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Perform Manual dnf history undo

8 minutes to read

My choices of GNU/Linux distributions are Fedora for desktop computers and CentOS for servers. Both of them feature DNF - Red Hat’s package manager front-end for RPM, which is the primary reason I use these distributions. Although one might argue that it is slow, DNF is very clear on not only what it will do for an action but also what it has done: it maintains a history of package installation and removal operations, which are called “transactions”. You can undo a transaction with dnf history undo or roll back to a previous state with dnf history rollback. Other common package managers, like APT and Pacman, also save operation logs, but they generally do not offer a similar operation reverting functionality. …

Install Raspberry Pi’s vcgencmd on Fedora

Updated: 5 minutes to read

This post is a continuation of my previous one about setting up a cluster of Raspberry Pis running Fedora. After I got the cluster to compute something, @ColsonXu, the cluster’s owner, asked me if I could monitor the CPU temperature of each Raspberry Pi by running this command: $ /opt/vc/bin/vcgencmd measure_temp The vcgencmd program is included in Raspberry Pi OS (formerly called Raspbian) as a utility for retrieving information about Raspberry Pi’s hardware. However, it is not included in Fedora’s software repositories. Luckily though, the source code of vcgencmd, along with the entire userland package that contains the program, is available, so we can compile it on our own. …

Set Up Fedora on a Raspberry Pi Cluster

14 minutes to read

First and foremost, I would like to thank @ColsonXu for giving me this opportunity to play with some Raspberry Pis. He had got a few Raspberry Pi 4’s and built a cluster with them for computing purposes, but there was nothing to compute until the morning when @mrdarcychen found an article about running Rosetta@home on Raspberry Pi from Fedora Magazine, and Colson approved the plan. I was able to take the job of installing software required to run Rosetta@home on the Raspberry Pis. …

Use grep as a Substitute for cat

4 minutes to read

I came across a fascinating and educative article, Unix Recovery Legend, when someone posted a link to it on Reddit. The article presents a story of the writer, Mario Wolczko, and some other colleagues attempting to recover a system partially destructed by rm -rf /. The rm command was interrupted before it scraped off directories like /usr, but it was too late to save /bin, /dev and /etc, which were respectively the directory for basic executable programs, device files, and system configuration files. Commands like ls and ps were now on strike since their executables were in /bin, the backup tape could not be mounted because the tape deck’s device entries were gone with /dev, and absence of network configuration files in /etc denied any possibility to rescue the system through the network. …

Use Cygwin’s Shell or Git Bash in Windows Terminal

5 minutes to read

Recently, Microsoft has made the first stable release of Windows Terminal, a new terminal program for Windows 10. Windows Terminal allows you to add and use multiple shells, like Windows PowerShell, the old command prompt, and any shell in your Windows Subsystem for Linux (WSL) environments. It also provides way more features and customization options than the old Windows console host conhost.exe, which has been used for command prompt and WSL. …

Share GTA V Game Files Between Steam and Epic Games

Updated: 5 minutes to read

After Epic Games announced that it would give away free copies of GTA V for a week, many people started to claim this gift on that game platform. Even some existing GTA V players who have already purchased the game on Steam had decided to get another free copy so they could have two or more GTA Online accounts. It appears that if you have already installed GTA V via Steam, you still need to download a full copy of the game files via Epic Games. However, by doing some tricks, you can let Steam and Epic Games share the same set of GTA V game files to avoid downloading the game again and thus save disk space. We will use the MKLINK command on Windows, which is not well-known, to create a link to the existing game files. The link works as if the linked files and folders are exactly there, but it occupies very little space. …

Restarting This Personal Site

4 minutes to read

I have been planning to repurpose my personal website on GitHub Pages as a blog for jotting down how I play around with different technologies. When I try something new, I usually spend some time reading tutorials, help articles, and blog posts about it. But of course, my reading is not limited to a single resource; instead, I often combine knowledge and steps across multiple resources and produce something not described by any single existing webpage. It would be very helpful if I write an article describing everything I’ve done, so just in case the same task needs to be performed again, the resources I would need could reduce from several different webpages to a single article, which is great. …