This tutorial walks through the motivation for Nvidia GPU kernel interception, explains Linux kernel module basics and privilege rings, shows how to set up an Ubuntu environment, write and compile a minimal LKM, load and test it, then create a fake GPU character device and mount it into a Docker container for verification.
This guide walks you through downloading, installing, and configuring Elasticsearch 7.10 on CentOS, covering environment setup, user creation, service start options, essential settings like paths, heap size, system limits, and troubleshooting tips for a production‑ready deployment.
This article provides a detailed, step‑by‑step overview of every Linux interprocess communication mechanism—including pipes, signals, files, semaphores, shared memory, message queues, sockets, and Unix domain sockets—complete with concepts, usage scenarios, diagrams, and full code examples.
This guide explains why Linux cache memory isn’t automatically freed, when manual cache dropping is appropriate, and how to safely release page cache, reclaimable slab objects, or both using the /proc/sys/vm/drop_caches interface, including practical command examples.
This guide walks you through using firewalld on CentOS 7, covering status checks, starting and restarting the service, configuring zones, managing ports and sources, applying rich rules, and persisting changes, while providing clear command examples for each step.
This guide explains Unix shell wildcards, their syntax, and how to use symbols like *, ?, [] and [!...] for file name matching, includes practical find command examples, redirection, quoting, pipelines, and shortcuts for efficient command‑line operations.
This guide explains how Linux’s locate and find commands work, compares their performance and features, and provides detailed usage examples, options, and advanced techniques such as depth control, type filtering, size and time queries, permission checks, combined conditions, and xargs integration.
This guide introduces fifteen entertaining Linux commands—from reversing strings with rev and viewing images with asciiview to playing classic games like ninvaders and pacman4console—providing installation instructions, example usages, and screenshots that showcase each tool’s quirky behavior for both learning and amusement.
This tutorial explains RAID concepts, compares RAID levels, and provides a complete, command‑by‑command walkthrough for creating, monitoring, repairing, and removing a software RAID10 array on a Linux server using mdadm.
This guide explains how to locate Linux network‑script files, edit the interface configuration to use DHCP or a static address, and restart the network service, with example commands and screenshots illustrating virtual machine network settings and dynamic IP acquisition.
This guide shows how to install and use the Linux stress tool to generate CPU, memory, and I/O load, provides command examples for each stress type, and explains a testing approach for realistic server stability assessment, followed by a free 2024 operations resource pack.
This article surveys the main characteristics of Linux, classifies its many distributions into general‑purpose, enterprise, lightweight and specialized groups, and details the key features, package managers, desktop environments and typical scenarios for each major distro.
This tutorial explains how to design and deploy a high‑availability web cluster using Linux Virtual Server (LVS) and Keepalived, covering terminology, test environment setup, detailed configuration steps, HA testing procedures, and a concise summary of the solution.
This article explains what ELF files are, details their header, program header table, sections and section header table, and walks through how Linux uses fork and execve to clone a child process and load an ELF binary into a new address space.
This article explains common Linux network packet loss scenarios, details the kernel’s packet receive and transmit paths, examines hardware and ARP issues, Conntrack limits, UDP buffer problems, and provides practical troubleshooting tools and commands to accurately detect and fix packet drops.
This article explains the complete journey of a browser request—from entering a URL, through DNS hierarchy, recursive and iterative queries, to TCP handshakes and HTTP exchange—while also providing step‑by‑step guides for building your own DNS server with BIND or dnsmasq and using dig to trace resolutions.
The article explains the true purpose of the Linux kill command, compares signals like SIGTERM and SIGKILL, warns about the dangers of force‑killing processes, and provides practical Java shutdown‑hook examples and a shell script for safe, graceful termination.
This guide walks you through Linux's directory layout, how to inspect CPU details via /proc, monitor utilization with top, retrieve version, memory and disk statistics, manage character sets, control services, and use common commands for file handling, permissions, networking, and process management.
This guide explains how to view and follow Linux log files in real time using tail (including -f, -F, and -n options), multitail for multiple logs, lnav as an alternative viewer, and less with Shift+F, plus installation commands for each tool.
The article provides a detailed comparison of China’s two mainstream community Linux desktop distributions, Deepin and OpenKylin, covering their origins, desktop environments, UI components, file managers, browsers, office suites, input methods, app stores, and AI integration, and highlights their hardware requirements and user experience differences.
This guide explains how to set password expiration periods, minimum length, complexity requirements, and reuse restrictions on Linux systems by editing /etc/login.defs and PAM configuration files with concrete examples and recommended values.
