Linux

A Migration Guide from Powerlevel10k to Starship (2025 Edition) Introduction I migrated from Powerlevel10k, which I had used for years, to Starship. In this article I summarize the differences between the two, recent developments, the migration procedure, and how to customize it. Powerlevel10k vs Starship Powerlevel10k Features: A prompt theme for Zsh only Extremely fast startup time (under 10ms) Beginner-friendly setup through a configuration wizard (p10k configure) More than 10 built-in themes Advanced customization is possible Drawbacks: [Read More]

To begin with, I decided to look at the logs from just before the previous boot, so that I could tell whether this was really a reboot coming from the OS or a problem around the hardware power supply. On AlmaLinux (RHEL based), running journalctl -b -1 shows the logs of the one previous boot all together, so I used that command as a starting point and went over the kernel messages and the systemd logs. [Read More]

After editing a shell configuration file (.bashrc, .zshrc and so on) on Linux or macOS, how should you apply the changes? Many people probably think of logging out once and logging back in, but in fact there are quite a few more efficient ways. This article explains the various commands for reloading a shell configuration, what characterises each of them, and how to choose between them. 1. The source command - the most basic method The source command is the most common way to run a shell script or a configuration file in the current shell environment. With this command you can load the contents of the specified file into the current shell session without starting a new shell. [Read More]

Until a few years ago I had sync configured across several PCs with Dropgox, but a change for the worse in Dropbox put a limit on the number of devices, so these days I use Resilio Sync to keep my PCs in sync. Lately I have been using node-based tools such as React and Git frequently, and if I keep those working directories inside a Resilio Sync folder, an enormous number of files get synced. In particular, I do not want the contents of node_modules produced by node builds, or the git management folder, to be synced, so - late in the day though it is - I began to wonder whether Resilio Sync has an exclusion setting. [Read More]

In Linux environments I often have occasion to add an HDD after the fact, so I am writing it down again. (About ten years ago I posted a similar article (adding an HDD with fdisk from the command line (in Japanese))) Environment The Linux used is Debian 12 The format is xfs The HDD to be added is 4TB I assume Linux (Debian) is already running and the HDD to be added is already installed [Read More]

Homebrew has become pretty much the standard on macOS, but these days you can install Homebrew on Linux too. On Debian and RedHat you can manage packages with apt or dnf (yum), but Homebrew makes it easier to install and update programs that are not in those packages and are not published as a repository. For example, tools I use often such as Hugo, Docker’s docker-compose, and lazydocker have to be downloaded from the official site and swapped out every time there is an update, but this can now be simplified to something like brew update hugo, just as on macOS. [Read More]

I wanted to install Debian on a PowerEdge R410 that I no longer used, so I created a bootable USB disk, but even after setting USB as the highest boot priority in the BIOS it would not boot from the USB, and I spent several hours on it. When I looked for a solution on the internet, the article below was a perfect match The boot solution On the startup screen (while the Dell logo is showing), press F2 to open the BIOS setup screen. In the BIOS settings, change USB Flash Drive Emulation Type from AUTO to Hard Disk. Save the settings and leave the BIOS setup screen (it reboots) On the startup screen (while the Dell logo is showing), press F11 to open the boot media selection. In the boot media selection, the USB flash media appears under the “Hard Disk” entry, so choose to boot from the USB flash media. The installer boots from the USB without trouble. The network is unusable The NIC is recognized, but it cannot connect to the network [Read More]

The root partition (/) of the machine I run Docker on was getting tight, so I moved /var/lib/docker These days, when you install Linux without thinking about it, the automatic configuration often gives the root partition (/) something small such as 30GB. When you run Docker, /var/lib/docker grows and grows, so / ended up in a state close to full. So I moved it to /home, which is on a separate partition and has room to spare [Read More]

After logging in to a certain Linux (Debian) machine, I ran into a symptom where I could not create files or directories. Copy $ mkdir test mkdir: ディレクトリ `test' を作成できません: 許可がありません $ touch test touch: 'test' に touch できません: 許可がありません I tried various things Logging in works normally Checked the UID and GID with the id command Checked the attributes of the home directory and its contents Tried changing the shell None of them showed a problem, and when I looked at the error log, there was an error like the one below [Read More]