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How To: Free Some Disk Space By Deleting Old Logs

In today’s article, we’re going to free up some of your disk space by deleting old logs. It’s a relatively safe and easy thing to do, and can free some space up if you’re running low. Unless there’s a problem, you really don’t need a bunch of old logs kicking around and taking up space.

There are other reasons for deleting old logs, such as keeping things tidy or even ensuring old activities aren’t easily discovered by browsing old log files. You may have done some debugging and now want to start with a new slate, so there’s another reason to delete logs.

Who knows what motivations you’ll have, but today we’ll be covering how to do it. The tool we’ll be using for log cleaning is ‘journalctl’, which is used for (according to the man page):

journalctl – Query the systemd journal

While ‘journalctl’ is a pretty nifty tool, we’re only going to scratch the surface. This article is only about deleting old logs and ‘journalctl’ is just the tool we’ll be using. If you want an article about all the features of ‘journalctl’, this is not that article. See? I’m saving at least a few people some time!

Anyhow, this article obviously requires a distro that uses ‘systemd’. If you don’t have ‘systemd’, you probably don’t have ‘journalctl’ and you’ll have to find another way to delete your logs. As most mainstream distros are using ‘systemd’, there’s a pretty good chance that you have ‘journalctl’ available.

So, with all that preamble gibberish out of the way, let’s go about …

Deleting Old Logs:

Like oh so many articles here, this one requires an open terminal. Why? Because of course it does. 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 have a look and see how much space your logs are taking up. You can do that with this command:

sudo journalctl --disk-usage

1	sudo journalctl --disk-usage

Now that you’ve seen how much space your logs are taking up, there are a couple of commands you can use for deleting old logs. If you want to go by space, you can use this command:

sudo journalctl --rotate --vacuum-size=100M

1	sudo journalctl --rotate --vacuum-size=100M

You can edit the ‘100m’ to whatever suits your needs. You can also use ‘g’ for gigabytes if you’d like to keep using that much log space.

If you want, you can also delete your old logs by the day. Let’s say you want to retain the last 3 days of logs. Well, that command would be:

sudo journalctl --vacuum-time=3d

1	sudo journalctl --vacuum-time=3d

I suspect you can figure out that the ‘d’ stands for ‘day’ and the 3 is how many days. You can, of course, change that to any number of days you wish. If you want, you can even use ‘w’ for weeks. Though, if you’re deleting log files to clear up disk space, you’re probably going to want to trim the logs even more than that.

Anyhow, when you’re done running one of the cleaning commands from above, you can verify that the space has been cleaned by running the very first command listed. That will do exactly what it did the first time you ran it – it’ll tell you how much space your logs are taking up. If they’re still not small enough for your liking, feel free to edit and run one of the above commands a second time.

Closure:

Well, there you have it… You have another article! This time I tell you how to go about cleaning old logs from your system. It’s a handy skill to have, though most folks probably have ample disk space – except those running on stuff like Chromebooks or the likes. If you’ve gotta live within 16 GB, you’re going to want to keep your logging to a minimum. Also, I still haven’t skipped a day from writing articles. It seems likely that I’ll do so eventually!

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How To: Add A User To A Group

Today’s article is going to teach you how to add a user to a group. It’s not particularly difficult, but it’s something everyone should know. If you don’t know how to add a user to a group, this article is meant for you.

This article is going to make a few assumptions. The first is that you’re familiar with cat /etc/passwd which will tell you what groups a user belongs to. It also assumes that you’re familiar with cat /etc/group – where you can find supplementary information.

Furthermore, you should also be aware of the groups command, which is a handy command, probably worthy of its own article, that lets you know what groups you already belong to. So, there’s a bit you’re expected to know already, or at least be familiar with conceptually, but trust me when I say this is a very simple article and very straightforward.

Anyhow, if you’ve looked at those previous commands, you’ll see there are a lot of groups. Your user may or may not be a member of those groups, as the groups command will let you know. For myriad reasons, you may wish to add yourself or another user to different groups. Well, that’s what this article is actually about. It’s about showing you how to …

Add A User To A Group:

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.

