This guide explains what symbolic and hard links are in Linux and provides step‑by‑step commands—using rm, unlink, and appropriate options—to remove single or multiple links, including those pointing to directories, while avoiding common pitfalls.
The article explains how a MySQL 5.7 service fails to start on a CentOS 7.9 server because SELinux blocks write access to err.log, walks through log inspection, strace tracing, SELinux context analysis, and provides a simple fix by disabling SELinux.
This guide explains how to download, compile, and install the Kube-OVN FastPath kernel module on CentOS, showing steps for both 3.x and 4.x kernels, how to verify the installation with dmesg, and notes on module loading and removal.
Learn to overcome NAT limitations and create a high‑speed, peer‑to‑peer network by installing and configuring Headscale, an open‑source Tailscale controller, including server setup, certificate handling, Docker deployment, client installation across platforms, and optional DERP relay configuration for reliable connectivity.
This article showcases seven visually impressive Linux distributions—elementary OS, Deepin, Pop!_OS, Manjaro, KDE Neon, Zorin OS, and Nitrux OS—highlighting their design focus, underlying bases, key features, and providing their official website links for readers seeking an attractive desktop experience.
This article explains why Docker containers often stop right after starting by examining the Linux PID 1 init process, the behavior of foreground versus daemonized commands in Dockerfiles, and how container runtimes like containerd‑shim and runc manage the container’s main process.
Real‑world Linux server failures show that missing PAM support in SSH prevents ulimit changes, misordered pam_faillock entries break cron authentication, and custom pam_script setups for Squid require careful configuration, highlighting that module order, thorough testing, and proper hardening are essential for reliable PAM authentication.
This comprehensive guide explores Linux kernel memory management, explaining virtual and physical address concepts, the layout of process and kernel virtual memory spaces on 32‑ and 64‑bit systems, the role of mm_struct and vm_area_struct, and how ELF binaries are mapped into memory, while also detailing DRAM organization and CPU memory access.
This guide explains how to monitor Linux system performance by using core commands such as top, vmstat, iostat, and sar to evaluate CPU usage, memory allocation, I/O activity, and network traffic, while also covering load interpretation, cache behavior, huge pages, zero‑copy techniques, and practical command examples.
This guide lists popular Linux text editors and IDEs—including Vim, Nano, Geany, Emacs, Sublime Text, Atom, Brackets, Komodo Edit, gedit, and Qt Creator—provides brief feature overviews, official website links, and step‑by‑step installation commands for both Ubuntu/Mint (apt) and CentOS (yum).
The article examines the rise of domestic IT infrastructure in China, the heavy reliance on open‑source code, how licensing changes by companies affect perceived ‘国产化’, and why active community participation and strict compliance are essential for a sustainable ecosystem.
This guide walks through installing Prometheus, node_exporter, and mysql_exporter on a Linux server, editing Prometheus configuration to scrape node and MySQL metrics, verifying the setup, and creating a Grafana dashboard to visualize MySQL performance data.
This guide explains the purpose of the SSH known_hosts file, how it protects against man‑in‑the‑middle attacks, and provides practical commands and techniques for adding, updating, and removing host keys safely across multiple users.
This guide compiles practical Linux shell commands for extracting IP counts, page visit frequencies, time‑range queries, bandwidth usage, HTTP status distribution, and TCP connection states from Apache or Nginx access logs, helping administrators quickly spot traffic patterns, bottlenecks, and potential attacks.
This article explains why the Linux find command is essential for backend developers and interviewees, demonstrates how to delete log files older than a year, and walks through seven practical find usages—including name patterns, file types, timestamps, size, permissions, ownership, and executing actions on matched files.
This guide explains the SCSI protocol, compares common hard‑disk interfaces such as IDE, SCSI, and SATA, shows how to install and use the lsscsi command with its options and examples, and details Linux SCSI file nodes and logging configuration.
