Linux
Adventures with ArtixArtix is a low-resource Linux that can be configured to run well on old, low-powered computer hardware. In this article, I describe my first attempts at setting it up.
Categories: general computing, Linux
Extending the bash 'cd' command in LinuxThe built-in cd command in the bash shell is not as smart as it could be; but it's a little fiddly to extend its functionality.
Categories: Linux
Command-line hacking: countdown timerUsing Linux date calculations to displaying a running countdown time in the terminal.
Categories: Linux, command-line hacking
Command-line hacking: Assigning folder icons to directoriesHow to use basic Bash constructs, along with the Gnome gio utility, to assign folder icons to a set of directories.
Categories: Linux, command-line hacking
Command-line hacking: calculating the phase of the MoonHow to use Bash shell arithmetic, along with the 'date' utilty, to calculate the phase of the Moon on a particlar day.
Categories: Linux, command-line hacking
Command-line hacking: displaying news headlines in the manual viewerHow to use tools like curl and xsltproc to retrieve news headlines from the BBC, and display them using the manual viewer
Categories: Linux, command-line hacking
Command-line hacking: paced breathingUsing a Linux Bash script to generate audio/visual cues for timing paced breathing exercises.
Categories: Linux, command-line hacking
Command-line hacking: querying an Internet radio databaseUsing Linux command-line utilities to query an on-line database of Internet radio stations.
Categories: Linux, command-line hacking
Command-line hacking: extracting audio metadata (tags)How to use Bash shell techniques to extract metadata (tags) from various audio file formats.
Categories: Linux, command-line hacking
Command-line hacking: displaying system temperatureUsing simple file and string handling techniques in the Bash shell.
Categories: Linux, command-line hacking
Command-line hacking: creating a tide tableHow to use Bash shell arithmetic to create a simple tide table
Categories: Linux, command-line hacking
Command-line hacking: displaying a weather summaryHow to use tools like curl, sed, and groff to retrieve a weather forecast from the BBC, and format it for the terminal.
Categories: Linux, command-line hacking
Command-line hacking: timezone conversionsUsing 'date' and 'timedatectl' to build a utility to help with scheduling meetings in different timezones.
Categories: Linux, command-line hacking
Why the Linux console is so awesomeWe've all gotten so used to graphical desktops that we're losing sight of how much can be accomplished on Linux using only a console. This is a shame, because efficient console-only operation is possible on a computer that would otherwise be fit only for landfill, and on modern high-efficiency devices with limited computing power.
Categories: Linux
Using media keys in a Linux console applicationMapping keyboard keys to key codes on Linux is well-documented for the graphical desktop. But what about console applications on embedded Linux systems? There's not much documentation in this area.
Categories: Linux, C, embedded computing
Container from scratch: building a Linux container from the ground upContainers have become increasingly important for Linux developers and administrators. A number of frameworks like LXC, Docker, and Podman are now available to automate the management of containers. However, all these frameworks rely on similar kernel features, particularly control groups, namespaces, and virtual networks. This article demonstrates how to build a functional container from first principles, using only simple command-line tools. It's objective is to make clear all the details that the more sophisticated tools conceal.
Categories: Linux, containers
Why you can't rely on system calls to obtain limits, when running an application in a containerThe notion of resource limits (on memory, CPU, etc) has never been very well-defined, and the use of container-based deployment makes the situation worse. This article describes why, and what can be done about it.
Categories: Linux, containers
Yet another Darktable/Lightroom comparisonDarktable isn't supposed to be an alternative to Adobe Lightroom, but many people hope to use it as one. After all, Darktable's (free) pricing is very appealing. Here are my views on whether a move to Darktable makes sense.
Categories: general computing, Linux
You be the linker -- building Hello, world from scratch, in hexadecimalThis article describes how to write a trivial program for Linux using no compiler tools at all, but entering machine language directly in hexadecimal. Because we can.
Categories: software development, Linux
Making a Java JAR file self-executing (on Linux)A quick-and-dirty way to make it possible to execute Java JAR files at the prompt, without needing to invoke the JVM.
Categories: software development, Java, Linux
Using the FreeType library to render text nicely onto a Linux framebufferWriting graphical applications for minimal and embedded Linux systems can present a challenge. One of the problems is producing nicely-rendered text without the facilities that a graphical desktop would provide. This article describes how to use the FreeType library to render text to the Linux framebuffer.
Categories: software development, C, Linux, embedded computing, Raspberry Pi
Are Flatpak, et al., saving or drowning the Linux desktop?Desktop Linux will take off next year -- or so people have been saying for years. Do desktop containerization technologies like Flatpak make this more, or less, likely?
Categories: Linux, containers
Extracting software from the Raspbian repository, for assembling a custom Linux image for the Raspberry PiUsing the official Raspian repository to assist the construction of a custom Linux for embedded applications is quick and convenient, compared to building everything from source. However, this approach has certain hazards.
