Colas.Nahaboo.net - hardware

Magnets, magnets everywhere

2026-08-27T00:00:00+00:00

I have started putting magnets on small things around my desk. A cable that was wandering around now stays where I need it, and a USB hub now sits on the top of my PC case instead of taking space on the desk.

Cables🔗

For cables, I use round magnets with a hole in the middle. A small tie goes through the hole and loops over the cable. The cable rests on top of the magnet, and the magnet holds the whole thing to a magnetic surface.

I can move the cable, pull it away when I need it, and put it back without fighting a fixed clip. The magnet stays with the cable, so I do not have another small part to lose.

The photo below also shows another version. I bolted a double-sided Velcro band through the central hole of a round magnet. It makes a reusable strap for a thicker cable or a small bundle.

USB hubs🔗

I glued square magnets (the leftlmost ones on the photo above) made for cabinet doors to the sides of the USB hub. I used MS polymer glue and waited for it to cure. The magnets now attach the hub to the steel side of my PC case.

The hub remains removable, but it stays put. The same trick should work with metallic desk legs, provided that the metal is magnetic.

One small detail matters: a metal surface is not necessarily magnetic. I test it with one of the magnets first. I also let the glue cure fully before hanging the hub and keep strong magnets away from cards and magnetic storage.

This is the kind of DIY I like: cheap parts, no drilling, and an arrangement I can change later.

Buzz was right. Magnets, magnets everywhere. :-)

Remediate subpixel color fringing on Linux

2026-08-14T00:00:00+00:00

I plugged in my new MSI 491CQPX, a QD-OLED ultrawide, and the first thing I noticed was that text looked dirty: every letter bordered by a red fringe on one side, a green one on the other. Not blurry, but colored — as if my glasses had chromatic aberration.

That is subpixel color fringing. QD-OLED panels arrange their red, green, and blue subpixels in a triangle, while font rendering engines — ClearType, FreeType, all of them — assume the classic RGB stripes of LCD panels. Subpixel antialiasing is the culprit: it lights up individual subpixels to fake a higher resolution, and on a triangular layout the colors bleed sideways into a fringe.

PC Monitors has the full story, with macro photos (QD-OLED and WOLED both suffer). nuxx was so bothered that he returned his OLED — it made his eyes feel funny. I did not return mine: on Linux the fix is one setting.

The fix: grayscale antialiasing🔗

Subpixel rendering is the problem, so I stopped using it. Set your fonts to plain grayscale antialiasing and the fringes disappear. On GNOME:

Install GNOME Tweaks: sudo apt install gnome-tweaks
Open Tweaks → Fonts
Set Antialiasing to Grayscale — this is the whole fix

The letters lose a bit of the LCD-crisp sharpness, but I had to look hard to tell the difference. Hinting is a matter of taste, not part of the fix: I left it alone.

Not on GNOME?🔗

Any desktop works — the switch is in fontconfig, the config file every Linux font stack reads. Create ~/.config/fontconfig/fonts.conf with this:

<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<fontconfig>
  <match target="font">
    <edit name="rgba" mode="assign"><const>none</const></edit>
  </match>
</fontconfig>

run fc-cache -f, log out and back in. Setting rgba to none is precisely what turns subpixel rendering off.

Black is too black🔗

The fringes are most visible at maximum contrast — white text on pure black. I keep my editor and terminal backgrounds at a very dark gray (#121212) instead of #000000, which calms things down further and looks just as "OLED" to me.

Do not try the ClearType Tuner under Wine🔗

Tempting, I know, but do not. The tuner writes Windows registry keys (Software\Microsoft\Avalon.Graphics), which FreeType and Wayland never read — zero effect. And on Windows it would not help either: the tuner cannot adapt ClearType to a triangular layout, which is why there is a long-running PowerToys issue begging Microsoft for OLED subpixel support.

Alas, the Linux advantage here is real: Windows users are still waiting for Microsoft, while I fixed my monitor with one toggle. Done.

... But still annoyed by the pixel refresh🔗

However, I still have to cope with the other trouble with OLED monitors: They just stop working for 10 minutes at least once a day... at the most inconvenmient times: the dreaded pixel refresh.

ups-monitor.sh: staged shutdowns when the power goes out

2026-08-12T00:00:00+00:00

I released ups-monitor.sh, a bash script that decides what happens when the power goes out.

My UPS powers my servers, NAS, main switch and wifi access point. I want to cut off first my workstations in a clean way, to keep as much battery power to provide my main file server access via wifi for my phones and tablets.

Configuring NUT scripts for this seemed verbose and complex for my small setup, so I basically coded a simple but flexible bash control layer over the NUT infrastructure

The staged shutdown🔗

So the script shuts things down in stages, as the battery drains:

90% battery: shut down the non-essential "first" servers — storage, backups, the toy boxes.
80% battery: shut down the "extra" servers.
20% battery: shut down the monitoring host itself, and put the UPS in standby.

The UPS on the final step powers everything off and goes to sleep; when the mains come back, it wakes up, powers the equipment, and the machines can boot again. Recovery is automatic.

The staging is fully configurable: the thresholds and the server lists live in /etc/ups-monitor.conf, and servers can be prefixed h: to hibernate instead of shutdown, or wh:/ws: for Windows hosts.

The config is bash🔗

As I often set up my scripts, the config file is sourced by the script, so it is not a list of options in some syntax, it is pure bash. You can override any variable — and any function. Redefine info to text you instead of mailing you. Redefine remoteshut to do whatever exotic thing your network needs. You can even write "pseudo servers" as funcname:params in the server lists, and the script will run that function before shutting down — say, dump the databases before the machine dies. The anti-framework approach, same as my colas-bash-lib collection.

It just polls the UPS every five seconds, so bash provides simplicity, stability and flexibility with a negligible overhead.

Goodies🔗

A dry-run mode toggled by touch /tmp/NOUPSMON — no restart needed — so you can unplug the UPS and watch the logs before trusting it for real.
Email alerts for power lost and restored, overload, and battery-to-replace. AVR events (TRIM/BOOST) logged with the exact input voltage, for info. Logs rotated monthly, and a clean command for the cron.

Compatible UPS🔗

One advice: choose a pure sine wave UPS, otherwise some active-PFC power supplies may panic and shut down abruptly when the UPS switches to batteries. Save yourself the uncertainty.

Installation, Usage, and more info🔗

github.com/ColasNahaboo/ups-monitor.sh

Note: This is AI-co-advised: chatting with Gemini helped me as a UPS novice, but it did not write the code or the docs.