This article explains PHP's pcntl_fork() function, how it creates child processes on Linux, the return values in parent and child, code examples demonstrating variable copying and process multiplication, and clarifies why a loop with three forks results in seven child processes.
Learn how to install Tmux on various Linux distributions, create and manage named sessions, split and navigate panes, synchronize commands across panes, and safely detach, attach, or kill sessions, with clear command examples and shortcuts for efficient terminal multiplexing.
This comprehensive guide explores Linux’s core concepts—from its UNIX heritage and system architecture to process creation, inter‑process communication, scheduling, virtual memory, file‑system design, I/O handling, networking, loadable modules, and the security model that governs users, permissions and privileged operations.
This article shares a step‑by‑step Linux incident‑response workflow, including an automated Bash information‑gathering script, analysis of malicious cron jobs and a 439‑line mining malware, its SSH‑based lateral spread, and practical cleanup procedures with a reusable toolbox on GitHub.
Android inherits Linux file descriptors, which are indexed by non‑negative integers and limited per process, and this article explains their kernel structures, common leak sources such as HandlerThread eventfd, unclosed streams, and SQLite cursor windows, plus practical commands and monitoring techniques to detect and fix FD leaks.
The article introduces duf, a Go‑based disk usage and free space viewer for Unix‑like systems, explains its features such as colored, resizable output, sorting and JSON mode, and provides step‑by‑step installation instructions for Debian/Ubuntu, RPM‑based distros, Arch AUR, Termux, macOS, FreeBSD, and Windows, plus usage examples and customization options.
An in‑depth look at the core differences between Linux and Windows kernels, covering kernel fundamentals, user‑ versus kernel‑space, system calls, Linux’s monolithic design with multitasking, SMP and ELF format, and Windows NT’s hybrid architecture with the PE executable format.
This article presents a concise, beginner‑friendly list of the most useful Linux command‑line utilities, explaining each command’s purpose and syntax to help newcomers transition from Windows to Linux and become comfortable with terminal operations.
This article provides two practical approaches, complete with theory, kernel tuning, source code links, and detailed step‑by‑step commands, enabling readers to set up and verify one million concurrent TCP connections on Linux systems.
This article explains how to view a machine's IP address on Windows and Linux, describes the structure and classification of IPv4 addresses, introduces CIDR subnetting, distinguishes public and private IP ranges, and clarifies the role and format of MAC addresses.
This guide introduces duf, a Golang‑based command‑line utility that displays disk usage across Linux, macOS, BSD, Android and Windows, explains its key features, provides step‑by‑step installation methods for various distributions, and demonstrates common usage options and output formats.
This guide explains the ldd command, its underlying environment variables, available options, and practical examples, showing how to safely display a program's shared library dependencies without executing the program itself.
This article explains the concepts of Linux hard and soft (symbolic) links, demonstrates how to create and inspect them with the ln command, and outlines their characteristics, advantages, and limitations compared to Windows shortcuts.
This article explains the architecture and design of Deepin's desktop operating system, covering its core components, programming languages, desktop environment layers, display manager, session daemons, UI services, bundled applications, and the rationale behind building a custom desktop environment for better user experience.
This guide walks through creating an Oracle RAC on Oracle Cloud, covering account setup, virtual network configuration, SSH key creation, cluster provisioning, Flex ASM features, high‑availability service setup, and troubleshooting steps, all illustrated with command examples and screenshots.
This article introduces the Python‑based WebSSH tool that lets you access Linux machines through a web browser, outlines its key features, provides step‑by‑step installation and service‑startup commands, and explains how to configure root login for seamless remote management.
This guide walks you through installing JumpServer—a secure bastion host—on CentOS, covering architecture overview, MariaDB and Redis setup, Docker configuration, container deployment, key generation, UI access, and essential administration tasks such as user, asset, and permission management.
This guide provides a comprehensive overview of common Linux compression and decompression utilities—including gzip, bzip2, zip/unzip, xz, and tar—detailing their descriptions, key options, usage examples, and tips for handling files and directories efficiently.
This comprehensive guide explores Linux's four main components—kernel, shell, filesystem, and applications—detailing kernel architecture, memory and process management, VFS, device drivers, networking, file types, directory structures, mounting, and practical commands for managing partitions and links.
This tutorial explains what HAProxy is, its core capabilities and key features, provides step‑by‑step instructions for installing and running it on CentOS 7, demonstrates how to build both L7 and L4 load balancers, details essential configuration options, and shows how to achieve high availability with Keepalived, all illustrated with practical code examples and screenshots.