Categories: Linux, Raspberry Pi, embedded computing
Using ImageMagick to generate anti-aliased bitmap fonts for a microcontroller's LCD displayThis article describes how to generate and use compressed, anti-aliased font data, for use in a microcontroller application.
Categories: C, Linux, embedded computing, Pico
Creating an animated score for demonstrating musical compositions on YouTube, etcAnimated musical scores are quite common on YouTube, for educational and promotional purposes. This article explains how to create one, using OpenShot and other Linux tools.
Conway's Game of Life in 3D perspectiveImplementing a program to run Conway's cell population simulation, using a 3D perspective view on the Linux framebuffer.
Categories: software development, C, Linux
How Linux home directory encryption worksEncryption of home directories is out of favour in modern Linux distributions, but it offers some compelling advantages over the alternatives, if used with care.
Categories: Linux
A Linux storage management cheat-sheetThis article outlines, with step-by-step examples, how to carry out the most fundamental Linux storage management tasks: partitioning a disk, creating a filesystem, setting up swap space, managing a logical volume management (LVM) storage pool, and configuring a RAID mirror.
Categories: Linux
Using the Linux framebuffer in C/C++ -- just the essentialsThe absolute minimum information needed to start using the Linux framebuffer as a graphical display in C/C++ applications.
Categories: software development, C, Linux, embedded computing
Using the Linux framebuffer in C/C++ -- just the essentials (part 2)This article continues my original framebuffer just the essentials article, by describing how to handle less straightforward framebuffer configurations.
Categories: software development, C, Linux, embedded computing
More like Windows every dayThe ease of installation and use of modern desktop Linux distributions comes at a price. I review a couple of low-complexity alternatives to mainstream Linux distributions: Alpine and Devuan.
Categories: general computing, Linux
Making a Raspberry Pi bootable SD card from a root filesystemYou've created a custom Linux installation for the Raspberry Pi. How do you turn that into a bootable SD card image that can be distributed?
Categories: Linux, Raspberry Pi
Converting push-button events to keyboard events in the Raspberry PiThe Raspberry Pi has a bunch of GPIO pins we can use to connect push-buttons. But how do we interface push-buttons to an application that expects only keyboard input?
Categories: Raspberry Pi, electronics, Linux
Rolling your own minimal embedded Linux for the Raspberry Pi -- part four: audioThis article is part of a series on building a customer Linux installation for a Raspberry Pi-based appliance. It explains how to install and set up the minimum software to get audio playback working.
Categories: Raspberry Pi, Linux, embedded computing
Rolling your own minimal embedded Linux for the Raspberry Pi -- part one: booting to a root shellThis article is part of a series on building a custom Linux installation for a Raspberry Pi-based appliance. It explains how to make a bootable SD card with Pi firmware, a Linux kernel, and a shell. It's about as minimal as a Linux system can be.
Categories: Raspberry Pi, Linux, embedded computing
Rolling your own minimal embedded Linux for the Raspberry Pi -- part two: early initializationThis article is part of a series on building a customer Linux installation for a Raspberry Pi-based appliance. It explains how to obtain and install fundamental utilities for use in a system with a read-only filesystem, and no package manager.
Categories: Raspberry Pi, Linux, embedded computing
Rolling your own minimal embedded Linux for the Raspberry PiIntroducing a series of articles on building a custom Linux installation for the Raspberry Pi, for appliance applications.
Categories: Raspberry Pi, Linux, embedded computing
Rolling your own minimal embedded Linux for the Raspberry Pi -- part three: services and remote accessThis article is part of a series on building a customer Linux installation for a Raspberry Pi-based appliance. It explains how to set up a system which hitherto only boots to a root shell, to a network-aware installation with service management.
Categories: Raspberry Pi, Linux, embedded computing
Rolling your own minimal embedded Linux for the Raspberry Pi -- part five: XIt's entirely possible to run simple, X-based applications in an appliance-based Linux installation: you just have to dispense with the graphical desktop and all its baggage. This article explains how.
Categories: Raspberry Pi, Linux, embedded computing
Using flash memory as non-volatile storage on the Pi Pico microcontrollerThe Pi Pico is an impressive microcontroller for its size and cost, but it lacks specific non-volatile memory. This article explains how to use the program flash ROM for that purpose.
Categories: software development, C, Linux, embedded computing, Pico
C-to-parallel ICMake an auxiliary LCD display for a computer that displays data sent to it over a USB connection. Ready-made devices of this sort are widely available, but it's more fun to build your own.
Categories: software development, C, Linux, embedded computing, Arduino
Sorting files and directories on a FAT-formatted USB memory stickMany portable and automotive media players accept USB memory sticks or SD cards containing audio files. Very often, these players have no sorting logic, and display files and directories in the arbitrary order they appear in the filesystem. This article describes how to sort a FAT filesystem using Linux utilities, to make playback more convenient.
Making simple stop-motion animations using Linux and a DSLR cameraCreating stop-motion animated movies using a DSLR camera and some basic Linux tools. It won't rival Pixar, but it's something to do with your kids on a rainy Sunday afternoon.
Categories: science and technology, Linux