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.
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 guide walks through CentOS7 network configuration, explaining interface naming conventions, using NetworkManager tools like nmcli, editing ifcfg files, changing hostnames, renaming interfaces to eth0, adding kernel parameters, and applying changes with service restarts.
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 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.
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 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.
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 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.
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 guide explains what RAID is, outlines the benefits of different RAID levels, compares hardware and software implementations, and provides a step‑by‑step Linux tutorial for creating, monitoring, repairing, and removing a RAID10 array using mdadm.
This guide explains the purpose of NFS for Linux file sharing, its architecture and RPC relationship, step‑by‑step server and client deployment, integration with Nginx, and common troubleshooting techniques for reliable shared storage in production environments.
This guide explains where Linux network‑interface configuration files are stored, how to list and edit them, and the steps for setting up virtual machine networking and dynamic IP addresses, illustrated with command examples and screenshots.
This guide walks you through adding the required repositories, installing or uninstalling PHP 8.4 via WLNMP, configuring its files and disabled functions, managing the service with SysV or systemd, and upgrading or querying the installation on various Linux distributions.
Learn how to use essential Linux commands—lsmod, lsof, lspci, and lsscsi—to inspect kernel modules, open files, PCI devices, and SCSI devices, including syntax, useful options, and practical examples that illustrate interpreting their output for effective system administration.
This guide compiles the 20 most common Linux and Kubernetes troubleshooting commands, illustrating typical outputs and step‑by‑step diagnostic reasoning for high CPU load, disk pressure, network failures, pod crashes, node issues, service outages, database errors, and application performance problems.
This guide explains Linux user concepts, differences from Windows, how to view, create, modify, and delete users and groups, manage passwords, configure sudo and su for privilege escalation, and understand the critical /etc/passwd and /etc/shadow files, providing practical command examples and security tips.
Linux’s OOM Killer activates when memory is exhausted, scoring processes based on usage, priority, and kernel settings, then terminating the highest‑scoring one; the article explains its background, scoring algorithm, influencing parameters, and practical steps such as adjusting oom_score_adj, optimizing memory use, and using cgroups to safeguard essential services.
This guide explains Linux user and group classification, UID/GID ranges, the locations of account files, and provides step‑by‑step commands for adding, modifying, and deleting users and groups, as well as detailed coverage of file and directory permission concepts and special permission bits.
This guide explains Linux's multi‑user architecture, the meaning of UID/GID, how to view and edit /etc/passwd and /etc/shadow, and provides step‑by‑step commands for creating, modifying, and deleting users and groups, including su and sudo usage.
This article presents a detailed multi‑phase Linux learning curriculum, covering environment setup, basic and advanced command usage, system services, security, monitoring, high‑availability clustering, virtualization, containerization, cloud platforms, and provides extensive recommended reading links for further study.
This comprehensive guide walks you through Linux storage fundamentals, covering CHS terminology, partitioning with MBR/GPT, LVM creation and expansion, RAID levels, file system selection, mounting, swap handling, package management, private YUM repository setup, OSI layers, ports, TCP basics, and IP address classification.
This comprehensive guide explains Linux user and group concepts, classification, security contexts, essential configuration files, password policies, and detailed command examples for creating, modifying, and deleting users and groups, helping administrators efficiently manage system access and permissions.
This guide explains mounting USB storage, checking device status, configuring NTFS support, and creating, enabling, and disabling swap partitions or swap files on Linux, including practical commands and configuration steps for Ubuntu and CentOS.
Shortly after Microsoft released Windows Server 2025, many administrators discovered that their Windows Server 2022 machines were silently upgraded to the unlicensed 2025 version, exposing several known bugs, licensing issues, and a mis‑labelled update that required immediate mitigation and rollback strategies.
This guide introduces the Linux shell, explains how to view and set the current shell and hostname, customize the command prompt, differentiate internal and external commands, manage aliases, use common utilities, handle sessions with screen and tmux, and employ advanced echo formatting and safety deletion techniques.
