Category: Tips

A Quick Look At The Shutdown Command

This is going to be just a quick article about a command many of you will be familiar with, as we take a quick look at the shutdown command. This is pretty basic and something everyone should be familiar with.

Our pure-GUI users will just shut the computer down with the menu option but sometimes a GUI is unresponsive. There are other times when you don’t have GUI access, as there’s no desktop environment loaded. When this happens, you can still shut the computer down. To do this, you can use the shutdown command.

There’s not a lot to the shutdown command, but the good news is that you won’t have to install anything to use it. If you’ve got a Linux system, you’ve got access to the shutdown command.

In fact…

shutdown:

As I said, you won’t need to install anything to use the shutdown command. It’s something that’s built in. You can check the man page with the following terminal prompt:

If you run that command, you’ll see that this is the correct tool for the job. It will in fact shut down the computer, though it has a few options that we’ll cover. We won’t cover everything,  just the things you’re likely to need.

The man page describes the command like so:

shutdown – Halt, power-off or reboot the machine

See? If you want to shut the computer down (including halt and reboot) then this is the correct command for the job.

The Shutdown Command:

As mentioned above, this is a terminal-based command. That means you’re going to need an open terminal. If you press CTRL + ALT + T a terminal should pop up. If not, there’s a terminal in your application menu.

Some systems may require ‘sudo‘ for this. This is not true for all distros and you’ll need to discover that on your own. I’ll omit the sudo in this article.

The basic syntax is this:

That command will stop anyone from logging in and shut the computer down in five minutes. It’s the basic usage of the shutdown command.

If you want to shut down the computer immediately, try this command:

If you want to reboot, try this command:

Again, that will reboot the computer in five minutes and stop anyone from logging into the system. 

If you want to reboot immediately, add ‘now’ to the command like so:

You can also halt the system. If you halt the system, it will remain powered on but all CPU functions will cease immediately. That works just like the above commands. To halt the system in five minutes run this command:

If you want to halt the system immediately, run this command:

You’ll need to power the system down and back on with the power button.

You can also schedule a shutdown, reboot, or halt. To do that, you use the HH:MM (hours/minutes in 24-hour time), like so:

If you schedule a shutdown, nobody will be able to log in within five minutes of the scheduled shutdown command. You’ll remain logged in and people can log in until that time is reached, but after that time is reached no new users can log into the system.

There is more to the shutdown command but that’s all you’ll realistically need, even as a system administrator. And, if you don’t know this already, you’re a system administrator even if you’re just a basic Linux desktop user. You’re in control of your computer.

Closure:

I thought I’d cover the shutdown command because it’s something I haven’t covered yet. I started off trying to cover the basics first, but I didn’t cover everything. There are still basic functions that I’ve yet to cover. I’ll get to them 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 site. If you scroll down, you can sign up for the newsletter, vote for the article, and comment.

Setting Up Coding Environments on Linux for Educational Use

With so many strong attributes, such as robustness and flexibility, Linux stands as a powerful platform for teaching coding among many other educational purposes. So this guide is meant to help educators and students set up a suitable coding environment when they are on this journey of learning to program.

Step 1: Choose the Appropriate Distribution of Linux

The first thing needed is choosing a suitable distribution of Linux. For novices, it is Ubuntu or Linux Mint, as these two can be user-intuitive and include many documented features and options. Some other users more advanced may incline towards Fedora or Debian for the vastness of packages and community support. If you want a comprehensive course for children programming that can work with these distributions, Codemonkey offers quite a few interactive coding courses.

Step 2: Install Required Software

Once the Linux system runs on your computer, you are supposed to install software in order to be able to code. Essential tools include:

Text Editors: Using Atom, Visual Studio Code, or Sublime Text for writing out code.

Compilers/Interpreters: If you’re going to teach a programming language, then just install Python, GCC for C/C++, or JDK for Java.

Version Control Systems: Git for tracking changes in code and enabling collaborative development.

Step 3: Setting up a Development Environment

Configure the environment post installation of the required software.

Customize the IDE: Most IDEs, and text editors, for that matter, will support the ability to easily change settings. Make slight changes to the settings to fit your educational needs, such as setting up auto-save, and enabling line numbering and syntax highlighting.

Install Extensions: Extend the functionality of VS Code to include linters, code formatters, and debuggers.

Create a Project Template – You can create project templates for subjects that students may use to jumpstart their assignments.

