Linux System Optimization: 5 Essential Tips for Beginners
The article introduces five practical tips for Linux system optimization, covering basic maintenance, performance improvement, and security hardening. Tip 1: Regularly update the system (use `apt update/upgrade` for Debian/Ubuntu, and `yum/dnf update` for CentOS/RHEL), and clean up caches (`apt clean` + `autoremove`) to ensure security and performance. Tip 2: Reduce resource usage by disabling redundant services (`systemctl disable`) and adjusting the kernel parameter `vm.swappiness=10` to avoid excessive memory swapping. Tip 3: Optimize the file system by checking disk health (`fsck`), and modify `fstab` to add `noatime` to disable file access time recording and improve read/write speed. Tip 4: Enhance command-line efficiency by using `htop` instead of `top`, and set aliases in `~/.bashrc` (e.g., `alias ll='ls -l'`). Tip 5: Perform basic security hardening by enabling the UFW firewall (allowing SSH ports) and modifying `sshd_config` to disable `PermitRootLogin` to prevent attacks. These operations can improve system fluency and security, suitable for beginners to solidify basic knowledge. Advanced optimizations such as kernel parameters can be explored subsequently.
Read MoreLinux SSH Service Configuration: Remote Connection and Security Settings
SSH is a secure protocol for remotely managing Linux servers, replacing the plaintext-transmitted Telnet. Installation requires installing openssh-server on the server using apt (for Ubuntu/Debian) or yum/dnf (for CentOS), followed by starting the service and enabling it to launch on boot. For connection, Windows users can use PuTTY or the system's built-in client, while Linux/macOS users can directly execute the ssh command in the terminal. The core configuration is in sshd_config, where it is recommended to change the port (e.g., to 2222), disable direct root login, and switch from password authentication to key-based login (by generating a key pair locally and copying the public key to the server). The corresponding port must be opened in the firewall. Key-based login enhances security, and changes take effect after restarting the service. Common issues can be checked via logs, and permission errors may require setting ~/.ssh permissions to 700 and authorized_keys to 600. These key security settings ensure secure remote management.
Read MoreLinux Server Basics: From Installation to Network Configuration
This article introduces the basics of Linux servers, covering core steps and key skills. Linux servers, based on open - source systems, are suitable for stable service scenarios (such as those adopted by Alibaba Cloud). For beginners, it is recommended to use Ubuntu Server (user - friendly for novices), CentOS Stream (enterprise - level), and Debian (for basic learning). When installing, virtual machines (VMware/VirtualBox) are preferred, and ISO images and resources of 2 cores, 4G memory, and 40G storage are required. Taking Ubuntu as an example, during virtual machine installation, a username and password need to be set, and automatic partitioning should be used. The core of the system is the command - line interface. Basic commands such as `ls` (list files), `cd` (change directory), and `sudo` (elevate privileges) are commonly used. For network configuration, a static IP needs to be set (CentOS modifies the network card file, while Ubuntu uses Netplan), and ports 80 and 22 should be opened. After installing the SSH service (sshd for CentOS and ssh for Ubuntu), remote connections can be made using Xshell on Windows, or directly via the `ssh` command on Linux/macOS. Key steps include: choosing a distribution → installing in a virtual machine → basic commands → network configuration → SSH connection. Beginners are advised to further study permission management, deploying services such as Nginx, and system monitoring tools. For issues, they can refer to the `man` manual or official documentation.
