标签：#UX

In 2008, Richard Thaler and Cass Sunstein needed an example simple enough to explain the whole of economic theory from a single application. They used a cafeteria menu. By moving the fruit to eye level and sending the fries to the periphery, they demonstrated that a slightly adjusted environment could convince thousands of students to make healthier choices. No one is stopped from choosing fries and the fries-loving student still chooses fries. But the undecided student chooses the apple, simply because it is now right in front of him. In 2017, Thaler was awarded the Nobel Prize in Economics for his body of work, including the development of “The Nudge Theory” with Sunstein. In the years that followed, product teams building mobile applications have taken to referring to any call-to-action on-screen as a nudge. The design of an effective nudge There are two requirements for a nudge to work reliably. The user should have an apparent desire for the thing they are being nudged toward, and the nudge should appear at the moment when this desire is at its peak. The first requirement ensures the user has a mental model of the target action, meaning they understand roughly what they are supposed to do. The second requirement serves to remove any extraneous context, ensuring the nudge does not fail due to poor timing. A checkout confirmation modal shown straight after launching the application will fail miserably as a nudge. The desire to checkout is non-existent at the launch moment, and the context of the action has little to do with the action itself. A tooltip shown after a specific number of unsuccessful attempts to checkout after viewing the cart, however, is a nudge. It has the desired behavior and the right timing. Why the difference shows up in the numbers In the example with Duolingo, the product team has effectively used the framing of an existing streak as a reference point for the next level of engagement. The players who saw streak-based progress notifications

In bioinformatics we are handling a lot of tabular data. Be it VCF files, tabular Blast output, or just creating a CSV or TSV samplesheet. Actually, one of my favorite tabular formats is by using SeqKit to convert Fasta or FastQ files to tabular format, as this allows to do various filtering operations by row , using standard unix tools if so wished. Scrolling through this type of data in the terminal can be messy to say the least though. Although CSVs can of course be imported into a spreadsheet software for viewing, it would be very powerful to be able to view them comfortably right from the terminal, isn't it? To take one example that fits within the code window of a blog post, let's take a selected set of columns from the CSV output from the Mykrobe tool. And to make it emulate another common problem with many csv formats, let's also use tr to convert the _ :s in the headers into real spaces (Mykrobe does not do this, but many other tools do): $ cat SOME_SAMPLE.csv | cut -d , -f 2,3,10,14,15,17,18 | tr '_' ' ' > selection.csv $ cat selection.csv "drug" , "susceptibility" , "kmer size" , "phylo group per covg" , "species per covg" , "phylo group depth" , "species depth" "Amikacin" , "S" , "21" , "99.672" , "98.428" , "372" , "347" "Capreomycin" , "S" , "21" , "99.672" , "98.428" , "372" , "347" "Ciprofloxacin" , "S" , "21" , "99.672" , "98.428" , "372" , "347" "Delamanid" , "S" , "21" , "99.672" , "98.428" , "372" , "347" "Ethambutol" , "S" , "21" , "99.672" , "98.428" , "372" , "347" "Ethionamide" , "S" , "21" , "99.672" , "98.428" , "372" , "347" "Isoniazid" , "R" , "21" , "99.672" , "98.428" , "372" , "347" "Kanamycin" , "S" , "21" , "99.672" , "98.428" , "372" , "347" "Levofloxacin" , "S" , "21" , "99.672" , "98.428" , "372" , "347" "Linezolid" , "S" , "21" , "99.672" , "98.428" , "372" , "347" "Moxifloxacin" , "S" , "21" , "99.672" , "98.428" , "372" , "347" "Ofloxacin" , "S" , "21" , "99.672" , "98.428" , "372" , "347" "Pyrazinamide" , "S" , "21" , "99.672"

