Check Memory Usage With ‘free’ In Linux

In today’s article, we’ll chec memory usage with the free command. We’ve touched on the ‘free’ command before, but this is a whole article about the free command. This should be a pretty quick and easy article, as it’s not a complex command.

There have been a few other articles about RAM.

How To: Find The RAM Total In The Terminal
Check Your Memory In The Terminal: Part II
Let’s Determine The Number of RAM Slots Without Opening The Case

And, in the discussions of those articles, we often refer to free -m as our go-to tool for quickly checking memory usage. It’s a handy tool used by most, and it’s a good tool to have in your toolbox. On top of that, it does a bit more than just check memory usage.

The free command has been around forever and describes itself like this:

Display amount of free and used memory in the system

Which is exactly what it does. It’s a pretty useful command if you want to see how much RAM you’re using, how much is free, how much is reserved for buffers, and even more if you’re interested in your swap stats.

So, folks are generally already familiar with the free command, but there are indeed more options and it’s worth an article to explain a few of those choices. Like always, you can also run man free to get a bunch of information that may not be included in this fairly brief article.

Check Memory Usage:

Yeah, this is yet another article that insists on the terminal. That’s not a bad thing, if you check the byline. The goal here at Linux-Tips is to get you more comfortable with Linux – and that includes getting comfortable in the terminal. So, open one up by pressing CTRL + ALT + T on your keyboard, and your default terminal should pop right up.

With that done, let’s go ahead and try the command that everyone uses:

The output from that will look a little something like this:

output from free -m
Those columns should be reasonably easy to understand. You can figure it out, I’m sure of it!

You can see by the column titles what the columns mean. Like I said, it’s relatively easy to understand – which is why it makes a pretty great tool. There’s actually a pretty good description of those terms, if you don’t already know them, in the man page.

But, you can use it in other ways. See, the -m stands for megabytes (obviously). Well, you can use other flags, like -b, -k, and -g. That’s bytes, kilobytes, and gigabytes – where the -m is megabytes as previously mentioned.

If you want a nice human-readable format, you can try this:

The output of that may vary the units but it will also show you which units are in use. It’s a pretty handy way to use the free command to check memory usage in Linux.

Sure, there’s a wide format and you can even use units as large as pebibytes. I don’t actually have anything where that’d make sense, but it’s an option if you happen to have such a system. (If you have access to a system with pebibytes of RAM, call me!)

But, did you know that you can run the command over and over again with just a single command? To do that, you use the -s flag followed by the number of seconds you want it to wait before refreshing. So, if you want it to run every 10 seconds, the command would look like this:

You can combine that with a count – like how many times you want it to run. So, something like this:

That will run the free command (you could add other modifiers) every five seconds and will do so three times in a row.

There are other options, but those are the most common. You can have it output the low and high numbers (when run over a period of time), display column totals, and even opt for a wider display. Personally, I don’t really find those options all that interesting and don’t bother with them, but they’re a man page away from being a part of your toolbox.

Closure:

And there you have it, an article teaching you how to check memory usage with the free command. The free tool is a pretty handy tool and one everyone should be familiar with. If your system is slowing down, it’s nice to know things like how much RAM is being used. If you work in application development, it’s nice to know how much more RAM your application adds to the system. There are any number of reasons why you’d want this information.

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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Check Your Memory In The Terminal: Part II

Today’s article is all about how you can check your memory in the terminal. If it looks familiar, it’s because I’ve already written “How To: Find The RAM Total In The Terminal“, which covered a couple of ways to check your RAM – all of which were in the terminal. I left the article open for others to share how they check their memory, but nobody left any comments.

In the previous article, I invited people to comment and share other ways to check RAM, RAM total, RAM usage, etc… Seeing as nobody commented, I figured I might as well return to the previous article and throw in a couple more ways to do check your memory in the terminal.

The previous article includes some handy tools, such as the easiest way:

While also mentioning a much more extensive and informative tool:

Both of which are lovely ways to check your memory in the terminal.

This being Linux, there’s also other ways.

Me being me, I figure I might as well share them with you.

After all, it’s yet another article that I can write! So, as unoriginal as this article may sound, there’s also a couple of tools I really want to introduce you to. 

There’s always room for more tools, especially if they’ll help you…

Check Your Memory (in the terminal):

As the line above indicates, you’re going to need an open terminal to do the work in this article. You can open it from your start menu, or you can just press CTRL + ALT + T and your default terminal should open right up.

The first tool we’re going to use is ‘top‘. I think you’ll find top installed on pretty much everything, though some distros are including variants like htop. The venerable top application is a terminal-based task manager and has been with us since 1984.

Anyhow, the command is nice and simple. Just run ‘top’ in the terminal:

The output will look something like this:

using top tto find your memory information
Look up near the top, above the fold, you’ll see the memory information. Pretty easy, isn’t it?

