Learn step-by-step how to set up a private Certificate Authority on Linux using OpenSSL, covering CA and PKI basics, directory structure, configuration files, generating root and client certificates, managing revocation lists, and essential commands for secure certificate management.
WebVM is a serverless, client‑side virtual environment that runs an unmodified Debian Linux distribution in the browser via WebAssembly, offering a complete Linux toolchain, graphical interface, network support, AI assistant integration, and flexible deployment options.
This guide explains how to use the official 1panel‑migrator to upgrade a Linux server from 1Panel V1 to V2, covering prerequisites, installation of the migration binary, step‑by‑step service and website upgrades, important precautions, and post‑upgrade verification with example commands and logs.
This article explores the role of the Memory Management Unit (MMU) in Linux, detailing how it translates virtual addresses to physical memory, enforces protection, utilizes page tables, TLB caching, multi‑level paging, and supports process isolation and efficient memory allocation, illustrating concepts with diagrams and code examples.
This article walks through troubleshooting a failed deployment caused by a full disk, showing how to use df -h to check overall disk usage and various du options (including --max-depth and -sh) to pinpoint large directories and resolve the issue.
This tutorial walks through installing Samba on CentOS 7, creating system and Samba users, setting up a shared directory, configuring smb.conf, starting services, and then configuring a client to connect, mount, and auto‑mount the share using CIFS, providing a complete end‑to‑end solution.
This guide explains Linux’s UGO permission model, the meaning of read/write/execute bits for files and directories, and demonstrates how to manage permissions using chmod, chown, chgrp, as well as advanced ACL techniques including mask and default settings.
This article introduces Ubuntu’s Uncomplicated Firewall (UFW), explaining how to enable, disable, reset, set default policies, and create, modify, or delete specific IP, port, and protocol rules using concise command-line examples, helping users quickly secure client machines with practical firewall configurations.
This article explains the Linux kernel's CPU load‑balancing mechanism, covering concepts such as CPU load, balancing strategies, scheduling domains, groups, the PELT algorithm, CFS scheduling, trigger points, and practical code examples for both regular and real‑time tasks.
Learn how to create, configure, and manage a software RAID 5 array on CentOS 7 using mdadm, covering partition preparation, RAID creation, filesystem formatting, mounting, status checks, hot‑spare handling, device removal, and expansion, with complete command examples and expected outputs.
This comprehensive guide walks you through Nginx performance tuning, covering worker processes, CPU affinity, file descriptor limits, event models, gzip compression, fastcgi caching, expires headers, anti‑hotlinking, kernel tweaks, and system limits to dramatically improve web server efficiency.
Linux kernel I/O mechanisms, from basic file operations and descriptors to advanced models like blocking, non‑blocking, multiplexed, signal‑driven, and asynchronous I/O, are explained in depth, covering their structures, system calls, caching strategies, and performance optimizations such as io_uring.
Learn step‑by‑step how to create a dedicated Linux SFTP user with chroot confinement, configure group permissions, set up a secure upload directory, adjust SSH settings, and restart the service to ensure the account can only upload files without shell access, following the principle of least privilege.
This article explains the role of the interrupt system in ARM‑based Linux platforms, covering hardware modes, vector tables, exception handling, GIC architecture, and kernel integration, and provides detailed code examples and optimization techniques for developers working on embedded and high‑performance systems.
This step‑by‑step guide shows how to download, compile, and configure Nginx so that the version information is hidden and a custom Server header (e.g., "Please guess it!") is displayed, including code modifications, build commands, and verification.
Learn step‑by‑step how to troubleshoot MySQL master‑slave replication problems, from verifying component roles and executing the correct SHOW SLAVE STATUS command inside the MySQL client, to fixing missing command errors, checking IO/SQL threads, and restarting replication in Docker‑based environments.
This article explains what Podman is, highlights its daemon‑less and rootless architecture compared to Docker, lists essential commands, shows installation and configuration steps, and provides practical tips for using Podman in Linux environments.