Quick Note In my previous article, I mentioned that Linux Troubleshooting Flow for Beginners would be the final post in this series. While preparing it, I realized there were a few practical Linux skills every beginner should learn first. These topics will make the troubleshooting guide much easier to understand and follow. Before we wrap up the series, we'll cover: Package Management Finding Files & Text Viewing Files Efficiently File Compression Then we'll bring everything together in the final Linux Troubleshooting Flow for Beginners. Introduction Installing software on Linux is very different from Windows. On Windows, you usually download an .exe installer. On Linux, software is typically installed and managed using package managers . This is one of the most practical skills every Linux beginner should learn early. What is a Package? A package is a ready-to-install bundle that contains: The main program Required libraries Configuration files Documentation Examples: nginx , git , docker , curl , vim Think of a package as a ready-to-install software box. What is a Package Manager? A package manager is a tool that installs, updates, removes, and manages software packages. Instead of downloading software manually, you simply run a command. Example: sudo apt install git The package manager automatically: Downloads packages from trusted repositories Install required dependencies automatically Upgrade installed software Removes them cleanly Instead of manual downloading, you just run one command. Why Use a Package Manager? Without package managers, you would have to: Search for software manually Download files from websites Install dependencies yourself Update each application separately Package managers automate all of this. What is a Repository? Package managers download software from repositories. A repository is a trusted online collection of software packages maintained by your Linux distribution. Instead of downloading software from random websites, Linux install

Automation is the part of DevOps that actually earns the title. Day 6 was two of the most everyday automation tasks there are, and both had a trap sitting in plain sight. One Linux task, one AWS task. Schedule a recurring job with cron, and launch an EC2 instance from the AWS CLI. The tasks come from the KodeKloud Engineer platform if you want the same lab to work through. Cron: five fields, one rule that trips everyone Cron is the scheduler that has quietly run Linux automation for decades. You hand it a job and a schedule, and its daemon, crond, wakes up every minute to check whether anything is due. If that daemon is not running, nothing fires, so the first move is making sure it is installed and enabled. # Become root sudo su - # Install the cron daemon if it is missing yum install cronie -y # Enable it at boot, start it now, and confirm it is alive systemctl enable crond.service systemctl start crond.service systemctl status crond.service cronie is the package name on RHEL-family distros. enable makes the service survive a reboot, start brings it up right now, and status is how you confirm it is actually running instead of assuming it is. Now edit the crontab: # Edit the current user's crontab crontab -e # minute hour day-of-month month day-of-week command 0 2 * * * /path/to/script.sh # List what is currently scheduled crontab -l That line runs the script every day at 2am. The five fields, in order, are minute, hour, day of month, month, and day of week: minute: 0 to 59 hour: 0 to 23 day of month: 1 to 31 month: 1 to 12 day of week: 0 to 7, where both 0 and 7 mean Sunday Here is the rule that quietly breaks schedules. When you set both the day-of-month field and the day-of-week field to something other than a star, cron treats them as OR, not AND. So 0 0 13 * 5 does not mean midnight on Friday the 13th. It means midnight on every 13th of the month, and also every Friday, whichever lands first. If you actually want the AND, you restrict one field in cron and che

I built a daily Linux documentation site I created this site because I've noticed that Linux documentation is generally confusing. What is xybss? xybss is a simple site that publishes Linux documentation every day. No ads No tracking No JavaScript Just plain HTML docs I add at least one new command every day. Who is it for? Beginners learning Linux Anyone who needs a quick reference People who want simple, clean docs Current content Right now, the site covers basic commands like ls and rm. More commands are added daily. Check it out 👉 https://xybss.github.io Feedback is welcome

I missed the tiny "x" on a browser tab again today. Meant to close it, switched to it instead. Aiming a one-pixel pointer at an eleven-pixel checkbox is basically microsurgery, and somewhere along the way we all just accepted that. Here's the strange part: HCI research solved this twenty years ago. It just never shipped. The paper In 2005, Grossman and Balakrishnan published The Bubble Cursor at CHI. The whole idea fits in one sentence: Make the cursor's hit area a dynamic circle that always contains exactly one target. That turns out to be the same thing as always selecting the target nearest to the pointer. Picture the screen divided into Voronoi cells, one per clickable thing, and the cursor picking the owner of whatever cell it's currently in. The clever part is what it refuses to do. Naive "gravity" cursors snap to every link on the way to the one you actually want, and they get stuck. The bubble cursor grabs exactly one target by definition. The moment a second target becomes nearer, it switches. So it stays calm on link-dense pages, and the paper showed significant speedups in controlled experiments. Twenty years later our cursors are still naked, so I built it as a Chrome extension. It's called MagPoint . The core is about 30 lines A content script collects clickable elements ( a[href] , button , input , ARIA roles and so on) and, every frame, picks the one with the smallest point-to-rectangle distance: function pointToRect ( x : number , y : number , r : DOMRect ): number { const dx = Math . max ( r . left - x , 0 , x - r . right ); const dy = Math . max ( r . top - y , 0 , y - r . bottom ); return Math . hypot ( dx , dy ); } Clicks that land in the empty space near a captured element get re-routed to it. Past a max radius of 120px the magnet lets go, and empty-space clicks behave like the normal web. It also stands down while you type or select text, because getting yanked toward a link mid-sentence would be infuriating. The rule that kept me sane: the vis