Learn how to define, modify, and apply Linux environment variables permanently for all users or individually, as well as temporary session variables, with clear examples of editing /etc/profile, .bash_profile, .bashrc, and using export, echo, and other common commands.
This guide explains what Filebeat is, how it fits into the Beats ecosystem, its architecture and processing flow, installation steps, key configuration options, keystore usage, and practical examples of sending logs to Logstash or Elasticsearch, helping you set up reliable log collection on Linux.
This guide walks through troubleshooting Kubernetes issues such as partially deleted resources, resetting etcd, apiserver start failures due to missing ServiceAccount certificates, SELinux permission errors, ServiceAccount key generation, etcd startup errors, host trust configuration, and resource limit pitfalls, providing concrete commands and scripts for each problem.
This article explains the differences between the traditional apt-get command and the newer apt command on Ubuntu and Debian‑based systems, covering their histories, command syntax, functional distinctions, new features, and practical recommendations for regular users on which tool to adopt.
This guide explains how to use MySQL’s built‑in mysqlslap tool and the third‑party sysbench utility to perform comprehensive database stress testing, covering configuration changes, command examples, result interpretation, and additional CPU and I/O benchmarks for accurate performance evaluation.
This article explains the Linux I/O stack, detailing how data moves from user‑space buffers through libc and page cache to the disk, covering system calls, synchronization primitives, scheduler behavior, consistency, safety, and performance considerations.
This tutorial introduces the most frequently used Linux commands—including pwd, cd, ls, touch, mkdir, cp, rm, mv, find, and du—explaining their purpose, options, and providing concrete shell examples to help beginners confidently navigate and manage files and directories.
This comprehensive guide covers Unix/Linux operating system fundamentals, file system structures, common commands, user and permission management, editor usage, remote access via SSH, file transfer, and building a simple C‑based web server, providing practical examples and step‑by‑step instructions for developers and system administrators.
This article compiles practical Linux shell commands for locating and moving files, batch extracting archives, using sed for text manipulation, checking directory existence, monitoring disk usage, analyzing logs, managing firewalls, and automating common sysadmin tasks, all presented with clear examples and explanations.
This guide walks through preparing a Linux server and client, adjusting kernel and user limits, configuring multiple IP addresses, and running PHP scripts to create and monitor up to one million concurrent TCP connections for performance testing.
This article explains the purpose of swap partitions, shows how to check current swap usage, and provides step‑by‑step instructions for creating swap space both via a dedicated disk partition and by using a swap file on a Linux server.
The article explains how to use the Linux commands ifconfig, ifup/ifdown, and route for querying and modifying network interfaces, IP addresses, subnet masks, MTU values, and routing tables, providing example usages and practical tips for immediate effect.
This article explains the five Linux I/O models—blocking, non‑blocking, I/O multiplexing, signal‑driven, and asynchronous—detailing their system calls, synchronization characteristics, and how they map to Java BIO, NIO, and AIO implementations, with illustrative analogies and usage scenarios.
This comprehensive guide walks you through Linux command line fundamentals, directory and file manipulation, text processing, compression, system installation, permission management, regular expressions, and disk operations, providing practical examples and code snippets for each topic.
Learn how to master Linux command‑line history by displaying timestamps, reverse‑searching, re‑executing previous commands, running specific entries, adjusting history size, renaming the history file, clearing records, and even disabling history altogether, all with simple shell configurations and commands.
This guide explains how to install the open‑source Zeit tool on Ubuntu 20.04, launch its graphical interface, and use it to create both one‑time and recurring scheduled tasks via the at and crontab back‑ends, complete with command examples and screenshots.
This guide explains how to install GNU screen, create shared sessions across multiple hosts, keep tasks running after network interruptions or window closures, and use screen's vertical split feature to manage multiple terminals within a single session.
This article explains the concept of per‑CPU variables in the Linux kernel, how they are defined with DEFINE_PER_CPU, linked into the .data..percpu section, initialized during boot, and accessed at runtime via the GS register and macro expansions such as this_cpu_read_stable.
This guide introduces Vim’s core concepts, explains each editing mode, and provides step‑by‑step commands for inserting, navigating, editing, searching, and visual selection, enabling Linux users to become proficient with this powerful text editor.
The article explains Linux zero‑copy I/O techniques—mmap, sendfile, splice, and tee—detailing their design principles, execution flows, context‑switch and data‑copy reductions, advantages, limitations, and appropriate use cases, helping developers choose the optimal method for high‑performance file and network transfers.
