Category: Command Line

How To: Generate a List of Installed Applications in Linux

Before making this site, I had a similar article that explained how to list installed applications in Linux, but it was only relevant to those that used distros with ‘dpkg’. This expanded article will explain how to generate a list of installed applications for multiple distros, in order to be more complete.

There are any number of reasons why you might want a list like this. Maybe it’s for compliance reasons, needing to know everything installed on the machine. Maybe it’s for making a manifest to establish a baseline for future installs. You could also just be curious, need a list for support questions, or want a list for backup purposes.

Whatever your reason, you can generate a list of installed applications fairly easily. You can also do a couple of other neat things that I’ll explain below.

Generate a List of Installed Applications:

For all of these commands, you’ll want a terminal. You can probably open your default terminal by using your keyboard to press CTRL + ALT + T. If that doesn’t work, you can just open it from a menu or whatever shortcut you’ve set up for yourself. (I’m looking at you, you people with strange window managers!)

The command you’ll use will vary depending on your distro. I’ve got a few of them covered below. In some cases, you may need elevated permissions, so a ‘sudo’ in the front of the commands should do the trick for you.

Debian (& dpkg using distros):

If you’re using Ubuntu, or a distro with snaps, you can list those with:

If you’re using flatpak applications with any distro:

Arch (& Mandriva, etc.):

RHEL (& Fedora, etc.):

OpenSUSE (& derivatives):

Those are the major distros. There are smaller distros, independent distros, and they’ll have their own package management systems and ways to make a list of installed applications.

Bonus:

You can actually do a few things with this listing. Two immediately come to mind and I’ll share them.

First, you can count them. At the end of each of these commands, you can pipe it and count the lines. It may not be a 100% accurate number, but it will be pretty close. (Some of the commands output more than just a list of installed applications.)

That’ll give you an output similar to:

You can also write the list of installed applications to a text file, to save for archiving or whatever. I like to make a list now and then and check against it when I do a new installation. Your reasons are your own, but here’s how:

The .txt isn’t mandatory and you can write the file to anywhere you want, assuming you have the correct permissions. It’s your list, you can do anything you want with it!

Closure:

And, there you have it. You can now make a list of all applications that you’ve installed. You can even count the list, and you can write the list to a file for storage. If you want, you can generate a list of installed applications on one computer, generate a list of all applications on a second computer, and then use ‘diff’ to see what the differences between them are. There’s all sorts of things you can do with this list.

As always, thanks for reading. Your reading and feedback help me stay motivated. My goal is to keep up this publication rate for a year, though we’ll see where we are when that year ends. I have enough notes for that, and more. 

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What is my Hostname in Linux?

For most of you, your hostname in Linux is going to be the same as your username. This article will help you figure out your hostname in Linux, and it should be a relatively short article. If this article looks familiar, it’s because it existed at the old site, but with far less information.

Let’s start at the beginning, by learning what a hostname is.

A hostname is generally meant to be a human-readable way to identify a computer. Yes, the computer is truly identified by the associated IP address, but the hostname resolves to that computer. It is meant to be easily remembered instead of having to remember a bunch of IP addresses. Without it, the web (and your own local networks) would be more difficult to navagate.

In many instances, it’s a FQDN (Fully Qualified Domain Name), such as a domain name like linux-tips.us. However, this site doesn’t have a dedicated IP address, so it’s known by a virtual hostname as a FQDN. If the site had been constructed differently, you’d be able to access it with the IP address. For example, https://172.217.10.14 will take you to Google (after some warnings).

So, your hostname in Linux isn’t always going to be the same as your username. For most of the readers here on L-T.us, it will be. You probably don’t really need to worry a whole lot about things like virtual hosts and stuff like that. But, even as a home user, you can make use of this information.

How is it useful? Well, if I want to SSH into my MSI laptop, I don’t have to use the IP address. Not only that, if the IP address changes then I don’t need to look it up. I just connect with something like:

You may notice that I added the .local. You too can just add .local with many distros, in others the default might be something like .localdomain – which you can keep as the default or change it easily enough.

So, let’s figure out how to find your hostname in Linux.

Find your hostname:

Let’s start by cracking open the terminal. You can use your keyboard to do this, just press CTRL + ALT + T and your default terminal should open up.

