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.
This guide walks through a comprehensive Linux hardening checklist for RHEL7, covering account locking, password policies, SSH port changes, SELinux activation, firewall tightening, and file attribute protections to elevate the system to a B1 security level.
This guide explains four practical techniques—parsing System.map, using vmlinux with nm/objdump/readelf, reading /proc/kallsyms, and calling kernel lookup APIs—to locate the exact address of any Linux kernel function for deeper debugging.
This guide provides a comprehensive introduction to the Vim editor on Linux, covering its built‑in help, core modes, essential commands for inserting text, moving the cursor, deleting, searching, copying, replacing, exiting, and handling swap‑file protection, all illustrated with clear examples and images.
This article walks through Docker privilege escalation techniques on Linux, covering Docker basics, permission discovery, manual and automated enumeration with LinPEAS, and three practical breakout scenarios—including abusing Docker group rights, escaping privileged containers, and breaking out of non‑privileged containers using SUID binaries and release_agent attacks.
This guide explains what Linux environment variables are, lists common ones, and provides step‑by‑step commands for viewing, temporarily or permanently setting, and deleting variables, plus practical script examples to help users manage their shell environment efficiently.
This guide explains what NFS (Network File System) is, its advantages, required packages, configuration file syntax, export options, essential tools like rpcinfo, exportfs, showmount and mount.nfs, and provides step‑by‑step examples for mounting, fstab entries, and integrating autofs on CentOS systems.
An AWS EC2 instance behind an Elastic Load Balancer became unresponsive due to repeated TCP out‑of‑memory errors, which were resolved by examining kernel messages, adjusting tcp_mem‑related kernel parameters, and rebooting the server after a long uptime.
This guide explains how to permanently disable SELinux, set the system runlevel, enlarge file descriptor limits, fine‑tune kernel networking parameters via /etc/sysctl.conf, configure firewall settings, and troubleshoot common Linux socket errors to significantly improve server performance.
This guide shows how to install the command‑line version of WoeUSB on Ubuntu, identify the target USB device, and use a single sudo command to write a Windows 11 ISO to a bootable NTFS USB stick, with safety warnings about data loss.
This article introduces Zabbix’s core features, flexible data collection, custom alerting, visualization, high‑availability architecture, security auditing, and compares it with Prometheus, then walks through a step‑by‑step installation, configuration, and deployment on a CentOS server.
This article reviews elementary OS 8, a major release built on Ubuntu 24.04 LTS and Linux 6.8, highlighting visual redesigns, dock and quick‑settings upgrades, system‑settings improvements, hardware support, and enhanced security features such as Secure Session and Portals.
This tutorial explains why running fsck on a mounted root filesystem fails, shows how to inspect the last check time with tune2fs, and provides step‑by‑step commands to create a forcefsck file, reboot, and verify that the root filesystem check was performed.
This guide explains how newcomers can operate Linux entirely through graphical tools—choosing a user‑friendly distro, customizing the desktop, managing software and files, adjusting system settings, and even running Windows applications—without ever opening a terminal.
This tutorial walks you through checking the OS architecture, preparing the environment, downloading and extracting the MySQL 5.7 ARM package, configuring my.cnf, setting up auto‑start and environment variables, initializing the server, securing the root account, and configuring master‑slave replication on Linux.
This article explains why the java.lang.OutOfMemoryError: Kill process (java) or sacrifice child occurs, outlines system‑level memory‑shortage causes, and provides practical steps to prevent, fix, and troubleshoot the issue on Linux‑based Java applications.
This guide explains four practical ways to obtain Linux kernel function addresses—using the System.map symbol table, inspecting the vmlinux image with tools like nm, objdump and readelf, reading the live /proc/kallsyms file, and calling kernel APIs such as kallsyms_lookup_name and sprint_symbol.
Learn step‑by‑step how to configure iptables to log all dropped inbound and outbound packets to syslog, including creating a LOGGING chain, setting rate limits, customizing log prefixes, directing logs to a specific file, and interpreting the resulting log entries.
This guide explains how iptables works, covering common scenarios such as blocking IPs, port forwarding, NAT configurations, the structure of tables and chains, and how to persist rules across reboots, with concrete command examples and practical tips.
This article explains the concept of interrupt top‑half and bottom‑half processing, why splitting an ISR improves system efficiency, and introduces common Linux mechanisms such as soft interrupts, tasklets, workqueues, timers, and delayed work for handling deferred tasks.
The article explains how Linux triggers a page fault when a process accesses a virtual memory page that is not resident in physical RAM, describes the underlying virtual memory and MMU concepts, the kernel data structures involved, the detailed fault‑handling flow, different fault types, and their performance impact.
Learn step-by-step how to change a Linux system’s timezone to China Standard Time (CST, Asia/Shanghai) using the modern timedatectl command, creating a symbolic link to /etc/localtime, or setting the TZ environment variable for temporary adjustments, with verification commands and important cautions.
This guide walks through essential Linux file‑management commands—cat, cmp, diff, file, and find—detailing their purpose, syntax, key options, practical examples, and sample outputs so readers can confidently manipulate and compare files from the shell.
This guide explains how to identify hidden crypto‑mining processes on a Linux server, stop the malicious services, block suspicious IPs, secure the system with tools like SafeDog and ClamAV, and install Sysdig for deeper forensic analysis.
This guide explains what traceroute does, how to install it on various Linux distributions, and provides detailed command syntax, common and advanced options, practical examples, and important precautions for effective network troubleshooting.
The article outlines Kalle Valo's decade‑long contributions to Linux wireless drivers, his unexpected resignation, the community’s concerns about succession, and the urgent need for new maintainers to ensure the long‑term health of the kernel’s Wi‑Fi subsystem.
