Category: Tutorials

Use ‘apt’ To Download A Program And Its Dependencies

In this article, we’ll discuss a way to use ‘apt’ to download a program and its dependencies. The usual reason to do this is to install said program on an offline computer. We’ll be doing it all nice and neatly, just using the ‘apt’ application along the way. It won’t be all that difficult, but will be easy to link to and reference.

As I said, the usual reason to do this is because you have a computer that’s not online and you want to install some software on that computer. This could be a remedy for when you need wireless drivers in order to connect the device, or other sorts of situations. It’s a handy way to get those drivers up and running, so we might as well learn how to do so today.

We’ll be using ‘apt’ for this. We’ve used ‘apt’ for all sorts of software management tasks in the past. In fact, in the past this required a bit more effort. You’d use the ‘–download-only’ flag and get some files in your apt archives directory. Today, it’s just a quick task that outputs a handy file that is extremely portable.

In fact, this article really only needs one command, making ‘apt’ do its thing. It’s not all that difficult, either. By the way, if you don’t already know, ‘apt’ stands for Advanced Package Tool. Anyhow, I’ll still make it an article – as it’s a useful one to know and reference.

Download A Program And Its Dependencies:

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 your terminal emulator now open, you need to know the name of the program you want to download. For example, I tested this with ‘openjdk-17-jre’ and it worked as expected. (For the commands you’ll use, I’ll just use my traditional brackets.) Before I tested with openjdk, I made sure it had dependencies, and it did. To see if it had dependencies, I used this command:

Once you see that it has dependencies, you can go straight to downloading the program and its dependencies. You no longer need any long commands, it’s just (even if it doesn’t have dependencies):

All you have to do at that point is wait for the files to download. When they’re done downloading you can find the file in your ~/Downloads directory combined into a single compressed file. In my case, the filename was openjdk-17-jre.tar.gq and the download completed without error.

The process is the same if you have dependencies or not. The reason we pay attention to dependencies in this article is so that you know to check and make sure those dependencies are included, so that you’re able to install the software on your offline computer.

And, with all that said, now is a good time to verify that it contains all the files it should contain. Assuming the files are what you expected, with dependencies as needed, now is the time to sneakernet them to the offline computer, where you can install the program by first installing the dependencies before installing the program.

NOTES: It does build an ‘install.sh’ which should let you install the program and dependencies in one fell swoop, but it accessed the ‘net in my testing. So, just do ’em manually if you want to be sure, otherwise make it executable and give it a shot. This will only work if the versions are all compatible with the offline computer. If that’s not the case, you could end up in dependency hell or perhaps not able to install the program at all.

Closure:

And there you have it… You have yet another article! This one is handy if you want to install a program and its dependencies on an offline computer. It may also be handy if you want to establish a base-line and standardize on that specific version of the software. In that case, you’ll have a copy of what it once was. It’s something you can reference and restore as needed. But, yeah, it’s most likely to be used by people who want to install software on offline computer.

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How To: Change The UUID For Your Disk Partitions

Today, in an article of little use to anyone, we’re going to learn how to change the UUID for your disk partitions. It’s not something you’ll want to do often, or even at all. There really isn’t much motivation to do so. In fact, this might just be one of the more useless articles (that isn’t a meta article) on the entire site! (I should mark it as ‘important’ for my own amusement.)

Why then is this an article? Well, it’s kinda neat, a little informative, and it was in my notes! As to why it is in my notes, I think I documented the process for a person on one of the various forums. I have no idea why they wanted to do this, but it is something you can do. I did check to ensure that it should still work.

A ‘UUID’ is a Universally Unique Identification. Your partitions have one. It’s a 128-bit alpha-numeric identification used internally seldom by you the user. At 128 bits, odds are very good that your ID is truly unique – but there’s no actual verification or anything. Your system generates ’em more or less pseudo-randomly and that’s the end of it.

If you want, run this command in your terminal (open a terminal, per my usual remarks):

That should show you your partitions and their UUID. It’ll also spit out a bunch of information that will help you identify it – such as the label field. That’s good, as you’ll want to pick one that you just don’t like and we’ll work on changing that one UUID to something new.

Change The UUID For Your Disk Partitions:

Up above, you should have opened a terminal and loaded up some information about your various partitions. Lemme see if I can get you a good example output – I’ll plug in an external drive with a bunch of partitions:

So, there… You can see some data and see the UUID. Should you want to actually change the UUID, now’s the time to pick it.

Now, we’re going to generate a new UUID. Yup, you can do that. Try one of the following two commands – though both should probably do the trick:

Or:

One, or both, of those will surely work on any modern Linux distro – unless it’s stripped down. If you don’t like the first one, you can keep generating them until you’re happy with the results. (You’re very, very unlikely to have a duplicate – as I’ll explain later, in the closure section.)