The command we’ll be using for this exercise is ‘usermod‘. You can get a head start by using ‘man usermod‘ but we really won’t be needing most of that information. In reality, we only care about a couple of the flags. Still, usermod is a pretty expansive command, with many options. Still, it defines itself simply as:

usermod – modify a user account

See? Pretty straightforward still. The command we actually want is:

sudo usermod -a -G <group_name> <user_name>

1	sudo usermod -a -G <group_name> <user_name>

The -a means append (add) the user. The -G means groups – so the -a -G means add a user to a group. You can verify the command worked (though, well, you really don’t need to – ’cause, assuming you did it properly it’ll work) with the following:

grep <user_name> /etc/group

1	grep <user_name> /etc/group

See? That’s it. You’ve learned how to add a user to a group – in under 500 words!

Closure:

Yup, it’s a nice and easy article for a skill you may need as you work with advanced group permissions. If you want to refine the permissions in your system, the sky’s the limit and it’s easy enough to add a user to a group if you need to. So, there’s another tool in your toolbox.

Find Your Linux System’s Timezone

This article, telling you how to find your system’s timezone, is more aimed at server users than desktop users. Desktop users probably know this already.

This command is most useful when you’re dealing with servers across the globe. You may want to schedule things (for one small example) to run at local times and knowing the local time will help with that. Knowing the timezone is pretty important, and the timezone itself is important.

The timezone dictates things like when your clocks change to adjust for Daylight Savings Time. While that may not seem like a big deal, having the proper date and time is a big deal. So, this article will tell you a couple of quick and easy ways to find your Linux system’s timezone.

Find Your Linux System’s Timezone:

This is going to need an open terminal. You probably could have guessed that. You can open a terminal with your keyboard – just press CTRL + ALT + T and your default terminal should open.

With your terminal open, you can try one of the following commands (I prefer the first):

cat /etc/timezone

1	cat /etc/timezone

The second option is easier to remember, but you don’t get the full name of your timezone. It may require a bit more thinking, just to be sure. Try:

date

date

And the timezone will be at the end of that string of characters. If you’re still confused, you can type the abbreviation into your favorite search engine and they’ll get you sorted out.

Thee is a third way, but keeping that way crammed into memory isn’t as easy as the date command. It’s just:

timedatectl | grep "Time zone"

1	timedatectl \| grep "Time zone"

Of course, you can just use ’timedatectl’ without grep. That’s a viable option, it just spits out more information. So, if you were to remember just one of the commands, the third one is probably the best.

Those are three ways I know of to find the timezone within the Linux terminal. It may show up in the GUI. If you want to add it to your system’s time display, you add %Z to the string (ISO 8601 standardizes this) and it’d look something like this when you changed it and the change took place:

Using the #Z to show the timezone in the system clock. — Tada! That’d be how you’d do that!

So, you can display the timezone in the GUI if you really needed to. But, this article is mainly for those who admin servers across the globe and need to know the timezone the system is in.

Closure:

Woohoo! Another article done and ready to publish. However, I’m going to leave this one unscheduled (scheduled way in the future) so that I have an ’emergency’ article, an article that can be used when Mother Nature has taken out my ‘net or motivation just isn’t there.

Either way, this article covered how to find your timezone in Linux. It’s information you may want, and information you may want to check before rolling out changes. The data is in the system, we just need to pry it out.

Find Out Which Shell You’re Using

Today’s article is going to teach you how to find out which shell you’re using. Knowing which shell you’re using is important if you’re using an unfamiliar system. Most of the time, it’s something you’d already know, but once in a while you might need to find out which shell you’re using.

As you’re visiting this site, it’s fairly safe to assume you’re using Linux (or at least interested in Linux). In that case, you’re quite likely using Bash. Bash is the most common, from my observations.

If you’re curious, Bash is a replacement for Bourne Shell – and is ‘Bourne Again SHell’. It has existed, thanks to the Brian Fox and the GNU Project, since the late eighties. It’s pretty ubiquitous, pretty stable, and pretty feature complete.

While Bash is the most common, it’s certainly not alone in the field of shell options. There are other shells, from ZSH to Fish, or from Dash to Nushell. In some distros, you might find one of them installed by default, but it’s usually going to be Bash.

So, odds are pretty good that you will already know if you’re using something other than Bash. After all, you’d likely have been the person who installed the alternative. Still, there are a couple of commands you can use when you want to figure out which shell you’re using, for when you do need to know.

Find Out Which Shell You’re Using:

On the off-chance that you don’t know what a shell is, Wikipedia describes the shell as:

A Unix shell is a command-line interpreter or shell that provides a command line user interface for Unix-like operating systems. The shell is both an interactive command language and a scripting language, and is used by the operating system to control the execution of the system using shell scripts.

