you’ll find software that is not FOSS. Due to licensing reasons, the folks behind Ubuntu can not maintain any of this software.

The software gets updated, but nothing in this archive is going to have Ubuntu doing so. Ubuntu also can’t ship this repository as enabled by default. To enable the Multiverse Repository, use this command:

sudo add-apt-repository multiverse

1	sudo add-apt-repository multiverse

Ubuntu’s Restricted Repository:

In Ubuntu’s Restricted repository, you’ll also have software that is not FOSS. The Multiverse repository contains things like drivers for hardware that doesn’t have FOSS drivers available. Well, the Restricted repository is where drivers exist.

A number of people are sticklers for FOSS-only operating systems. plus there’s the licenses to worry about, mean that these end up in a repository all there own. If you’re using hardware that doesn’t have FOSS drivers, you might need the Multiverse repository. To enable the Multiverse repository, you’ll want to use this:

sudo add-apt-repository restricted

1	sudo add-apt-repository restricted

Ubuntu’s Partner Repository:

In Ubuntu’s Partner repository, it’s still software that doesn’t have a FOSS license. It’s Ubuntu adding the software for partners of Ubuntu. It’s useless and will be axed at some point. (It has been empty in recent Ubuntu iterations.)

So, you can forget about this one. I will explain how to enable the Partner repository, as it’s both obvious and I’m pretty sure it’s still a thing on older versions of Ubuntu, and the LTS variants are going to be around for a while longer. It’s easy to enable Ubuntu’s Partner repository, the command is simply:

sudo add-apt-repository restricted

1	sudo add-apt-repository restricted

Closure:

Well, there you have it. You have another article and this one tells you to add Ubuntu’s default repositories. There’s a GUI way to do so, but this one takes place in the terminal. Besides, I already showed you how to do it graphically. This article almost got missed. I was at a funeral and that took a bunch of time and energy. But, I just couldn’t resist keeping up the same publication schedule.

How To: Change The Timezone

In today’s article, I’m going to show you how to change the timezone. This isn’t a task you’ll need to do often, but it’ll be nice to know how to do it when you do need to change the timezone.

Personally, I find myself mostly needing to change the timezone when I lease a VPS and want the system timezone to match my own timezone. All in all, the computer doesn’t actually care what timezone it is in, so you can set it to your local timezone and not have any issues. Normally, I’d configure the timezone during the installation process.

I suppose this is probably only going to work in systems that make use of systemd. It makes use of timedatectl and I’m pretty sure that’s a systemd thing. If this was a good site, the author would actually go verify this. You get what you pay for! Still, you may need another tool if you don’t use systemd.

It’s also going to be a fairly easy article. If you want to change the timezone, it’s not all that difficult. There really isn’t a whole lot to it. So, without further ado, let’s get into the article…

Change The Timezone:

I suppose you should first know what timezone you’re currently using. To learn that information, you can use this command:

timedatectl

1	timedatectl

Your output might look something like this:

Your timedatectl output may look different, obviously. You might not be in my timezone!

Anyhow, to change it, the format of the command is:

sudo timedatectl set-timezone <new_timezone>

1	sudo timedatectl set-timezone <new_timezone>

I suppose you might not know your timezone options. You can generate a giant list of ’em with this command:

timedatectl list-timezones

1	timedatectl list-timezones

If you don’t know your timezone options, you can use ‘grep’ to narrow it down. For example, if you’re pretty sure you’re in America, your command might look a little like:

timedatectl list-timezones | grep America

1	timedatectl list-timezones \| grep America

That’ll narrow it down. By the way, the “America” in this case actually more like ‘the Americas’ and far more than just the United States – or even more than North America. That information might come in handy for some of you.

Closure:

Whelp, there you have it… You have another article. This one will show you how to change the timezone, which might be something you need to know from time to time. It’s probably not something you need to remember, but now you can easily search for it.

Search For Command History By Date

Today’s article is going to show you how to search for the command history by date. This isn’t hard, but might seem a little advanced for some of the newer users. We’ll be doing this through the terminal, of course. That seems like a good idea to me!

Unless you’ve made some fairly drastic changes, Linux terminals keep a log of previously entered commands. This is on a per-user basis and considered relatively secure, or at least as secure as your user account is. It’s helpful to be able to look at your command history, especially if you’ve forgotten what you did and you really need to undo it!