Read MoreLinux Command Quick Reference: Essential Commands for Beginners
This Linux Command Cheat Sheet compiles daily core commonly used commands, categorized by functionality, to help beginners learn quickly. Basic operations include file and directory management: `ls` (list directories), `cd` (change directories), `pwd` (show current path), `mkdir/touch` (create directories/files), `cp/mv/rm` (copy/move/delete, with `rm` for irreversible deletion, use cautiously); system information viewing: `cat/head/tail` (view file content), `df/du` (check disk/directory sizes); process management: `ps/top` (monitor processes), `kill` (terminate processes); network commands: `ping` (test connectivity), `ip` (check configurations), `curl/wget` (download); software package management: `apt` (Debian/Ubuntu) and `yum` (CentOS/RHEL) for installation/update/uninstallation; user permissions: `sudo` (privilege escalation), `useradd` (create users). It is recommended to practice more, use `--help` or `man` for learning, and memorize commands in context to quickly form muscle memory.
Read MoreLinux Server Backup: Practical Tips for Data Recovery
Linux server data is the lifeline; backup and recovery are crucial for preventing data disasters and minimizing losses. Data loss can cause service outages, with backups serving as the first line of defense and recovery as subsequent security. Common backup tools: `tar` packages and compresses (full/incremental backups, example commands with parameters); `rsync` supports incremental synchronization (local/remote, reverse sync for recovery); `cp` is suitable for quick small file replication. For recovery: first stop services, verify backup integrity, create a recovery directory, then operate based on scenarios: extract tar packages with `-xzvf`, use rsync reverse sync, LVM snapshots for accidentally deleted data recovery, and for databases, use cold (service-stop) or hot (`mysqldump`) backups. Automation strategy: Use `crontab` to execute backup scripts regularly, combine local + offsite storage, incremental + full backups, and periodically test recovery (verify data integrity). Pitfalls to avoid: Ensure backup permissions, avoid file locking, and test before recovery. The core principle is "simple, reliable, and automated"—master basic tools, timing, and testing; data security lies in preparation.
Read MoreLinux System Security: An Introduction to Basic Protection Strategies
Linux security requires attention to basic configurations; neglecting them can lead to risks like weak passwords and open ports. The core protective strategies are as follows: **Account Security**: Disable shared root access, use strong passwords (including uppercase, lowercase, numbers, and symbols), and **mandatorily use SSH key-based login** (generate a key pair locally, copy the public key to the server's `authorized_keys`, set permissions, and disable password authentication). Delete default/test accounts; use regular users with `sudo` for privilege elevation in daily operations. **File Permissions**: Follow the principle of least privilege. Set home directories to `700` (only the owner can operate), regular files to `644` (owner can read/write, others can read), and system files to `600`; avoid high-privilege settings like `777`. **Firewall**: Only open necessary ports (e.g., SSH 22, Web 80/443); default to blocking others. Use `iptables` or `firewalld` for configuration, and disable outdated services like Telnet. **System Updates**: Regularly perform `yum update`/`apt upgrade`, and restart after updates. Disable insecure services like Telnet to prevent vulnerability exploitation. **Log Monitoring**: Use tools like `journalctl`, `last`, and `auth.log` to monitor... (Note: The original text was truncated at "关注" and the translation reflects the uncompleted content as-is.)
Read MoreDetailed Explanation of Linux File Permissions: Must-Know Knowledge for Beginners
Linux file permissions are the core of system security, controlling user access methods to prevent misoperations or data breaches. Files are associated with three types of users: the owner (highest authority), the associated group (shared within the group), and others. Permissions are divided into three categories: read (r=4), write (w=2), and execute (x=1). Permissions can be represented in two forms: symbolic (e.g., `rwxrwxrwx`, where the first character indicates the file type, and the next three groups represent permissions for the three user categories) and numeric (octal, where the sum of permissions for the three user categories gives the value, e.g., `755`). Proficiency in mutual conversion between these forms is required. File and directory permissions differ: for files, `r` = view, `w` = modify/delete, `x` = execute; for directories, `r` = list contents, `w` = create/delete, `x` = enter. To modify permissions, use `chmod` (in symbolic or numeric form with `-R` for recursive directory changes) and `chown` (to change owner/group). Special permissions (SUID/SGID/SBIT) are used for specific scenarios. Mastery of symbolic-numeric conversion, `chmod` usage, and the differences between file and directory permissions enables proficiency through practice.