Now, we can try the following:

Or you can try:

Or you can also try:

As near as I can tell, one of those should work on all major distros. If it none of them work for you, please leave a comment letting me know what does work – helping those who come behind you.

Using Your hostname in Linux:

There are a number of ways that this information can be used. With many distros, as mentioned above, you can add .local to the hostname and just use that instead of IP addresses. Here’s a picture that shows a few examples:

using hostname in Linux
Instead of using the IP address, use the hostname. It’s a pretty handy feature.

There are, of course, other things you can do with this information. Those are just a few examples. The great thing about using a hostname in Linux is that you’ll not have to recall IP addresses. You’ll only need to recall a name – a name that you picked.

You can change your hostname, but that goes beyond the scope of this article. I’d expect to see an article about that in the future! In the meantime, if you can think of any ways that you’d use the hostname, please leave a comment.

Closure:

Thank you, my dear reader, for your viewership. Your comments and feedback keep me motivated and your feedback helps to improve this site. For those who have been keeping track, you can actually now click on large images to see the larger versions. This will only be for future articles, as I’m unlikely to go back through every previous article and change it. But, it was direct feedback that resulted in the change.

If you’d like to contribute, there are a number of ways. You can donate, write an article, unblock ads, buy hosting, and sign up for the newsletter. I promise, I’ll never share your email address with anyone and I won’t send you any spam. Until next time…

A Few Ways to Determine Which Distro and Version You’re Using

This article will show you a few ways to determine which distro and version you’re using. There are many ways to learn this, but these are three easy ways to tell.

There are any number of reasons why you might not know this information off the top of your head. Perhaps you’re working in a multi-platform job? You might have many devices. It’s possible that you may have a bunch of virtual machines, each different. One can’t always tell by just looking at the desktop, especially if you’ve done any customizing.

Additionally, you may have upgraded and not know things like the point release. You may have different versions across your network, each for its own purpose. You might just be forgetful and so you’ll need to determine the distro you’re using, as well as which version of that distro you’re using. You might be in a position where you need support, and being able to share this information is essential.

No worries, there are a few easy ways to determine which distro you’re using. All of them are pretty easy.

Determine Which Distro (and Version):

All of these methods will rely on the terminal. So, before you begin, you can open your default terminal emulator by using your keyboard and pressing CTRL + ALT + T.

Once you have that open, you can try any combination of the following:

Method #1

The first method will involve a program known as ‘neofetch‘. Many distros actually provide this by default. If not, it’s probably in your default repositories and you can install it pretty easily. For example, with a Debian-based, or APT-using distro, the command to install it would be:

Once installed, you can simply run it with the name of the application. No modifiers are required. You simply run:

You’ll get an output similar to:

neofetch in action
This should be entirely self-explanatory. You can do more with neofetch, by the way.

See? Nice and easy. The information to determine which distro you’re using is right there in the output and on the top-most line.

Method #2

The following two methods need no additional software. You simply need to run the command in the terminal. 

The first of these two methods is:

Which will give you an output similar to:

Again, this is self-explanatory. The top-most is the major name, the second is the version, then the release number, and then the codename. With this information, you can determine which distro you’re using.

Method #3

Your distro may not have any LSB data and may not contain that information. That’s okay, there’s still one more command for you to try. Again, you don’t need to install anything, it just works out of the box.

This time, the command you’ll be running will be ‘cat’ and you’re looking for release data in the /etc directory. The command looks like this:

Your output should look similar to this:

As you can see, that contains a ton of information, including where to go for support and where to file bugs. 

Closure:

One of those is bound to work for you. I checked across a number of virtual machines and was able to determine which distro each was using. In many cases, all three of them will work for you.

At the end of the day, you can probably just pick your favorite (or the one that works) and commit it to memory. Personally, I try the ‘lsb_release -a’ first, as that one is firmly locked in my memory.

Like always, thanks for reading. I love the feedback folks provide, either here or at one of the sites I frequent. You may have noticed that I am now the owner/moderator of the LinuxTips Reddit Sub. If you frequent Reddit, and you’re interested in helping out, just drop me a note on Reddit and I’ll get you set up as a moderator there.

Of course, you can also unblock the ads used here. You can sign up for the newsletter. You can donate or write an article. There’s a few ways you can help keep this site going, or show your support. I currently write a new article every other day, though I’ve been considering increasing the frequency. Either way, let me know in the comments what you think of any of this stuff. I’m always curious about your thoughts regarding this site.

