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Linux Fu: Fake Webcams Have Many Uses

May 28, 2026 by 14 Comments

Dealing with text streams is a fundamental skill for the Linux power user. You can sort, merge, and search text files easily from the command line. What if you could do the same thing with video? Well, you can. Maybe you want to add a logo to a webcam feed before sending it to a conference app. Maybe you want to blur, color-correct, or annotate video in real time. Or perhaps you want to inject prerecorded video into Zoom while pretending it is a live camera. Linux can do all of this, and the key ingredient is usually the same: a loopback video device.

The basic idea is simple. Instead of an application reading directly from /dev/video0, you create a fake camera device using the v4l2loopback kernel module. Your software pipeline writes processed video into the fake camera, and applications read from it as if it were a normal webcam. The result is surprisingly powerful.

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Linux Fu: The Bluetooth Regression

May 26, 2026 by 24 Comments

There’s a line in a [Weird Al] (no relation) song that says, “I upgrade my system at least twice a day…” I know how that is. I primarily use a rolling distro, OpenSuse Tumbleweed, and if I’m having a problem that I’m too lazy to run down, it is extremely tempting to do an upgrade and see if it just happens to fix the problem.

Of course, the problem is often caused by a previous upgrade. Recently, I’ve been having a lot of trouble with the NVIDIA proprietary drivers, so I updated them yet again. After a huge amount of effort to sort out the video problems, I found that the latest kernel didn’t like my MediaTek Bluetooth adapter, which is built into the motherboard’s WiFi chipset.

This post isn’t about how to fix your Bluetooth problem. You probably don’t have the same setup I do, and even if you do, it will be sorted out in a week or two anyway. But how I temporarily fixed this issue is worth documenting. The details are going to apply to Tumbleweed and this particular adapter, but the general approach should work anywhere with any sort of kernel module problem.

My Own Fault

Part of my problem is my own fault, of course. I have a complex disk setup and do not use the recommended btrfs root file system. That means I can’t do the snapshot thing where I can just undo a bad upgrade. If I did, then sure, I should just roll back and wait for an upstream fix.

I do have “normal” backups, but they are not always totally up to date. Worse, I have found that for things like NVIDIA, the user stuff and the kernel module stuff have to match up. That makes it very hard to roll back a kernel with older modules. The modules themselves live with the kernel, but the user space stuff gets pushed out. Or, if you uninstall things, it uninstalls it for all kernels.

Truthfully, NVIDIA and others like that should keep all the user space stuff in a kernel-specific place, and then symlink it at boot to /usr/bin or wherever. But they don’t. In the end, I didn’t want to go through the trouble of rolling things back and decided to push ahead.

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Linux Fu: The USB WiFi Dongle Exercise

March 4, 2026 by 18 Comments
The TX50U isn’t very Linux-friendly

If you’ve used Linux for a long time, you know that we are spoiled these days. Getting a new piece of hardware back in the day was often a horrible affair, requiring custom kernels and lots of work. Today, it should be easier. The default drivers on most distros cover a lot of ground, kernel modules make adding drivers easier, and dkms can automate the building of modules for specific kernels, even if it isn’t perfect.

So ordering a cheap WiFi dongle to improve your old laptop’s network connection should be easy, right? Obviously, the answer is no or this would be a very short post.

Plug and Pray

The USB dongle in question is a newish TP-Link Archer TX50U. It is probably perfectly serviceable for a Windows computer, and I got a “deal” on it. Plugging it in caused it to show up in the list of USB devices, but no driver attached to it, nor were any lights on the device blinking. Bad sign. Pro tip: lsusb -t will show you what drivers are attached to which devices. If you see a device with no driver, you know you have a problem. Use -tv if you want a little more detail.

The lsusb output shows the devices as a Realtek, so that tells you a little about the chipset inside. Unfortunately, it doesn’t tell you exactly which chip is in use.

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Linux Fu: Yet Another Shell Script Trick

January 6, 2026 by 3 Comments

I’m going to go ahead and admit it: I really have too many tray icons. You know the ones. They sit on your taskbar, perhaps doing something in the background or, at least, giving you fingertip access to some service. You’d think that creating a custom tray icon would be hard, but on Linux, it can be surprisingly simple. Part of the reason is that the Freedesktop people created standards, so you don’t typically have to worry about how it works on KDE vs. GNOME or any of the other desktop environments. That’s a big win.