This guide explains the Linux stat command, its syntax and options, and provides step‑by‑step examples showing how to display detailed file metadata and filesystem information, with clear explanations of each output field.
This guide introduces the powerful Linux grep command, explains its regex-based searching capabilities, and walks through ten hands‑on examples—including filtering by keywords, context lines, line numbers, and exclusion—followed by a concise reference of the most useful grep options.
This guide walks you through using the systemctl tool on modern Linux distributions to start, stop, restart, reload, enable, disable, and query services, manage system power, work with targets, handle remote hosts, and leverage related utilities like journalctl, systemd-analyze, and hostnamectl.
This guide walks through the concepts, volume types, and step‑by‑step commands needed to set up a highly available GlusterFS distributed storage cluster, configure various volume layouts, integrate NFS‑Ganesha for NFSv4 access, and mount the storage on clients using both GlusterFS and NFS protocols.
This article explains how Linux, combined with open‑source tools like LibreOffice, Abiword, Gnumeric, and Pandoc, can dramatically boost developers' efficiency by streamlining document handling, enabling powerful command‑line workflows, and offering lightweight alternatives to traditional office suites.
This article explains the complete Linux operating system boot sequence using CentOS 6 and CentOS 7 as examples, covering BIOS initialization, GRUB, kernel loading, runlevels, systemd, and final login steps in a clear, step‑by‑step manner.
This guide explains what MTR (My Traceroute) is, how to install it on Windows, Linux, macOS, and Android, demonstrates basic usage, details its output columns and command‑line options, and shows how to interpret loss and latency data to troubleshoot network problems.
This article explains why the “Too many open files” error occurs on Linux, analyzes the three related kernel parameters (fs.nr_open, nofile, and fs.file-max), shows the relevant source code, and provides step‑by‑step configuration guidance to safely increase file descriptor limits.
This guide walks you through installing NVIDIA drivers, CUDA, and nvidia-docker2 on a Linux host and configuring Docker containers to access the GPU, including verification steps and sample TensorFlow and PyTorch commands.
This article introduces essential concepts behind operating system startup—including BIOS, UEFI, MBR, GPT, and the GRUB bootloader—explaining their roles, differences, and how they interact to enable Linux (and other OS) boot processes on modern hardware.
This guide shows Linux administrators how to use the versatile find command to locate files by name, type, size, modification time, permissions, and combined criteria, and demonstrates common actions such as listing, deleting, and executing commands on the results.
This guide explains Linux environment variables, covering system‑wide and user‑specific permanent settings, temporary shell variables, common variables like PATH and HOME, and essential commands for viewing, modifying, and managing them effectively.
This guide explains how to configure ClamAV on Linux, run the clamdscan command to detect malicious files, and invoke the scanner from PHP using the exec function, including sample configuration and output details.
This guide walks through setting up a three‑node Zookeeper ensemble, configuring ActiveMQ with replicated LevelDB storage, and starting the services on each host, providing full command‑line steps, configuration snippets, and verification screenshots for a production‑grade deployment.
The Linux 5.8 kernel, despite its record‑breaking size, remains maintainable thanks to a disciplined Git‑based workflow that follows seven fundamental principles, continuous testing, and a culture of trust that together set a gold standard for large‑scale open‑source development.
This guide explains why regular backups are essential on Linux and provides step‑by‑step commands for creating full system archives with tar, cloning disks with dd, synchronizing files with rsync, and performing image‑based restores on new machines.
The article explains how China’s homegrown UOS, built on a Linux kernel and evolving from Deepin, aims to reduce reliance on Windows, outlines its versions and user feedback, and discusses the challenges and future prospects of expanding its ecosystem.
This article walks through a real‑world LNMP case where slow backend responses and 502 errors were diagnosed and resolved by analyzing Nginx logs, increasing file descriptor limits, adjusting FastCGI timeouts, and fine‑tuning PHP‑FPM settings, followed by performance testing with ApacheBench.
This guide shows how to manually install and configure systemd-timesyncd on Ubuntu or Debian, choose reachable NTP servers for China, restart the service, verify synchronization, and provides a list of domestic Alibaba Cloud NTP servers.
The article explores China’s domestically developed UOS operating system—its Linux‑based origins, evolution from Deepin, multiple consumer editions, current compatibility with Windows applications, and the challenges and prospects for broader adoption in a Windows‑dominated market.
This article provides a comprehensive, step‑by‑step walkthrough of how Linux handles system calls, covering the low‑level assembly entry point, register conventions, the sys_call_table registration process, struct pt_regs usage, and a practical write‑syscall example with a custom extension.
