This article provides a comprehensive overview of the Linux /proc virtual filesystem, detailing how to mount it, the structure of its directories and files such as /proc/pid, /proc/self, and various system information files, and includes practical command examples and security considerations.
This article surveys the most popular Linux distributions—including Red Hat Enterprise Linux, Gentoo, Debian, Ubuntu, Linux Mint, Fedora, Kali Linux, CentOS Stream, Arch Linux, and OpenSUSE—highlighting their target audiences, key features, package management, and typical use cases for desktop, server, and security environments.
This guide explains how to monitor disk usage on CentOS 7, collect iostat, sar, and pidstat snapshots, troubleshoot at‑daemon issues, and finally use SystemTap’s inodewatch script together with kernel‑devel and debuginfo packages to pinpoint the exact PID that is writing to a specific file.
This article explains Linux network‑stack enhancements—RSS, RPS, RFS, accelerated RFS, and XPS—detailing their purpose, configuration steps, and recommended settings to improve parallelism and latency on multi‑CPU systems.
This guide explains how to use the Linux stress utility and the dd command, together with a custom shell script, to deliberately consume CPU, memory, disk space, and I/O resources for realistic load‑testing and performance analysis in production‑like environments.
This guide walks through installing Squid on Linux, configuring it as a transparent and reverse proxy, setting up internal and external hosts, adjusting routing and firewall rules, and applying common ACL parameters to control access and improve performance.
This article compiles seven hands‑on Linux performance‑optimization practices, covering key factors such as CPU, memory, disk I/O, network, swap usage, and TCP tuning, and provides concrete commands and step‑by‑step troubleshooting methods for system administrators and DevOps engineers.
The intermittent timeout between cloud host A and game server B was traced to the server’s net.ipv4.tcp_tw_recycle setting, which dropped SYN packets with non‑monotonic timestamps after NAT translation, and disabling this kernel parameter restored normal connectivity.
This article explains how Linux user namespaces isolate UID/GID for processes, shows how to map subordinate users via /etc/subuid and /etc/subgid, configures Docker's userns‑remap feature, verifies isolation with Docker daemon settings, and discusses known limitations.
This comprehensive tutorial explains how to set up and manage Linux disk quotas, logical volume management (LVM), and various RAID levels using command‑line tools, providing clear examples for checking kernel support, configuring limits, creating volumes, resizing, snapshotting, and handling RAID arrays.
The article explains the complete shutdown of CentOS, outlines viable alternative Linux distributions, and provides detailed guidance on planning and executing database migrations to ensure security, performance, and compatibility during the transition.
The latest Linux 6.10 merge introduces Rust language support for the RISC‑V architecture and expands Qualcomm Snapdragon X Elite features such as DisplayPort and eDP, while also noting a brief autumn recruitment reminder.
This guide explains how to configure Linux routing for multiple subnets by using the route command to add host routes, network routes, and default routes, detailing each option, required parameters, and how to verify or delete the entries.
This guide explains Linux's unified file concept, the hierarchical directory layout, the role of inodes in mapping logical to physical storage, and the differences between hard and soft links, providing clear examples and visual diagrams for each topic.
This guide explains what Linux distributions are, how open‑source licenses enable them, compares popular distros such as Ubuntu, Fedora, Mint, RHEL, SUSE and Kali, and helps newcomers decide which distro best fits their desktop, server or security needs.
This article provides a comprehensive, hands‑on tutorial for planning, installing, configuring, and verifying a PostgreSQL master‑slave (streaming replication) setup on two Linux nodes, including user creation, remote connection settings, data export/import, and troubleshooting tips.
Learn how to understand IPv6 address types, enable IPv6 support, configure static addresses on Debian/Ubuntu and CentOS/RHEL, verify settings, and test connectivity using Linux commands, with detailed examples and scripts for both global unicast and unique local addresses.