Read MoreLinux System Monitoring: Basic Tools and Performance Metrics
Linux system monitoring is fundamental for ensuring server stability and requires mastery of tools and metrics. Common tools include: process monitoring (`ps` for basic viewing, `top` for real-time dynamics, `htop` for tree-like structure/mouse operations); memory (`free -h` to check memory/cache, focusing on `available` and Swap); disk (`df -h` for partition inspection, `du -sh` for directory location, `iostat -x 1` for IO monitoring with `%util > 80%` indicating bottlenecks); and network (`ss -tuln` for port checking, `ss -s` for connection status). Key metrics: CPU load (should not exceed core count within 1 minute) and `wa` (high values indicate disk bottlenecks); memory should alert on Swap usage; disk monitoring requires cleaning when partition usage exceeds 85%. For system lag diagnosis: first use `top` to check load/CPU, then `free` for memory, `df` for disk confirmation, and `ss` to排查异常 connections. Through the "observe-analyze-optimize" cycle with tools and metrics, regular practice enables rapid problem localization and system stability maintenance.
Read MoreLinux Service Management: Starting, Stopping, and Checking Status
Linux services are background-running programs with specific functionalities. Managing services is fundamental to system operations and requires administrative privileges (e.g., `$ sudo`). Core operations are implemented via the `systemctl` command: `systemctl status [service_name]` checks the status (e.g., `active (running)`); `start/stop/restart` are used to start, stop, and restart services respectively; `list-units --type=service` lists all services, and `is-active [service_name]` quickly determines the running status. For enabling/disabling services at boot, use `enable/disable`, and verify with `is-enabled`. When services fail, `journalctl -u [service_name]` checks logs (e.g., port conflicts, configuration errors). Mastering these commands fulfills most service management requirements.
Read MoreLinux Server Basics: A Detailed Explanation of User and Permission Management
User and permission management in Linux is the core of system security and resource allocation. Users are the operating subjects, groups are used for unified permissions, and UID/GID are numerical identifiers (root UID=0). For user management: use `useradd` to create (add `-m` for home directory), `passwd` to set passwords, and `userdel -r` to delete. Switch identities with `su` and escalate privileges with `sudo` (requires adding to the sudo group). File permissions are represented by three sets of characters (rwx) for user/group/other permissions, set via numbers (e.g., 755) or symbols (e.g., u+x). Modify permissions with `chmod`, and change owners/groups with `chown`/`chgrp`. Directory permissions have special rules: execute permission (`x`) is required to enter, read permission (`r`) to view contents, and write permission (`w`) to create files. Special permissions include SUID (temporarily elevates program privileges, e.g., `passwd`), SGID (inherits group permissions for files), and SBIT (prevents accidental deletion, e.g., `/tmp`). `umask` controls default permissions for newly created files/directories (default 022, resulting in 644 for files and 755 for directories). Best practices: Follow the principle of least privilege, avoid routine operations as root, and regularly check high-risk permission files.
Read MoreLinux System Updates: A Beginner's Guide to Secure Upgrades
Updating the Linux system is a necessary step to ensure security and enhance performance, as it can fix vulnerabilities, optimize operations, add new features, and improve hardware compatibility. Before updating, important data (such as files in the `/home` directory and critical configurations) should be backed up, and non-essential services (e.g., `systemctl stop nginx`) should be shut down. For different distributions (Ubuntu/Debian use `apt`, CentOS/RHEL use `yum`/`dnf`), the core steps are: update package indexes → upgrade software → handle dependencies (`dist-upgrade`) → update the kernel (requires reboot) → clean up cache. After updating, check the system status (`dmesg | tail`), verify service operation (`systemctl status`), and confirm kernel and software versions (`uname -r`, etc.). Common issues include stuck updates (switching sources to resolve), system unbootability (rolling back the kernel), and software failures (reinstalling). Beginners should update at fixed times, prioritize backups, use official sources, and cautiously test beta versions.
