Linux Tips • Page 27 of 115 • Getting you up to speed!

Extract Multi-Part rar Files In Ubuntu

Today’s article is limited to just a subset of users as there aren’t that many people who want to extract multi-part rar files in Ubuntu. This isn’t something you’re going to face often (unless you’re still pirating stuff from Usenet) but it’s something some folks will face. So, this article is for all of those people, all three of you!

I suppose we first need to talk about WinRAR. For those that do not know, WinRAR is a proprietary company that uses a proprietary compression method. Even though it’s proprietary, it has some pretty great features. You have to give credit where credit is due. There are multiple versions of compression used over the years but they all share the same .rar file extension and are all reasonably compatible with one another.

The GUI version of WinRAR is a Windows-only trialware application but there’s a command-line version that can be installed in most distros. While this article is Ubuntu-specific, it’s sure to work with other distros though the installation method may be different. On top of that, many Linux tools (such as file-roller) are capable of extracting files compressed with WinRAR.

This isn’t going to be a very complicated article. It also shouldn’t be all that difficult. I figure folks can follow along if they need to when they need to. This isn’t something the average Linux user is going to face daily. After all, the majority of our software is free! There’s no reason to pirate it! (Seriously, I’m sure there are legitimate uses for multi-part rar files but I’ve only really seen them in frequent use with software piracy.)

Install unrar In Ubuntu:

To extract these multi-part rar files in Ubuntu, you’ll want to install the unrar application. That makes sense, after all. So, like so many things, we’re going to do this in the terminal. You can certainly install unrar with the GUI software installation tools, but we might as well do so in the terminal.

With that in mind, and with this unrar process also being in the terminal, we might as well go ahead and get unrar installed in Ubuntu. First, you can press CTRL + ALT + T to open your terminal. You should also be aware that this is going to pretty much work with any Debian (or Ubuntu) derivative out there. So, this works just as well with Mint, ElementaryOS, or the like…

I suppose we should update first, and you can do that easily enough:

sudo apt update && sudo apt upgrade

1	sudo apt update && sudo apt upgrade

If you trust your upgrades and don’t want to have to manually approve them, then you can just add the -y flag to the end of that, like so:

sudo apt update && sudo apt upgrade -y

1	sudo apt update && sudo apt upgrade -y

The next step is going to be installing unrar. You do so like this:

sudo apt install unrar

1	sudo apt install unrar

At this point, you can check the man page (man unrar) where you’ll learn that the unrar application describes itself like so:

unrar – extract files from rar archives

That’s a good description and, as you can see, is exactly the tool we want for this operation. If you’re going to extract multi-part rar files in Ubuntu, this is a good tool to do it with. (You can just as easily find a GUI application that will take care of this.)

Extract Multi-Part rar Files In Ubuntu:

I hope you left your terminal open after the installation phase. If not, you’re going to need to open it again. I envision people searching for this specific process and following along. I don’t envision people doing this just for the sake of following along. After all, it’s not like I made multiple-part rar files for you to test this with. You’ll want this article when you need this article.

Anyhow, the process is quite simple.

First, move all of the files into a single directory. This is going to make it much easier. In theory, you could specify the individual paths, but we’re not going to be doing that. No, move all the multiple parts to a single directory. Trust me on this one.

The syntax you’re going to use will be as follows:

unrar x /path/to/file.rar

1	unrar x /path/to/file.rar

No, you do not include all the other parts. You only need to unrar the first file and the unrar tool will realize that it’s multiple parts and extract them sequentially. It will even tell you that it’s doing so, as it writes that data to the standard output.

This is why you move all the files to their own directory. Again, you only need to tell unrar to extract the very first of the files. It’ll happily find and extract the rest. Of course, you need ownership of the files or you’ll need elevated permissions (such as sudo) to extract the files.