This article provides a detailed overview of Docker, covering its definition, core components, advantages over virtual machines, common use cases, installation steps, storage configuration, image management commands, network modes, data volumes, private registry setup, backup procedures, and MySQL deployment, all illustrated with practical command examples.
The article explains how modern Linux distributions offer a graphical interface, robust development tools, efficient command‑line workflows, and numerous practical advantages that make them a compelling, customizable, and often faster alternative to Windows for everyday and professional use.
The article explains Linux hung‑task detection, detailing both a system‑wide polling method that compares unchanged D‑state task context‑switch counts and a watchdog approach for critical processes, describes kernel implementations, analysis of real‑world hang cases, and emphasizes log analysis and parameter tuning to prevent system hangs.
This article explains the limitations of the traditional Unix fork model, introduces lightweight POSIX threads as a faster alternative, and provides a comprehensive guide to thread creation, attributes, synchronization primitives, and cleanup functions using the pthread library in Linux.
This article provides a comprehensive guide to Linux performance monitoring, covering essential tools such as vmstat, iostat, dstat, iotop, pidstat, top/htop, mpstat, netstat, ps, strace, perf and sar, with usage examples, command syntax, and explanations of the metrics they report.
This article shares practical Linux administration techniques, including using rsync to delete massive files quickly, employing Bash parameter expansion to protect rm from accidental root deletion, adding iSCSI disks in vSphere without reboot, mounting remote filesystems with sshfs, and managing supplementary groups efficiently with gpasswd.
The article explains how a senior architect leverages SSH reverse tunneling and remote port forwarding to enable a headquarters server to reach a branch office's internal web server despite restrictive network policies, detailing the commands, verification steps, and packet flow involved.
This article explains how Linux implements processes and threads, showing that both are represented by the same task_struct structure, detailing thread creation via pthread_create and clone, and comparing the kernel‑level steps—including flag handling, copy_process, and resource sharing—that differentiate threads from full processes.
This article explains seven practical uses of the Linux find command—searching by name, type, timestamps, size, permissions, ownership, and executing actions—provides clear code examples, and shows how to solve a common interview question that deletes files older than one year.
Users of Fedora 35 reported severe screen flickering after upgrading to Linux kernel 5.19.12‑100.fc35, a problem not seen in the previous 5.19.11‑100.fc35 kernel, which Intel engineers identified as a potential LCD power‑sequencing delay and fixed in kernel 5.19.13.
This guide explains how to monitor disk usage on CentOS 7, collect snapshots with iostat, sar and pidstat, troubleshoot common errors, and finally use SystemTap to pinpoint the exact process that is writing to a specific file.
This article shares practical Linux operations guidelines—including thorough testing, cautious use of destructive commands, strict backup policies, security hardening, continuous monitoring, performance tuning, and a disciplined mindset—to help avoid costly incidents and maintain stable production environments.
This guide shows how to monitor disk usage on a CentOS 7 server, collect periodic snapshots with iostat, sar and pidstat, troubleshoot atd scheduling issues, and finally use SystemTap to pinpoint the exact PID that writes to a specific file, providing complete scripts and command‑line steps.
This article provides an overview of InfiniBand and Remote Direct Memory Access (RDMA), explains their underlying protocols and hardware, and offers detailed step‑by‑step guidance for configuring InfiniBand, RDMA, RoCE, and related services on Red Hat Enterprise Linux systems.
This article explains the fundamentals of Linux interrupt handling, covering the distinction between hardware and software interrupts, the processing flow of hard IRQs, maskable versus non‑maskable interrupts, the need for deferred execution, and a deep dive into softirqs, tasklets, and workqueues with code examples and performance considerations.
This article documents a real‑world Linux server compromise, detailing the observed symptoms, forensic commands, malicious scripts, file‑locking tricks, and a step‑by‑step remediation process including SSH hardening, cron cleanup, chattr usage, and preventive security recommendations.