How To: Sanitize Exif Data From Your Digital Images For Privacy Sake

When you take a digital picture, the resulting file contains potentially personal information. It is known as ‘Exif‘ and it contains sensitive information. This article will explain how to sanitize Exif data to avoid leaking your personal information.

If this article looks familiar, I’ve previously authored an article on this subject. It’s at the old site, which will be redirected here. I might as well write it anew, using the current style.

UPDATE: I received an email one Morgan Kinney, inviting me to review and include a link to a study they (authored by one Paul Bishoff) had done regarding Exif data and the privacy implications. If this article wasn’t clear enough about the privacy aspect of sanitizing Exif data, then please consider reading the following link:

EXIF metadata privacy: A picture is worth a thousand data points

I’d not normally do this, but their work is well done and is a worthy addition to your understanding of Exif data and the privacy risks associated with Exif data. See the “Closure:” section for more updated information.

Moving on…

Exif is the additional information included in the file your digital camera makes, among other things. It can be as benign as color correction data to orientation settings. In some cases, it can also contain such privacy-wrecking gems as when and where (the GPS coordinates) and when  the picture was taken. It is defined as thus:

Exchangeable image file format (officially Exif, according to JEIDA/JEITA/CIPA specifications) is a standard that specifies the formats for images, sound, and ancillary tags used by digital cameras (including smartphones), scanners and other systems handling image and sound files recorded by digital cameras.

The Exif data can even contain information about the camera’s brand and, as you can see, isn’t limited to just a fancy digital camera. Your other devices, from smartphone to scanner, add this extra data to the file. Anyone who is aware of this can easily look for this data. Exif data has even been used as evidence by the judicial system.

Obviously, there are huge privacy implications with this. You can probably minimize some of the data that’s created by changing your phone/camera’s settings. That does nothing for existing files, and nothing for when your device has no such configuration options.

Let’s See This Exif Data

There are any number of ways to examine the Exif data. For example, this is some of that data and it is being drawn from a program called XNViewMP.

Exif data
Exif data sample. There’s not a whole lot of data with this one.

That one tells you how old the picture is, and not a whole lot more. But, it also now contains the information about the last time it was accessed. That could be of interest, perhaps giving away things like the age of the photo’s subject.

This next picture is the Exif data from one of my cellphone pictures. I have the GPS data turned off, so that wasn’t included. You’ll see a ton of additional information.

More detailed Exif data.
See? Now you can tell I don’t bother updating my phone often.

As you can see, there’s even more data in that file. There may well be even more data in your pictures. It tells you what camera I was using (a cell phone, and an old one at that) and that I took the picture at 14:30, in a well lit room. It even tells you the software version, which may be exploitable to an attacker.

Don’t worry too much about this. It’s a solved problem. You can sanitize Exif data and maintain a bit more privacy. It’s actually remarkably easy.

Many image hosting sites will automatically strip the Exif data when you upload your image.

Let’s Sanitize Exif Data

The tool we’re going to use for this is ‘exiftool‘ and it’s pretty simple. It’s quite likely already in your default repositories, or at least the repositories you can add trivially. In Debian/Ubuntu/Mint/similar, you can install it with:

You’ll need to adjust the command for your distro, of course. Once you have it installed, you can navigate to the directory where you store your images and run something like this to sanitize png files:

Or, if you’re trying to sanitize .jpg images, you’d run this command:

Depending on the number of files in the directory, it could take a little while to run. It’s pretty speedy and it does give you confirmation when it’s done. I’ve used it on large numbers of images at once and it took care of them all in less than a minute. I probably should have paid more attention, that way I’d have some actual numbers for you.

NOTE: The exiftool can actually strip data from other files, including files like PDFs and other such types of documents. A complete list can be found here. Yes, those documents contain data beyond that of the text contained in them. They may contain such data as the computer name, username, and dates and times of file creation and editing.

Personally, I combine both the .png and .jpg commands into one command and I run that command with an alias. We haven’t covered aliasing yet, so I’ll just go ahead and show you what I use.

That, if added to .bash_aliases, would let you use ‘picclean’ to sanitize an entire directory’s worth of png and jpg files. It comes in pretty handy if you’re sharing a bunch of files and want to make sure they’re all clean before you send ’em.