Read MoreLinux Network Configuration: IP Address and Subnet Mask Setup
Configuring IP addresses and subnet masks on Linux servers is fundamental for network communication. An IP address (32-bit binary, dotted decimal format) identifies a device, while a subnet mask (32-bit, with 1s indicating network portions and 0s indicating host portions) distinguishes between network and host segments. To view current configurations, use `ip addr` (recommended for modern systems) or `ifconfig` (traditional, requiring `net-tools` installation on some systems). Temporary settings can be applied with `ip addr add <IP>/<mask_prefix> dev <interface>` or `ifconfig <interface> <IP> netmask <mask>`, which only persist during the current session. For permanent configuration, distributions vary: CentOS/RHEL 7+ requires editing `/etc/sysconfig/network-scripts/ifcfg-<interface>` and setting `BOOTPROTO=static` with IP/subnet parameters. Ubuntu 18.04+ uses `netplan`, editing `/etc/netplan/*.yaml` to disable DHCP and applying changes with `netplan apply`. Verification is done via `ip addr` to confirm the assigned IP, or by pinging local devices, same-subnet hosts, and the gateway. Key considerations: ensure unique IPs, correct subnet mask alignment, verify interface names (via `ip addr`), and use root/administrator privileges.
Read MoreLinux Firewall Configuration: Opening Ports and Security Policies
Linux firewalls are the core of server security, filtering traffic to prevent intrusions. Major tools include: firewalld (recommended for beginners, zone-based management such as public/trusted), iptables (underlying advanced), and ufw (Ubuntu-specific). Key firewalld configurations: Check status (systemctl), open temporary/permanent ports (e.g., 80), view rules (--list-ports). Note testing rules, backing up configurations, and avoiding tool conflicts. Mastering basic configurations reduces risks; advanced strategies (e.g., rate-limiting connections) can be extended for enhanced security.
Read MoreLinux User Permission Management: Resolving Common Issues for Beginners
This article introduces the basics of Linux permission management and solutions to common problems for beginners. The permission system can be analogized to an apartment building: users (residents), groups (families), and files/directories (rooms). Permissions include read (r=4), write (w=2), and execute (x=1). Common problem solutions: 1. Password reset: For regular users, administrators use `passwd` to change passwords. To reset the root password, enter single-user mode (add `init=/bin/bash` to Grub under CentOS, then execute `passwd root`). 2. Insufficient sudo privileges: Switch to root with `su -`, then use `visudo` to add the user's permission line. 3. Permission format parsing: For example, `-rw-r--r--` (regular file, owner can read/write, group/others only read). Modify permissions using `chmod` (numerical method like `755`, symbolic method like `u+x`). 4. Directory access denied: Execute permission is required. Use `chmod +x` or `chown` to change the owner/group. 5. Create user groups: Use `useradd`/`adduser` and `groupadd`, then `usermod -g/-G` to assign groups. Security prompt: Principle of least privilege, `
Read MoreLinux Server Basics: From Installation to Basic Configuration
Linux servers are the preferred choice for servers due to their stability, security, open-source nature, and ease of customization. Before installation, download the Ubuntu Server or CentOS Stream image, create a bootable USB using Rufus or dd, and boot from the USB drive at startup. During installation, select the language and time zone; for beginners, automatic partitioning is recommended. Set up a regular user and check the option to install OpenSSH. After installation, restart and log in. For basic configuration, set a static IP (using Netplan for Ubuntu and NetworkManager for CentOS), manage software with apt/yum/dnf, create a regular user, and disable direct root login. Use ufw on Ubuntu and firewalld on CentOS to enable the firewall. Subsequent learning topics include web server, database, and Docker deployment, with practice being key.