This comprehensive guide walks you through configuring Linux file‑sharing services—including anonymous and authenticated VSFTPD, mixed‑mode FTP, virtual users, SSL‑encrypted transfers, Samba shares, NFS exports, and iSCSI targets—covering installation, configuration files, firewall settings, user management, and client mounting procedures.
A Linux user’s attempt to clean /var/tmp with systemd‑tmpfiles --purge unintentionally deleted files in /home, exposing a documentation gap and prompting a GitHub discussion that led to clearer warnings and a protective pull request to prevent future data loss.
This guide explains Linux syslog fundamentals, common log file locations, their purposes, the roles of syslogd and klogd, how to configure rsyslog, set up log rotation with logrotate, and deploy a centralized log server for multiple hosts.
Ubuntu 24.04 LTS ‘Noble Numbat’ introduces the Linux 6.8 kernel, enhanced desktop installer, new GNOME desktop, performance‑engineered features like default frame pointers and bpftrace, updated developer toolchains for Python, .NET, Java, Rust, and fresh management tools for both desktop and WSL environments.
This tutorial explains Linux LVM fundamentals, covering physical volumes, volume groups, logical volumes, and physical extents, and provides detailed commands for creating, extending, shrinking, removing, and snapshotting LVM components with practical examples.
The article explains that CentOS Linux 8 ceased updates at the end of 2021 and CentOS 7 will reach end‑of‑support on June 30, 2024, describes the shift to CentOS Stream, and outlines several alternative operating systems—including Rocky Linux, Ubuntu, RHEL, and domestic Chinese distributions—providing guidance for enterprises and developers on migration paths.
This guide explains how to set up automated MySQL database backups using a shell script that runs mysqldump (optionally compressed), stores the files on a local disk, makes the script executable, and schedules it with a cron job after verifying disk space and cron availability.
This article explains Docker’s core isolation mechanisms, focusing on how Cgroups and PID namespaces create separate process spaces, demonstrating with Ubuntu container commands, and clarifying why each container sees its own PID 1 despite the host’s actual process IDs.
This guide explains how to enable VLAN tagging on a Linux server, create VLAN interfaces for different subnets, assign IP addresses, and make the configuration persistent on CentOS/RHEL systems using kernel modules, ip commands, and network‑script files.
This guide walks through practical steps to harden a RHEL7 Linux server—including account restrictions, password policies, SELinux enforcement, SSH port changes, firewall rules, and file attribute protections—using concrete commands and configuration edits to boost system security.
This guide introduces the most commonly used Linux command‑line tools for file handling, content viewing, system monitoring, networking, and permission management, providing clear examples and options to help users quickly become proficient in everyday Linux administration tasks.
When upgrading MySQL 8.0 to 8.4 on a host running multiple instances, some instances fail to start with a series of InnoDB errors caused by io_setup() returning EAGAIN, which can be resolved by increasing the system's aio‑max‑nr limit and adjusting InnoDB I/O thread settings.
This guide explains how to tune Tomcat 8.5 by adjusting server.xml parameters such as maxThreads, acceptCount, maxConnections, and connectionTimeout, while also covering related Linux kernel settings, file‑descriptor limits, and JVM options to achieve optimal concurrency and response times.
This tutorial walks through Docker privilege‑escalation techniques, showing how to enumerate Docker permissions, exploit docker group membership, use GTFOBins and LinPEAS, and break out of both privileged and non‑privileged containers to obtain a root shell on the host.
Debian developer Luca Boccassi announced that the Debian installer will support systemd‑boot, initially available only in expert mode, with plans to open it to all users after thorough testing and UEFI Secure Boot integration, while GRUB remains the default bootloader, expected in Debian 13 “Trixie” around 2025.
This comprehensive guide explains how the Unix find utility searches files and directories, covering its syntax, expression components, operator precedence, options, tests, actions, debugging techniques, and practical examples for advanced usage.