When a Linux server shows performance problems, Netflix's performance team recommends using ten standard CLI tools within the first minute to capture key utilization, saturation, and error metrics, enabling rapid root‑cause identification before deeper analysis is needed.
This guide explains how to detect and mount USB storage devices on Linux, install NTFS support, view system logs, and set up swap space—either as a dedicated partition or a swap file—while covering swappiness tuning and enabling or disabling swap.
This guide explains Linux user and group concepts, classifications, UID/GID ranges, essential system files, and provides step‑by‑step commands for creating, modifying, and deleting users and groups, helping administrators securely manage system access.
The article covers Linux commands, shortcuts, file and directory management, permissions, users, searching, software repositories, manual pages, advanced topics like redirection, pipelines, processes, daemons, compression, compilation, networking, backup, and system control, providing practical examples and code snippets.
This article provides a comprehensive guide to the Linux su and sudo commands, explaining their differences, usage options such as login-shell and non-login-shell, how to switch users, set passwords, configure sudoers, and practical examples for managing user privileges securely.
This guide walks through the most frequent Linux system problems—boot failures caused by mis‑configured fstab, corrupted root partitions, missing kernel files, or hardware issues; network connectivity errors; MBR and GRUB bootloader faults; forgotten root passwords; and read‑only file‑system errors—providing step‑by‑step diagnostics, command‑line solutions, and recovery procedures.
This guide explains what a program and a process are, describes process creation, lifecycle, and identifiers, and provides detailed usage of essential Linux commands such as ps, top, pgrep, pstree, lsof, vmstat, iostat, iftop, dstat, as well as foreground/background control and scheduling with at and crontab.
This tutorial explains how to use Linux Logical Volume Management (LVM) to create physical volumes, volume groups, and logical volumes, covering essential commands, formatting, mounting, and expanding storage without data loss, all illustrated with clear examples and screenshots.
This tutorial explains Linux LVM fundamentals, walks through creating and removing physical volumes, building volume groups, managing logical volumes—including formatting, mounting, extending, shrinking—and demonstrates how to take and restore snapshots using concrete command‑line examples.
This article walks operations engineers through the concepts, components, and detailed installation steps for setting up a Zabbix distributed monitoring system on Linux, including server and agent configuration, web front‑end deployment, custom items, triggers, and email alerts.
This article presents an extensive collection of Linux interview questions that span core concepts such as kernel fundamentals, memory management, process handling, interrupt mechanisms, filesystem structures, device driver development, and system performance tuning, providing a thorough preparation resource for candidates.
This article demonstrates how to use xargs with find and tar for file handling, ps for identifying high‑memory and high‑CPU processes, and netstat combined with awk and sort to inspect TCP connection states and the top requesting IP addresses, providing essential command‑line techniques for system administrators.
This guide compiles 50 practical troubleshooting and remediation techniques covering system, network, application, database, and security layers, enabling operations engineers to quickly diagnose failures, apply targeted fixes, and maintain stable, secure infrastructure.
This guide explains Linux network management, covering IP address and routing configuration, interface naming rules, GRUB tweaks for CentOS and Ubuntu, file‑based setups for CentOS 7, Ubuntu 16.04, Ubuntu 18.04+ with netplan, and graphical configuration via NetworkManager, plus service differences.
This guide walks you through essential Ubuntu system administration tasks, covering SSH configuration and key management, enabling root login, using sshpass, scp and rsync for file transfer, configuring sudo privileges, mastering PAM modules, setting resource limits with ulimit, and synchronizing time with chrony.
This guide walks through practical Linux command-line techniques—including generating file checksums, locating files quickly, editing long commands, inspecting and managing processes, capturing terminal output, examining binary dependencies, and using various text‑viewing utilities—to boost everyday system administration efficiency.
This comprehensive guide explains DNS fundamentals, Linux client configuration, BIND9 server setup, advanced features like DNSSEC and DoH, and essential troubleshooting and security practices, empowering system administrators and network engineers to manage and secure DNS services effectively.
This article explains what swap space is, why it matters for system stability and performance, and provides detailed Linux commands and procedures for creating, configuring, activating, and monitoring swap files or partitions.