Closure:

So, if you ever need to extract multi-part rar files in Ubuntu, you now know there’s an article that covers this. I don’t expect all that many people to need this information. I do anticipate those who need this information will be able to find this site (or another, I suppose) through a search engine. This isn’t something you’re likely to need every day, even though it’s relatively simple.

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.

How To: Show Disk Information With hwinfo

Today we’re going to be having some fun with hwinfo, available everywhere and used (in this case) to show disk information with hwinfo. This isn’t going to be the most complicated of articles, so it’s safe to assume you can follow along – even if you’re a beginner. You just need to follow the directions.

The tool we’ll be using to show disk information will be hwinfo. This probably isn’t installed by default, but is a very useful tool. We’ll just explore one aspect of hwinfo but there’s a lot more to the application. There may be other articles on this hwinfo application.

Anyhow, if you’d already installed hwinfo and checked the man page, you’d learn that the application defines itself accurately, specifically as:

hwinfo – probe for hardware

That’s a pretty good description and might also be a bit of a clue about hwinfo’s features and goals. In this case, we’re simply examining one particular feature and that is how to show disk information with hwinfo.

I suppose that it’s a bit archaic calling it ‘disks’, but there are plenty of people with spinning platters. It could also be ‘drives’, to ensure we also cover solid-state drives. But, for this article, we’ll use the words interchangeably. After all, you know what I mean.

The hwinfo application is a great application, with a ton of options. It’d be far too much to cover in a single article. There’s enough fodder here for multiple applications, which is nice.

Install hwinfo:

As hwinfo is a terminal-based application, you’re going to need a terminal. You could trivially install this via a GUI application, but I needn’t explain that. I will show you how to install hwinfo with the terminal. It’s available for most distros by default. Just press CTRL + ALT + T to open your terminal, or open it manually from your application menu.

Once you have your terminal open, you’re ready to install hwinfo. You can pick from the following, as it’s a fairly universal application. Try one of the following to do so:

Debian/Ubuntu/etc:

sudo apt install hwinfo

1	sudo apt install hwinfo

SUSE/OpenSUSE/etc:

sudo zypper install hwinfo

1	sudo zypper install hwinfo

RHEL/Rocky/etc:

sudo yum install hwinfo

1	sudo yum install hwinfo

Arch/Manjaro/etc:

sudo pacman -S hwinfo

1	sudo pacman -S hwinfo

Gentoo/Calculate/etc:

sudo emerge -a sys-apps/hwinfo

1	sudo emerge -a sys-apps/hwinfo

See? You’ll find that hwinfo is an option in pretty much all the default reports. You can get a head start, and learn a lot, by checking the man page (with man hwinfo) if you’d like.

Show Disk Information With hwinfo:

Don’t close your terminal after installing hwinfo. You’re still going to need an open terminal to use hwinfo to show disk information. Fortunately, the commands are a bit unusual but not taxing. As we’re just covering how to show disk information, that will make it easier.

NOTE: To get complete information, you will need elevated permissions. In our case, we’ll be using sudo. If your distro doesn’t support sudo, you’ll need to gain elevated permissions in the manner your distro has designed.

So, with your still open terminal, you can try the first command, which is simply:

sudo hwinfo --disk

1	sudo hwinfo --disk

That will spit out a lot of information about the various disks you have in your system. It’s a lot of information, perhaps more than you need. If you want to show a nice summary, you’d want this command:

sudo hwinfo --disk --short

1	sudo hwinfo --disk --short

If you want to see a nice summary of block devices, you can just use the following command to show said block devices:

sudo hwinfo --short --block

1	sudo hwinfo --short --block

Most folks are either going to want the full information for troubleshooting or one of the latter two choices for basic information. But, you can use any of them that you want to show disk information. It’s a pretty easy process and hwinfo is a very useful application. Perhaps we’ll explore its uses soon.

Closure:

Well, today we have had a “Nor’easter” and the remains of Hurricane Lee. I was expecting it to be much more mild, but we have trees down and power outages all over the place. In fact, one outage has started a fire.