Now that you have your new UUID in hand, you’ll need to unmount the partition you’re going to change. If you don’t know how to do that, it’s just:

For example, that might be /dev/sdb2 or /dev/sdb4 that you’ll use to unmount the partition.

With that unmounted, let’s go ahead and finally change the UUID! You do that with:

Be sure to change the obvious for the obvious. Copy and paste from your terminal, perhaps even using two terminals, to ensure you get all the information correct.

When you’re done, the effects should be immediate. though you may need to mount the partition first. Run the following command to check:

If you’re satisfied with the results, great! If you need to first mount the partition, you can try this:

All should be wrapped up nicely in a bow, with your UUID happily changed to something else. Again, I don’t really have any good reasons for doing this – but you can do so if you want. I did mention that this was pretty useless… You were warned!

Closure:

Well, there you have it – another article? Hmm… Let’s really wrap it up. You know how it says it’s a “Universally Unique Identification”? Let’s look into that with some math.

Well, it’s 128 bits. That’s 2128 (less if a signed integer) which is equal to ~3.4 x 1038. I decided to look that up and find someone who did the work for me. This is that number represented in English:

three hundred forty undecillion, two hundred eighty-two decillion, three hundred sixty-six nonillion, nine hundred twenty octillion, nine hundred thirty-eight septillion, four hundred sixty-three sextillion, four hundred sixty-three quintillion, three hundred seventy-four quadrillion, six hundred seven trillion, four hundred thirty-one billion, seven hundred sixty-eight million, two hundred eleven thousand, four hundred fifty-five

Source: Quora

So, is the UUID you have truly unique? If you change the UUID, is it truly unique among all others? Perhaps, but you have better odds of winning the lottery multiple times in a row than you have of finding a matching UUID anywhere on the planet. 128 bits is a lot, an amount your human brain isn’t able to understand, which is also kinda why we will likely be a while longer before we move there from 64 bit. 64 bit is still pretty darned huge and there’s no real need for 128 bits at this time.

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Check Your (Write) Disk Speed In The Terminal

Today we’re going to discuss one way for you to check your write disk speed in the terminal. That is, we’re going to learn how long it takes you to write data to your disk drives. It’s a very simple set of commands and easy enough for anyone to try. There are other methods, this is just one of them.

After all, I recently did an article that let you check your (read) disk speed in the terminal. I might as well do an article that lets you check your write disk speed in the terminal. The former article was about how fast you can read data from your disk drives. The current article is about how fast you can write data to your disk drives.

There’s not really all that much real world work that this is going to benefit. You’re able to read and write data as fast as you’re able to read and write data. If you want to change that, invest in different hardware. Knowing the read and write rates really doesn’t do you much good – it’s just an interesting bit of information and maybe a reason for you to brag to your friends.

Today we’ll be using the ‘dd’ command. Be sure to be careful with this command because once you set it loose it does exactly what you told it to do. It can and will cause you to reach for your backups… If you don’t know, ‘dd’ defines itself as a tool to convert and copy files. You should read the man page sometime. It’s a rather robust, and potentially complicated, application.

Anyhow…

Check Your (Write) Disk Speed In The Terminal:

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.

The first thing we’re going to do is make a new directory and move to it.

Now, let’s start testing. I’m going to assume you have at least 10 GB worth of space (we’ll be using ~5.5 GB, or 5 GiB). If you do not have enough space, don’t run this command until you do have that much free disk space. The command to run the test is:

Here’s a test result on a slower, in use SSD, about what I expect most users to have:

It will show you the progress, as we’ve enabled that in the dd command. It won’t take all that long for the test to complete. Unless your drive was otherwise heavily occupied, there’s little to gain from running the test multiple times.

Anyhow,  how about we cleanup after ourselves? As the file was made with ‘sudo’ so too shall it be removed with ‘sudo’. It will probably even ask you for confirmation.

And delete the directory:

That should have cleaned up our mess, all nice and fancy like. There’s no real reason to keep a 5.4 GB test file hanging around and you already have the test results.

Closure:

There you have it! You now have another article and this one will show you how to check your write disk speeds for your drives. If you want to test other drives, just write the file to those drives by navigating there first in the terminal. ‘Snot all that difficult.

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How To: Remove AppArmor From Ubuntu

In today’s article, we’re going to learn how to remove AppArmor from Ubuntu. This will work for other distros, like Debian. It’s actually not a very difficult task to remove AppArmor from Ubuntu, but it’s not something you necessarily want to do. Just because you can, doesn’t mean you should…

As many of you know, I write many of these articles based on the notes I’ve taken over the years. I’m a little reluctant to write this one, because removing AppArmor is probably not the best of choices.

AppArmor is similar to the various jails and application isolation techniques. It’s a security tool that restricts applications to a constrained set of resources. If the application is then compromised, it only has access to that set of resources and not to the whole system.

In other words, unless you know what you’re doing, you almost certainly don’t want to remove AppArmor from Ubuntu. In fact, if you don’t know what you’re doing then doing this is almost certainly a ‘not-bright’ choice.

