This guide walks through the most frequently used Ansible modules—including file, copy, yum_repository, yum, service, systemd, user, group, fetch, get_url, and setup—explaining their key options and demonstrating ad‑hoc command usage with complete code examples for Linux automation.
Learn how to use the Linux cut command for powerful text processing, including selecting character columns, ranges, specific fields with delimiters, complementing fields, changing output delimiters, and combining cut with other Unix tools such as grep, sed, and ps.
This tutorial explains what a VPN is, outlines its two main types, introduces OpenVPN, and provides detailed, command‑line instructions for installing, configuring, and testing both the OpenVPN server and client on a Linux environment.
This guide explains how to bind two network interfaces into a single virtual NIC on Linux using the bonding driver, covering supported modes, detailed configuration files, command-line steps, verification commands, and practical tips for ensuring high‑availability without IP duplication.
This guide shows how to create a Bash script that backs up a specific MySQL database using mysqldump, compresses the dump, automatically deletes old backups, explains the find -mtime option, and schedules the process with cron, plus detailed steps for restoring the data.
This article compiles 19 practical Linux, security, networking, and Python interview questions covering command‑line techniques, system monitoring, load‑balancing, HTTP protocols, common vulnerabilities, TCP handshakes, TIME_WAIT optimization, and code snippets to help candidates prepare for sysadmin roles.
This guide explains how to configure additional routing tables and policy‑based routes on a Linux server with two network interfaces, covering IP address inspection, routing table edits, ip rule commands, and persistence across reboots.
A practical guide explains how to use top, iostat, netstat, df, du and other common Linux commands to monitor CPU, memory, disk, and network status, interpret their output, and troubleshoot performance problems in production environments.
This comprehensive guide explains Linux permission fundamentals, user and group management, file permission modes, special bits like SUID, SGID and Sticky, hidden attributes with chattr/lsattr, ACL configuration, and privilege escalation using su and sudo, complete with practical command examples.
This article provides a comprehensive overview of Nginx’s high‑performance features, module architecture, process and I/O models, FastCGI integration with PHP‑FPM, configuration best practices, tuning techniques, and common error troubleshooting, offering practical guidance for optimizing and securing Nginx deployments.
This article compiles several Zhihu users' candid accounts of a typical Linux operations day, highlighting constant interruptions, emergency firefighting, performance tuning, monitoring, tool development, and a balanced time‑allocation strategy to make ops work more efficient and sustainable.
This article explains how to configure Docker and Containerd to use domestic image‑mirror services, providing detailed commands and verification steps that dramatically reduce image‑pull latency and improve development and operations efficiency in cloud‑native environments.
This article introduces Supervisor, a client‑server process monitoring tool for Unix-like systems, explains why it solves persistent process deployment issues, walks through installation, configuration, command‑line usage, advanced features such as process groups and auto‑restart policies, and provides code examples for practical implementation.
Learn how to install and use the Linux traceroute utility across Debian/Ubuntu and CentOS/RHEL systems, understand its basic syntax, explore common and advanced options, and see practical examples for network path diagnostics and troubleshooting.
This article explains what disks are, compares mechanical HDDs and SSDs, describes disk I/O concepts, outlines key performance metrics such as IOPS, throughput, utilization and latency, and introduces Linux tools like iostat, iotop, sar for monitoring and analyzing storage performance.
This guide explains how to install, use, and interpret the Linux route command for displaying and manipulating the kernel IP routing table, covering options, output fields, persistence tricks, and practical examples for querying, adding, deleting, and rejecting routes.
Version 1.2 of the Linux Emergency Handbook introduces critical updates such as SSH key backdoor checks, detailed command timestamp logs, new journalctl log viewing techniques, enhanced password checks, added data USB guidance, and revamped post‑incident stages including routine security checks, loss assessment, and targeted investigations.
This article defines Linux distributions, explains how they build on the open‑source kernel, and reviews ten popular distros—Linux Mint, Manjaro, openSUSE Leap, Elementary OS, Ubuntu, Fedora, Zorin OS, Debian, Pop!_OS, and MX Linux—highlighting each one's key features and ideal use cases.
This guide walks through SSH secure tunneling techniques—including local, remote, and dynamic (SOCKS) port forwarding—detailing command syntax, option effects, binding addresses, and practical examples for accessing otherwise unreachable services across network boundaries.
This guide walks you through expanding a Linux block device from 500 GB to 2 TB, adjusting the partition table with fdisk, resizing ext4 filesystems, remounting the volume, and configuring persistent or on‑demand mounts via fstab, rc.local, systemd, and autofs.