However, that didn’t stop me! Nope! I have still not missed a single publication date. I’ve published an article every other day for a long time. So far, so good.

This time around, you got an article about how you can show disk information with hwinfo. That seemed like a fine article to write. It’s not all that long, nor is it all that complicated. If you follow the directions, you should be all set.

As such, I assume a beginner will be able to follow along and able to learn something in the process. I sometimes get feedback about using the terminal in so many articles, but it is a fairly universal tool. There’s no reason to be afraid of the terminal. Instead, embrace it and learn to use it. Once you do, you’ll understand why I write about it so frequently.

A Bit About The Finger Command:

Today’s article is not going to be all that difficult to follow as the subject is just helping us learn a bit about the finger command. This probably isn’t useful for many of my readers, but it may be useful for those running full multi-user systems. So, let’s talk about the finger command.

The finger command is a bit weird. It’s an application you can call from the terminal and a protocol. It’s a tool used to get user information. It was more widely used back when things like a user’s real name and email address weren’t considered private information. In fact, finger has been used to compromise systems in the past.

Now, for the average reader, this isn’t a major concern. The average reader probably doesn’t need to know anything about finger.

See, the finger application gives you information about a user.

That doesn’t seem like much for my average reader but it’s possible to store a lot more information than just a username. On a multi-user system, you can store more than just a username. You can store fields like their email address, their workstation, their office address, their phone number, and many other fields.

As you can guess, that’s now considered sensitive information. A lot has changed since the early 70s, which is when the finger program was written, and then in the mid-70s when name/finger was proposed as a useful way to see if a person is online (logged into the system) and may be available for a meeting.

But, finger is still useful today. You’re not storing all that information anyhow. There are far better tools in an office environment these days.

Install finger:

If you install the finger application, you can check the man page to learn that finger identifies itself as this:

finger — user information lookup program

Which is what you can use it for today, especially for those of you who have more than one user on your system. You’re not storing things like email addresses in any of these fields, not as a regular desktop user. So, you can certainly install this (though there are other ways to see who is logged in or whatnot).

So, if you want to install finger, you’ll need an open terminal. To do that, you can usually just press CTRL + ALT + T. That should do the trick, otherwise, you’ll have to open the terminal manually.

With the terminal open, you’ll find finger is easily installed from your default repositories. Some examples follow:

Debian/Ubuntu/etc:

sudo apt install finger

1	sudo apt install finger

Fedora/derivatives:

sudo dnf install finger

1	sudo dnf install finger

RHEL/CentOS/derivatives:

sudo yum install finger

1	sudo yum install finger

See? It’s nice and easy to install finger. It’s likely in your default repos on other systems, so try that first before hunting it down to compile it on your own.

The Finger Command:

If you followed the above directions, you installed finger with the terminal. That’s good because you need an open terminal for this. So, you should still have an open terminal. If not, you’ll need to open one, of course…

Now, the syntax is simple:

finger <user_name>

1	finger <user_name>

The output from this command would look similar to this:

output from the finger command — See? Some useful information about the user from the finger command.

There are many options, but that’s the most useful and the one with the information you’re likely after. However, you should read the man page for this one. It’s a beauty.

For example, you can tell finger to not show anything by having a ~/.nofinger file in your home directory. You can even include your PGP key by adding a ~/.pgpkey (containing said key) if you want. As you can see, this is very much aimed at a multi-user system.

Probably the most useful of the flags is the -m flag. If used properly, it will avoid finding real names. This is useful when you want to find just the username and not match it with any real names. Usernames are unique, while real names might not be. The syntax would be:

finger -m <user_name>

1	finger -m <user_name>

Other than that, it’s a fun command to play around with. It does output some useful user information, so it’s not useless on your regular desktop system – especially if you have multiple users (and you do, technically).

Closure:

So, there’s another one for the books. Another article is done and published. This time around, we discussed the finger command. I’m not sure how many folks will find it useful, but it’s worth sharing the information. Eventually, someone will find it useful.