In fact, it is simple enough that you can even make your own tray icons with a lowly shell script. Well, of course, like most interesting shell scripts, you need some helper programs and, in this case, we’ll use YAD — which is “yet another dialog,” a derivative of Zenity. It’s a GTK program that may cause minor issues if you primarily use KDE, but they are nothing insurmountable.

The program is somewhat of a Swiss army knife. You can use it to make dialogs, file pickers, color selectors, printer dialogs, and even — in some versions — simple web browsers. We’ve seen plenty of tools to make pretty scripts, of course. However, the ability to quickly make good-looking taskbar icons is a big win compared to many other tools.

Docs

Depending on what you want to do, YAD will read things from a command line, a file, or standard input. There are dozens of options, and it is, honestly, fairly confusing. Luckily, [Ingemar Karlsson] wrote the Yad Guide, which is very digestible and full of examples.

Exactly what you need will depend on what you want to do. In my case, I want a tray icon that picks up the latest posts from my favorite website. You know. Hackaday?

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Linux Fu: Compose Yourself!

December 30, 2025 by 20 Comments

Our computers can display an astonishing range of symbols. Unicode alone defines more than 150,000 characters, covering everything from mathematical operators and phonetic alphabets to emoji and obscure historical scripts. Our keyboards, on the other hand, remain stubbornly limited to a few dozen keys.

On Windows, the traditional workaround involves memorizing numeric codes or digging through character maps. Linux, being Linux, offers something far more flexible: XCompose. It’s one of those powerful, quietly brilliant features that’s been around forever, works almost everywhere, and somehow still feels like a secret.

XCompose is part of the X11 input system. It lets you define compose sequences: short key sequences that produce a Unicode character. Think of it as a programmable “dead key” system on steroids. This can be as simple as programming an ‘E’ to produce a Euro sign or as complex as converting “flower” into a little flower emoji. Even though the system originated with X11, I’ve been told that it mostly works with Wayland, too. So let’s look deeper.

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Linux Fu: The SSD Super Cache

December 8, 2025 by 14 Comments

NVMe solid state disk drives have become inexpensive unless you want the very largest sizes. But how do you get the most out of one? There are two basic strategies: you can use the drive as a fast drive for things you use a lot, or you can use it to cache a slower drive.

Each method has advantages and disadvantages. If you have an existing system, moving high-traffic directories over to SSD requires a bind mount or, at least, a symbolic link. If your main filesystem uses RAID, for example, then those files are no longer protected.

Caching sounds good, in theory, but there are at least two issues. You generally have to choose whether your cache “writes through”, which means that writes will be slow because you have to write to the cache and the underlying disk each time, or whether you will “write back”, allowing the cache to flush to disk occasionally. The problem is, if the system crashes or the cache fails between writes, you will lose data.

Compromise

For some time, I’ve adopted a hybrid approach. I have an LVM cache for most of my SSD that hides the terrible performance of my root drive’s RAID array. However, I have some selected high-traffic, low-importance files in specific SSD directories that I either bind-mount or symlink into the main directory tree. In addition, I have as much as I can in tmpfs, a RAM drive, so things like /tmp don’t hit the disks at all.

There are plenty of ways to get SSD caching on Linux, and I won’t explain any particular one. I’ve used several, but I’ve wound up on the LVM caching because it requires the least odd stuff and seems to work well enough.

This arrangement worked just fine and gives you the best of both worlds. Things like /var/log and /var/spool are super fast and don’t bog down the main disk. Yet the main disk is secure and much faster thanks to the cache setup. That’s been going on for a number of years until recently.

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Linux Fu: Windows Virtualization The Hard(ware) Way

August 21, 2025 by 31 Comments

As much as I love Linux, there are always one or two apps that I simply have to run under Windows for whatever reason. Sure, you can use wine, Crossover Office, or run Windows in a virtual machine, but it’s clunky, and I’m always fiddling with it to get it working right. But I recently came across something that — when used improperly — makes life pretty easy. Instead of virtualizing Windows or emulating it, I threw hardware at it, and it works surprisingly well.

Once Upon a Time

First, a story. Someone gave me a Surface Laptop 2 that was apparently dead. It wouldn’t charge, and you can’t remove the keyboard without power. Actually, you can with a paper clip, and I suggested pulling it to see if the screen would charge by itself. They said they had already bought a new computer, so they didn’t care.

Unsurprisingly, once I popped the keyboard off, the computer charged and was fine. You just have to replace the keyboard or use another one. Or use it as a tablet, which it is set up for anyway. But I have plenty of laptops and computers of every description. What was I going to do with this nice but keyboardless computer? Continue reading “Linux Fu: Windows Virtualization The Hard(ware) Way” →