Step 4: Using Learning Tools

Think about including instructional and collaboration tools:

  • Code Sharing Platforms: Use tools such as GitHub Classroom to be able to distribute assignments and collect student submissions.
  • Interactive Learning Environments: Jupyter Notebook is a really good platform to write Python since you are able to see code and output in real time.

Step 5: Ensure Accessibility and Security

It ensures that every student is provided with the necessary resources for their needs.

Accessibility: Configure accessibility options available in Linux to accommodate all students.

Security: Install a firewall and regularly update to prevent unauthorized access to the systems.

Step 6: Documentation and Additional Support

Finally, give resources that can enable the learner to self-study:

  • Write Documentation: Provide tutorials or links to online tutorials, on tools and languages you are teaching.
  • Support Offered: Providing forums or chat groups where students can ask questions and help one another.

Final thoughts

Setting up a Linux-based educational coding environment first requires making extensive plans on all the necessary tools and resources and then going ahead to implement the laid plan. Through these steps, instructors can create a stable and effective environment in which their students can learn.

How To: Disable CPU Cores

This is not something everyone is interested in doing but you might as well learn how to disable CPU cores. This is something that’s easily done and easily reversed, so you might as well have an article on the subject.

Why would you do this? Well, maybe you have a low-power project and want to save energy. You may have more CPU horsepower than you need and you prioritize energy use. This might even be something you do to increase the battery life in your mobile devices. Maybe you want to lower the heat output from your CPUs.

There are valid reasons why you might want to disable CPU cores.

It’s just that this isn’t going to apply to most of you. I’d say that 99% of you aren’t going to want to disable your CPU cores.

What are cores? Well, you probably have one single CPU chip in your computer. That computer is then probably broken down into multiple cores. Each core looks like a single CPU to the hardware and operating system.

Of course, each core may also have multiple threads. Threads would also represent themselves as individual cores. If you disable a CPU core, you’ll also disable the threads on that core, if you use a multi-threaded CPU.

NOTE: Moden CPUs may have high-power and low-power CPUs. I have no clue which will be disabled if you follow this article. I don’t have a fancy CPU to test with. You can test and let us know the results! It’s easily reversed. You can add your cores back with no problems.

GRUB:

GRUB is the application we’ll be playing with. I should also mention that GRUB stands for Grand Unified Bootloader and is the default bootloader for most Linux distributions.

GRUB controls how your system boots and GRUB can also give you the option of which operating system to boot if you use a multi-boot system. It’s one of those things that you can modify pretty heavily. You can even modify your boot screen’s appearance when you’re using GRUB.

Trying to access the GRUB man page is interesting. It isn’t your traditional man page and isn’t accessed in the same way. If you want to check the man page, you use this command:

If you run that command you’ll see what looks like an index page. That’s because it is an index page. Use your arrow keys to navigate and use the enter button to open a category page. It’s pretty simple to navigate but there’s a whole lot of information there.

If you’re a newbie, you might just want to look and see that info page. Trying any of that out may result in a system you can’t boot. You have been warned. Tinkering blindly with GRUB will eventually break your system unless you know what you’re doing. Not even I understand everything – but that’s true about a lot of things.

This article assumes that you have GRUB and Nano installed.

So, now that you know what we’ll be using, let’s get into the article!

Disable CPU Cores:

If you didn’t figure it out from the ‘Nano’ mentioned above, this is one of those things you do in the terminal. More often than not, you can open a terminal by pressing CTRL + ALT + T on your keyboard. If that doesn’t work, look in your application menu to find your terminal and open it.

Next, you need to know how many CPUs you have. You should probably already have that information. If you don’t have that information, you can use something like ScreenFetch to find that information. (I used lscpu to find my information, but I’m trying to keep it simple for you.)

Just run this command (once you’ve installed ScreenFetch):

The output should tell you how many cores you have available. Like so:

screenfetch showing CPU cores
This should be easy enough for anyone to figure out! You can find this information easily.
The Exercise Itself:

Now that you know how many cores you have, you can modify GRUB.

Find the following line:

Change that line to something like this:

As you saw above, this system has 8 CPUs listed. Let’s say I wanted to cut that in half, perhaps to save battery life while I’m on a trip and not doing any computationally heavy tasks. I’d change that line to match this:

Now that you’ve made the edit, you need to save the file. As you’re using Nano for this, you save files by pressing CTRL + X, then Y, and then ENTER.

The next step is to update GRUB, telling GRUB to reconfigure itself because you’ve changed some of the information. This step is essential but simple.

Next, you reboot the system for the changes to take effect:

When you next open your system, run screenfetch again to confirm that you’re using fewer cores and that you’re using the number of cores you specified.