This article explains the Linux kernel’s perf utility, covering its architecture, key features such as lightweight event sampling, tracing, profiling and debugging, step‑by‑step installation, common commands with real code examples, and how to use perf and flame graphs to locate and optimise performance bottlenecks.
This article explains how to use the Linux kill command with SIGTERM, SIGQUIT, SIGKILL, and SIGSTOP signals to gracefully terminate, debug, force‑stop, or pause processes while minimizing data loss and providing practical command examples.
This article compiles ten real-world server‑operation disasters, explains the technical fallout of each forbidden action, and provides concrete command‑line remedies and best‑practice safeguards to help engineers avoid career‑ending mistakes.
This guide explains Docker’s basic concepts, advantages, architecture, installation steps, common image and container commands, and provides a practical example of configuring SSH access inside an Ubuntu container for both local and remote connections.
This article compares Windows and Linux across five major aspects—business model, system freedom, support, software compatibility, and user control—highlighting each OS's advantages, drawbacks, and practical considerations to help readers decide which platform best fits their needs.
This guide explains how to use the Linux lsof command‑line utility to list information about files opened by processes—including regular files, directories, sockets, and pipes—while covering options for filtering by file, directory, process name, user, PID, network connections, repeat mode, and more.
This guide explains the role of the /etc/init.d directory in embedded Linux, walks through common startup scripts such as rcS, rcK, and service-specific files, and provides detailed code examples and command‑line options to help developers understand, customize, and troubleshoot system initialization and shutdown processes.
This guide walks you through installing OpenVPN on a public cloud, setting up Easy‑RSA for certificate management, configuring the server and client, creating authentication scripts, and connecting Windows or macOS clients, complete with commands and configuration examples.
This guide walks you through systematic Linux password hunting techniques—including searching filenames, scanning file contents, extracting credentials from web and config files, cracking hashes with Hashcat and John, leveraging hidden files, MySQL databases, backup archives, and automating discovery with LinPEAS—to elevate privileges and gain full root access.
This article provides an in‑depth, step‑by‑step analysis of Linux GICv3 interrupt architecture, the kernel driver initialization, hardware‑to‑virtual interrupt mapping, the full interrupt handling state machine, and the workqueue subsystem including its data structures, initialization, and usage patterns.
This guide explains how to install Erlang, download and compile RabbitMQ 3.0.4, start the server in detached mode, verify its status, and troubleshoot common issues such as port conflicts on CentOS 6, providing complete command‑line instructions and configuration tips.
This article introduces a comprehensive set of shell scripts that automate system initialization across dozens of Linux distributions, detailing supported features, version‑specific updates, usage instructions, and code examples for network, security, package management, and more.
This guide explains Linux user types, file ownership categories, symbolic and octal permission representations, and provides step‑by‑step commands (chmod, chown, chgrp) for modifying permissions, owners, and groups on files and directories.
This tutorial explains how to use the Linux cut command for text processing, covering character and field selection, range specifications, output delimiters, and integration with other Unix tools through clear examples and code snippets.
PageCache is an operating‑system mechanism that uses physical memory to cache disk blocks, dynamically resizing with available RAM and employing LRU replacement and read‑ahead, turning slow storage accesses into fast memory reads, yielding up to twenty‑fold speed gains for tasks such as compilation, video editing, and database operations.
This tutorial explains how to install, configure, and run OpenVPN on Linux, covering VPN concepts, types, OpenVPN features, server‑side certificate creation, key generation, configuration files, and client setup, with step‑by‑step commands and troubleshooting tips for secure remote access.
Linux does not expose all physical memory to users; this article explains why the kernel reserves memory, detailing the early memblock allocator, crash kernel reservations, page structure overhead, and the handoff to the buddy system, illustrating how these mechanisms consume several hundred megabytes of RAM.
This guide walks through Linux's startup sequence, covering the BIOS/UEFI hardware check, GRUB2 bootloader configuration, kernel loading, initramfs handling, systemd target units, service initialization, and a concrete CentOS 8 example with command snippets and configuration files.
This tutorial walks through installing Bind on CentOS 8, disabling SELinux and the firewall, configuring /etc/named.conf and zone files for the test.com domain, setting proper permissions, enabling the named service, and verifying DNS resolution.
This guide explains how to install iPerf on Linux, macOS, and Windows, shows basic server‑client usage, details advanced command‑line options, and provides practical examples for measuring TCP and UDP bandwidth performance.
The article provides an in‑depth technical analysis of Linux’s memory reclamation system, covering zones, watermarks, page flags, LRU lists, the shrink_zone workflow, kswapd, direct reclaim, OOM handling, page‑cache structures, and practical tuning tips for optimal performance.
The article explains how the tilde (~) shortcut for the home directory in Linux stems from the 1975 Lear Siegler ADM‑3A terminal's Home key, detailing its historical keyboard origins, influence on vi cursor commands, and lasting impact on modern software shortcuts.
This article explains the fundamental concepts of I/O models—including blocking, non‑blocking, multiplexing and asynchronous approaches—detailing their mechanisms, advantages, drawbacks, code examples in Python, and practical optimization strategies for high‑concurrency backend systems.
PageCache, a kernel-managed memory cache that stores disk data in RAM, dramatically speeds up file operations by turning repeated reads and writes into pure memory accesses, and its dynamic sizing, read‑ahead, and LRU eviction are demonstrated through Linux experiments with large files.
Learn how to install the traceroute utility on Debian/Ubuntu and CentOS/RHEL systems, understand its basic command syntax, explore common and advanced options, and see practical examples for network path tracing, while noting important considerations and usage tips.