This guide explains multiple Linux techniques—including nologin shells, sshd_config allow/deny lists, and hosts.allow/hosts.deny rules—to prevent selected users, groups, or IP addresses from logging in via SSH, with practical commands, examples, and a ready‑to‑run script.
This article reviews Linux virtual memory layouts for 32‑bit and 64‑bit systems, explains the kernel and user address spaces, details how threads consume stack memory, and outlines both virtual‑memory and kernel‑parameter limits that affect the maximum number of threads a process can create.
This guide maps Linux kernel subsystems to key performance metrics and presents a curated set of CPU, memory, disk I/O, and network tools—complete with visual charts, metric explanations, and practical notes for effective system analysis.
This guide walks you through key Linux commands such as top, free, iostat, netstat, df, and du, explaining each output field, how to interpret system load, memory usage, CPU statistics, network connections, and disk space to quickly diagnose production issues.
This guide walks through enabling the Ceph NFS manager module, creating an NFS cluster, exporting a CephFS directory via NFS, mounting it from a client, verifying data consistency, and configuring high‑availability for the nfs‑ganesha service using haproxy and keepalived.
This guide explains how to fine‑tune Linux kernel settings—including sysctl network parameters, shared memory limits, local port ranges, and disk scheduler options—using configuration files and command‑line tools to improve system stability and throughput.
When multiple CentOS 7 servers in the same rack experience 30‑60 second delays before prompting for an SSH password, the slowdown is usually caused by reverse DNS lookups and GSSAPI authentication, which can be resolved by disabling UseDNS and GSSAPIAuthentication in sshd_config and restarting the service.
This guide introduces ShellCheck, a static analysis tool for Linux shell scripts, outlines its key features, shows how to install it on various distributions or use it online, demonstrates command‑line usage with a practical example, and explains integration with editors like VSCode.
This guide explains multiple techniques—nohup, disown, setsid, tmux, screen, and at—to run scripts in a Linux environment so they continue executing after the user logs out, providing command examples, usage details, and a comparison of terminal multiplexers for reliable background processing.
This guide explains the KDUMP mechanism in Linux, walks through configuring a crash kernel, setting up the KDUMP service, verifying the setup, and using the crash utility to analyze memory dumps with detailed command examples and practical use cases.
An introductory guide to Linux's man command explains its sectional organization, configuration file, essential navigation shortcuts, bookmarking, shell execution, and useful options like -a, -aw, -M, -k, and -f, helping users efficiently access and search manual pages.
This article explains how Ceph cache pools work, compares read‑only and write‑back cache types, provides step‑by‑step commands for creating and configuring cache pools, adjusting CRUSH rules to target SSDs, and outlines safe removal procedures for both cache modes.
Linux 6.10 adds a new DRM Panic infrastructure that displays a blue‑screen‑of‑death style message on kernel crashes, supporting drivers like SimpleDRM, MGAG200, IMX and AST, while systemd‑255 introduces an experimental systemd‑bsod component for emergency error reporting.
This guide walks through installing iptables, loading kernel modules, starting the firewall, mastering core iptables options, creating and managing rules for ports, IPs, and protocols, saving configurations, troubleshooting pitfalls, and provides hands‑on exercises for Linux network security.
This tutorial explains the fundamentals of DNS, introduces BIND components, walks through installing the bind package, configuring named.conf and zone files for forward and reverse lookups, adjusting network settings, and testing the DNS server on a Linux host.
Linux 6.10 adds a new DRM Panic infrastructure that displays a BSOD‑style screen on kernel crashes, supporting drivers like SimpleDRM, MGAG200, IMX and AST, while systemd‑255 introduces an experimental systemd‑bsod component for full‑screen emergency messages, offering a clearer way to diagnose panics.
This article explains the concepts, reasons, and implementation methods of Linux kernel synchronization, covering mutual exclusion, various lock types, compiler and memory barriers, atomic operations, semaphores, read‑write semaphores, and spinlocks with illustrative code examples and usage guidelines.