This guide shows how to identify a Linux process’s PID and safely terminate it using kill, killall, or pkill, covering signal options, common signals like SIGTERM and SIGKILL, and practical command examples for both foreground and background processes.
This guide walks beginners through the complete process of publishing a website online, covering domain registration and ICP filing, DNS configuration, selecting and configuring a cloud server, installing Java and Tomcat, and finally uploading the site source files via FTP.
A whimsical tale explains how Docker solves application deployment pain by using chroot/pivot_root for filesystem isolation, Linux namespaces to hide host resources, and cgroups to limit CPU, memory, and I/O, illustrating core container technologies with practical code snippets.
This article chronicles the development of operating systems from the early Z1 computer without an OS to modern platforms like Linux, Android, iOS, and Chrome OS, highlighting key milestones, innovations, and the impact on computing over the past decades.
Mist is a command‑line helper for Debian‑based systems that brings AUR‑style package discovery and management to Ubuntu and Debian, allowing users to search, install, update, and remove packages from the makedeb Package Repository with simple commands.
Linux kernel 6.0, released on October 2 by Linus Torvalds, brings major enhancements such as Rust support, ARM and RISC‑V improvements, CPU fault detection, better ACPI power management, SMB3 performance, Intel Arc GPU certification, and even Atari PC optimizations, marking it as one of the most commit‑heavy releases in recent history.
This article explains the fundamentals of Linux interrupt handling, covering hardware and software interrupt types, the IRQ processing flow, maskable versus non‑maskable interrupts, the need for deferred execution, and detailed mechanisms of softirqs, tasklets, and workqueues with practical code examples.
Drawing from three and a half years of Linux operations, this guide outlines practical standards for testing, confirming commands, avoiding concurrent edits, mandatory backups, data safety, security hardening, continuous monitoring, performance tuning, and the right mindset to keep production environments stable and secure.
This article compares macOS and Linux by exploring their histories, kernel architectures, openness, hardware requirements, software ecosystems, user experience, customizability, gaming support, package management, and update policies, helping readers decide which operating system best fits their needs.
This guide explains how to terminate Linux processes using the kill, killall, and pkill commands, covering signal types, how to find process IDs, command syntax, and practical examples for both foreground and background tasks.
This article walks through installing BIND, configuring the named.conf file, creating forward and reverse zone files, setting up a master DNS server and a slave server, starting the services, and verifying the setup with nslookup, including a fail‑over test.
The article demonstrates how to examine a running Go program’s memory layout by defining example structs, using unsafe.Sizeof/Alignof, dumping writable regions via a Bash script and GDB, and locating fields and string constants in the resulting memory dumps to verify object representation.
This article explores how Kubernetes Pods differ from simple containers by examining their underlying implementation, shared network and IPC namespaces, cgroup hierarchies, and the role of the pause sandbox, while also demonstrating how similar pod-like behavior can be achieved using Docker and cgroup tools.
This article outlines the fundamental differences between Linux and Unix, covering topics such as the non‑standard Bash shell, the absence of long‑option support in Unix, variations in Make and C compilers, the distinction between GNU and Linux, and the trademarked UNIX name, providing a concise guide for developers navigating these operating systems.
This article explains how Kubernetes forwards packets from the initial web request through pod network namespaces, the role of the pause container, veth pairs, bridges, CNI plugins, and iptables‑based service NAT, providing a step‑by‑step view of intra‑cluster and external traffic handling.
This guide explains the ping utility’s core functions, interprets its output fields such as bytes, time, and TTL, and demonstrates advanced options like -t, -a, -n, -l, -r, as well as batch pinging of IP ranges for network troubleshooting.
This article reviews the most effective Linux antivirus solutions, explains why antivirus protection is still needed on Linux servers despite the platform's inherent security, and provides detailed descriptions of each tool along with installation guidance and usage tips.
This guide explains how to use the ping utility to test connectivity, interpret bytes, time, and TTL values, and leverage advanced options like -t, -a, -n, -l, -r, as well as batch‑ping techniques for efficient network troubleshooting.