This article explains the exact meaning of the “buffers” and “cached” fields shown by the Linux free command, detailing how they are derived from /proc/meminfo, the kernel source calculations, swap cache interactions, and provides verification experiments with code examples.
Steve Langasek, a pivotal Debian core developer and former Ubuntu release manager, passed away at 45, leaving a lasting legacy of open-source contributions, community leadership, and a bridge between commercial and community interests that continues to inspire developers worldwide.
This article explains the fundamentals of network I/O, covering hardware basics, process scheduling, blocking and non‑blocking models, multiplexed I/O techniques such as select/poll/epoll, asynchronous I/O, socket types, and the user‑kernel boundary, providing a comprehensive guide for backend developers.
This article explains the Linux kernel’s memory management for a process, covering virtual address spaces, page‑fault handling, VMA allocation, stack and heap initialization, sbrk/brk usage, thread‑stack creation, and the glibc ptmalloc heap allocator with concrete code examples and diagrams.
This article explains the Linux kernel's four‑level page‑table mechanism, the performance impact of TLB misses, why using 2 MB HugePages improves address‑translation efficiency, and provides step‑by‑step instructions for reserving and allocating HugePages via boot parameters, sysfs, and mmap.
This guide explains the Linux sort command, covering its most useful options—such as numeric, human‑readable, case‑insensitive, field‑based, and reverse sorting—and demonstrates practical examples for default sorting, column sorting, deduplication, and writing results to files.
This guide explains how to manage Linux users and groups—including creating, modifying, and removing accounts, setting passwords, switching users, configuring sudo, and adjusting file ownership and permissions—using the core command‑line tools and practical examples.
This guide explains Linux shell I/O redirection, covering output and input redirection, file descriptor semantics, the importance of order, using /dev/null to discard output, and common patterns for merging and appending streams, all with clear examples.
This article explains DHCP fundamentals, its four‑stage broadcast workflow, allocation methods and advantages, then provides a complete CentOS 6.5 environment setup with commands, configuration file edits, and client testing to help you deploy a DHCP server efficiently.
This guide explains how Wine translates Windows API calls to POSIX, compares its low‑resource performance to full virtual machines, and provides step‑by‑step installation and usage instructions—including command‑line examples and graphical tools like Bottles—to help you choose the best solution for running Windows software on Linux.
This guide introduces four essential Linux commands—lsmod, lsof, lspci, and lsscsi—detailing their purpose, syntax, key options, example outputs, and how to interpret each column for effective system monitoring and troubleshooting.
This article walks through a real‑world incident where a PHP service consumed over 80% CPU, detailing how to identify the offending processes with htop, examine their status, trace system calls with strace, inspect file descriptors via lsof, and ultimately locate and correct a looping SQL query that caused the overload.
This guide explains Docker’s origins, core container technologies such as cgroups and namespaces, essential commands for managing container lifecycles, and practical examples covering environment variables, volumes, and networking, enabling readers to understand and operate Docker containers effectively.
With CentOS 8 reaching end‑of‑life, this guide reviews seven viable server‑grade Linux replacements for 2025—including AlmaLinux, Ubuntu/Debian, Oracle Linux, OpenSUSE, Rocky Linux, VzLinux, and Springdale—detailing their compatibility, support cycles, package managers, and migration considerations.
Learn practical tcpdump examples to boost network troubleshooting and security testing, covering common parameters, ASCII output, protocol and IP filtering, file writing, buffering modes, combined filters, and advanced use cases like extracting HTTP headers, detecting port scans, capturing ICMP, DHCP, SNMP, and more.
This guide explains multiple Linux techniques—setting a user’s shell to /sbin/nologin, editing /etc/passwd, configuring sshd_config with Allow/Deny directives, and using hosts.allow/hosts.deny—to prevent unwanted SSH access for particular users, groups, or IP addresses, and shows how to apply the changes safely.
The article explains how the Linux kernel’s initcall mechanism automatically orders and executes driver initialization functions through specially defined macros and linker sections, improving maintainability, memory usage, and system stability during the boot process.
This guide shows how to check a KVM virtual machine's disk format, convert raw images to qcow2, create and list snapshots, revert to a specific snapshot, and delete snapshots using qemu-img and virsh commands on a Linux host.
This article walks you through configuring a Linux virtual machine's network settings, covering dynamic IP setup, static IP assignment with gateway and DNS, and hostname changes, using command‑line edits and verification commands to ensure connectivity.