This guide explains the principles of MD5 and SHA‑512 checksums, demonstrates how to generate and compare them using Linux commands such as md5sum and sha512sum, and shows how to automate integrity verification for files like calico.yaml during transfer or backup.
This guide explains how to use ifconfig to view and modify network interfaces, manage them with ifup/ifdown, edit CentOS 7 configuration files, apply additional ip commands, and troubleshoot common VM cloning network issues.
This article walks through a real Linux kernel hard lockup case, explaining what hard lockup is, analyzing stack traces and register values, identifying a spinlock contention on a per‑CPU runqueue, and showing how an inappropriate GFP flag caused interrupts to be enabled at the wrong time, leading to a deadlock and the eventual fix.
This article explores essential Linux I/O techniques, covering basic file operations with system calls like open, read, write, and close, advanced methods such as memory‑mapped files and asynchronous I/O, network programming with sockets and multiplexing, plus performance‑tuning strategies for efficient resource utilization.
To handle high‑traffic web workloads, the default Linux kernel settings must be adjusted; this guide explains the key sysctl parameters—such as file‑max, tcp_tw_reuse, tcp_keepalive_time, and buffer sizes—and how to apply them for optimal Nginx concurrency.
This guide explains the concepts of network bandwidth, shows how to check physical and virtual NIC speeds on Linux using ethtool, dmesg, and mii‑tool, demonstrates real‑world throughput testing with iperf3, and provides tips for identifying network bottlenecks.
This guide walks through preparing three CentOS 7 nodes, installing Erlang and RabbitMQ, configuring users and permissions, setting environment variables, enabling the management plugin, synchronizing erlang.cookie, joining nodes in RAM or disc mode, and verifying cluster status via the web UI.
This guide walks you through preparing a Ceph cluster, enabling the NFS module, creating an NFS service with nfs‑ganesha, exporting a CephFS share, mounting it from a client, and configuring high‑availability using HAProxy and keepalived.
The article details the complete process of porting QQ's NTRTC audio/video SDK to Linux, covering platform surveys, packaging, build‑time issues like GLIBC mismatches and fPIC errors, debugging steps, Qt/Electron demos, GPU blocklist workarounds, and future compatibility plans.
This article explains the Linux thundering herd phenomenon, its impact on processes, threads, and epoll, demonstrates it with C code examples, analyzes system overhead, and presents mitigation techniques such as accept mutex, SO_REUSEPORT, and proper locking to improve server performance.
This guide explains Linux file permission concepts—including owner, group, and others—covers read, write, and execute rights, demonstrates how to view permissions with ls -l, and provides detailed usage of chmod and chown commands with symbolic and numeric modes.
This guide walks through setting up a Linux server and client, installing hping3 and netcat, and using them to reliably detect whether specific UDP ports are open or closed, including command examples, expected outputs, and troubleshooting tips.
This guide explains what rsync is, walks through cross‑compiling it for an ARM board, shows how to install the binary, and demonstrates practical file‑synchronization commands with detailed flag explanations.
This article explains common scenarios that cause MySQL or Java processes to consume 900% CPU, walks through step‑by‑step diagnosis using Linux tools, and provides concrete optimization techniques such as indexing, caching, thread analysis, and code adjustments to bring CPU usage back to normal levels.
An in‑depth comparison of PostgreSQL and MySQL covers their histories, ACID compliance, performance, scalability, advanced features, security, backup strategies, installation on Linux, and provides practical SQL code examples to help full‑stack developers choose the right open‑source relational database for their projects.
This guide walks through SSH secure tunneling techniques—including local, remote, and dynamic port forwarding—detailing command syntax, option usage, binding address considerations, and practical examples for accessing otherwise unreachable services through encrypted tunnels.
This article compiles several Zhihu contributors' insights explaining why Linux dominates modern server environments, covering historical Windows dominance, IIS shortcomings, licensing costs, ecosystem advantages, container support, and the broader shift toward open‑source infrastructure.