This article explains why certain Linux commands—such as rm -rf /*, overwriting partitions, moving data to /dev/null, formatting disks, fork bombs, and malicious script execution—are extremely hazardous, illustrates their destructive effects with examples, and offers practical safety recommendations to protect your system.
This article details the investigation of an unexpected native memory consumption issue in a Spring Boot service, describing how JVM and system‑level tools were used to pinpoint the leak caused by the Spring Boot loader's Inflater usage and how configuring MCC scan paths or upgrading Spring Boot eliminated the problem.
Linux futexes provide a fast userspace lock backed by a kernel wait queue, using atomic operations when uncontended and system calls such as FUTEX_WAIT, FUTEX_WAKE, and priority‑inheritance variants to manage contention, requeueing, and priority inversion via rt‑mutex structures.
This article explains how zero‑copy techniques such as DMA, sendfile, mmap and Direct I/O reduce data copies and context switches in Linux, compares their mechanisms, advantages and drawbacks, and shows typical use cases like Kafka for high‑performance I/O.
Learn how to identify and terminate Linux processes using commands like kill, killall, and pkill, including signal options, PID retrieval methods, and practical examples for both foreground and background tasks, ensuring safe and effective process management on Unix-like systems.
This article explains the evolution, principles, use cases, workflow, and limitations of eBPF, showing how programmable kernel extensions enable advanced observability, networking, and security capabilities across Linux systems and cloud‑native environments.
This article explains how Kubernetes forwards packets from the initial web request through container networking, covering the cluster's network model, Linux network namespaces, the role of the pause container, veth pairs, bridges, CNI plugins, and how services use iptables and conntrack for pod-to-pod and pod-to-service communication.
An overview of essential Linux firewall solutions—including iptables, IPCop, Shorewall, UFW, Vuurmuur, pfSense, IPFire, Smoothwall, Endian, and ConfigServer—covers their core functions, key features, and typical use cases, helping administrators choose the right tool for network protection.
This article explains why CentOS 7 is reaching end‑of‑life, reviews community and domestic alternatives such as Rocky Linux, AlmaLinux, Anolis OS, openEuler and Galaxy Kirin, and provides detailed automatic (Leapp) and manual (dnf distro‑sync) upgrade procedures with code examples for a smooth migration.
This article provides a comprehensive technical overview of DPDK, covering its architecture, core libraries, platform modules, polling and CPU‑affinity techniques, huge‑page memory management, NUMA considerations, OS tuning steps, and integration with OVS for high‑performance packet processing.
The article explains why the free command reports more memory than the available column, describes how the kernel calculates MemAvailable using min_free_kbytes and watermarks, and provides practical guidance on tuning min_free_kbytes to meet OceanBase's memory requirements.
This article summarizes a series of technical Q&A from an OSChina event covering Linux networking fundamentals such as port limits, network namespaces, TCP connection handling, C10K problem, packet loss troubleshooting, TCP memory usage, high CPU causes, useful monitoring tools, kernel parameters, and practical socket examples.
This article explains why backing up a Linux system is essential and walks you through four reliable disk‑cloning tools—dd, Partimage, Partclone, and Clonezilla—detailing installation, command usage, and best‑practice tips for creating recoverable disk images.
RedisInsight is a powerful GUI for Redis that enables monitoring, CLI interaction, and module support; this guide walks through its features, step‑by‑step installation on physical servers and Kubernetes, environment configuration, service startup, and basic usage including memory analysis and data operations.
This article compares macOS and Linux across history, kernel architecture, openness, hardware requirements, software ecosystems, user experience, customizability, gaming support, package management, and update policies, helping readers decide which platform better fits their personal or professional use cases.
This article categorizes Linux high‑risk commands, explains why a blanket ban is unsuitable, and offers practical handling, monitoring, and bastion‑host strategies to protect data across system, database, and big‑data operations.
