Tightening a dev VM that was quietly living without a firewall
What a routine security audit found on a small always-on dev VM: passwordless databases, no host firewall, over-privileged jobs, and how it got fixed.
Tag: linux
Production Ruby Debugging: A Progressive Escalation Guide
A progressive escalation guide to debugging Ruby applications in Kubernetes production without restarting: rbspy, kubectl debug, signals, rbtrace, and gdb.
Incus vs. Docker: System Containers vs. App Containers
A practical comparison of Incus and Docker: when system containers suit development environments better than single-process application containers.
Fixing the Asia/Rangoon Postgres Error on Alpine Linux
If you recently updated your Docker images and were greeted by a PG::InvalidParameterValue: ERROR: time zone "Asia/Rangoon" not recognized, you aren't alone.
Sending Email from an Ubuntu VM on Oracle Cloud (OCI)
A Postfix and OCI Email Delivery setup guide covering SMTP auth, sender approval, SPF/DKIM/DMARC, and the errors that block delivery.
Optimizing a 1C1G Ubuntu Cloud Server
A production-tested checklist for making a 1 vCPU, 1GB RAM Ubuntu server stable: swap, kernel tuning, service removal, and MySQL/PHP-FPM limits.
PostgreSQL on Ubuntu: install, user setup, and auth debugging
Install PostgreSQL from the PGDG repo on Ubuntu, set up a matching development role, and debug the password authentication failures Rails hits most.
OpenSSH on WSL: enabling remote SSH access on Windows 10
Install and configure OpenSSH inside WSL2, enable systemd, and forward a Windows port so you can SSH into your WSL environment from anywhere on your LAN.
Nokogiri vs libxml2: Debugging a Dynamic Library Conflict
Why Nokogiri XPath queries failed in Docker but not on an M1 Mac: a libxml2 version mismatch caused by indirect dynamic library loading in Ruby.
Zsh Command-Line Editing: Shortcuts Worth Learning
A practical rundown of Zsh command-line editing: ZLE widgets, history reuse, globbing, and the handful of plugins that actually save keystrokes.
Linux kill signals: graceful shutdown in containerized workers
SIGTERM, SIGKILL, and grace periods control whether a containerized worker finishes its job before Kubernetes or Supervisord kills it outright.
Kubectl aliases and functions that actually save time
A set of kubectl aliases and shell functions for pod access, JSONPath queries, and log searching that cut real typing out of day-to-day Kubernetes work.
List of tools
A saved reference link to fmwconcepts.com's ImageMagick script for removing watermarks from images, kept here as a personal bookmark.
k3s on Ubuntu: Install, kubectl Access, and Unauthorized Errors
How to install k3s on Ubuntu, connect with kubectl, and fix the 'You must be logged in to the server (Unauthorized)' error caused by kubeconfig or expired certs.
Container Security with Fine-Grained Permission Control
How Linux file permissions and Kubernetes securityContext settings enforce least-privilege access for containerized workloads, with a worked example.
Supervisord: Process Management for Containers and VMs
How supervisord monitors and restarts UNIX processes through simple INI-style config, with a working example for MySQL, PHP, and an init script.
When the OOM Killer Silently Kills a Background Job
A missed notification email traced back to the Linux OOM killer terminating a Sidekiq job mid-run, leaving a stuck Redis lock and no error logged anywhere.
rsync技巧：高效实现主机间文件同步
rsync是一款强大的文件同步工具，能够在本地及远程主机间高效复制或同步文件和目录。本文将介绍rsync的基本使用方法，包括从本地复制到远程Ubuntu主机，以及反向操作，并探讨如何配置rsync服务和保持Linux服务器间的文件同步。
rsync：系统管理员的备份利器
系统管理员的日常工作重点在于维护系统稳定运行并提供服务，其中数据备份尤为关键。尽管许多管理员对服务器安全性关注不足，但对备份技术却兴趣浓厚。鉴于商业产品成本高昂，自由软件如rsync成为理想选择。本文将详细介绍rsync的特性、使用方法及实用脚本。
Linux下实现路由功能
Linux 下的路由配置：静态路由与动态路由的区别，以及用 route 命令管理内核路由表的选项、示例和输出字段说明。
UNICON安装及中文支持指南
在 Linux 控制台显示 CJK（中文、日文、韩文）字符：UNICON 的内核补丁、编译配置，以及在 RedHat 和 Gentoo 上的完整安装步骤。