I did this in a virtual machine with 2 CPUs. This was done to confirm that it works and to provide you with some screenshots. When I did so, I did so with lscpu and not ScreenFetch. I hadn’t thought of ScreenFetch and I’d already taken the screenshots. So, that’s what you get.

The Results:

The original configuration:

using lsusb to show the number of CPU cores
As you can see, there are two cores in this instance. Core 0 and Core 1.

After the change:

using lscpu to show that there are now fewer cores loaded
Sure enough, there are now fewer cores in use than there were before. It’s just core 0.

As you can see from the screenshots (again, taken in a virtual machine), it’s easy enough to disable CPU cores in Linux. Well, assuming you’re using GRUB… I’m sure it’s possible with other bootloaders but I don’t have any real experience with them in the memorable past. I’ve used GRUB, more or less exclusively, for quite some time.

If you want to undo this change, or if you want to change the CPU cores to some other number, just remove or edit the added text. If you do that, be sure to run sudo update-grub again to ensure that your changes take effect. If you don’t remember to do that, any changes made will be lost. So, it’s important to update GRUB when you’ve changed any of the information – not just this information.

Closure:

Well, I’m not sure how many Linux users are going to want to change their CPU cores to a lower value. It was in my notes and seemed like a fine article to share with you. I can see doing this in a few instances, such as when you want to save power. Of course, modern operating systems are pretty good at saving power on their own, but it’s still something one might consider.

If you have any other reasons as to why one might want to disable CPU cores, leave a comment. I’m a bit curious. I’d probably do it if I needed longer battery life while on the road or something. I don’t do too many computationally heavy tasks these days. So, I could get away with it on some systems.

Also, this is from my notes. My notes predate the modern CPUs. Quite literally, I have no idea how this will work on systems that have cores that are different, such as high-power and low-power cores. Feel free to test and let me know what you learn. Again, leave a comment. I promise I won’t share your information with anyone and I’ll never send you an email you didn’t ask for.

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 site. If you scroll down, you can sign up for the newsletter, vote for the article, and comment.

Seeing as you’re here, why not visit our friends at Blunix?

“Blunix GmbH offers Debian and Ubuntu focussed Linux Emergency Support 24/7, Project-based Linux Consulting, FOSS-based Managed Hosting on your company IaaS provider account as well as custom Training and Workshops. We prioritize fair business partnerships and employee quality of life over profit. We focus on reasonable security by default and encourage your employees and developers to keep things secure enough to avoid 99% of security issues with automated attack vectors. We focus exclusively on this and do partner with other companies to refer customers that do not fit exactly what we do, or where we require additional help (for example we have a security-focused company that we partner with for higher risk factor hosting setups).”

Click to visit Blunix GmbH. 

View Some Logs In The Terminal

Today we’ll have a relatively simple set of commands that will show you how to view some system logs in the terminal. We’re only going to cover a few of them that are similar in operation. There are far more things that get logged.

You generate logs as you use your computer. These will vary and there are quite a few logs kept. Logs aren’t just kept by the system. Some third-party applications create logs. We’ll only be covering a few system logs. I just want to keep things simple.

The tool we’re using for this exercise is the cat command. The cat application is one tool that lets you read text files in the terminal. It’s a frequently used tool at my house. Hopefully, you too will get comfortable using this command at your house.

It seems like that should be enough of an intro. If you have any questions, you can always leave a comment. Those get seen and addressed more quickly than when you try to contact me elsewhere. (Comments almost instantly send a notification to whatever computer I’m using. They’ll even ping my phone if I turn the notification sound on.)

Anyhow… Ask away, should you have any questions…

View Some System Logs In The Terminal:

We’ll be viewing a few different types of logs. As mentioned above and in the heading, this is something we do in the terminal. You can usually open a terminal by pressing CTRL + ALT + T. If that doesn’t work, you’ll almost certainly find a terminal in your application menu.

First, we’ll view the kernel log.

The kernel is the actual “Linux” in your Linux. The kernel deals with task scheduling, and running processes as needed. It’s an abstraction between you and the hardware.

If you want to view the current kernel log, use this command:

If you want to view the previous session’s kernel logs, use this command:

Both of those commands will flood your terminal. That’s okay, you can use the pipe operator and the less command like so:

Next, we’ll view the boot log.

When you boot your computer, the computer keeps track of what happens during that process. This is known as the boot log. It can be exceptionally handy when you have a problem booting. 

If you want to check the current boot log, use this command:

If you want to check the previous boot log, check it with this command:

Again, you can use a pipe and the less command to manage the flow of data.