And now, with your terminal emulator open, let’s go about finding out which shell you’re using.

The first command you can try would be:

echo $SHELL

1	echo $SHELL

You can also use the echo command in a different way. It’s even a bit more clear with this command:

echo $0

echo $0

You can also use ‘ps’ which takes snapshots of current processes:

ps -p $$

ps -p $$

There are certainly other ways to find out which shell you’re using, but those are a few ways that are easy enough. If you have other ways, please feel free to leave them as a comment.

Oh, and here’s a bonus… If you want to see which shells are installed on your system, you can use the following command:

cat /etc/shells

1	cat /etc/shells

The output of this would look similar to this:

list of installed shells — This is the defaults from Lubuntu 20.04 LTS. Your output may vary, of course.

As I said, that’ll let you know which shells you have installed. In a future article, we might discuss how to change your default shell – but that’s something I seldom bother with these days. Bash works and works well.

Closure:

Yup… There it is! Another article. Now that the year is up, I’m not sure what to look forward to as a goal. I highly doubt I’ll make it a full two years, but it could happen. We shall see…

Change Snap Application Privileges In Lubuntu

In today’s article, we’re going to learn how to change Snap application privileges in Lubuntu. With Ubuntu, it’s a bit more straightforward. In Lubuntu, you have to dig around a little bit. Don’t worry, ‘snot hard – it’s just not all that intuitive.

Snap applications come with their own privileges. This is useful because sometimes you may want to change them, to enable something that was disabled or to disable something that was enabled. I think it’s sorted now, but at one point you even had to change the permissions to let the Firefox browser access removable media.

In Ubuntu it’s pretty straightforward and there are a ton of tutorials already out there that will help you change Snap application privileges. It’s just one of those things that comes with Snaps, so we’ll cover Lubuntu.

I’ve written about Snap applications before, including sharing how to disable Snaps completely. However, the reality is that they’re going to be a part of the Ubuntu ecosystem for the foreseeable future.

Like them or not, they will be a part of Ubuntu and official Ubuntu flavors. I suspect trying to avoid them will get more difficult. With the new Lubuntu, for example, the Firefox browser will come as a Snap application by default.

So, well, even we folks using Lubuntu must come to grips with Snap applications. This can be a pretty painless process, if you’re armed with some information. That’s what this article is meant to do. This article is meant to teach you how to …

Change Snap Application Privileges In Lubuntu:

This is actually pretty easy, but not necessarily intuitive. Unlike many of my articles, you don’t actually have to start with an open terminal. No, you need to start with “Discover”.

So, crack open your menu, click on System Tools, and then click on Discover. Once you have Discover open, you can use the search or installed option to find the application in question. In this article, I decided to just use Firefox – seeing as we Lubuntu users will be faced with a Snap app Firefox.

When you find the application, you just click on it. It looks like so:

click on Firefox to begin — See? I even started you off with a handy arrow! *It’s a recurring theme!*

Once you’ve clicked the application, then you just click on the obvious! You just click on “Configure permissions”. That looks like this:

click on permissions to continue — Yup. I gave you another handy arrow – but it should be obvious now.

Finally, you can adjust the individual permissions. That looks like this:

finally, adjust your permissions as needed — There are a bunch of settings you can change. Again, you get a handy arrow!

That’s about it, really. The thing is, you have to use Discover. While the Muon application is able to install applications, it doesn’t deal with Snap applications. Only the Discover application has these menus and it’s the only way (at least graphically, by default) for you to adjust the individual Snap application privileges.

So, while it’s not necessarily intuitive – it’s not dreadfully difficult. You just have to know where to look and then it becomes obvious.

Closure:

Guess what? As of tomorrow, a day where no article is scheduled, it will have been a full year that this project has been alive. That’s right! I’ve gone the full year without missing a single publication date! If I can do it, so can’t you!

So, am I done? No… No, I don’t think so. I still have articles that need to be written, things that need to be said. I’ve had a great deal of fun, though it has been a lot of work. I’ve learned some, you’ve learned some, and I’d say it’s a net benefit to the Linux community – though I suppose I’m a bit biased. (Feel free to agree with me!)

I may take a few days off. I’m not actually sure. I haven’t decided. I have decided that this can’t be the last article, so there’s that. Which is nice… If nothing else, I’ll see you again in a few days. I might enjoy taking a break. Then again, I kinda suck at taking breaks. I truly suck at retirement.