Monitor Bandwidth In Real Time

Today we’re going to have a fun article, an easy enough article, where we simply talk about one way to monitor bandwidth in real time. This is not something you’re normally going to do unless you’re in an unusual situation. It’s still something fun and easy, so why not cover it?

This might be useful if you want to monitor bandwidth at an edge system. Let’s say you have a public-facing server and you’re not behind a router that gives you this information in a fancy widget or whatnot and you want to monitor the bandwidth in real time. Well, you can do that. In fact, there are all sorts of tools that will let you do this. Heck, I think I may have even shared some of this type of stuff in the past.

Maybe take a gander at some of the following articles:

Monitor Bandwidth With nload
‘vnStat’ A Tool For Monitoring Your Bandwidth Usage
Visualize Your Network Traffic With ‘darkstat’

(There are more, just search the site for ‘bandwidth’ – which is how I came up with those links. I wasn’t picky, I just picked the first few that looked like they might interest people and be similar to this one.)

As I mentioned, it’s easy to monitor your bandwidth. It’s easy to monitor your bandwidth in real time. There are countless options and applications for this, so today we’re just going to cover one more option from the myriad options available to you as a Linux user.

Today’s article will be about ‘cbm’… Trust me, it’s easy. It’s very easy!

What Is This cbm?

Well, cbm stands for Color Bandwidth Monitor and it’s not a new application. In fact, the GitHub page indicates that it hasn’t been updated in a while. That’s not necessarily a bad thing, as it could mean that it’s just feature complete and in need of nothing.

I’ve only checked on Ubuntu (technically Lubuntu) and Mint, but cbm is in the default repositories. I’m a bit of a slacker, so I haven’t checked elsewhere, but it’s probably in their default repositories too. It’s just a tiny application with a very specific purpose. Those are the kinds of apps that make it into default repositories.

If you check the man page, you’ll see that cbm defines itself simply as:

cbm – display in real time the network traffic speed

Supposing you’re using Ubuntu (or Debian, or Mint, or any other distro with those repositories and using the apt package manager) it’d be easy enough to install.

You’d simply install cbm with the following command:

sudo apt install cbm

1	sudo apt install cbm

So, let’s pretend you’ve already got that cbm application installed…

Monitor Bandwidth In Real Time:

So, we’ll assume you’ve already installed cbm but you’re still going to need an open terminal to use cbm. Funny how that works! You know what, I’m just going to assume you’ve opened a terminal to install the application and skip that whole cookie-cutter silliness.

Well, now that you have cbm installed and you’ve run cbm in the terminal (which is your only option – I did mention this was absurdly simple), you’ll see an output similar to this:

cbm letting you monitor bandwidth in real time — It’s not polite to laugh at another man’s paltry bandwidth! Be polite!

Yes, yes I work just fine within these bandwidth constraints… Mostly…

As you can see, it shows each network interface.

How To: Show Your Network Interfaces

You can see that it shows how much data you receive, how much data you transmit, and the total. I did not let it run all that long for the screenshot, as that’s not necessary.

That’s pretty much it. There are few options and that’s a good thing.

You can press the + or – to change the refresh rate.

You can press B to change from bits to bytes.

When you’re done monitoring your bandwidth in real time, press Q to exit the application.

That’s it. That’s all you need to know. It’s a very purpose-built application. There aren’t a bunch of frills and options. This is one of those tools that does exactly what it says on the tin and nothing else. If you want to monitor bandwidth in real time, this is one way to do so.

Closure:

See? I told you this would be a nice and simple article. It’s easy to follow and easy to learn. There isn’t a whole lot to it. You can monitor bandwidth in real time with all sorts of tools, but this might be one of the easiest. The program doesn’t need to be updated. It doesn’t need additional bells and whistles.