This tutorial explains Linux Logical Volume Manager (LVM) fundamentals, walks through creating and removing physical volumes, building and deleting volume groups, provisioning logical volumes, formatting and mounting them, and performing size extensions, reductions, and snapshot operations with concrete command examples.
Learn how to use Linux process-monitoring tools—ps, dstat, top, and htop—by mapping each command to a character from the classic “Four Great Detectives,” while covering essential options, output fields, and practical tips for effective system observation.
This guide provides a concise reference of essential Linux commands for file handling, process control, networking, system information, and package management, helping users quickly perform common administrative tasks from the command line.
This guide walks through creating a ZFS filesystem from a pool, setting quotas and reservations, configuring an alternate mount point, enabling compression, and verifying compression effectiveness, helping Linux users save disk space with ZFS.
A collection of Zhihu answers examines the perception that IT operations is low‑tech, sharing real‑world experiences that reveal hidden complexities, the evolution of ops responsibilities, and why the role is actually far from trivial.
This guide walks you through installing NTP, configuring server and client settings, applying security restrictions, adding a local clock backup, logging, and verifying synchronization to keep Linux systems accurately timed across a network.
This article presents a collection of practical Bash scripts that automate common system administration tasks such as disk usage monitoring, MySQL backups, service health checks, temporary file cleanup, resource monitoring, user creation, and subnet IP scanning, each with clear explanations and ready-to-use code.
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 comprehensive guide explains what cron jobs are, how the crond daemon works, the structure of crontab files, user versus system scheduling, syntax details, special characters, environment setup, creation, editing, listing, deletion, troubleshooting, and best practices for reliable Linux automation.
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.
This article presents a comprehensive collection of Bash scripts that perform tasks such as verifying file consistency across servers, scheduled log cleaning, network traffic monitoring, numeric analysis in files, automated FTP downloads, interactive number games, Nginx 502 detection, variable assignments, bulk file renaming, IP address validation, and various system administration operations.
This article introduces six relatively obscure yet powerful Linux distributions—Slackware, Arch Linux, Manjaro, openSUSE, Gentoo, and Deepin—detailing their origins, design philosophies, and main features such as stability, manual configuration, rolling updates, package management, and user‑friendly interfaces.
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.
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.
The International Earth Rotation Service’s decision to skip the 2024 leap second and ultimately abolish leap seconds by 2035 relieves programmers of complex time‑keeping hacks, as current NTP, PTP, and newer Windows systems can already handle adjustments while past leap seconds have repeatedly disrupted software.
This article introduces common Linux log files, essential command‑line utilities such as cat, less, tail, grep, awk, and sed for viewing logs, and powerful analysis tools like logrotate, journalctl, logwatch, and goaccess, providing practical examples for effective system log management.
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.
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 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.
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 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 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.
This guide explains why nginx logs need regular rotation, shows how to manually split logs using a shell script that backs up, renames, and signals nginx to reopen log files, and demonstrates configuring and testing the logrotate utility for automated daily log rotation and compression.
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 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.
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 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.
This guide explains how to use the Linux df command with various options to display filesystem disk space, inode usage, and filesystem types in human‑readable, kilobyte, megabyte, or gigabyte formats, and shows how to filter or exclude specific filesystem types.
This guide provides a concise reference of essential Linux commands for file and directory handling, file operations, permission management, searching, process control, networking, system monitoring, hardware information, log handling, text processing, and package management on both Debian‑based and RPM‑based distributions.
This guide walks you through installing NFS on CentOS 7, creating a shared directory, configuring export options, starting the service, and then configuring a client to automatically mount the share using /etc/fstab, with verification steps included.
This guide details how to configure Linux services for automatic boot startup using systemd (systemctl), the legacy chkconfig method, generic script approaches, and crontab @reboot syntax, plus best‑practice recommendations for production environments.
This guide explains how to define log management goals, handle special logging scenarios for services like MySQL and nginx, and implement automated cleanup using crontab and logrotate, including detailed configuration options and practical examples for reliable log rotation and storage control.
