Software Archives • Page 23 of 34 • Linux Tips

Kill Frozen Applications The Easy Way

Linux is an operating system and, like every operating system, you sometimes need to kill frozen applications. Computers are not now, nor will they ever be, perfect devices with perfect software. Sometimes, crap happens and you find yourself in a situation where you need to kill a frozen application or two. (Even if it were perfect, your RAM is bombarded with EMR and will eventually knock a bit loose, even with ECC RAM.)

There are all sorts of ways to deal with frozen applications. You can do everything from sigterm to pkill. Worst case scenario, you always have RIESUB to fall back on – for a completely frozen system. All of those are great and have their place, as does this method.

As this is meant to be quick and simple, so we’re just going to jump into it – and have a relatively brief article today.,,

Kill Frozen Applications:

Let’s say you’ve somehow managed to make your browser freeze. It is unresponsive, though the rest of the system seems to work just fine. You could open a terminal and try the pkill and sigterm types of resolutions or you can use xkill. It’s literally point and click!

So, open your terminal and enter the following (read the rest before doing this):

xkill

xkill

When you do, your terminal will look a little like this:

Your cursor might also change. In one test my cursor is an X and on another test, with a different OS, it’s a red skull and crossbones. I couldn’t caputer either in a screenshot, so you get what you get.

NOTE: If you change your mind and don’t want to click-to-close, you can still type in the terminal. You can use sudo pkill <terminal-name> to get back to normal.

Anyhow, take that cursor and click on the application you want to close. This sends a shutdown command to the frozen process and things should go back to normal after the frozen application closes. Of course, sending the shutdown command to a process in no way indicates a certainty of it listening, it may still fail and stay frozen – perhaps depending on how exactly frozen the application is.

NOTE: It has come to my attention that I should warn you. If you click on it after typing xkill, it WILL close it. It’s pretty indiscriminate. It doesn’t care if you’ve saved. It will kill it. I’m also told that CTRL + ALT + ESC is a shortcut in Mint for this, but I can’t seem to make it work.

Closure:

See? I told you that it’d be a quick and easy article. This one is about you you can kill frozen applications – but there are all sorts of ways to do that. You can expect future articles to cover this very subject, but with different methods. I just figured this would be quick and easy for everyone.

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What Exactly Is A Linux Distro?

You’ll hear the phrase “Linux distro” tossed around quite a lot and this article will explain what exactly is a Linux distro. It’s not overly complicated and this article shouldn’t take a whole lot of time.

You should also be aware that I’m writing this article in a way that is aimed at the lowest common denominator. I’ll be trying hard to make it simple to read and easy to understand. I don’t want to overwhelm folks with details. I want folks to understand the general concepts.

On to the article…

What Is Linux:

The term ‘Linux Distro’ is short for ‘Linux distribution’.

I don’t suppose that’s all that helpful…

So, what is Linux? We use the term loosely, but Linux is just the kernel. That’s all Linux is – by itself.

Again, that’s probably not all that helpful.

Then, well, what is a kernel? The kernel is an interface between hardware and software. It also schedules tasks, such allocating memory and keeping track of the memory space where things are stored. It manages processes, memory, and device drivers – interfacing hardware with software.

You really shouldn’t need to interact with the kernel at a personal level, at least not directly. At the same time, everything you do requires kernel participation. Without it, hardware would be useless.

Okay, so now we know what the kernel is – and we know that it is called Linux. Well, that’s all Linux is – and, by itself, the kernel is not all that useful.

Introducing GNU:

Instead, we have some tools around the kernel that make the kernel useful. These tools are often from GNU. Many of these tools existed before the kernel was invented, actually. They’re (many of them) clean-room implementations of Unix tools that were just waiting for the right kernel to come along.

In 1991, Linus Torvalds released his kernel to the world at large. The GNU tools already existed. People put the two together and we started to have the basics of a working operating system.

See, an operating system is much more than just the kernel. At bare minimum, it must have some tools to interact with the kernel. The GNU tools will let you do that *(and more). As GNU tools predated the kernel and because the kernel is newer, many advocate calling it “GNU/Linux”.

That is not an argument without merit as all the major Linux distros make use of tools from the GNU Project. Without one, the other is useless. While there was an expected GNU kernel (for GNU Hurd), that has not had much attention and success.

And Now, A Linux Distro:

You could actually accomplish quite a bit with just GNU/Linux but it still didn’t have tools like a useful browser, a graphical text editor, a graphical desktop, or anything like that. By itself, it’d have limited appeal and you’d need to write any software you needed that wasn’t already included. A lot of what people expect would not have been included with just the GNU tools.