In this episode, Alex Zenla (CTO/Co-founder, Edera) challenges the "laissez-faire" attitude toward modern infrastructure. She promotes "spite-driven development", building software to solve genuine technical pain points rather than passively accepting flawed abstractions, as a philosophy of improving the world of software. By Alex Zenla

This is the first article in a four-part series where I document how I turned a 10€/month VPS into a production-grade platform hosting my portfolio, a university group webapplication and a SaaS product, all isolated from each other with Kubernetes. In this part, we take a fresh Ubuntu server and lock it down properly before installing anything else. Why bother with hardening? The moment your VPS gets a public IP address, it starts receiving attacks. Not "might receive", it starts . Within minutes, automated bots will probe port 22, try root:root , admin:admin123 and thousands of other credential combinations. If you skip this step and jump straight to deploying your apps, you are building on sand. The good news: an hour of work is enough to eliminate the vast majority of these threats. Here is what we will set up: A non-root user with sudo privileges SSH key authentication, with passwords and root login disabled UFW as a simple, effective firewall Fail2ban to ban brute-force attackers automatically Automatic security updates What you need A fresh VPS running Ubuntu 24.04 LTS or newer. I use a Hostinger KVM 2 (2 vCPU, 8 GB RAM, 100 GB NVMe), but any provider works: Hetzner, DigitalOcean, OVH, Contabo. The root password or SSH key your provider gave you. A terminal on your local machine (macOS, Linux, or WSL on Windows). Throughout this tutorial, replace YOUR_SERVER_IP with your server's IP address and deploy with the username you want to use. Step 1: First login and system update Connect as root for the first and last time: ssh root@YOUR_SERVER_IP Update everything before touching anything else: apt update && apt upgrade -y apt autoremove -y If a kernel update was installed, reboot now: reboot Wait a minute, then reconnect. Step 2: Create a non-root user Working as root is like driving without a seatbelt: fine until it isn't. One mistyped rm -rf and the party is over. Create a dedicated user: adduser deploy Choose a strong password (you will still need it for sudo ,

It Started With a Simple Misunderstanding I was spelling something over a phone call. I said: "B" The other person heard: "D" So I repeated it. Still wrong. Then I remembered something I'd heard before: "B as in Bravo." Instantly... There was no confusion. That's When I Realized Some letters sound almost identical. Especially over: Phone calls Weak connections Noisy environments Different accents And repeating the same letter five times doesn't always help. Why I Built This Tool So I built something simple: 👉 https://allinonetools.net/phonetic-alphabet-converter/ A tool that instantly converts normal text into the NATO phonetic alphabet. For example: CHAT Becomes: Charlie Hotel Alpha Tango No signup. No setup. Just: Paste → Convert → Read What I Learned Before building this, I thought the phonetic alphabet was mostly for pilots or the military. Turns out it's useful for anyone who needs to spell things clearly. Like: Email addresses Usernames License keys Customer support Phone conversations The Small Problem It Solves Have you ever said: "M" And someone replied: "N?" Or: "P?" 😅 That's exactly the kind of confusion this avoids. Why It Works So Well Instead of similar-sounding letters... You use unique words. Like: A → Alpha B → Bravo C → Charlie D → Delta It's much harder to misunderstand. What Surprised Me I expected only developers or IT people to use it. But it also makes sense for: Customer support Call centers Students Remote workers Anyone spelling things over the phone What I Focused On I wanted the tool to be: Fast Simple Easy to copy Beginner-friendly Because if you're already on a call... You don't want extra steps. The Real Insight Good communication isn't always about saying more. Sometimes it's about making sure the first attempt is understood. Simple Rule I Follow Now If people keep repeating themselves... 👉 There's probably a simpler way to communicate. Final Thought The NATO phonetic alphabet has been around for decades. But after using it once... Yo