This article explains the Linux /proc virtual filesystem, detailing its purpose as a kernel interface, how to mount it, and describing the most important files and directories—such as /proc/[pid], /proc/self, /proc/net, and security‑related entries—along with example commands for inspecting process information.
This guide explains how to configure both permanent and temporary environment variables on Linux for different shells (bash and csh), covering per‑user and system‑wide settings, the required configuration files, and practical command‑line examples to verify the changes.
This article explains the fundamentals of iptables, detailing how rules, tables, and chains work together to filter packets, the role of NAT, and provides practical command examples for configuring Linux firewalls effectively.
A collection of firsthand accounts reveals how seemingly harmless actions—changing system time, mistyping a script name, accidental deletions, and reckless debugging—triggered large‑scale service disruptions, forced emergency rollbacks, and costly penalties, highlighting the high stakes of operational negligence.
This guide introduces three essential Linux I/O commands—iostat for disk activity statistics, iotop for real‑time I/O usage per process, and lsof for listing open files—detailing installation, output interpretation, key parameters, and practical usage examples.
This guide explains how to use the Linux type command to discover whether a command is built‑in, external, or an alias, and shows how to display its location and full filesystem path with practical examples.
Learn how to use the Linux su command with the -s option to execute a single command as a non‑login user whose shell is set to /sbin/nologin or /bin/false, while preserving security and avoiding a full interactive shell session.
Becoming a Linux master means first grasping why operating systems exist, then steadily acquiring fluency with the command line, system configuration, scripting, performance tuning, security, kernel internals, virtualization, containers, networking, and monitoring tools, while continuously learning across distributions to diagnose faults and optimize resources.
This guide explains how to use the Linux alternatives system to install, configure, add, view, switch, and remove multiple versions of software, providing step‑by‑step commands and examples for both Debian‑based and RPM‑based distributions.
Learn why handling Daylight Saving Time is critical for global IT operations, how NTP interacts with time zones, and step‑by‑step commands using timedatectl, zdump, and NTP services to correctly set, verify, and maintain DST on Linux servers.
This guide details how to configure Linux services to start on boot using systemd (systemctl), legacy SysV init (chkconfig), generic startup scripts, and crontab @reboot, and offers best‑practice recommendations for production environments.
A collection of seasoned Zhihu contributors share candid experiences, challenges, and the evolving technical demands of operations roles, highlighting career prospects, skill requirements, and the impact of cloud, containers, and DevOps on the profession.
This guide presents twelve practical Linux techniques—from basic commands like free and top to advanced tools such as Grafana with Prometheus—enabling administrators to comprehensively track memory consumption, identify bottlenecks, and maintain system stability and performance.
This article provides a concise guide to using the apt package manager on Ubuntu, covering installation, updating package lists, upgrading, searching, displaying information, removing packages, and cleaning up unused files with clear command examples.
This guide explains how to create custom systemd service unit files, configure permissions, environment variables, logging, and resource limits, and shows how to start, stop, and monitor services using systemctl, with detailed examples and advanced options for Linux administrators.
This guide explains what the lscpu command does, shows its syntax and options, demonstrates how to view help, retrieve version information, display detailed CPU architecture data in default, parsable and extended formats, and lists important usage tips for Linux administrators.
This guide explains how to use a set of Linux commands—lshw, lscpu, free, df, lspci, and lsusb—to quickly retrieve comprehensive hardware information, helping administrators and users diagnose issues, plan upgrades, and understand system performance.
Windows 11 Insider builds are adding a native sudo command that lets users elevate individual commands with familiar Linux‑style privilege management, offering finer‑grained control than the traditional "Run as administrator" option while reflecting Microsoft's growing embrace of Linux technologies.
A seasoned cloud operations engineer reflects on age‑related career myths, the evolving job market, the shift from legacy hardware to cloud platforms, diverse ops specializations, relentless learning demands, and advice for newcomers navigating the modern operations landscape.
This guide explains how to install the Atoms GUI tool via Flatpak, create and manage isolated chroot environments for various Linux distributions, and perform common tasks such as adding users and destroying the environment, all without risking the host system.