This article explains the practical limits on how many TCP connections a Linux server or client can support, covering file‑descriptor parameters, memory consumption per socket, kernel tuning examples, and scaling calculations for large‑scale long‑connection services.
This article explains what Podman is, compares its daemon‑less, rootless architecture to Docker's daemon‑based model, and provides step‑by‑step installation, configuration, and command‑line examples for managing containers, images, volumes, and networking on Linux.
This guide explains the LVM snapshot mechanism, demonstrates how to create snapshots, restore individual files or entire volumes, merge snapshots back into the original LV, and use snapshots to build disposable test environments on Ubuntu systems.
This tutorial explains how to build an eBPF‑based tracing tool that intercepts CUDA runtime API calls via uprobes, captures detailed event data such as memory sizes, transfer directions, kernel launches and errors, and presents it in a readable format for debugging and performance analysis.
The article explains that the 65,535 limit refers only to available port numbers, while actual TCP concurrency on Linux depends on the 4‑tuple identification, memory, file‑descriptor limits, and port reuse, allowing servers to handle far more connections than the port count suggests.
This guide walks through ten core Linux operations topics—precise system resource monitoring, deep process diagnostics, network and port‑conflict troubleshooting, permission models, link‑type comparison, boot sequence analysis, layered log auditing, automation with cron, advanced file search, and systematic performance‑tuning—providing concrete commands, examples, and step‑by‑step procedures for interview and on‑the‑job success.
This tutorial walks you through downloading the Nginx source package, extracting it, compiling and installing the binary, setting up the required directories, creating a systemd service file, and finally enabling and starting the Nginx service on a Linux system.
This comprehensive guide explores Linux's memory management ecosystem, detailing user‑space allocators like malloc, kernel‑space mechanisms such as kmalloc, vmalloc, and mmap, and core kernel algorithms including the Buddy system, CMA, slab allocator, and memory pools, while providing code examples and practical usage tips.
This guide explains the fundamentals of Linux programs and processes, their lifecycle, creation methods, and provides detailed usage of key commands such as ps, top, pgrep, pstree, lsof, vmstat, free, iostat, iftop, dstat, as well as background job control, at, and crontab for scheduling tasks.
This guide explains how to use the Linux df and du commands to inspect disk space, interpret their options such as -h, -k, -i, and -T, view partition usage, directory-specific usage, inode information, and avoid common pitfalls when measuring file sizes.
This article explains Docker’s fundamental technologies—how Linux namespaces provide process, network, and filesystem isolation while cgroups enforce resource limits such as CPU, memory, I/O, and process counts—offering a concise guide for building secure, efficient containerized applications.
This guide walks you through SFTP server planning, user naming conventions, directory structures, SSH configuration, account creation, permission setup, client usage, log auditing, rotation, connection limits, monitoring, and high‑availability deployment across multiple servers, providing ready‑to‑run commands and scripts.
This article presents a comprehensive guide on applying Linux Cgroups to isolate MySQL resources, covering CPU, memory, I/O, and network bandwidth controls, detailed configuration steps, performance testing with sysbench, and practical observations to ensure stable and predictable database behavior.
This comprehensive guide explains what Podman is, compares it with Docker, shows how to install and configure it on Linux, and provides detailed examples of common commands, container management, image handling, rootless operation, volume usage, and user namespace configuration.
This article explains Linux inode table structure, how commands like ls, stat, cp, mv, and rm interact with inodes, compares hard and soft links, outlines common system log files and their formats, and demonstrates centralizing logs on a rsyslog server.
This guide explains how to manage systemd journal logs on Linux, covering persistent storage configuration, size limits, various journalctl commands for viewing service, user, command, and boot logs, as well as log rotation, vacuuming, and integrity verification.
This tutorial explains how Linux processes use memory, distinguishes between shared and private memory, demonstrates how to interpret ps output, and shows how to obtain detailed memory maps using pmap and other utilities such as /proc, smaps, smem, exmap, and valgrind.