Installing Ubuntu Server 24.04 LTS in an offline mode (no LAN cable or WiFi connected) leaves you with an unmanaged network interface which requires manual configuration post-install. The interface enp4s0 is unmanaged by systemd-networkd and also the service itself is disabled. NOTE: This guide applies to Ubuntu server. On Ubuntu desktop you have the NetworkManager service installed and the steps would be different. To fix the problem follow the steps below: Create a Brand New Netplan Configuration File Look into /etc/netplan . You will probably see the dir is empty. This means the installer completely gave up on configuring the network and didn't create any profiles. Create a new file, e.g. vim /etc/netplan/01-netcfg.yaml . Paste the following configuration network : version : 2 renderer : networkd ethernets : enp4s0 : dhcp4 : true This makes the interface managed by networkd instead of the desktop NetworkManager. Fix permissions The new file needs to be readable only by root so fix it's permissions chmod 600 /etc/netplan/01-netcfg.yaml . Enable network service Enable the network service and make it start on boot: systemctl enable systemd-networkd systemctl start systemd-networkd Run netplan Finally, we need to tell Ubuntu to use our new configuration and activate the network netplan generate netplan apply Network should be up! ip a

When you delete files in your virtualbox VM in order to free up space on the host filesystem, this space is not automatically reclaimed. In order for the host system to see the changes you need to rewrite the free space with zeroes. Follow the below steps to perform this operation: Install zerofree package. It is needed to rewrite the free space with zeroes. Mount the filesystem as "readonly". This is needed for the tool to be able to perform it's task. If you're working with the "/", easiest way to mount it as readonly is to edit the kernel parameters. Edit /etc/default/grub . Find the GRUB_CMDLINE_LINUX_DEFAULT line. Add init=/bin/bash to it reboot Run zerofree -v /dev/sdX . This could run for some time, depending on the size of your disk. After it's done, run exec init to finish booting up. Shutdown the VM in order to be able to run the next command which requires a lock on the VDI volume. On the Windows host run VBoxManage.exe modifymedium "path\to\disk.vdi" --compact

I had just aced my mentor’s Docker exam, so of course I thought I understood containers. I had said all the right words: namespaces, cgroups, images, layers, PID 1, Kubernetes Pods. Then I typed my first serious command and Linux reminded me that knowing the nouns is not the same thing as building the thing. $ sudo unshare -p 1 test unshare: failed to execute 1: No such file or directory That was the opening scene. I had not even built anything yet. I had typed the flags wrong and accidentally asked unshare to execute a program called 1 . This was going to be less “implement Docker” and more “let the kernel correct my confidence, one error at a time.” v1: namespaces, or the first time PID 1 lied to me The first version was supposed to be easy: run a process in a new PID namespace and prove it sees itself as PID 1. So I ran the command the way I thought it worked: $ sudo unshare --pid bash # echo $$ 25184 That was not PID 1. That was just embarrassing. The rule I had missed is simple: PID namespaces apply to children. The process that calls unshare --pid does not magically become PID 1. You need to fork. The first child born into the new namespace becomes PID 1. So the working version was: $ sudo unshare --pid --fork bash # echo $$ 1 That one line changed the tone. I was inside a different process universe. The shell thought it was process 1. Signals felt different. Orphans came home to it. Then I ran ps , and got humbled again. # ps -o pid,ppid,comm PID PPID COMMAND 25310 25304 bash 25344 25310 ps That made no sense at first. I was PID 1, but ps was showing host-looking PIDs. The next reveal: ps does not ask the kernel some pure “what processes exist?” question. It reads files. If /proc still points at the host procfs, your tools will tell you the host story. So I remounted /proc from inside the namespace: # mount -t proc proc /proc # ps -o pid,ppid,comm PID PPID COMMAND 1 0 bash 7 1 ps That was when it clicked. The namespace did not become real to my eyes until /pr