The last two lines of data, above the list of tasks, tell you all you need to know (unless you need a ton of details, I suppose) about your RAM, your RAM usage, what’s buffered, etc… It also tells you about swap, another facet of memory. 

Next we have a lovely command called ‘vmstat‘ a tool for showing virtual memory statistics. This lovely tool has been around since 1985 and has a ton of options. It’s an excellent tool and you’re highly encouraged to use the man vmstat command.

We actually don’t need all those lovely options for this. We don’t have to dig down very far to get the information you need. In fact, once again, you’re going to run the command without a single flag, like so:

The outcome of which is also self-explanatory. It looks like:

vmstat showing information, including ram information.
Look under the line clearly marked memory. See? There it is! There’s the memory info!

Just look under where it’s clearly marked ‘memory’ and you’ll see that you can use this to check your memory. It’s a bit more cryptic as it doesn’t directly show the total – but it does show you the information that’s actually important.

The total doesn’t matter. What really matters is how much RAM you’re using and how much RAM you have free. But, vmstat being vmstat, it will of course give you that information if you want it. If you do want that additional information, just use the --stats flag – like this:

Where you can see an output similar to this;

use the --stats flag to get a ton of memory information about your memory.
It contains not just that, but all sorts of information about your memory!

Pretty sweet, huh?

Closure:

There you have it, a follow-up article that tells you how to check your memory. After all, nobody wanted to add them as comments! Either way, you got to play with a couple of new tools, or at least tools not really mentioned here on this site.

Speaking of the site, the end of my year long project is in less than 2 months. That’s right, I’ve kept this up for this entire time, with a few guest articles in between. I’ll do a meta article, but I have to say that this has been a pretty fun (and educational) project. Maybe we’ll keep it rolling? It seems likely that I will. I quite like writing these things.

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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Let’s Determine The Number of RAM Slots Without Opening The Case

Today’s article is going to show you how to determine the number of RAM slots without actually opening up your case. It’s actually a pretty easy task, consisting of just a single command. 

But, wait! There’s more! You may want to know than how many RAM slots you have, you may want to know a lot more about the RAM you have already installed, how many slots are filled, if your RAM has ECC (error correction), the speed, the quantity of RAM per stick, etc…

Well, you can do all that and you can do it all with just a single command. The command in question is dmidecode. While dmidecode isn’t guaranteed to be 100% accurate, it’s usually pretty close. It pulls its data from tables in the DMI (SMBIOS) and presents them to you. Hardware manufacturers aren’t always as nice to Linux users as they could be, so there’s some risk of bad information – or wrongly interpreted information.

While dmidecode has partially been covered previously, it defines itself as:

dmidecode – DMI table decoder

And dmidecode is a pretty handy tool. In a previous article we used it with some success, and we’ll be using it again today, this time to determine the number of RAM slots available to you. On a scale of 1 to 10, I’d say this is a solid 2 – meaning even a rank beginner can follow along.

Determine The Number of RAM Slots:

This article requires an open terminal. 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 your terminal open, enter the following command:

The line that is important is, “Number of Devices”. On my laptop, the output looks like this:

using dmidecode to determine the number of RAM slots available
The answer is two. Two slots. Ah ah ah ah! Oh how I love to count things!

So, from that, we can determine the number of RAM slots is equal to two. If you want, you can then scroll down and it will show you what RAM is installed. You can see if you have the same number of devices as you have slots. You can even see the size, number of slots, location, vendor. You can use it to learn a great deal about your RAM. 

As I mentioned above, it’s not necessarily going to be 100% accurate. With bleeding edge of hardware, you’ll find it may be less accurate. If your hardware has been around for a bit, you can be pretty sure of the accuracy.

One of the things I notice is the “Maximum Capacity”. That may mean OEM suggested max capacity. I’ve sure seen more RAM than the claimed maximum. On the system, I see a max capacity of 8 GB of RAM. The box has 16 GB of RAM. I’ve seen it claim a maximum of 4 GB of RAM but had 16 GB of RAM in that box. 

Otherwise, it is usually pretty accurate. In the above, I suspect some OEMs are less than honest and would rather you not know that you can add as much RAM as you can. They’d rather you buy a more expensive device, so report the maximum RAM as less than it really supports. However, that’s just a guess and I have zero evidence to support it. It does seem pretty common, however.

Closure:

And there you have it, another article said and done. This one will help you determine the number of RAM slots that you have available. It’s a pretty easy article and a good tool to have in your toolbox. 

As you may have surmised, the antibiotics are kicking in. I’m feeling quite a bit better. Hopefully the articles reflect that. For the past few, I’ve kinda been phoning it in. My goal is to get ahead again. I can probably do that over the coming weekend. 

… Also, anyone reading this out of sequence probably has no idea what half of these closure comments are about. Then again, how many of those folks keep reading after the important bits? Probably not a whole lot. I could write darned near gibberish down here and nobody would be the wiser.

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: 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. 

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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