If you’re going to remove AppArmor, you should consider replacing it with something else. SELinux is an option that’s similar, though I suppose you could use something like Firejail and be prepared to craft your own application profiles.

Again, removing AppArmor from Ubuntu (or whatever distro you’re using that has it) is probably not a good idea. I include the article because the information is already out there and because some folks may just decide to operate their system without such protections. This is Linux, you have the freedom to make bad choices. This isn’t even the first time I’ve shown you how to make bad choices.

Remove AppArmor From Ubuntu:

Like oh so many of these articles, you’re gonna need an open terminal. Just press CTRL + ALT + T and your default terminal should open. (I say that a whole lot on this site.)

We should first check to ensure AppArmor exists and is running. To do so, enter the following command:

What you’re looking for is several lines into the output. You’re looking for ‘apparmor module is loaded‘. If you see that, AppArmor both exists and is running. So, the next step in removing AppArmor is to stop the service. You do that with:

In case AppArmor is somehow installed again, we’ll make sure that it won’t start at boot by disabling the service entirely. That seems like a good idea.

Finally, we nuke AppArmor from existence with a purge command:

And that should do it. You probably want to reboot, just to make sure there are no tendrils sticking around – but stopping the service first should mean you don’t need to. Either way, you have now removed AppArmor from your system – assuming you followed the directions.

Closure:

Again, and I can’t stress this enough, don’t do this unless you know what you’re doing and unless you have something to replace AppArmor with. It’s really a bad idea and you’ll gain very little. I wouldn’t even do this with a system air-gapped from the network, unless I had a very good reason to do so.

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Turn Your Ubuntu Into A Wireless Hotspot

Have you ever wanted to use your Linux computer as a wireless hotspot? It’s actually pretty easy. Today’s article will get you started and it really isn’t all that difficult. We will actually be cribbing a bit of this article from the software’s homepage, but while some more, rather important, information added.

For many years, I used my own router that I had configured on my own hardware. It was built on Linux. The preceding version actually ran on BSD, but that’s not important for a site called Linux-Tips. Today, you can get a NUC or Pi for dirt cheap and so making a new router is back on my list of things to do. In other words, it’s a fun project that won’t take a lot of money to get into.

All of the varied software and hardware components are already there to make your own router, but I want to enable wireless connectivity. a wireless hotspot, and that’s what we’re going to look at today. The tool we’re going to use is called ‘linux-wifi-hotspot‘ That’s is a great tool, complete with GUI if wanted, written by lakinduakash. It has only been around for a few years, but it’s spoken of very highly – and it just works and works well.

At least it worked the last time I used it. This article is from the old site and I’m just moving it to this site. I actually haven’t bothered much with my own router for the past year or so. So, this information is a bit dated.

Turn Your Ubuntu Into A Wireless Hotspot:

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.

The software is easy enough to install. If you’re using Debian/Ubuntu, just add the PPA and install the software. To add the PPA, you just run:

On a modern Ubuntu, you shouldn’t need to do this, but you might want to go ahead and run a quick update with:

Then you can install the software, starting to get your system into a workable wireless hotspot. To do that, it’s just:

If you want, you can visit the link above (in the preamble), click on releases, and download the .deb file for the current release and just install it with gdebi. In this case, I’d suggest installing with the PPA – just to make sure

Then, you can go ahead and start it. You can also go ahead and make it start at boot, which would be prudent if you intended to use this to make your own router. It’s really self-explanatory and without specific questions for using it, I’m just going to refer you to the man page and the information at the project page.

Caveats:

But, before you can even do all of this, you need to know that your wireless adapter actually supports doing this. To find out, you need to know if your wireless adapter supports “AP” mode. AP obviously meaning ‘Access Point’.

To check this, you need to run the following command:

The project page is noticeably silent with this, but it’s a necessary step. See, you need to know if your hardware actually supports it before you even bother trying. Come to think of it, I probably should have put this closer to the top of the page! Ah well…

Anyhow, the output should contain one or both of the following lines:

Device supports AP scan.

And/Or:

Driver supports full state transitions for AP/GO clients.

So long as you see one or both of those, you should be all set to proceed. If you don’t see either of them, there’s no software solution and you’ll need to get hardware that supports AP mode. In many cases, that’ll mean doing a bunch of research and may even mean contacting the vendor or OEM.

Nobody appears to have compiled a list of hardware that supports AP mode and I don’t think I’ve ever bought wireless adapters that explicitly stated they do on the box. As near as I can tell, more modern adapters support it just fine, so you’ll probably be alright. Online specs are more thorough than what’s printed on the outside of the box, so maybe searching is okay.

Closure:

Alright, there’s your article for the day. I have no idea if you want to make a wireless hotspot for your Linux box, but now you know how. It’s pretty self-explanatory, and you shouldn’t have any questions. If you do, you know where to find me – or to find others who can help you – at Linux.org.

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