This guide explains how Linux uses packet queuing for traffic shaping, walks through creating qdisc, class, and filter structures with tc, and shows step‑by‑step commands to limit bandwidth for specific IPs, ports, and inbound traffic using ifb devices.
The upcoming Linux 6.0 kernel hints at future Rust driver support, but significant hurdles remain such as compiler compatibility, LLVM vs GCC toolchains, and limited architecture support, making widespread Rust integration unlikely until later releases.
Amid the current tech hiring slowdown, this guide outlines a comprehensive learning roadmap for software testers, covering fundamentals, Linux, shell scripting, web fundamentals, databases, packet‑capture tools, API testing, automation frameworks, mobile testing, TestOps, and performance and security testing to help engineers stay competitive and advance their careers.
When a Linux server’s load spikes, you can quickly pinpoint CPU, memory, disk I/O, and network bottlenecks by running ten concise commands—uptime, dmesg, vmstat, mpstat, pidstat, iostat, free, sar, and top—each providing specific metrics for rapid troubleshooting.
This guide explains multiple Linux techniques—such as lscpu, /proc/cpuinfo, lshw, dmidecode, inxi, hardinfo, hwinfo, cpuid, nproc, and hwloc—to display comprehensive CPU details like model name, core count, cache sizes, architecture, and NUMA nodes, with exact commands and example outputs.
This article documents a recent Linux server compromise, detailing observed symptoms, investigative commands, discovered malicious scripts, and step‑by‑step remediation actions such as restricting SSH access, unlocking and restoring system utilities, removing malicious cron jobs, and hardening the system against future attacks.
This comprehensive guide walks you through shell scripting fundamentals—including process management, function libraries, variables, control structures, loops, debugging tools, and automation—while providing practical code examples, best‑practice tips, and visual illustrations to help both beginners and seasoned developers write robust Bash scripts.
Learn how to enhance the Linux coreutils cp and mv commands with a visual progress bar by downloading the advcpmv patch, applying it to coreutils source, compiling, installing, and creating convenient aliases, complete with example usage and performance output.
This article explains how the Linux unlink command deletes files and links, details its usage syntax, highlights its limitations—such as inability to remove multiple items or directories—and compares it with the more versatile rm command, helping you choose the right tool for safe file removal.
The article compares two interviewee types, stresses that genuine interest drives faster Linux mastery, and outlines a step‑by‑step learning path that starts with building a personal blog, then expands to monitoring, load balancing, and a comprehensive Linux operations roadmap.
This article explains the TCP keepalive mechanism, its purpose, default parameters, how to configure and verify it on Linux, its drawbacks, and the distinction between TCP keepalive and HTTP Keep-Alive, providing practical code examples and network analysis steps.
This article examines whether Linux can meet the daily development and office needs of programmers, comparing its graphical interface, development tools, communication apps, Android support, and overall advantages such as efficiency, freedom, and lower resource consumption against Windows.
This guide introduces Linux Device Tree concepts, explains why it was added to the kernel, details its syntax and standard properties, describes common nodes, and provides practical examples of OF functions for accessing nodes and properties in kernel code.
Linux employs four main I/O schedulers—NOOP, Anticipatory, Deadline, and CFQ—to manage block device request queues, balancing throughput and latency through techniques like request merging, sorting, and priority handling, with each algorithm suited to specific hardware and workload characteristics.
China announced a plan to replace Windows with Linux on over 50 million PCs, echoing Germany’s earlier shift, aiming to eliminate foreign operating systems, reduce licensing costs, and boost domestic tech, while prompting mixed reactions from hardware manufacturers and software vendors.
This guide introduces the most common Linux package management tools—dpkg, apt, rpm, yum, and dnf—explaining their purposes, supported distributions, core command‑line options, and practical examples for installing, updating, querying, and removing software packages.
This guide explains the SCSI protocol and common disk interfaces, details how to install and use the lsscsi command on various Linux distributions, describes its options and output formats, and provides examples of querying devices, interpreting results, and enabling SCSI logging for debugging.