I broke my own project on purpose, twice, before it worked. Here's the story. Round one: the debate club My first idea for this hackathon sounded great in my head. Six AI agents, each with a "role" — security, architecture, performance, whatever — and they'd debate each other across multiple rounds before agreeing on a final answer. Like a mini panel of experts arguing it out. I built it. I ran it against some vulnerable test code. It came back with 127 findings. I got excited for about four minutes. Then I actually read them. Maybe three were real. The other 124 were the agents politely agreeing with each other about problems that didn't exist, or restating the same bug five different ways because five different agents happened to notice it. Precision was somewhere around 2%. Worse than a single model working alone. That stung a little, not going to lie. I'd spent days on the debate logic. Round two: quieter, and better So I ripped it apart. No more debate rounds. No more six agents shouting over each other. I went down to four, gave each one exactly one job, and — this is the part that actually fixed things — made them depend on each other in order instead of all firing at once. One agent maps out the code first. Two others use that map to look at security and quality separately. A last one compares what they found, throws out duplicates, and — importantly — actually checks the line numbers against the real file instead of trusting the AI's word for it. Same test file. This time: real vulnerabilities, correctly flagged, nothing made up. Point it at clean code afterward and it correctly said nothing was wrong, which honestly felt like a bigger win than finding the bugs did. The annoying lesson I wanted this project to feel impressive. More agents, more debate, more "look how sophisticated this is." What actually worked was the boring answer: fewer agents, clear roles, one checking the other's work instead of everyone talking at once. I named the final version Synod

I like neofetch / fastfetch , but I wanted one with a genuinely empty dependency graph — nothing pulled from crates.io. So I built purefetch : a small system-info fetcher written entirely in Rust using only std plus raw Linux syscalls. Disclosure up front: purefetch was built largely with AI assistance (Claude Code). I directed the design, and every change was reviewed and tested — including running it on four architectures under QEMU — but most of the code is AI-generated. I'd rather be honest about that than pretend otherwise. _,met$$$$$gg. ooonea@unicorn ,g$$$$$$$$$$$$$$$P. ────────────── ,g$$P" """Y$$.". OS Debian GNU/Linux 13.5 (trixie) x86_64 ,$$P' `$$$. Host ThinkPad P53 (20QQS0JD01) ',$$P ,ggs. `$$b: Kernel 6.12.94+deb13-amd64 `d$$' ,$P"' . $$$ Uptime 6 days, 15 hours, 30 mins $$P d$' , $$P Packages 2477 (dpkg), 1 (flatpak) $$: $$. - ,d$$' Shell zsh 5.9 $$; Y$b._ _,d$P' Display 1920x1080 (eDP-1) Y$$. `.`"Y$$$$P"' DE GNOME 48.7 `$$b "-.__ WM Mutter (Wayland) `Y$$ Terminal kitty 0.41.1 `Y$$. CPU Intel(R) Core(TM) i7-9850H @ 4.60 GHz `$$b. GPU Quadro RTX 3000 `Y$$b. Memory 15.28 GiB / 62.61 GiB (24%) `"Y$b._ Swap 0 B / 8.00 GiB (0%) `""" Disk (/) 8.52 GiB / 489.57 GiB (2%) Locale en_US.UTF-8 Battery 76% (Not charging) Zero dependencies, really No libc crate, no sysinfo , no nix , no color crate — nothing from crates.io. Almost everything is just reading and parsing /proc and /sys . The result is a single ~484 KiB binary that builds offline. The only things std can't do are statfs (disk usage) and ioctl (terminal size / tty check). Instead of pulling in a binding crate, those are issued as raw Linux syscalls via core::arch::asm! : #[cfg(target_arch = "x86_64" )] unsafe fn syscall3 ( n : usize , a1 : usize , a2 : usize , a3 : usize ) -> isize { let ret : isize ; core :: arch :: asm! ( "syscall" , inlateout ( "rax" ) n as isize => ret , in ( "rdi" ) a1 , in ( "rsi" ) a2 , in ( "rdx" ) a3 , out ( "rcx" ) _ , out ( "r11" ) _ , options ( nostack ), ); ret } Four arch