Next, we’ll view the system log.

The system logs all sorts of additional information. If you’re not finding the information you want in the previous two logs, checking the system log is prudent. The system logs all sorts of things that are useful for resolving problems.

If you want to check the current system log, use this command:

If you want to check the previous system log, run this command:

Don’t forget that you can use a pipe and less in this command. This will give you a slower output you can manage with your arrow keys.

And that will show you your system log.

That’s all it takes to view the major system logs. There are other logs and we’ll have to cover them at some point.

Closure:

Well, this didn’t take too many words or too much time… That’s nice. If you want to start troubleshooting your own problems, learn to read the system logs. If you don’t want to ask for help, learn to read the system logs. Well, that and learn to read the man pages, but that last bit is outside the scope of this article.

I do hope you enjoyed this article. They’re fun to write but it does sometimes feel like work. I never wanted this to feel like it was work, but here we are. It probably would have been wiser to not set such a schedule and to allow some vacation time in there. This whole project started when I had far more time due to the pandemic.

We do have a special day coming up… You’ll see!

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 site. If you scroll down, you can sign up for the newsletter, vote for the article, and comment.

Another Way To Show Mounted Filesystems

We’ve covered this topic before, but I want to show you another way that you can show mounted filesystems. As previously covered, you have multiple filesystems mounted at any one time. So, let’s examine them, shall we?

If you use Linux, you use multiple filesystems. There are real and virtual filesystems created and used by the operating system. A real filesystem would be something like a partition on your storage device (one filesystem per partition, of course). A virtual filesystem would be things like your temporary files or cached files, among other filesystems used by the system.

We’ve covered this before and this is just another way to show your mounted filesystems. This is good information to have, as it’s handy to know the path for those things so that you don’t do something silly like misfire a dd command and hosing your OS partition. (Ask me how easy that is.)

Show Your Filesystem In The Linux Terminal
Another Way To View Attached Storage Devices
Another Way To View Attached Storage Devices

(And there are more! This is an oft-covered subject on Linux-Tips!)

So, what will we be using?

findmnt:

You shouldn’t need to install anything for this article. The findmnt tool should be installed by default. You can verify that findmnt is installed by running the following command:

The output of that command should probably match this one:

You check the man page with this command:

There’s additional information available in this application. Run this command:

But, if you check the man page, you’ll see that this is indeed one of the correct tools for the job. This being a basic task, there are many ways to show mounted filesystems. It’s up to you to pick a favorite – or find the most useful of commands for your particular situation.

Anyhow, the man page describes it as:

findmnt – find a filesystem

That’s what we want to do. That means that this is the correct tool for the job.

Show Mounted Filesystems:

You’ve been here long enough to know that we’re likely to use the terminal. If your hunch was that we would be using the terminal, your hunch was correct. You’ll find that findmnt is a terminal-based application so open your default terminal emulator by finding it in your application menu or pressing CTRL + ALT + T on your keyboard.

With your terminal open, you can show mounted filesystems with this command:

You’ll see that it even has a nice tree output. You’ll find things like Snaps have their own filesystem if you’re using a system that uses Snaps. Other jailed applications may also use their own filesystem as a way to keep things separate from the system as a whole. 

Here’s an example truncated output from Lubuntu:

That’s not nearly as complicated as it looks, once you get used to it.

Now, you can trim all that down. You can opt to show only the ‘real’ filesystems. That’s done with the --real flag.

This is an example of that command on that same Lubuntu system used above (Snap applications are seen as ‘real’ filesystems as a part of their separation from the system):

Here’s an example output from a Linux Mint system that does not use Snaps:

You can do more with the findmnt command, such as select the columns you want in your output, so be sure to check the man page. This is just a quick overview because the vast majority of you will never need more than just the basic command.

As I said, it’s a useful command for when you want to verify the path to a filesystem. Beyond that, the usage is up to you. That’s what I use it for when I don’t bother with any one of several other commands.

Closure:

You might see no reason to add this to your list of commands, but it is useful when you want to see all the mounted filesystems on your system. If you need the path for a filesystem, this is a good command. It’s also useful for finding out some attributes of your mounted filesystems.

This is one of those commands you really could keep in your back pocket. You might first lean on a command like lsblk but that only lists block devices – that is, storage devices, and doesn’t include the many other mounted filesystems. If you don’t need this command today, that’s fine. You might need this command in the future, and now you know it exists.

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 site. If you scroll down, you can sign up for the newsletter, vote for the article, and comment.

Linux Tips
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.