This article explains Linux's CFS scheduler mechanics, including the impact of priority, virtual runtime, event‑driven scheduling, the differences between PELT and WALT load‑tracking algorithms, and the complexities introduced by big‑LITTLE architectures on task placement, throughput, and latency.
This guide explains the fundamentals of Linux host file systems, LVM logical volumes, and Docker storage drivers, showing step‑by‑step how to format, mount, and persist MySQL data using Docker volumes and bind mounts on AlmaLinux servers.
This comprehensive guide covers SSH installation on Ubuntu, connection syntax, key management, file transfer with scp, port forwarding techniques, configuration file handling, service control via service, init.d and systemd, common issues, security hardening, and methods to keep SSH sessions alive.
This guide walks you through Squid's features, how it works, hardware requirements, step‑by‑step installation, default and custom configuration, initialization, testing, and detailed ACL examples to control access and improve network performance on Linux systems.
This comprehensive guide walks you through the fundamentals of shell and shell scripting, covering common shells, script creation, shebang usage, variable handling, environment variables, string manipulation, and practical examples to boost your Linux automation skills.
This guide walks through installing Certbot, configuring Nginx, obtaining a free Let’s Encrypt SSL certificate, automatically applying it to Nginx, verifying HTTPS, and setting up automatic renewal on Linux systems.
This guide explains how to set up an automated MySQL backup solution on AlmaLinux using Docker containers, a Bash script, and crontab, covering environment preparation, script creation, command checks, logging, error handling, and optional enhancements such as email notifications and security best practices.
This guide shows how to generate a self‑signed SSL certificate for an internal IP address using OpenSSL, configure Nginx to serve HTTPS without security warnings, and import the certificate into Chrome with the necessary extensions to avoid common name errors.
This tutorial walks through downloading, extracting, configuring, starting, creating topics, producing and consuming messages, and finally stopping Apache Kafka 3.8.1 on a Linux system, including all necessary command‑line instructions.
This guide provides step‑by‑step instructions for installing Docker Engine on a CentOS 7 system, including removal of any existing Docker packages, adding the Alibaba Cloud yum repository, installing required utilities, starting and enabling the Docker service, and verifying the installation.
Microsoft announced at Build 2025 that the Windows Subsystem for Linux (WSL) is now open‑source, detailing its component architecture, evolution from WSL 1 to WSL 2, recent releases, community contributions, and how developers can now build and contribute directly from the GitHub repository.
This article explains why using 777 permissions on production servers is dangerous when deploying a Spring Boot Docker service, and provides step‑by‑step guidance on applying minimal permissions, creating dedicated users, and automating secure deployments with Docker, CI/CD, and Kubernetes.
This article explains the Linux Page Cache mechanism, covering its core concepts, read/write workflows, data consistency, optimization strategies, real-world use cases, advanced topics, common misconceptions, and practical tips for improving system performance and resource management.
This guide explains how to use Alibaba's open‑source DataX tool to perform high‑performance offline synchronization between heterogeneous MySQL databases, covering installation, framework design, job configuration, full‑ and incremental sync, and practical command‑line examples.
This article explains Linux redirection, the three standard streams and their file descriptors, how to adjust descriptor limits, practical redirection examples, and the fundamentals of pipes—including anonymous and named pipes, their characteristics, and typical use cases for inter‑process communication.
This article explains what page faults are, why frequent faults degrade performance, how to measure them with Linux tools like perf, vmstat, and ftrace, and provides practical solutions ranging from memory upgrades to kernel parameter tuning.
This guide explains how to verify physical links, test ping latency, trace routes, check HTTP/HTTPS availability with wget and curl, assess TCP/UDP ports using netcat, telnet, and nmap, inspect local connections via netstat/ss, understand TCP states, and validate DNS resolution, providing practical command examples for each step.