Every meditation app I have tried wants something from me. Headspace wants me to maintain a streak. Calm wants me to listen to a Daily Jay. Insight Timer wants me to join a group. One after another, apps designed to reduce my stress started creating new forms of it. The Feature Trap Here is what happened to meditation apps between 2015 and 2026: 2015: "Just meditate 10 minutes a day." 2018: "Track your streak! You do not want to break it, do you?" 2021: "Compare your stats with friends. See who meditated more this week." 2024: "AI-generated personalized guided meditation based on your emotional state, delivered at the optimal time based on your circadian rhythm." Wait — was not the whole point to stop optimizing everything? Subtraction as a Feature I switched to OneZen last month. Here is what I noticed: No onboarding. Open the app. Breathe. Close the app. That is the entire user flow. No streaks. I missed three days last week and the app did not shame me. It did not even notice. It just opened to the same calm screen, waiting, as if three days was the same as three hours. No gamification. No XP points. No badges. No "you are in the top 14% of meditators this month." Because meditation is not a competition you can win. What Subtraction Feels Like The first week was uncomfortable. I kept checking if I had "done it right." There was nothing to check. No dashboard. No stats. Just me and my breath. By week two, something shifted. Meditation stopped being a task on my to-do list and started being... just breathing. I was not practicing to maintain a number. I was practicing because it felt good. This is what minimalism actually means. Not fewer pixels. Less cognitive load. Less obligation disguised as features. The Bigger Idea OneZen's philosophy applies far beyond meditation apps: The best productivity tool is the one with the fewest notifications. The best social network is the one that respects when you leave. The best habit tracker does not exist — because the ha

A gente sempre ouve falar que o sistema operacional impede que um processo veja a memória do outro ou que o programa fale diretamente com o hardware, mas normalmente não explicam o "como". Eu sempre achei isso meio mágico até que eu resolvi ir atrás da resposta, e é bem interessante. Vou me basear na arquitetura x86, mas é provável que outras arquiteturas sejam parecidas. O problema: a CPU Pra CPU não existe processo, kernel, sistema operacional. Existe só endereços de memória de onde ela lê a próxima instrução e executa. Se a CPU pode falar direto com a RAM, SSD, teclado, mouse, tela... O que me impede de escrever um programa pra ler suas senhas e tokens direto da RAM? Ou de ler arquivos e alterar arquivos sensíveis direto no SSD? Por outro lado, se o kernel fiscalizasse cada instrução que da CPU antes dela executar, isso seria extremamente lento... Outro problema: os interrupts Se a CPU só executasse sequencialmente, seu sistema poderia executar várias coisas e esquecer de checar se uma tecla foi apertada, se o mouse mexeu, etc... Então certos eventos interrompem o que quer que a CPU esteja fazendo para serem tratados assim que possível. Alguns exemplos de interrupt são: Teclas do teclado pressionadas ou soltas Botões e movimento do mouse Timers Operações de disco assíncronas Pacotes de rede recebidos/transmitidos Uma solução: rings Os processadores da arquitetura x86 tem o esquema de rings. Pense em rings como grau de limitação. Ring 0 significa limitação zero, ou seja, acesso a todas as instruções da CPU e consequentemente acesso total ao hardware e memória. O kernel roda em ring 0, ou kernel mode. O kernel assim que é carregado configura todos os interrupts handlers da CPU para executar o handler apropriado do kernel, em kernel mode, claro. Em ring 3 a CPU fica limitada e não pode fazer instruções consideradas privilegiadas. E obviamente em ring 3 a CPU não consegue se colocar em ring 0 sozinha, pois dessa forma qualquer programa conseguiria se pôr em ring 0. O

Seven days of flow. Fixed a peer identity binding issue in py-libp2p, automated my Neovim lockfile merges, and added a massive batch of notes on xv6 and Category Theory. 10 commits and a solid PR in the works. TL;DR I managed to hit a perfect seven-day streak this week, balancing some deep-dive p2p networking work with necessary maintenance on my local environment. The highlight was opening a PR in py-libp2p to tighten up how PeerRecords are handled in the Kademlia DHT. On the side, I spent time automating the annoying parts of my Neovim config and dumping a fresh batch of notes into my knowledge base. 10 commits, 204 lines added, and a much cleaner workflow to show for it. What I Built Neovim Configuration & CI I’m a firm believer that your editor should work for you, not the other way around. My nvim repo saw a lot of action this week—9 commits in total—but most of it was under-the-hood maintenance. I’ve been leaning on Lua to keep things snappy, and this week was about ensuring my plugin ecosystem doesn't rot. I pushed several updates to keep plugins at their latest versions, but the real "quality of life" improvement was adding a chore to auto-resolve lazy-lock.json merge conflicts. If you’ve ever worked on your Neovim config across multiple machines, you know the headache of the lockfile drifting. I set up a flow to prioritize incoming changes, which saves me from manually triaging JSON diffs every time I pull from dev . It’s a small tweak, but it removes a recurring friction point in my daily flow. I also spent time cleaning up the root of the config, with about 37 additions and 33 deletions—refactoring is a constant process when you live in your terminal. The Knowledge Base I also put some serious time into main-notes . I’m currently going deep on a few different subjects, and I use this repo as my "second brain." I added 167 lines of new material across 13 files, covering a pretty diverse range of topics: xv6 (the re-implementation of Unix V6), Category Theo