And so the concept of a ‘distro’ is born.

Enterprising people, people who’d join others with their efforts, would combine GNU/Linux with a bunch of other tools – creating a concept of a set of tools fit for a purpose. You’d have distros meant to be used for running servers, distros for home use, distros for security purposes, distros for privacy reasons, etc…

And those distros would all be built around the GNU/Linux tools.

Each Linux distro out there was made for a reason. If there were already distros that filled that roll, then the distro author’s reasons were that they could do it better or in a different way.

Today, there are like 500 active Linux distributions out there. Each one of them fills a niche, scratches an itch, performs a task (or set of tasks), at least a little bit different from the others. So, finding a Linux distro that suits your needs can be either easy or hard. It all depends on what you need.

Why Call It Linux:

Well, we call it Linux because that’s the most important bit. Without it, none of the rest of the system works. Without the Linux kernel, you’re stuck looking for a different kernel. (Note: Other kernels do exist.)

There’s absolutely some merit in calling it GNU/Linux. The GNU tools are in most every distro and without the GNU tools the kernel is pretty useless. At the same time, the GNU tools are older than the kernel. Combined, the provide a great deal of the functionality that is an operating system.

I don’t call it GNU/Linux because it’s unwieldy and everyone who needs to know that GNU is involved already knows that GNU is in there. I find those that insist on it are mostly okay people, they’re just pedantic and want to highlight the distinction. They’re not bad people, they just want to make sure GNU is recognized.

When important, I’ve been known to refer to Linux as GNU/Linux. I just don’t make a habit of it. Also, really, not too many people care. Though, I suppose calling it GNU/Linux can be confusing for some new folks. Not my readers though, they’re witty, intelligent, and eager to learn!

Closure:

Well, it’s an article… This one tells you about the Linux distro. It explains what a Linux distro is and why we call it that. Hopefully this is enough information for a layperson. If not, you can always ask for more information and I’ll do what I can to oblige. Like I said, this is written for the lowest common denominator. It’s not written for the folks who have used Linux for a decade. Those people have been using Linux for a decade, they should darned well know what the Linux kernel is!

Enable PPAs In Elementary OS

Today’s article will tell you how to enable PPAs in Elementary OS. This is generally considered a bad idea, but it’s your computer and you can do anything you want with it. So, well, this one will have you enabling PPAs in Elementary OS.

I suppose that some folks will have no idea what I’m talking about. So, I’ll point out that Elementary OS is a Linux distro. Also known as eOS, it seems targeted at looking good, having cohesive apps, and charging you money for this. That’s fine. You can use it for free.

Elementary OS is based on Ubuntu, which is based on Debian. Ubuntu has PPAs, a way to install software that’s not in the default repositories, but Debian does not. Some Ubuntu derivatives also do not allow PPAs (by default) and Elementary OS is among those that do not.

Elementary OS developers would prefer you use AppImages or Flatpaks, instead of accepting the security burden that is allowing PPAs. After all, any PPA you add is pretty much like giving someone root access to your computer.

Well, today’s article is about just that. It’s a quick article that’ll teach you how to use PPAs in Elementary OS. Heck, the command to enable this is shorter than this intro, where I show you how to…

Enable PPAs In Elementary OS:

To get started, we’re going to have to have one of those open terminals. You can root through your menu (or use the search feature) or you can just press CTRL + ALT + T and your default terminal should open.

Next, to enable PPAs in Elementary OS, you really only need one command. But, we’ll make sure you’re updated fully before trying this. Thus, you get two commends!

sudo apt update && sudo apt upgrade -y
sudo apt install software-properties-common

1 2	sudo apt update && sudo apt upgrade -y sudo apt install software-properties-common

Now that you’ve done that, you can now add PPAs to eOS. If you wanted to keep up with the more recent versions of LibreOffice, you’d run the following commands:

sudo add-apt-repository ppa:libreoffice/ppa
sudo apt update
sudo apt install libreoffice

sudo add-apt-repository ppa:libreoffice/ppa

sudo apt update

sudo apt install libreoffice

That should install LibreOffice and then keep it updated as the PPA maintainers update the repository. Either way, congratulations! If you’ve done everything correctly, you can now enable PPAs in Elementary OS.

Closure:

There you have it, another article. This article tells you how to enable PPAs in Elementary OS. Their preferences for different packages isn’t too dissimilar than Ubuntu themselves recommending Snap applications. Plus, any PPA you add will the be able to install software by its very nature, Maybe it is time to start doing away with the old ways and moving towards modernity?

