Quickly switch between two custom screen resolutions from the Linux command line

Primarily as a reminder to myself, here’s a small script droppable into ~/bin that allows switching between two custom Linux screen resolutions, that is, resolutions the X server does not necessarily already know about, from the command line.

Configuring the default search engine for Microsoft Edge through initial_preferences so that it actually works

Microsoft Edge, since some time now based on Google’s Chromium, supports a similar mechanism to configure (not enforce!) default preferences through a file called initial_preferences. But when it comes to configuring the default search engine, neither Microsoft’s documentation nor their downloadable Microsoft Edge policy templates are of any help. In fact, I couldn’t find a… Continue reading Configuring the default search engine for Microsoft Edge through initial_preferences so that it actually works

Automatic mounting of known removable media with systemd in non-graphical environments

In a Unix/Linux context, the term “automount” is often interpreted as the automatic on-demand mounting of devices or remote filesystems as soon as a controlled path is accessed: the actual mounting is deferred to the moment the path is first accessed. Or in other words: only when it is needed. But what if we want… Continue reading Automatic mounting of known removable media with systemd in non-graphical environments

How Apple (and Avahi) effectively killed CUPS’ printer discovery for enterprise Linux environments

Not saying that you fell for clickbait but this is going to be a quite opinionated piece that didn’t go anywhere next to the scrutiny a LWN article would have gone and merely represents a summary of my findings on this particular topic so far.

APC SmartUPS 750, apcupsd and power failure: what exactly happens, where “UPS Rbt off” and “UPS StayOff” come from and which delays are configurable and which are not

In theory, an Uninterruptable Power Supply (UPS)’s workings such as the APC SmartUPS 750 in connection with an attached PC are trivial: when power fails and battery capacity runs low, the PC is shut down. When power returns, the PC is turned on again. In reality, there can be confusing messages such as UPS Rbt… Continue reading APC SmartUPS 750, apcupsd and power failure: what exactly happens, where “UPS Rbt off” and “UPS StayOff” come from and which delays are configurable and which are not

Executing arbitrary commands in your libvirt/Qemu virtual machine through Qemu guest agent

Many of us are used to installing additional Virtualization software-specific tools in virtual machines in order to get seamless Copy & Paste, higher screen resolutions — think “VMWare tools” or the “VirtualBox guest extensions”. So does Qemu, the working horse behind most libvirt-powered virtual machines these days, with the “Qemu guest agent”. But did you… Continue reading Executing arbitrary commands in your libvirt/Qemu virtual machine through Qemu guest agent

Filtering with Ansible’s selectattr()/rejectattr() when the tested attribute can be absent

Ansible’s selectattr and rejectattr allow filtering of a list of dictionaries based on a specific test being executed against each dictionary’s keys and values. But what if the dictionary is not guaranteed to always have the key being tested actually defined?