Read MoreMust-Know for Beginners: Linux Service Start and Stop Commands
This article introduces the basics of Linux service management, where mainstream distributions use the `systemctl` (systemd) tool to manage services. Key commands and their functions include: `start`/`stop` (start/stop), `restart` (restart), `reload` (reload configuration), `status` (check status), and `enable`/`disable` (enable/disable on boot), all requiring `root` or `sudo` privileges. Service names vary across distributions: for example, Apache is `httpd` in CentOS and `apache2` in Ubuntu; MariaDB (CentOS) or MySQL (Ubuntu) are the service names for database services. Common issues include: adding `sudo` for permission errors, using `status` or `journalctl` to troubleshoot startup failures, and searching for service names with `systemctl list-unit-files` if forgotten. Mastering core commands, service name differences, and troubleshooting methods enables proficient server service management.
Read MoreLinux System Maintenance: Disk Cleanup and Space Management
This article explains the necessity and methods of disk cleanup and space management for Linux servers. When disk space is insufficient, the system may become slow, applications cannot be updated, and even services may be affected, so regular cleanup and management are necessary. First, diagnose space usage: use `df -h` to check overall disk usage, `du -sh` to locate large directories, and `find` to search for large files (e.g., files exceeding 100MB). For cleanup, log files (e.g., `/var/log`) are a major space consumer. They can be automatically rotated using `logrotate` or manually emptied/deleted. System cache can be released by syncing data with `sync` and then setting `sysctl -w vm.drop_caches=3`. Temporary files (`/tmp`, `/var/tmp`) and APT cache (`apt clean`) can also be safely cleaned. Redundant files in user directories should be deleted after confirmation. If space remains insufficient after cleanup, a new disk can be mounted (requires formatting, creating a mount point, and configuring `/etc/fstab`). Partition expansion should be done cautiously with data backup. Daily maintenance suggestions: regularly check disk usage (cleanup is required when exceeding 80%), configure log rotation, avoid storing data in the root directory, and do not arbitrarily delete system files. The core is "locate -"
Read MoreLinux Server Security Hardening: Common Issues for Beginners
Linux server security is crucial for beginners. This article summarizes 7 common issues and their solutions: 1. Simple and long - unused passwords: Use strong passwords (8 characters with uppercase, lowercase, numbers, and special symbols), change them regularly, and switch to SSH keys (generate and upload public keys). 2. Disabling the firewall: Only open necessary ports (e.g., Web 80/443, SSH 22), and disable insecure services like Telnet. 3. Exposing SSH ports to the public network: Restrict IP access and use fail2ban to prevent brute - force attacks. 4. Unupdated system/software: Regularly update via yum/apt and enable automatic updates. 5. Permission confusion (777): Follow the principle of least privilege (directories 755, files 644) and avoid root abuse. 6. Ignoring logs: Configure log rotation and regularly check critical logs like auth.log. 7. Redundant services: Uninstall useless services (e.g., vsftpd) and close unused ports. Core principles: least privilege, closing entry points, timely updates, and log auditing. Beginners can start with strong passwords, restricting SSH access, and closing unnecessary services for long - term maintenance.
Read MoreLinux Command Complete Reference: A Must-Have Handbook for Beginners
This article introduces the basics of Linux commands and commonly used tools, covering core operations and beginner tips. The basic command format is "command [options] [arguments]". Essential beginner tips include: using --help or man for help, Tab completion, Ctrl+C to interrupt, Ctrl+L to clear the screen, and ↑/↓/Ctrl+R to manage history commands. Core operations: Use ls (-l/-a/-h) to view files and directories, cd to switch directories (relative/absolute paths and ~/. ..), touch/mkdir to create files/directories, and cp/mv/rm to copy, move, and delete (be cautious with rm). For system information, use uname -a, uptime, df -h/free -h, and ps/top to manage processes. For text processing, use cat/head/tail to view files and grep -r to search for text. Software package management is divided into Ubuntu (apt) and CentOS (yum), requiring sudo for privilege elevation. Beginner pitfalls: Pay attention to permissions (sudo), avoid dangerous commands (e.g., rm -rf *), and practice basic commands (ls, cd, etc.) to quickly master daily operations.