How To: List Cron Jobs

Today’s article is going to show you a few ways to list cron jobs on your computer. If you don’t know, cron is a way to schedule jobs in Linux. Cron goes all the way back to the mid-70s UNIX era. It’s a pretty handy tool that we’ve not yet really covered on Linux Tips.

In one of these future articles, I’ll have to explain how to add, remove, and change cron jobs. It’s easier than you might think. Importantly, even if you haven’t added any cron jobs, your system almost certainly has many of them. They’re useful for scheduling tasks and your computer does all sorts of task scheduling even if you don’t add anything to it.

In today’s article, we’ll show you how to list cron jobs by their type. By type, I mean by when they’re scheduled. Tasks are scheduled on an hourly, daily, weekly, and monthly basis. You can schedule them at other intervals, but generally speaking the system will only use those particular intervals.

List Cron Jobs:

Like many articles, this one will also require an open terminal. The terminal is a pretty useful tool! Anyhow, you can open one pretty easily. Just press CTRL + ALT + T and your default terminal should open.

Once your terminal is open, we can first examine the the hourly cron jobs. It’s really easy. Just enter:

ls -la /etc/cron.hourly

1	ls -la /etc/cron.hourly

You may start to notice a trend with this next one. If you want to list cron jobs by their daily status, your command would be just a little different.

ls -la /etc/cron.daily

1	ls -la /etc/cron.daily

Sure enough, if you want to list cron jobs by their weekly status, the command isn’t much different. That one is:

ls -la /etc/cron.weekly

1	ls -la /etc/cron.weekly

And of course monthly is like this:

ls -la /etc/cron.monthly

1	ls -la /etc/cron.monthly

See? Nice and easy. A little bite-size article that tells you how to list cron jobs.

Closure:

And there you have it. You have yet another article, this one dealing with showing you the cron jobs that you have running on your computer. These are all the tasks that are regularly scheduled. One of these days, I’ll do an article about editing them and adding them, including adding them with different interval schedules.

Install And Secure MariaDB In Ubuntu

I’ve recently purchased a couple of new VPSes (spelling?) and so today’s article is about how you install and secure MariaDB. As mentioned before, some articles are just going to be me scratching my own itch. In this case, I have a couple of virtual private servers that are doing nothing more than costing me money. I might as well put them to good use.

So, what is MariaDB? It’s a database management system that’s a fork of MySQL. Oracle purchased Sun Microsystems in early 2010 and MySQL went with it. Quite a few people didn’t trust Oracle’s stewardship of MySQL, they were already known for their own database management system, and so MariaDB was born.

MariaDB is actually a fork of MySQL. MariaDB is also permissively licensed, while the newer MySQL has an enterprise version with proprietary code in it. MariaDB is completely open and works just fine under a number of FOSS licenses.

MariaDB is just as fast, and faster in some operations. It supports the native languages used with databases. It’s well supported with a vast number of installs running some of the largest databases on the planet. MariaDB is one of many MySQL forks, which is to be expected. After all, MySQL was the first of its kinda – a free database management system that was released at a key point (mid 1990s) of Internet development.

In my observation, and despite all its goodness, MariaDB a testament to exactly how much people dislike and don’t trust Oracle! So, then, why not…

Install And Secure MariaDB:

As this is server related, you’re likely to be doing this in a terminal and you’re likely to be using SSH to do so. So, I’m going to assume you already have a terminal open, saving us some time.

Make sure you’re fully updated before attempting this, so:

sudo apt update && sudo apt upgrade -y

1	sudo apt update && sudo apt upgrade -y

Now, we’ll go about installing MariaDB. It’s trivial, just run:

sudo apt install mariadb-server mariadb-client

1	sudo apt install mariadb-server mariadb-client

That’ll take a minute and, when done, you can verify that the MariaDB service is up and running properly. That needs this command:

sudo systemctl status mariadb

1	sudo systemctl status mariadb

MariaDB should be installed and running – but it’s woefully insecure. In order to secure the MariaDB installation, you will want to run the following command:

sudo mysql_secure_installation

1	sudo mysql_secure_installation

It’s going to first ask you for your root password. You’ll enter your default root (sudo) password. One of the questions will let you assign a different password for MariaDB and it’s strongly recommended that you do so. For the other few questions, you can read them or you can just answer yes to all of them, as all of them are the best choices for securing your databases.

That’s actually all there is to it. You’ve learned to install and secure MariaDB. It’s one of the many steps you might take if you wanted to set up your own server, so be careful when you’re doing so and opt for the best practices.

Closure:

There you have it! It’s another article, this one tells you how to install and secure MariaDB. In some cases, rare cases indeed, you might want to open it up to connections outside of localhost. If you do that, be sure to open up the correct port in the firewall. Other than that, you’re good to go.