The article traces Azure’s evolution from a Windows‑only cloud to a platform that tests over a thousand Linux distributions monthly, detailing its Linux guest OS lifecycle, certification process, and the automated testing framework that ensures seamless large‑scale Linux operations on Azure.
This guide walks through a real‑world operations scenario, showing how to write and run a Bash script that uses the sort command with numeric and field options to correctly order a list of IP addresses for easier log analysis and network troubleshooting.
This guide explains how to declare, initialize, access, modify, iterate, measure length, and delete Bash arrays, and demonstrates practical scenarios such as file list handling, argument passing, and numeric calculations to boost script efficiency.
Virtio, the Linux standard I/O virtualization framework, uses a semi‑virtualized front‑end driver and back‑end device linked by virtqueues, works across hypervisors (e.g., QEMU/KVM) via PCI or MMIO, enabling high‑performance, low‑overhead device emulation—as illustrated by the virtio‑snd driver—while supporting cloud and Android virtualization scenarios.
This guide walks through practical Linux security hardening on RHEL7, covering TCSEC security levels, account lockdown, password policies, SSH hardening, SELinux activation, firewall minimization, immutable system files, and other configuration tweaks to raise the system to a B1 security rating.
This guide explains how to use Linux commands like df, du, find, lsof, and tune2fs to locate large directories, uncover deleted files that still occupy space, and adjust reserved root space, enabling you to resolve unexpected disk‑usage alerts efficiently.
Learn step-by-step how to prepare your Linux server, download and install Docker 20.10.24 manually, configure daemon settings, set up systemd service, start and verify the engine, and apply essential security and optimization practices for reliable production deployments.
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.
This guide shows how to set up a Ubuntu server and a CentOS client, install hping3 and netcat, and use them to reliably detect whether specific UDP ports are open or closed, interpreting packet loss, ICMP Port Unreachable, and connection refusal messages.
This guide explains the concept of Linux user namespaces, how they isolate UID/GID for Docker containers, the required subuid/subgid mappings, step‑by‑step daemon configuration, verification commands, and known limitations when using user namespace isolation.
This guide introduces five open‑source Linux utilities—NetHogs, nload, CBM, iftop, and iPerf—explaining their focus, usage commands, and how they help monitor process‑level bandwidth, interface traffic, and overall network performance in production settings.
This article provides an extensive collection of Linux command-line utilities covering system information, file management, networking, package handling, backup, and more, serving as a practical reference for developers and system administrators in daily operations.
This guide explains why zombie processes appear in Linux, demonstrates how to reproduce them with sample code, shows how to identify them using ps, discusses the system risks they pose, and provides proper cleanup techniques using wait/waitpid and parent termination.
The article traces Neofetch’s rise as a customizable Linux system‑info tool, details the sudden disappearance of its creator Dylan Araps, explains the 2024 repository archival with a farming note, and reviews emerging alternatives while reflecting on a broader trend of developers leaving tech for agriculture.
This guide explains the Linux /proc virtual file system, details the special role of /proc/self for accessing the current process's data, and provides command examples for retrieving cmdline, cwd, exe, environ, maps, and mem information.
When a VMware VM with a 200 GB system disk runs an 11 GB Docker service, it may report ‘no space left on device’ because the LVM logical volume for /var is only 1 GB, and the guide shows how to extend the relevant LVM volumes and resize the filesystems to resolve the issue.
This guide explains how to install the net-tools package, use the Linux route command to view the kernel IP routing table, add or delete static routes, make routes persistent, and interpret the output fields with practical examples.
This guide explains how to install the net-tools package, use the Linux route command to display the kernel IP routing table, and perform common operations such as adding, deleting, and rejecting routes with detailed option descriptions and practical examples.
This guide explains how to use the ssh -Q command to list all OpenSSH-supported ciphers, cipher‑auth methods, key‑exchange algorithms, public‑key types, certificate keys, MACs, protocol versions, and signature algorithms, providing concrete command output and common examples for each category.
This article provides a comprehensive guide to optimizing Kunpeng‑based servers, covering hardware characteristics, matrix multiplication benchmarks, Von Neumann architecture insights, soft and hard acceleration, compiler and JDK tweaks, NUMA tuning, Nginx and OpenSSL acceleration, disk and network optimizations, application‑level tuning, and a step‑by‑step MariaDB performance‑tuning checklist.
This article explains Linux's memory management architecture, covering physical memory organization, the buddy and SLUB allocators, virtual address spaces for user and kernel, page‑table translation, TLB caching, and the role of swap in virtual memory.
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.