I once spent forty minutes at eleven at night debugging a deploy that wasn't broken. The release script ran the database migration, the migration threw connection refused , the script exited non-zero, the deploy rolled itself back, and I got paged. So I did the things you do. I read the migration. I read the logs. I checked the database — it was up, it was healthy, it accepted my connection instantly. I re-ran the deploy and it worked. I chalked it up to gremlins and went to bed, which is the part I'm not proud of, because it happened again two days later. That time I watched the timing: the script brought up a fresh database container and started the migration about six seconds before Postgres finished initializing and began accepting connections. The migration was racing the database's boot. Most of the time it won. The times it lost, I lost forty minutes. The script wasn't wrong about anything except one assumption: that a dependency is ready the instant you ask for it. In production, dependencies are eventually ready That's the mental model shift. Networks blip. A service you call returns a 503 for the two seconds it takes to finish a rolling restart. An API rate-limits you with a 429 it fully expects you to retry. A fresh container's database isn't accepting connections for its first few seconds. Treating the first failure as fatal turns every one of these normal, transient conditions into a paged engineer — and the script that handles them isn't smarter — it declines to give up on the first try. But retrying naively is its own trap. Retry instantly and you hammer a recovering service into staying down. Retry forever and a genuinely dead dependency hangs your script indefinitely. Retry a 404 and you wait a minute to confirm what you already knew. Good retries are bounded, backed off, and selective. A retry function you can reuse anywhere #!/bin/bash # Purpose: survive transient failures instead of dying on the first error set -euo pipefail CHECK = "✓" CROSS = "

I'm curious... What's the one feature that instantly makes you stop using a resume builder? For me, it was simple: You spend time creating your resume, everything looks great, and then the site asks you to pay just to download it. That experience inspired me to build Resumship, a resume builder where downloading your resume is completely free. Now I'm thinking about the next features to add, and I'd love to hear from the community. If you were building the ideal resume builder, what features would you include? AI-powered resume suggestions? Better ATS optimization? More templates? Portfolio integration? Cover letter generation? Something completely different? If you have a minute, I'd also love for you to try Resumship and share your honest feedback. 🌐 https://resumship.com Your feedback will directly influence what gets built next. Every suggestion, bug report, or feature request helps make the platform better for everyone. Looking forward to hearing your ideas! 🚀

I connected one client to a blocking TCP server and held the socket open without sending a single byte. Then I connected a second client and sent it a line of text. The second client sat there for 1.51 seconds with no reply. It got its echo back one millisecond after I closed the first connection. That 1.51 seconds is the reason the other six versions of this server exist. Last week I wrote up why I rebuilt this server seven times : framework knowledge resets every few years, the layer underneath it compounds. That piece stayed at the level of outcomes. This one goes the other way, down into the code and the numbers. The claims that matter here are the kind you can read a hundred times without being able to derive them. "select is O(n)." "epoll only hands you the ready fds." I had read both for years. I wanted to make my own machine say them out loud. The target the whole exercise is built around is Dan Kegel's old C10K problem : how do you serve ten thousand clients at once on one server? Each of the seven versions hits a wall, and the wall is what names the next one. The whole thing is one echo server written seven times, no libraries beyond libc, on GitHub . Every number below is from running it on macOS (Apple clang 21, darwin 25.4) on 2026-06-29. The binaries are built with AddressSanitizer and UBSan on, so read the absolute microseconds loosely. The structure is what holds. Phase 01: blocking, and the 1.5 second stall The first server is the one everybody writes first. Accept a connection, talk to it, close it, accept the next. for (;;) { int client_fd = accept ( server_fd , NULL , NULL ); if ( client_fd == - 1 ) { perror ( "accept" ); continue ; } handle_client ( client_fd ); close ( client_fd ); } handle_client loops on read until the client hangs up. Both accept and read block: when there is nothing to do, the thread sleeps in the kernel. That is good for idle cost and fatal for everything else. While the server is parked in read waiting on client A, client