Sorry for not checking on alternative distros. That takes a while and I have limited time to write these things. If you use other distros, you can help by leaving a comment to indicate if it is in your default repos or not. You can even go so far as showing how to install cbm. It won’t hurt and you don’t even have to use real information!

Remove Unused Kernels From RHEL

Today’s article is only going to apply to some of you, specifically those who use RHEL and want to remove unused kernels from RHEL. That’s a pretty narrow subset of people, but it’s worth knowing this information if you’re a RHEL user.

Red Hat is one of the oldest Linux distributions out there. Along the way, they’ve turned into an ‘enterprise’ (business class) distro. They’ve made some strange strategic decisions lately, but I’m not going to get into that in this article.

As an enterprise distro, it is not entirely free (as in cost in dollars). They are a distro that has a great deal of support for long periods. They’re meant to be stable and ideal for business use. You’re expected to pay for RHEL – sort of.

RHEL has a free version if you sign up as a developer. You can learn about the RHEL developer program at this link. I thought it was free for a few devices, but it looks like I might be wrong and that it may be more than that. From the linked page:

An entitlement to register 16 physical or virtual nodes running Red Hat Enterprise Linux.

So, that’s more than three – but you’re not going to get support. If you want to go this route, you’re expected to support yourself. Fortunately, RHEL has extensive documentation and your dev subscription will get you access to any of that documentation that’s behind a paywall. Or, at least that’s my experience.

I don’t do enough with RHEL!

Linux Kernels:

I’ve explained what the kernel is before. Linux is just the kernel. We add stuff to the kernel to make an operating system. We then add more stuff to make it a specialized operating system – such as a desktop operating system, like the readers of this site use.

Along the way, as you update and upgrade, you’ll add new kernels. These are not necessarily removed by default. They can take up quite a bit of space and you might be paying for that space (especially if you’re using RHEL as a server somewhere). So, removing the oldest kernels is just good housekeeping.

That’s all we’re doing in this article. I suppose it’d probably also work for CentOS but I don’t pay any attention to that distro these days. It’s not that I’m angry or annoyed with RHEL’s decisions, it’s that I only care for things with long-term support. I’m old and changes scare me!

We’re just going to clean up any old kernels, probably while keeping the 2 most recent kernels, to keep things nice and orderly. This isn’t something you technically have to do. You can keep all the kernels you want. But, if you want to remove unused kernels from RHEL this might be the article for you!

Remove Unused Kernels From RHEL:

Now, if you’re using RHEL as a server then you’re already connected via SSH (probably) and already have a terminal open. If you’re using RHEL as a desktop OS, you will need to open a terminal. You can just press CTRL + ALT + T and your terminal will pop open.

With your terminal open, you first need to install yum-utils. That’s nice and easy, just use this command:

yum install yum-utils

1	yum install yum-utils

(You’ll need elevated permissions unless you’re logged in as root.)

Next, run the following command to see how many kernels you have installed:

rpm -q kernel

1	rpm -q kernel

If you have more than two kernels installed, you can run this command:

package-cleanup --oldkernels --count=2

1	package-cleanup --oldkernels --count=2

You can adjust that command if you’d like. That particular command will keep the kernel you are currently using and the previous kernel. (You can boot to older kernels via GRUB if you want. That article is actually about recovery mode on Ubuntu, but the pictures should clue you in until I write an article just for this purpose.)

If you use a --count= of 1 or 0, it will remove every kernel except the one in use, it will not remove the kernel that’s in use.

That’s all you have to do. There’s nothing more to it. The command will automatically remove older kernels at the level you decided. You can keep the most recent three kernels, four kernels, or however many kernels you want. It’s not terribly complex.

Closure:

I don’t do a whole lot of RHEL articles, but it’s nice to at least write one here and there. If you’ve got extra kernels, you now know how to remove unused kernels from RHEL. It’s a pretty easy task and something even a new user can handle. If you’re a new user, go for it! It won’t break anything – in and of itself. (I’d highly recommend keeping the current kernel and the most recent kernel, just in case.)