Previous history articles include:

Delete An Entry In Your bash_history

Dealing With Duplicates In Your Bash History

So, I haven’t really covered the .bash_history (proper name, I suppose) all that much. There really isn’t all that much to cover, but today we’ll learn how to search your command history by date. It’s most useful when you remember when you made changes but you can’t remember the precise commands used when you made those changes.

Find Command History By Date:

Like oh so many articles, this one too requires an open terminal. You can open one easily enough. Just press CTRL + ALT + T and your default terminal should open.

With your terminal open, we first have to tell Bash to store and show dates along with the history. That’s an easy command that you need only run once:

export HISTTIMEFORMAT='%F %T'

1	export HISTTIMEFORMAT='%F %T'

When you next type ‘history‘, it’ll look like a hot mess until you figure out what the command has done.

Now, to find command history by date. To do that, you just enter:

history | grep '2022-08-25'

1	history \| grep '2022-08-25'

The format for me is YYYY-MM-DD, though I suppose it could be different for others who have an alternative date format set up. I don’t really know, but it’s easy to figure out by just running the history command and deducing the format from those results. If you’ve done it properly, it might look a little something like this:

searching command history by date — See? It works! It does show the command used to show these results, of course.

So, if you want to see what commands were run on a certain date, you can do that. You can also find what you entered when you remember the day but not the commands you entered. It can be pretty handy so search the command history by date. Keep it as a handy tool, as you never know when you’re going to need it.

Closure:

And there you have it. You have another article in a very long list of articles. This one is handy if you need to know your command history by date. I know I’ve been known to use this myself, largely because I sometimes need to narrow down my history quite a bit, as I do a great deal in the terminal and my history is a hot mess.

Let’s Find The Size Of A Directory

Today’s article is one where we’re going to find the size of a directory. Why? Because that sounds like something fun to do. The site has more than 250 articles, most of which are reasonably productive and authored by me. (I do love me some guest articles – so long as they’re from the community. No more paid stuff! That lesson was learned.) They can’t all be winners!

So, why would you want to know the size of a directory? How should I know? Maybe you need to make space? You could want to upload the directories and want to know if you have space at the destination? Perhaps you are going to transfer the files and you want to estimate how long that will take? You do you. I don’t care why you want to find the size of a directory. That sort of thing is between you and your directories!

Anyhow, we’ll be using ‘du’ in this article. If you want a GUI way to find the size of your directories, you can visualize disk usage easily enough. You can also easily find large files. You shouldn’t need to install ‘du’, it should be installed as a part of the standard toolkit (GNU coreutils). To find out if you have ‘du’ installed, you can just try du --v in the terminal, which will spit out some version information.

So this should be a fairly short article – nice and easy. Let’s get on with it!

Find The Size Of A Directory:

We’re going to us ‘du -h‘ for everything, because that -h stands for ‘human readable’ and it’s just easier than seeing byte sizes. You don’t actually have to use the -h, it just makes good sense to do so.

The format for this is largely ‘du -h /directory‘, like so (using the Documents directory as an example):

du -h ~/Documents

1	du -h ~/Documents

You can just add more directories as needed (we’ll add downloads):

du -h ~/Documents ~/Downloads

1	du -h ~/Documents ~/Downloads

That will output the size of both directories. If you are unaware, the ~ (tilde) is a shortcut meaning your home folder. For example, if you’ve navigated away from your desktop, you can cd ~ and get back home. It’s faster than clicking your heels together three times!

By the way, if you’re stringing directories together, you can get the total size of the directories with the following:

du -sh ~/Documents ~/Downloads ~/Pictures

1	du -sh ~/Documents ~/Downloads ~/Pictures

That’s about it. That’s all you really need to know for this exercise. I told you that it’d be quick and easy! Most of my articles involve opening the terminal, and yet so many of them are really quite simple to learn and remember. I strongly urge new Linux users learn a bit about the terminal, not because it’s hard but because it’s often easier and faster than using a graphical tool.

Closure:

I wasn’t kidding about there being more than 250 articles. There are 256 of them at this time, and this will make 257. So far, I haven’t run out of ideas and I’ve been able to get one out to you every other day. I hope you find these articles as useful as I’d like them to be. It does take me longer to come up with ideas, so it might have to slow down at some point. I mean, I can’t keep writing these kind of articles forever, can I? No… No, I don’t think I can.