Learn how the nohup command lets Linux processes ignore SIGHUP, run in the background, and continue after terminal closure, including syntax, options, output redirection behavior, and practical examples for reliable background execution.
This guide reviews three popular graphical SSH tools for Linux—PuTTY, EasySSH, and Terminator—covering their key features, installation steps, usage tips, and security considerations to help system administrators choose the most efficient solution for managing multiple remote servers.
This guide details how to set up a high‑availability RocketMQ cluster with two name servers and four brokers across two Linux hosts, covering directory preparation, configuration file edits, service startup commands, and verification of the deployment.
Discover four essential Linux monitoring utilities—iotop, htop, IPTraf, and Monit—that help quickly diagnose I/O, CPU, memory, network traffic, and process health, offering detailed per-process insights and flexible alerting for effective system management.
This guide explains how to configure MySQL for high‑concurrency testing, use the built‑in mysqlslap tool and the third‑party sysbench utility to benchmark read/write performance, CPU, I/O, and memory, and interpret the resulting metrics for database optimization.
This guide explains how to install tmux on CentOS, create and name sessions, detach and reattach them, list existing sessions, and use keyboard shortcuts to open, switch, split, and close windows, providing practical commands and visual examples for seamless terminal multiplexing.
This article provides a detailed, step‑by‑step walkthrough of the Linux kernel’s packet‑receiving path, covering NIC DMA, hardware and soft interrupts, ksoftirqd threads, NAPI polling, protocol‑stack registration, IP/UDP processing, and the final recvfrom system call that delivers data to user space.
An infected Linux server shows high CPU usage but standard tools miss the culprit; this guide explains how mining malware hides its process via /proc tricks, demonstrates detection using network scans, unhide tools, and offers removal steps to eradicate the hidden miner.
This guide walks through downloading the Jira Server installer, setting up a PostgreSQL database, executing the installation, opening required ports, adding the Atlassian agent for licensing, and completing initial configuration to get Jira Software 8.13.2 running on a Linux server.
This article provides a thorough, step‑by‑step guide to using the Linux sar command for real‑time and historical monitoring of CPU, memory, I/O, and network statistics, including syntax, sample outputs, installation tips, common pitfalls, and data‑export techniques.
This article explains how to configure Linux network settings, describes the contents of key configuration files such as ifcfg, /etc/resolv.conf, and /etc/hosts, and introduces routing concepts, static and dynamic routes, gateways, IP/MAC headers, CIDR, and common virtual networking methods.
A concise reference of the most useful Linux shell commands—from file searching and process management to networking and file compression—explains syntax, common options, and practical examples to help developers interact efficiently with Linux servers.
This article traces Linus Torvalds' journey from studying operating systems with Minix to creating the Linux kernel, highlighting the technical choices, community dynamics, and historical factors that turned a personal project into the foundation of modern open‑source computing.
This guide walks you through installing the interactive TLDR client Tldr++, explains its usage for quickly learning Linux commands, and demonstrates a complete workflow of downloading, extracting, and moving files—all without leaving the terminal.
This article explains why using the forceful kill -9 command to stop Linux processes can cause data loss and inconsistent states, especially in distributed systems, and demonstrates several graceful shutdown methods for Spring Boot—including SIGTERM, ConfigurableApplicationContext.close(), Actuator shutdown endpoints, custom Tomcat connector handling, and @PreDestroy data‑backup hooks—complete with code examples and execution logs.
A 16‑year‑old developer repurposed a non‑functional iPhone 7 with a dead NAND chip by installing Ubuntu 20.04 using checkra1n, linux‑sandcastle and custom udev scripts, turning the device into a functional server that offloads load from his main machine.
This guide introduces Linux as the leading server OS, explains its top‑level directory hierarchy, outlines essential command syntax and file‑permission concepts, and provides a concise overview of Vim’s modal editing commands, all illustrated with clear examples and diagrams.
The article explains Google’s GKI transformation requirements—preserving a stable Kernel Module Interface, using only exported and whitelisted symbols, employing vendor hook mechanisms for custom SoC/OEM code, detecting interface mismatches, and offering alternatives such as padding macros and existing kernel event registration to avoid breaking KMI.
This article explains the fundamentals of IO events and multiplexing, compares thread‑based and event‑driven architectures, details the Reactor pattern variants, and clarifies synchronous versus asynchronous IO, providing a practical guide for building high‑performance network frameworks in Linux environments.