This guide explains Linux file permissions, covering the concepts of read, write, and execute rights, symbolic and numeric representations, the chmod command, special bits like setuid, setgid, and sticky, default permissions controlled by umask, ownership management with chown/chgrp, and an introduction to ACLs for fine‑grained access control.
This guide compiles a comprehensive set of Linux command‑line utilities—including shell quoting rules, environment handling, text processing, process management, system monitoring, networking, and /proc filesystem exploration—to help sysadmins diagnose, locate, and resolve a wide range of system issues efficiently.
This guide explains how to set password expiration periods, minimum length, and complexity requirements on Linux systems by editing /etc/login.defs and PAM configuration files, with example commands and recommended values.
This guide walks you through essential Linux command‑line utilities for network troubleshooting, system monitoring, and developer workflows, providing clear usage syntax, practical examples, and concise tips to help you diagnose connectivity issues, inspect logs, and boost productivity on any Linux host.
This guide explains how to expose an internal‑only server to the Internet by deploying Squid HTTP and HTTPS proxies on two public servers, configuring stunnel on the client, adjusting firewall rules, and testing connectivity for both ports.
This guide provides a comprehensive overview of essential Linux text‑processing commands—including grep, cut, sort, uniq, tee, diff, paste, and tr—detailing their key options, usage examples, and practical tips for efficiently searching, extracting, sorting, comparing, merging, and transforming file contents.
This guide compiles around 70 essential Linux command‑line utilities, covering navigation, file manipulation, text processing, permission handling, user management, archiving, disk operations, and system monitoring, with clear examples and practical tips for newcomers to master the shell.
This article explains Linux's paging mechanism, covering the basics of virtual memory, page tables, multi‑level paging structures, virtual memory layout, allocation and reclamation strategies, and the performance and security benefits that paging brings to modern operating systems.
A Spring Boot application on CentOS 6.x hung while fetching Apollo configuration because a single /etc/hosts entry listed dozens of domain names, causing hostname resolution to fail; splitting the entry into multiple lines restored normal startup and highlighted a kernel‑specific hosts parsing bug.
This tutorial walks you through downloading, installing, and configuring Syncthing on both master and slave servers across Windows, Linux, and Raspberry Pi, covering web UI access, device ID pairing, folder setup, sync interval tuning, and verification of bidirectional synchronization.
An in‑depth overview of the Linux kernel MemBlock allocator explains its purpose during early boot, its core data structures (memblock, memblock_type, memblock_region), initialization process, allocation strategies, key APIs such as memblock_add, memblock_remove, memblock_alloc, and how it hands off to the buddy system.
A detailed reference of Linux command-line utilities covering system information, shutdown, file and directory management, searching, mounting, disk usage, user and group administration, permissions, compression, package management, backups, networking, and other essential system administration tasks.
This guide walks through checking the current kernel, adding the ELRepo repository, listing available kernels, installing the latest long‑term 5.4 kernel on CentOS 7, setting it as default, removing old kernels, and verifying the upgrade after reboot.
This article explains how epoll works as Linux's high‑performance I/O multiplexer, compares it with select and poll, details its three‑step workflow, data structures, code examples, and the trade‑offs between level‑triggered and edge‑triggered modes for building scalable network servers.
Learn how to automate MySQL database backups on both Linux and Windows by using a Python script that leverages mysqldump on Linux and a batch file for Windows, including directory management, retention policies, and execution commands to keep your data safely archived.
This article introduces MySQL performance tuning utilities—including mysqltuner.pl, tuning-primer.sh, pt-variable-advisor, and pt-query-digest—provides download and usage commands with report‑analysis guidance, and then shifts to promotional content for ChatGPT‑4.0 services, a paid community, and related offers.
The article explains how the Earliest Eligible Virtual Deadline First (EEVDF) scheduler, introduced in Linux 6.6, replaces CFS by using virtual deadlines and a lag concept to achieve both fairness and interactivity, and walks through concrete formulas, parameter settings, and step‑by‑step scheduling examples.
This article explains the principles, advantages, and implementation details of Linux's epoll I/O multiplexing mechanism, compares it with select and poll, describes its level‑ and edge‑triggered modes, and provides practical C and Python examples for building high‑concurrency network servers.
This tutorial walks you through checking the current OpenSSH version, installing prerequisite packages, backing up existing SSH files, compiling and installing OpenSSH 8.4p1, verifying the configuration, restarting the service, and confirming the upgrade on a CentOS 7 server.
This guide explains how to use Linux commands such as netstat, ss, lsof, fuser, and nmap to inspect port usage, interpret their output fields, and install missing tools, enabling you to pinpoint which processes are occupying specific ports.