This article explains how to use the htop command to monitor CPU, memory, load average, uptime, and detailed process information in real time, and provides a full reference of its interactive keyboard shortcuts for efficient system management.
This article explains the fundamentals of VXLAN, compares it with VLAN, and provides step‑by‑step Linux kernel and Open vSwitch implementations, including configuration commands, packet‑flow analysis, and practical testing to demonstrate overlay networking in cloud environments.
German Linux‑hardware maker TUXEDO unveiled its ARM‑based “Drako” laptop at Computex, featuring a Qualcomm Snapdragon X Elite 12‑core CPU, 14‑inch 2560×1600 IPS display, 32 GB LPDDR5x RAM and PCIe Gen4 SSD, running the KDE‑Plasma TUXEDO OS ported to ARM, with Qualcomm’s upstream Linux support and collaborations with Lenovo, Arm and Linaro, and the first units slated for delivery by the end of 2024.
This guide explains the physical structure of mechanical hard drives, how data is organized into sectors, tracks, and cylinders, and provides step‑by‑step Linux commands for calculating disk capacity, creating MBR/GPT partitions, formatting filesystems, and managing swap space.
This guide explains Linux routing commands for adding host and network routes, setting default gateways, creating permanent static routes via rc.local, sysconfig files, and static‑routes, enabling IP forwarding, and demonstrates a dual‑NIC experiment using VMware and eNSP to achieve simultaneous internal and external network access.
Learn how to install Apache from source, understand its three MPM modes (prefork, worker, event), configure common server settings, set up port‑ and domain‑based virtual hosts, and deploy both static and dynamic (LAMP) websites with step‑by‑step command examples.
This article introduces RAID fundamentals, compares common RAID levels (0, 1, 5, 10), explains their performance and fault‑tolerance characteristics, and provides step‑by‑step Linux mdadm commands to create, inspect, and manage a RAID‑5 array, including simulating disk failures and recovery.
This guide presents twenty practical Linux command‑line shortcuts—from tab completion and directory navigation to history search and log monitoring—that help both beginners and seasoned users work faster, avoid common pitfalls, and streamline everyday terminal tasks.
This guide explains firewall fundamentals, classifications, and detailed usage of Linux iptables and firewalld commands, covering tables, chains, rule priorities, NAT/ SNAT examples, and zone-based configurations to help secure network traffic effectively.
This article explains the Linux OOM (Out‑Of‑Memory) mechanism, details how the kernel selects and kills the most memory‑hungry process, and shows practical steps to protect critical services from being terminated.
This guide walks through the complete Linux startup sequence, covering power‑on initialization, BIOS/UEFI boot, MBR/GRUB2 loading, kernel entry, init processes, ramdisk handling, run‑level configuration, fstab mounting, and user login mechanisms, illustrated with diagrams and key command references.
This guide explains why accidental database deletion is a serious risk, outlines essential permission and logging measures, and provides step‑by‑step scripts and cron jobs to automatically back up MySQL databases and critical files using Docker, OpenSSL, rsync, and expect.
This tutorial explains the Linux xargs command and provides six practical, step‑by‑step examples—including copying files, deleting by extension, compressing directories, renaming to uppercase, counting lines, and listing user accounts—to help automate common system tasks efficiently.
This guide explains how to configure both permanent and temporary environment variables on Linux for different shells (bash and csh), covering user‑specific and system‑wide settings, the required configuration files, and the exact commands to apply and verify the changes.
This guide explains how to use the Linux route command to display the IP routing table, install the necessary net‑tools package, and perform common operations such as adding, deleting, and blocking routes, including options for persistence and detailed output interpretation.
This guide walks through Linux primary and logical partition concepts, MBR structure, fdisk commands, creating and formatting partitions with XFS, automating mounts, handling large or faulty disks, and setting up swap space for virtual memory.