This guide explains how to install GNU Screen, create and share sessions across multiple hosts, keep long‑running commands alive after network loss or window closure, and use Screen's split‑screen feature for multitasking in a Linux terminal.
This article explains why file writes are non‑atomic, illustrates the risks of partial writes, and details how journaling (write‑ahead logging) and its variants—data and metadata journaling—ensure filesystem consistency and performance on Linux systems.
The article explains how the Linux kernel discovers and calls module initialization functions like inet_init by using the fs_initcall macro, which creates static initcall variables placed in specially‑named sections that the linker groups and the kernel iterates at boot time.
This article explains how Linux 3.10 organizes memory using NUMA nodes, zones, the buddy system, and the SLAB allocator, providing commands, code examples, and visual diagrams to illustrate each layer of the kernel's efficient memory management.
This article explains the Linux kernel memory management hierarchy—including NUMA nodes, memory zones, the buddy system for free pages, and the SLAB allocator—providing command‑line examples, code snippets, and visual diagrams to illustrate how the kernel efficiently allocates and reclaims memory.
This article explains common awk built‑in variables such as OFS, NR, and NF, demonstrates practical awk one‑liners for extracting and formatting /etc/passwd data, and shows how to use netstat (and ss) together with awk to monitor network connection states on a Linux system.
This guide walks Linux operations engineers through common signs of a compromised host—such as missing logs, altered password files, unexpected login events, and deleted critical files—and provides concrete command‑line techniques for detection, investigation, and recovery using tools like ll, du, lastlog, who, lsof, and tcpdump.
This guide outlines comprehensive Linux security hardening steps—including account protection, service minimization, password policies, sudo usage, file system safeguards, rootkit detection tools, and post‑attack response—to help operations teams secure their servers against common threats.
This article introduces the five Linux I/O models—blocking, non‑blocking, I/O multiplexing, signal‑driven, and asynchronous—explaining core concepts such as blocking vs non‑blocking calls, synchronous vs asynchronous processing, and detailing each model’s execution phases, advantages, and typical use‑cases.
Teen developer Daniel Rodriguez repurposes a non‑functional iPhone 7 by jailbreaking it, building a custom Ubuntu 20.04 root filesystem, compiling a tailored kernel, and using projectsandcastle and PongoOS to boot Linux, effectively turning the device into a networked ARM64 server.
This guide explains how to configure Ansible inventory, write a YAML playbook that updates the root password on two servers, execute the playbook, and verify the password change through SSH login, illustrating a flexible automation workflow for multi‑host deployments.
This guide introduces the most useful Linux text‑viewing commands—including cat, tac, more, less, head, tail, sort, sed, uniq, and vi—explaining their basic syntax, common options, and practical examples for efficient file inspection and manipulation.
This guide explains how to set up SSH certificate‑based authentication by creating a Certificate Authority, generating user and host keys, signing certificates, configuring both server and client to trust them, and managing revocation, offering a more secure alternative to password or key‑pair logins.
This guide walks through preparing the Linux environment on Kubernetes master and node machines, creating a bare Git repository, configuring SSH access, cloning the repository, and demonstrating core Git commands such as add, commit, status, diff, and push to a remote server.
This guide shows how to transform an outdated 2011 13‑inch MacBook Pro into a usable Linux machine by creating a Fedora 33 live USB, installing the OS, and configuring the Broadcom Wi‑Fi driver, all within about an hour of work.
This article explains how to use the Linux export command to set and view environment variables, demonstrates common options such as listing all exports, exporting specific variables, exporting functions, and shows how to persist settings in shell configuration files, providing practical examples for beginners.
This guide walks you through configuring SSH key‑based authentication, generating a public‑private key pair, copying the public key to a remote server, and using ssh‑agent to cache your passphrase for seamless logins.
This guide walks through the complete GCC compilation pipeline—preprocessing, compilation, assembly, and linking—using a simple C "Hello World" program, detailing each step, relevant commands, and how to inspect the resulting ELF binary.
This article explains the layered design of Linux file I/O, describes how data moves from application buffers through libc, page cache, and kernel I/O queues to disk, discusses synchronization primitives, consistency issues, and performance factors such as scheduling algorithms and hardware characteristics.
This guide explains why password‑based SSH logins are insecure, introduces asymmetric key concepts, walks through generating key pairs with ssh‑keygen, uploading public keys manually or via ssh‑copy‑id, using ssh‑agent and ssh‑add to manage passphrases, and disabling password authentication for hardened server access.