The article explains how Linux's Completely Fair Scheduler (CFS) uses nice values and weight tables to compute virtual runtime, organizes tasks in a red‑black tree, and demonstrates through experiments how SCHED_NORMAL, SCHED_BATCH, and SCHED_IDLE differ in priority, preemption rules, and CPU share.
This article details a real‑world Linux server breach, describing the symptoms, investigative commands, log analysis, malicious script removal, file attribute unlocking, and practical remediation steps, while highlighting key lessons and preventive measures for future security.
This comprehensive guide explains Linux Logical Volume Manager (LVM) concepts, terminology, installation, essential commands, and step‑by‑step procedures for creating, extending, reducing, migrating, and snapshotting physical, volume, and logical volumes, empowering system administrators to manage storage flexibly and safely.
This article provides a comprehensive guide to Linux resource limits, covering the role of /etc/security/limits.conf and its overrides, proper ulimit configuration, temporary versus permanent settings, common commands, and how systemd services manage their own limits.
In the early 1990s Linus Torvalds announced a free, Minix‑inspired monolithic kernel for i386 machines, sparking a heated debate with Minix creator Andrew Tanenbaum who championed microkernels, yet despite Tanenbaum’s criticism the monolithic design persisted and rapidly evolved into today’s dominant Linux operating system.
A comprehensive reference of essential Linux commands covering system information, shutdown, file management, searching, mounting, disk usage, user and group handling, permissions, package management, backup, networking, and common utilities for effective system administration.
This guide explains Linux file permissions, covering the concepts of read, write, and execute bits, the UGO model, symbolic and numeric chmod usage, advanced bits like setuid, setgid, sticky, default permissions via umask, ownership changes, and an introduction to ACLs.
This guide explains the Linux grep command, detailing its purpose, syntax, and a comprehensive list of options such as -i, -r, -c, and -w, followed by practical examples that demonstrate searching for strings, handling case sensitivity, counting matches, recursive directory scans, and displaying context lines.
This guide compares Linux's locate and find utilities, explaining their performance characteristics, usage options, and advanced search criteria so you can choose the right tool for quick, fuzzy, permission‑aware file discovery and automated processing.
thefuck is an open‑source command‑line utility that detects common typing and syntax errors in terminal commands, suggests the correct command (e.g., fixing “pathon” to “python”), and can be installed on Linux, macOS, and Windows via package managers or pip, with simple configuration for automatic use.
This guide explains how to use tcpdump for network packet capture, covering basic and advanced filtering options, interface selection, host and port targeting, saving captures to files, and a real‑world troubleshooting scenario involving a Node.js server behind Nginx.
The article explains the meaning of a process being in the “D” state on Linux, describing it as an uninterruptible sleep caused by blocked I/O, how to identify it with tools like ps or top, why it cannot be killed, and common troubleshooting steps.
This article compiles a concise reference of fifty commonly used Linux commands, detailing each command’s purpose, typical usage syntax, concrete examples, and handy tips to help developers and system administrators quickly master essential command‑line operations.
This article provides a comprehensive analysis of the Linux kernel's task_struct data structure, detailing its members such as task IDs, parent‑child relationships, state flags, credentials, scheduling information, signal handling, memory and file management, kernel stack layout, and its role in process creation via system calls like fork.
This article explains the Linux kernel bitmap data structure, its definition, macro-based declarations, related assembly instructions, core bitmap APIs such as set_bit and test_bit, various bit‑operation functions, and practical applications ranging from PID allocation to device management and file‑system indexing.
This article provides a comprehensive overview of ftrace, explaining its architecture, tracer types, configuration steps, and practical usage examples for debugging, performance analysis, and kernel development on Linux systems.
This guide walks you through Tomcat’s overview, multiple installation methods, essential configuration files, port settings, virtual‑host setup, and how to combine Tomcat with Nginx for static‑dynamic separation, providing a complete Linux‑based deployment workflow.
This guide walks you through creating a non‑root sudo user, configuring its password and group, disabling root SSH access by editing sshd_config, and restarting the service, ensuring secure remote login on Linux systems.
The article announces a free programmer book giveaway via a backend command and then introduces Wubuntu, a Windows‑styled Ubuntu distribution that fully replicates Windows UI, runs without TPM or Secure Boot, supports Windows .exe/.msi and Android apps, and provides download links for its free and professional editions.
This article presents a curated list of 50 common software testing interview questions covering API automation frameworks, performance testing, essential Linux commands, and efficiency‑boosting tools and methods, providing concise answers to help candidates demonstrate their technical expertise.