This article provides a concise, visual guide to Docker, covering its background, differences from virtual machines, resource isolation mechanisms (namespaces, cgroups, networking), file system handling, image layering, storage drivers, and practical commands for inspecting configurations, transferring files, and packaging images for remote repositories.
The article explains what page faults are, how the Linux kernel handles them, methods to measure their frequency with tools like perf, vmstat and ftrace, and discusses why frequent faults degrade performance and how to mitigate them through memory, configuration, and code optimizations.
This guide provides a comprehensive overview of essential Linux system administration tasks, covering how to view and set system time, manage hostnames, inspect kernel information, handle user and group files, use common network utilities, monitor disk usage, and track processes with tools like top and ps.
This guide demonstrates how to configure keepalived in a dual‑host (master‑master) setup, enabling VIP address migration between two servers by defining two VRRP instances that act as primary and backup for each other, and includes step‑by‑step commands, configuration files, verification procedures, and multicast traffic capture.
This article explains how to achieve million‑level concurrent connections with Nginx by tuning OS limits, worker processes, epoll event handling, gzip compression, and zero‑copy file transfer, providing concrete configuration snippets and performance rationale for each optimization.
xtool is an open‑source, cross‑platform Xcode replacement that lets developers build, package, and sign iOS applications on Linux or Windows by extracting the Xcode toolchain, generating a Swift SDK, using SwiftPM for compilation, handling resources, creating IPA files, and managing Apple developer authentication, though it has notable limitations such as lack of Interface Builder support.
This guide introduces ctop, a top‑like tool for real‑time multi‑container metrics, explains its key features, shows how to install it on Linux, Docker and Windows, and details its command‑line options and shortcuts for efficient container management.
This article explains how mmap maps files into a process's virtual memory to eliminate double data copies and reduce system‑call overhead, offering performance gains, a simpler programming model, and discusses its limitations such as address‑space constraints and page‑fault latency.
Monitoring key Linux log files—such as syslog, auth.log, kern.log, and others—is crucial for system health, security, and troubleshooting, and this guide explains the purpose of each log, practical commands for viewing them, and automation techniques using scripts, cron, and tools like journalctl and Sematext.
This article introduces Alibaba DataX 3.0, explains its architecture and role‑based design, walks through Linux installation, JDK setup, MySQL preparation, and provides step‑by‑step examples of full‑load and incremental data synchronization between two MySQL instances using JSON job configurations and command‑line execution.
This tutorial walks through preparing the environment, installing and uninstalling MySQL on CentOS 7, configuring firewalls, setting up remote access, handling character sets, adjusting security policies, managing SQL modes, and best practices for case sensitivity and version‑specific password policies.
This article explains how to measure, analyze, and improve CPU usage in software by examining key metrics, choosing efficient algorithms and data structures, leveraging compiler options, exploiting cache behavior and SIMD vectorization, and applying practical case studies with Linux profiling tools.
This article provides a comprehensive overview of NGINX, covering its architecture, module types, multi‑process event model, FastCGI integration for PHP, configuration best practices, performance optimizations, error troubleshooting, and a notable security vulnerability.
A collection of real‑world anecdotes from Zhihu users reveals servers and computers that have stayed online for decades, highlighting hardware longevity, power‑redundancy strategies, and the cultural mindset of “if it works, don’t touch it.”
This step‑by‑step guide shows how to upgrade the outdated OpenSSH 7.4p1 and OpenSSL 1.0.2k on a CentOS 7 server by first installing Telnet as a fallback, removing the old packages, installing OpenSSL 1.1.1g, compiling OpenSSH 8.3p1, adjusting the configuration, and finally testing the new SSH service.
This article explains how to obtain base images, use Docker Hub, pull images with docker pull, create images via Dockerfile, container commits, tag and push images, and import/export images between hosts using docker save and docker load, providing complete command examples and best‑practice tips.
This article compiles 174 essential interview questions for operations engineers, covering Linux fundamentals, container orchestration, networking, high‑availability, databases, security, and cloud‑native concepts, helping candidates prepare thoroughly for technical assessments.
