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:

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:

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:

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!

Thanks for reading! If you want to help, or if the site has helped you, you can donate, register to help, write an article, or buy inexpensive hosting to start your own site. If you scroll down, you can sign up for the newsletter, vote for the article, and comment.

Smash a button!
[Total: 3 Average: 5]

How To: Graphically Check Your Logs For Errors With ‘KSystemLog’

Today’s article is going to be about one of my favorite tools for checking the various system logs, KSystemLog. Checking your logs for errors has never been easier, and this is one of the first tools I reach for when I have a problem that I don’t know how to solve.

When you first notice a problem with your Linux box, you might only be noticing the symptoms and not actually seeing the reason. Those reasons can often be found by rooting through the various logs to see what’s actually causing the error.

Back in the early computing days it required the terminal to work with your system’s logs. You’d ask for help on a forum and they’d request that you run a command that looked something like this:

It that actually worked and it worked well enough for a long time. It worked even better when you knew what you were looking for and looking at. If you didn’t, you’d scroll through tons of text in the terminal with no real visual cues to sort through the data. Today, there are better tools for this.

Enter KSystemLog:

Thankfully, there’s KSystemLog. KSystemLog’s man page describes it thusly:

Description: system log viewer
KSystemLog show all logs of your system, grouped by General (Default system log, Authentication, Kernel, X.org…), and optional Services (Apache, Cups,etc, …).
It includes many features to read nicely your log files:
* Colorize log lines depending on their severities

* Tabbed view to allow displaying several logs at the same time
* Auto display new lines logged
* Detailed information for each log lines

Which looks like this:

ksystemlog
KSystemlog UI – The images are old and can’t be expanded due to a sudden bout of laziness.

As you see in the image, KSystemLog is a handy GUI that lets view your various system logs. When you look at the image above, you’ll be able see that one of the lines is a darker blue than the previous lines. This is because it’s a new entry, an event that happened after the application had been opened.

That means you can open KSystemLog and then open the application that’s giving you trouble. Doing it this way will let you see what log entries are made and what errors are thrown as the application is opened and used. Of course, you can always examine the entire log of errors and events. 

Even better, the events in the logs can be color-coded, providing easy visual cues. The events range in color, indicating severity, of from a light gray (normal) to a bright red for emergency-level events. You can even filter and search for events.

error messages in kystemlog
Note the color change for errors.

KSystemLog is a KDE application but pulls in very, very few dependencies. It starts rapidly and will show the installed log files by default. In a pretty default configuration, it finds these:

ksystemlog logs available
Currently available logs on this system. More are available.

Getting KSystemLog:

Assuming you are using a major distro, it’s almost certain to be your default repositories. For example, if you’re using a Debian derivative (Ubuntu, Mint, etc.) then it can be installed by opening the terminal and entering:

Just adjust the above installation command for your distro’s package manager and you should be good to go. If KDE is an option for your distro, then KSystemLog can’t be far behind.

By the way, you don’t have to know what the errors mean. You can just take the logged errors and use them as search terms to help. Just copy and paste, using the errors verbatim, and search! It’s absolutely amazing how many errors can be resolved by doing just that. I’ve personally used this method to troubleshoot so many times that I’ve decided that it’s a tool we all need in our Linux toolbox.

Closure:

And there you have it, another article. This one is about KSystemLog, a tool that lets you graphically examine your system’s logs. It’s a great tool for wading through long logs and searching for the root cause of various problems. In an ideal world you’d not need such a tool, but this is not an ideal world. It’s a world with bugs and errors, and KSystemLog is a tool for just that.

Thanks for reading! If you want to help, or if the site has helped you, you can donate, register to help, write an article, or buy inexpensive hosting to start your own site. If you scroll down, you can sign up for the newsletter, vote for the article, and comment.

Smash a button!
[Total: 3 Average: 5]
Linux Tips
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Zoom to top!