How To: Find The RAM Total In The Terminal

Today’s article will show you how to find the RAM total, because that’s basic information everyone might want to know. If you don’t already know how much RAM you have, this is a good article for you. If you’re like me and need to be reminded from time to time, this is also a good article for you!

You might have a computer that doesn’t run as fast as you want, and having not enough RAM may be a cause. Before you install a distro, you should know that distro’s minimum requirements, of which RAM is often one such prerequisite. Maybe you’re upgrading RAM and really want to make sure you know what you have inside? Dunno, but there are reasons why you might want to find the RAM total.

Not all my articles are long, and that includes this one. This one should be pretty quick and easy, suitable for folks just starting out who want to know how much RAM they have.

Find The RAM Total:

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.

With the terminal open, we’ll just use the free command. It looks like this:

The output is obvious and will look similar to this:

free -m in action
The output should be fairly obvious to all readers. The total RAM is listed in the output.

That’s the output from a fairly standard device. It should be obvious, but the column you’re looking for is under ‘total’ and you’re looking for the big number/top row.

You can also check /proc/meminfo for more information. Run the following command for a bunch of data about your installed RAM:

If you take a look at the output, you’ll be looking for the row starting with “MemTotal” in the results. Of course, you can just use ‘grep’ to pull out just the information you want. Try it with this command:

That should do it. It should give you an output that has just the row you’re looking for. Feel free to change ‘MemTotal’ to another row, but remember that it’s case sensitive – like most of Linux.

Closure:

There are surely other ways to find the RAM total, but those are a couple of easy ways to toss into your growing toolbox. This is also another article in the books. It’s just a short article, but it’s an article nonetheless. 

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How To: Restart TeamViewer From The Terminal

In a previous article, I wrote about TeamViewer, and this article will teach you how to restart TeamViewer from the terminal. The reality is, I like TeamViewer quite a bit but it has a nasty habit of failing during the authentication step.

The only way to make it work, without visiting the device in person, is to restart it. I actually do this with SSH, but it’ll work in the terminal. So, you’re doing it from the terminal – you’re just doing it remotely and using SSH to do that.

Well, no… I have no idea how you’ll be doing it. After all, you might choose to do it locally – where this will also work. So, is it really from the terminal? Yes. It just depends on which terminal, I suppose!

Anyhow, this is just a short article. If you’re physically at the computer, why are you using TeamViewer?!? If you’re physically at the computer, you can just restart it with the GUI – or you can use the terminal. 

Restart TeamViewer From The Terminal:

So, if you’re at the device, just open the terminal. If you’re not at the device and TeamViewer isn’t authenticating, just connect to it with SSH. We’ll assume you’ve already set up SSH and know how to connect. If you don’t, then go back and read the SSH link in the 2nd paragraph. You need to use the following commands. 

To stop the TeamViewer service, run:

To restart the TeamViewer service, run:

If you want to just run one command, you can do that too! Just run:

The latter command is probably the easiest, and TeamViewer fails often enough for me to have taken the time to alias the restart command. As far as I can tell, there’s no rhyme or reason for it to no longer authenticate, but that’s what happens.

Closure:

As I use it often enough, I figure this is worth sharing with the world. It’s not a very long article, but it is indeed an article. Hopefully this helps someone who’s having similar authentication errors. As near as I can tell, just restarting the service fixes it and I’d say that the authentication fails every other day, sometimes more and sometimes less. Thanks for reading!

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How To: Change Your Password In The Terminal

It’s considered good form to change your password once in a while. This may not be something important for you, but others may appreciate it. It may be corporate policy or regulations that make you need to change your password, or you could just be more security minded than many others. No matter what, this article tells you how.

The tool we’re using in today’s exercise is called ‘passwd‘, which is a tool to help make and manage passwords. It’s a bit complicated, but it uses something called hashing and stores a hash instead of a plain-text password.

When you login, your password is checked against the hash that was created when the password was created. This prevents people from easily reading your stored password, stored of course because there must be something to check against.

If one remembers way back to the start of this project, my goal is to put my notes online. This article is in my notes, which is why this is such a simple article. Indeed, this article should be pretty straightforward and easy to understand. I’d definitely call it a beginner-friendly article.

Change Your Password:

Like most always, you need to open your terminal. You can do so with your keyboard – just press CTRL + ALT + T and your default terminal should open.

Once you have your terminal open, the command you’re looking for is:

If you already have a password, you’ll need to type your current password and then you’ll type the new password twice. When you logout or next need to use your password, your new password will be required. You don’t need ‘sudo’ for this, as the password you’re changing belongs to you.

Seeing as this is short, I’ll toss in another use of passwd. If you want to change the password for a different user, you just use this command:

Change the obvious to the obvious, specifically the username. This command does require ‘sudo’, because you’re changing a password that doesn’t belong to the current user.

There’s more that can be done with passwd, but those things are beyond the scope of this article. I’d expect to see some more passwd uses covered in the future, but you can get a head start by typing man passwd into your terminal and learning about the other options.

Closure:

That’s it, really. I told you that this one would be short and easy! Sure enough, it’s pretty easy. Many of my notes are regarding people who are new to Linux, but it’s still nice to get more of them online. I dare say we’re coming along nicely.

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.

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How To: Check CPU Temps With lm_sensors

There are a variety of ways to check your CPU temps, and this one will be covering this with lm_sensors. It’s a handy application and it’s often installed by default. Moreover, it’ll be available for pretty much every distro out there.

This time around, we’ll be using the above-mentioned lm-sensors. Wikipedia describes lm_sensors as thus:

lm_sensors (Linux-monitoring sensors) is a free open-source software-tool for Linux that provides tools and drivers for monitoring temperatures, voltage, humidity, and fans. It can also detect chassis intrusions.