This article explains how to employ Alibaba's open‑source DataX tool to perform fast, reliable full‑ and incremental data synchronization between MySQL instances, covering installation, framework design, job execution, and practical shell commands for Linux environments.
Learn step‑by‑step how to install, configure, and launch an NFS server on CentOS 7, set up shared directories, edit export rules, adjust firewall settings, and mount the share on client machines, enabling reliable network file sharing for distributed and containerized environments.
This article explains why the Linux find command is essential for administrators, walks through a common interview question about deleting year‑old log files, and then presents eight practical find usages—including name patterns, file types, timestamps, size, permissions, ownership, execution actions, and directory searches—complete with ready‑to‑run code examples.
The article recaps the 3rd eBPF Developer Conference in Xi'an, highlighting talks on BPF‑on‑MPTCP, system‑wide PGO, bperf, autonomous‑driving use cases, and AI‑driven observability, while sharing the author's insights on continuous profiling, SysOM, and future challenges of scaling eBPF with large models.
This guide shows how to configure Docker registry mirrors for faster image pulls, run and manage containers—including starting, inspecting, networking, and file editing—using concise command‑line examples and practical tips for Linux environments.
This cheat sheet compiles essential Linux command‑line tools—including navigation (cd, pwd, ls), file manipulation (cp, mv, rm, cat), searching (find, grep), permission management (chmod, chown), archiving (tar), text processing (cut), and redirection or piping—each with common options and practical usage examples for everyday system administration.
Explore the essential role of DNS in the internet, learn how Linux resolves domain names, configure resolvers via /etc/resolv.conf, NetworkManager, systemd-resolved, set up a BIND9 server with zone files, and discover advanced techniques like DNSSEC, DoH, split views, and troubleshooting tools.
Learn how to use the versatile Unix ‘find’ command to search and manipulate files by name, type, size, timestamps, and more, with detailed syntax, common options, and practical examples for printing, deleting, and executing actions on matched files.
This guide explains what swap space is, why it’s essential for Linux systems, and provides step‑by‑step instructions for configuring swap files or partitions, viewing usage, and understanding its benefits for memory extension, performance optimization, and system stability.
This article provides a comprehensive, step‑by‑step tutorial on the Linux awk command, covering its origin, syntax, predefined variables, execution flow, functions, control structures, and practical examples, enabling readers to master text processing and data extraction directly from the command line.
This guide compiles the most important Linux performance analysis utilities—such as vmstat, iostat, dstat, iotop, pidstat, top, htop, mpstat, netstat, ps, strace, uptime, lsof, and perf—explaining their usage, output fields, and how they fit into a comprehensive system observability workflow.
This guide walks you through setting up a Squid proxy on Linux, configuring Jenkins to use the proxy, adding a domestic plugin repository, and adjusting firewall rules, enabling reliable network connectivity and plugin installation for Jenkins in environments with restricted internet access.
Linus Torvalds sharply condemned the case‑insensitive file‑system feature in Linux, labeling it a massive mistake that introduces serious security risks, citing recent Bcachefs patches that finally enabled the functionality, and sparking debate among developers about the trade‑offs between compatibility and safety.
This article explains how send and receive socket buffers work, why they are crucial for TCP flow and congestion control, how to tune kernel parameters and application settings, and what common pitfalls and testing methods help keep network services stable and efficient.
This article walks through configuring Ceph to provide NFS services using nfs‑ganesha, covering module checks, cluster creation, export setup, client mounting, data verification, and high‑availability configuration with haproxy and keepalived, complete with command‑line examples.
This guide walks you through the most important Linux performance‑monitoring utilities—top, htop, vmstat, iostat, mpstat, sar, iotop, perf, and more—explaining their purposes, installation steps, key options, and how to interpret their output for CPU, memory, disk, network, and process analysis, plus practical troubleshooting scenarios.