The article walks through the Flash Friendly File System’s on‑disk layout—zones, sections, segments, blocks, SuperBlock, checkpoint, SIT, NAT, and SSA—showing how formatting, mounting, creating, modifying, and deleting files updates these structures, offering a practical guide for kernel and storage engineers.
The article explains how to configure static and persistent routes on a Linux host using the route command, make them survive reboots via rc.local, sysconfig files, or sysctl, enable IP forwarding, and demonstrates a dual‑NIC experiment where a single static route lets the client access both external and multiple internal subnets.
This guide walks through installing Ansible via source, git or RPM, configuring its environment and SSH trust, adding hosts to the inventory, and testing connectivity with ping, providing essential commands and examples for effective automation on CentOS systems.
This article compiles over a thousand interview questions for operations engineers, covering operations fundamentals, Kubernetes, shell scripting, Linux, Docker, Jenkins, databases, and more, providing a comprehensive study guide for anyone preparing for DevOps or system administration roles.
This article explains Linux's page reclamation process, describing how the kernel recovers memory under pressure using PFRA, LRU algorithms, direct reclaim, compaction, and OOM handling, and provides detailed source code analysis of the involved kernel functions.
This guide explains Linux routing commands for adding host and network routes, setting default gateways, deleting routes, making routes permanent via rc.local, sysconfig files, and IP forwarding, and demonstrates a dual‑NIC experiment using VMware and eNSP to connect internal and external networks with step‑by‑step verification.
This guide walks you through installing Ansible on Linux, configuring inventory and settings, writing a basic playbook to deploy a web server, and executing it, while also covering variables, roles, templates, handlers, conditional tasks, and error handling for robust automation.
This article warns about ten extremely dangerous Linux commands—such as rm ‑rf, fork bombs, and disk‑wiping operations—explaining their destructive effects, how they work, and practical safeguards like using aliases or testing only in virtual machines to prevent catastrophic data loss.
This guide explains step‑by‑step how to install the GeoIP2 library, compile Nginx with the ngx_http_geoip2 module, download the MaxMind GeoLite2 database, configure Nginx to map country codes, and block non‑Chinese visitors by returning a 404 response.
This comprehensive guide introduces the 100 most frequently used Linux shell commands, covering file, directory, permission, network, process, system, and scripting operations with clear explanations and practical examples, helping both beginners and professionals improve efficiency and mastery of the command line.
This article explains the Linux /proc virtual filesystem, the special role of /proc/self for accessing the current process's information, and provides practical commands to read cmdline, cwd, exe, environ, maps, and mem files for system monitoring and debugging.
The article explains Linux kernel reverse‑mapping (RMAP), describing its purpose for efficient page‑reclaim, the underlying data structures such as vm_area_struct, anon_vma and anon_vma_chain, and shows how anonymous and file pages are tracked and unmapped through detailed code examples.
This tutorial explains how to capture live video from a camera with PHP, install necessary Linux drivers, extract frames using FFmpeg, and apply the Fer2013 emotion‑recognition model through a Python script to infer human emotions in real time.
This guide shows how to use df, du, find, and lsof commands to locate large directories, files, and deleted-but-open files that consume disk space, and explains how to adjust reserved filesystem space on Linux.
An inode is a crucial Unix/Linux filesystem structure that stores file metadata, links files to data blocks, and enables features like hard and soft links; this guide explains its role, composition, related commands, and how inode exhaustion can affect system storage.
Linux dominates modern server environments because its free, lightweight distributions and robust open‑source ecosystem outperform the costly, configuration‑heavy Windows/IIS stack, offering superior performance, native container support, and community‑driven innovation that overcame early Microsoft resistance and drove industry-wide adoption.
This guide explains what sersync is, its main features and use cases, and provides step‑by‑step instructions—including server preparation, rsync daemon setup, configuration files, password handling, and command examples—to deploy a real‑time file synchronization service on Linux.