It then says that a citation is needed. Thank you, Wikipedia. That’s helpful.

With so little to go on, we can check the man page. Alas, man lm_sensors has no entry. You’ll actually need to use the less obvious man sensors. That description isn’t much better, but it beats a blank.

sensors is used to show the current readings of all sensor chips. sensors -s is used to set all limits as specified in the configuration file. sensors –bus-list is used to generate bus statements suitable for the configuration file.

This will, of course, also tell you more about using lm_sensors, though there really aren’t a whole lot of options. It outputs what it outputs and you’ll like it. You’ll potentially get more information than just the CPU temps, but this article is about how to check CPU temps.

Check CPU Temps:

This rest of this article should be short and straightforward. Like normal, open up your default terminal emulator by pressing CTRL + ALT + T. Once the terminal is open, you can install lm_sensors easily enough. Try one of the following (note the varied names):

Debian/Ubuntu/etc:

Suse/OpenSUSE:

Fedora/RHEL/Rocky:

Arch/Manjaro/etc:

So far so good, yes? Well, now we need sensors to find our hardware and that’s another command in the terminal. Specifically, it’s this:

That’s going to run and it’s interactive. You will have to type “YES” over and over again. You’ll eventually need to hit the ENTER button. Fortunately, once you’re done, it’s all over and you never have to do it again – unless you add/change hardware that has sensors.

With lm_sensors loaded properly, let’s check CPU temps! It’s a really simple command – and it’s just:

If you are an American that is easily frightened by the metric system, you can just add the -f switch for Fahrenheit, like so:

Your output should look something like this:

lm_sensors in action
That’s a pretty standard output. Note the included CPU temps (listed by core, starting at core 0).

It should be noted that there’s more to the output than the CPU temps. This is not always the case. Your hardware may not have sensors that report back the operating conditions – but your CPU will almost always report that data so that the OS can do things like throttle-down for energy saving purposes. Be sure to run man sensors to see the rest of the options.

Closure:

Congratulations! You can now easily tell how hot (or cold) your CPU is running. You should also look up your CPU’s temperature thresholds. This way you’ll be able to tell if your CPU is running hotter than it should be running. Doing this can save your hardware or give it greater longevity.

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.

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Guest Article: What Are SSH Keys?

The following article is a guest-written article from Andy Brooks (aka captain-sensible) about SSH keys. So, let’s put our hands together for a guest author and appreciate that I got a break from writing articles! Thanks, Andy!

There are a few articles about SSH already:

Install SSH to Remotely Control Your Linux Computers
Enable x11 Forwarding With SSH (Remotely Use GUI Applications)
How To: Change The Port SSH Uses

What Are SSH Keys?

Recently, I created an account for the AUR (Arch user repository) with a view to taking over an maintaining an Aurphan AUR package. On the registration form, which included the usual user name etc, was a text box asking for my SSH public key? You might wonder what is that, why do the AUR want it, and how are they going to use it?

Well the AUR would hold my public key and that would be associated with my user account. What I would want to do with the AUR for a package would be update the PKGBUILD file and get those changes published on AUR repository. So basically that would require getting access to the server of the AUR by logging in and then pushing up my changes to it.

So how are SSH keys involved in that process ? Well on my PC in my home folder there is a directory called .ssh inside are two text files called id_rsa id_rsa.pub. The information held inside the id_rsa.pub, the AUR has a copy of.

If and when I access AUR to make changes, to any package on the repo, there is an exchange of information over my terminal that I am using as a communication channel via ssh. The server sends a challenge, which is to see if my private key matches up with the public key which the AUR server is holding a copy of.

A couple of points are the process involves encryption and the only key that should be “given out” to anybody is the public key. The private key should be, well kept private and out of peoples hands. Putting it simply, ssh-keys are a way of securely giving users access to remote servers. Secure Shell was created in 1995 by Tatu Ylönen a Finnish national following a password-sniffing attack at his university.

Now for registration for accounts such as with the AUR, there are really only two things you need to do.

1) create as a “once off” a pair of private & public keyserver-options.
2) Give the details of the public key to the AUR server.

Creating SSH Keys:

Lets start with item 1):

ssh-keygen is a utility of openSSH so you need to install that, then from a terminal simply issue the command (as a normal user not sudo): ssh-keygen

To keep things simple, you can accept the defaults by hitting return button.

At the end you should see something like in the adjacent image.

ssh keygen
Yours should look pretty similar to this!

Note: At this point, you can generate a password/passphrase. Doing so can increase the level of security, but the choice is yours to make.

Now lets look at 2):

From your terminal, check you are in your home folder, or cd to it eg ($ cd ~ )
Then change directory into the .ssh directory with cd .ssh
Then get contents via cat
cat : [andrew@darkstar:~/.ssh]$ cat id_rsa.pub

You should get something like : ssh-rsa AAAAB3NzaC1yc2EAAAAD… There will be something like 569 chars in all. 

From the terminal you can just copy starting from the ssh-rsa ….. to the end; then you can just paste that into a text box asking for your public key.

A quick warning the two keys generated are a matched pair. Once you submit your public key, don’t just repeat the default way of generating keys otherwise the keys will be overwritten and then you will be rejected from getting access to where you last put your public keys.

Also to see the .ssh directory in your home folder, you may need to click view hidden files and dirs.

Closure:

And there you have it, a guest-authored article about SSH keys! I’m very grateful for the help. If you’re interested in writing an article, you can do that. The easiest way for you is to use the Contribute Your Article link at the top of any page. The easiest way for me is if you just register and ask to be made an author. Either is awesome and even if you’re an author I will still need to edit and schedule posts.

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

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