Closure:

Well, there you have it. Hopefully you’ll now know a little bit more about how to sanitize your image files, removing the private data from them as much as you can. If you don’t generate the data in the first place, you don’t have to delete it. So, disable embedding GPS coordinates in your phone (or some fancy cameras) and don’t take pictures of yourself while doing illegal activities.

UPDATE: As mentioned, I’d not normally do this – but there are exceptions. I don’t mind linking to other sites if the content is worth the attention of my readers. If you have your own content and would like to have it referenced here, don’t be afraid to contact me. Just be aware that I decline about 60% of these sort of requests. While I do love guest additions and guest articles, no I won’t be including articles about mortgage rates and the benefits of CBD oil. My readers aren’t interested in articles like that. So, your content needs to be both good and topical.

Thanks, as always, for reading. I always look forward to the feedback, here and on other sites. Don’t forget that you can unblock ads, sign up for the newsletter, donate, or contribute by writing an article or two. Don’t forget to share this site with your friends. Share the love!

UPDATED: (Updated on 01/23/2022)

Prevent Application Updates With ‘YUM-VERSIONLOCK’

I recently wrote a similar article, illustrating how you can use ‘apt-mark’ to prevent application updates. While that was handy, it only applied to those who use APT as their package manager. It offered nothing of value to those who use YUM.

This article will explain how you can prevent application updates with ‘yum-versionlock’. You will learn how you can temporarily prevent application updates when you have no choice but to.

In the previous article, I explained that you should always use the most up-to-date software that you can, at least if your system is connected to the public internet. Software updates provide security fixes, not just bug fixes.

Not updating means you’re vulnerable and your vulnerabilities may impact other users. For example, your computer may become a part of a botnet, a spam relay, or even be used as a command and control device for those things. As a global citizen of the ‘net, you’re obligated to do what you can to minimize harm.

So, it is possible to prevent application updates, but you really should only do so when it’s absolutely necessary. In an ideal world, you’d be able to always use the updated version, but we don’t live in that world. We live in the real world, where we have things like compliance and compatibility issues. 

YUM, what is it? YUM stands for Yellowdog Updater, Modified. It’s a package management utility for RPM based distros. You’ll find YUM in distros like RHEL, Fedora, and even OpenSUSE. It’s fairly widely used, though many of the RPM-based distros are more prominent in the server space than they are in the desktop space.

These days there’s actually DNF (which stands for Dandified YUM – don’t blame me, I don’t name these things) but that’s not important today. Today, we’ll be using ‘YUM-VERSIONLOCK‘ to prevent application updates.

Prevent Updates with ‘yum-versionlock’

Unlike ‘apt-mark’, you’ll need to install something in order to do this. It should also be mentioned that there are other ways to accomplish this, but this is the easiest way to prevent application updates. Using versionlock is the most straightforward way of accomplishing this.

First, you’re gonna need to crack open your terminal. You can do that by using your keyboard. Just press CTRL + ALT + T. 

Once your terminal is open, you’ll need to install ‘yum-versionlock’. You can try this first:

If that gives you an error, I can’t figure out where the name changed, then you can most likely install it with:

Once you have it installed, you can check the man page to see how you use it. Even if you installed it with the second command, the man page is still found at:

The one-liner quite accurately defines versionlock as:

yum-versionlock – Version lock rpm packages

Anyhow, to use it to hold a package at its current version, you simply use:

NOTE: The command supports wildcards. You can use an asterisk with this command. The command will give you feedback. You can also use ‘add’, but it’s redundant.

If you want to remove the lock, which you should do as soon as realistically possible, then the command is fairly evident. It’s just:

If you, like me, don’t always keep the best notes and don’t have the greatest memory, then you can list the locked packages with this command:

There’s no need for elevated permissions with that command, but it will take a little while for it to complete. It will output any locked packages and you can unlock them individually. Again, you can use wildcards in this command.

However, you can remove all the locks with just one command:

As you might expect, that removes all the locks and your system will resume updating normally. You should not keep software locked to one version for long. Though you may be using a LTS-type distro, only getting minor point release upgrades, you are still getting security updates. Keeping your system secure makes you a good netizen. 

Closure:

And there you have it. Another article in the books, this one explaining how to stop updates for specific applications. Thanks for reading and feel free, nay encouraged, to leave feedback. If you have any ideas for articles, feel free to share them. You can also contribute by writing your own article. I’ll even edit it up for you!

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