Blackbox is a GTK4‑based Linux terminal emulator that prioritizes sleek appearance over extensive features, offering theme support, customizable UI, optional header bar, easy copy‑paste shortcuts, and straightforward Flatpak installation, while remaining in early development with occasional crashes.
This article provides a comprehensive overview of Docker's evolution, its modern architecture involving containerd, runc, and CRI, explains how containers are created and managed, and offers step‑by‑step instructions for installing, configuring, and operating containerd with the ctr command‑line tool on Linux.
This guide explains how to use Linux's TC tool to shape network traffic by creating qdisc queues, defining class hierarchies, and applying filters that bind specific IP addresses or ports to bandwidth limits, including both egress and ingress shaping via an ifb virtual interface.
This guide introduces Rsync’s core concepts, demonstrates local and remote synchronization via SSH and daemon modes, details configuration parameters, and shows how to combine Rsync with inotify‑tools for real‑time, bidirectional file replication across Linux servers.
The 2022 Chinese domestic operating system development report analyzes the current landscape of desktop and server OSes, examines industry experiences, outlines market dynamics, discusses open‑source community impacts, and forecasts future trends amid policy support and ecosystem challenges.
This article details a step‑by‑step investigation of Java service log garbled‑character problems caused by incorrect LC_CTYPE and locale settings, describing how environment variable synchronization via SSH led to ASCII encoding defaults and outlining preventive configurations for both client and server.
Linus Torvalds announced the fourth release candidate of Linux 6.0, describing it as a regular mid‑cycle test version with various bug and regression fixes, and confirming that the stable 6.0 release is on track for October.
After taking over a system via a server image, the author uncovered malicious modifications that used a ternary expression to force id=1, causing MyBatis to generate a “where 1=1” clause that deleted the entire T_QUART_DATA table, and later discovered cron jobs that removed core jars, illustrating a thorough forensic debugging process.
This guide explains Linux traffic control fundamentals, showing how to create qdisc, class, and filter structures with the tc tool to shape traffic, limit bandwidth for specific IPs or ports, and manage both egress and ingress traffic using ifb devices.
This guide shows how to use iptables to allow only a designated IP address to access a host's port 80, how to apply the same restriction to Docker containers by adding rules to the DOCKER-USER chain, and how to make the settings persistent across reboots.
This article explains how TCP connections behave when any of the three-way handshake or four-way termination packets are lost, detailing the kernel‑controlled retransmission mechanisms, timeout intervals, relevant sysctl parameters, and the exact sequence of events for each loss scenario.
This guide explains the purpose of the Linux cheat utility, compares it with man and info, shows how to install both the Go and Bash versions, and provides detailed usage examples, configuration tips, and ways to extend its cheat sheets for faster command reference.
This article provides a comprehensive guide to diagnosing and fixing a wide range of Docker problems, including storage migration, disk space shortages, missing libraries, container corruption, network configuration, permission errors, image management, and timeout issues, with detailed command-line solutions and configuration examples.
This guide explains how to identify and troubleshoot TCP throughput limitations by examining sender, receiver, and network bottlenecks, understanding rwnd and cwnd values, using Linux tools like ss and Wireshark, and interpreting packet traces to pinpoint congestion or loss.
This guide explains why TCP throughput may fall short of network capacity, covering sender, receiver, and network bottlenecks, how to read receiver window (rwnd) and congestion window (cwnd) values on Linux, and how to interpret Wireshark graphs to pinpoint the root cause.
This article explains the four Linux kernel I/O schedulers—NOOP, Anticipatory, Deadline, and CFQ—covering their design goals, how they manage request queues through merging and sorting, and when each scheduler is best suited for different storage hardware and workloads.
This guide walks you through installing Git, creating a dedicated git user, configuring SSH keys, preparing a repository directory, initializing a bare repository, and applying essential security hardening to run a private Git server on a Linux machine.