This guide explains how Linux syslog collects system messages, details common log files and their purposes, describes syslogd, klogd, and logrotate services, shows log formats, configuration syntax, and provides step‑by‑step examples for setting up both log receivers and senders.
This guide explains how to monitor memory usage on a Linux 7.9 system using a variety of commands and tools—including free, /proc/meminfo, vmstat, top, htop, sar, smem, glances and ps_mem—showing key metrics, options, example outputs and interpretation tips for both servers and desktops.
This article walks through the theory of Linux file systems, compares flash‑specific filesystems, outlines the essential rootfs directories, details required tools like a cross‑compiler and TFTP/NFS servers, and provides a complete step‑by‑step procedure—including BusyBox compilation, rootfs population, init scripts, and ramdisk creation—to produce a bootable root filesystem for an embedded board.
This guide explains Linux file permission concepts, from basic read/write/execute rights and numeric representations to advanced SetUID, SetGID, sticky bits, default umask settings, ownership changes, and ACL strategies, with practical chmod examples and command-line demonstrations.
This article explains Redis's single‑threaded network model, the role of IO multiplexing, the multithreading features introduced in Redis 6.0, and how to configure IO threads to improve throughput and latency.
This guide explains why the default CentOS 7 YUM repositories are slow for Chinese users and provides step‑by‑step instructions—including backing up existing .repo files, downloading Alibaba Cloud mirrors, adjusting version numbers, refreshing the cache, verifying updates, troubleshooting common errors, and advanced tips such as adding EPEL—so you can achieve faster, more reliable package management.
This comprehensive guide compiles essential Linux command-line techniques, covering command connectors, system resource monitoring, file searching, editing with vi/Vim, file transfer, text processing tools, user and file management, NFS setup, scripting utilities, and SELinux policy management, providing practical examples and command syntax for system administrators.
This guide walks through installing Squid on Linux, configuring it as a transparent proxy for internal clients, setting up a reverse proxy for external web servers, and applying common ACL rules to control access and improve network performance.
This tutorial walks through preparing the Linux environment, installing MySQL 5.7, configuring master and slave servers, creating replication users, verifying synchronization, troubleshooting common issues, and applying advanced options such as GTID and semi‑synchronous replication, all with complete command examples.
This guide walks you through configuring Linux file‑sharing services—including VSFTPD for FTP, Samba for SMB/CIFS, NFS for network file systems, and iSCSI for block‑level storage—covering installation, security options, client access, and automatic mounting.
Linux treats all I/O devices as files, enabling a single thread to monitor many descriptors via I/O multiplexing; while select and poll use linear scans and suffer size limits, epoll employs an event‑driven red‑black tree with edge‑triggered mode, offering scalable, high‑performance handling for thousands of concurrent connections.
This guide explains how to optimize Nginx by configuring worker processes, CPU affinity, file descriptor limits, event handling, efficient file transfer, connection timeouts, FastCGI, gzip compression, caching, anti‑hotlinking, kernel parameters and system limits for high‑traffic web services.
This guide presents twenty essential shell one‑liners—using awk, grep, sort, uniq, and netstat—to quickly count unique IPs, identify hot pages, filter bots, monitor Apache processes, and measure traffic, helping sysadmins and security analysts extract actionable insights from web server logs.
This guide explains Linux LVM fundamentals, covering physical volume creation, volume group management, logical volume operations such as creation, resizing, removal, as well as snapshot creation and restoration, complete with practical command-line examples for each step.
This guide explains how to set up a development environment for the OK3588 board, apply the PREEMPT‑RT real‑time patch to Linux 5.10.66‑rt53, configure and compile the kernel, flash it, and then validate latency improvements using cyclictest and stress‑ng under both idle and full‑load scenarios.
Learn how to combine Zabbix and Prometheus by deploying Node_exporter, configuring systemd, creating Zabbix templates, HTTP proxy items, and Prometheus pattern items, enabling seamless monitoring of server metrics without fully replacing your existing Zabbix setup.