This guide explains Linux user types, the structure of /etc/passwd and /etc/shadow files, and provides detailed examples of using useradd, usermod, passwd, and userdel commands to create, modify, lock, and delete user accounts.
This article demonstrates how to write an eBPF program that attaches to Linux soft‑interrupt entry and exit points, records timestamps in eBPF maps, computes handling duration, updates counters and histograms, and exposes the data to user space for performance analysis.
This article provides a comprehensive overview of Linux socket programming, covering socket definitions, classifications such as stream, datagram, and raw sockets, connection-oriented versus connectionless communication, IP/port/MAC addressing, byte order considerations, and practical C API examples for creating and using sockets.
Learn how to install, configure, and operate the ELK stack—Elasticsearch, Logstash, and Kibana—by following detailed steps for preparing servers, setting up each component, tuning performance, deploying plugins, and testing log collection and visualization, enabling efficient log management and analysis.
This guide explains what SSH (Secure Shell) is, details its encryption handshake process, shows how to log in via command line, outlines key server configuration options, and demonstrates setting up password‑less authentication using key pairs.
The article explains how Linux systems can determine whether they are running inside a virtual machine or container by using the systemd‑detect‑virt command, inspecting DMI sysfs files, and checking for hypervisor identifiers such as VirtualBox, VMware, QEMU, or Docker.
This guide explains the differences between firewalld and iptables on CentOS 7, introduces zone management, details iptables packet flow, tables, chains, and provides practical commands for installing, configuring, and managing firewall rules, including examples for SSH and ping traffic.
This article provides a comprehensive walkthrough of Keepalived, covering its VRRP‑based address failover, architecture components, installation methods, detailed configuration files, notification scripts, logging, unicast/multicast settings, brain‑split prevention, and practical LVS‑Keepalived high‑availability deployment steps.
This article explains Docker's core technology by detailing how Linux namespaces—PID, Network, Mount, UTS, IPC, and User—provide process, network, filesystem, hostname, inter‑process communication, and security isolation for containers, including the underlying implementation via nsproxy and code examples.
This article explains what programs and processes are, details process states and types, shows how to view and control processes with commands like ps, top, pgrep, pstree, free, iostat, and iotop, and covers manual start, termination, and scheduling of tasks on Linux.
This guide compares Linux’s locate and find utilities, explaining their performance characteristics, usage options, search criteria, and actions, while providing practical examples and tips for efficient file searching and manipulation on Unix-like systems.
This article provides a comprehensive overview of the Linux ptrace system call, explaining its role in process debugging, detailing request parameters, demonstrating practical C examples for tracing system calls, single‑stepping, setting breakpoints, and exploring how DWARF debugging information links source code to executable addresses.
This guide explains how to use iostat and related Linux commands to monitor I/O performance, interpret key metrics such as %util, await, and svctm, and apply practical analysis and optimization techniques for diagnosing and resolving storage bottlenecks.
This guide explains how to identify high CPU usage caused by mining trojans on Linux servers, isolate and block malicious network traffic, clean scheduled tasks, startup services, compromised libraries, SSH keys, and finally terminate and delete the malicious processes and files.
This article explains the Linux kernel buddy system, detailing its data structures, initialization, allocation and free processes, and discusses its advantages and drawbacks in managing physical memory and reducing fragmentation.
Naver, Korea’s internet powerhouse, has launched its own RHEL‑compatible Linux distribution called Navix, offering a decade of free support and targeting developers, enterprises, and HPC users, while also showcasing the company’s massive data‑center capabilities and cloud integration.
This comprehensive guide explains every step of how a browser retrieves a webpage—from DNS lookup and TCP handshake to HTTP request handling—while also covering DNS hierarchy, terminology, using dig for tracing, and practical setups of BIND and dnsmasq DNS servers on Linux.
Zero‑copy eliminates CPU‑mediated data copies between user and kernel spaces by using DMA and memory‑mapping, dramatically improving I/O performance, reducing context switches, and enabling high‑throughput applications such as file servers, Kafka brokers, and Java networking frameworks.
The article explains how Linux, especially the Deepin distribution, offers a full graphical desktop, supports everyday development tools, runs Android apps efficiently, and provides numerous advantages such as elegance, efficiency, command‑line power, and freedom, making it a viable alternative to Windows for many users.
This guide explains Linux inter‑process communication (IPC) mechanisms—including anonymous and named pipes, signals, file‑based communication, semaphores, various shared‑memory techniques, message queues, TCP/UDP sockets, and Unix domain sockets—providing concepts, typical use cases, and complete C code examples for each method.