Read MoreLinux Server Infrastructure: From Installation to Service Deployment
This article introduces Linux server installation and basic service deployment, suitable for zero-basic learners. Linux is the preferred choice for servers due to its stability and security. Unlike the desktop version, the server version focuses on performance optimization. Installation preparation: Minimum hardware requirements are 1-core CPU, 2GB memory, and 20GB hard disk (SSD is better). Recommended distributions include CentOS (enterprise-grade stability) or Ubuntu Server (user-friendly for beginners). Taking CentOS 7 as an example, download the minimal ISO, perform automatic partitioning, set the root password, and restart. Basic configuration: Configure a static IP (to avoid changes), create a regular user, and disable direct root login. The firewall should only open necessary ports (e.g., 80 for web services). Core service deployment: Practical deployment of Nginx (web server), vsftpd (FTP server), and MariaDB (database), with installation, startup, and verification methods introduced respectively. Summary: The process is minimal installation → network security configuration → core service deployment. Security and stability are key, and subsequent exploration can be done on complex architectures (e.g., LAMP/LNMP).
Read MoreBeginner's Guide: Linux System Updates and Upgrades
Updating and upgrading the Linux system is actually straightforward for beginners. The core purposes are to fix vulnerabilities (security patches) and enhance software versions (new features/performance). Regular operations ensure the system is more secure and powerful. For beginners, follow these steps (taking Ubuntu/Debian and CentOS/RHEL as examples): 1. **Verify system information** (optional): Use `uname -a` to check the kernel and `lsb_release -a` to view the distribution. 2. **Update package lists**: For Ubuntu, run `sudo apt update`; for CentOS, use `sudo dnf check-update`. 3. **Perform system updates**: For Ubuntu, execute `sudo apt upgrade`; for CentOS, use `sudo dnf upgrade` and confirm as prompted. 4. **Resolve dependency conflicts**: Select `y` or `n` as prompted. For "keep configuration files," choose `N` to overwrite old configurations for safety. 5. **Reboot the system**: If the kernel or core components are updated, execute `sudo reboot` immediately. Pitfall avoidance: Back up data before updating; distinguish between distribution-specific commands (Ubuntu uses apt, CentOS uses dnf/yum); avoid updating during critical service operations; ensure network stability; if updates fail, check the software sources.
Read MoreSSH Service Configuration: A Detailed Explanation of Linux Remote Connection
SSH is a secure remote login protocol that encrypts data transmission, used for remote management of Linux servers (such as cloud servers and local servers), replacing insecure protocols like Telnet. Key configuration steps: Install `sshd` on the server (using `apt` for Debian/Ubuntu, `yum` for CentOS/RHEL), start it and set it to boot automatically (`systemctl start/ enable sshd`). Modify `/etc/ssh/sshd_config` (backup first). Critical configurations: Change the port (e.g., 22→2222 to prevent brute-force attacks), disable root login (`PermitRootLogin no`), allow specific users (`AllowUsers`), and disable password login in favor of key-based authentication (generate a key pair locally and use `ssh-copy-id` to transfer it to the server). Restart `sshd` after changes. Client connection: Use PuTTY on Windows, and the terminal on Linux/macOS with the command `ssh username@IP -p port`; key-based authentication is more secure. Security notes: Allow the port through the firewall (UFW or cloud security groups), disable direct root login, and regularly update the system and SSH. Common issues: Timeout (check IP/network), connection refused (check port/service), permission errors (
Read MoreServer Performance Optimization: An Introduction to Linux System Tuning
Linux system tuning aims to address server performance issues, enhance speed, stability, and resource utilization, and prevent business disruptions or degraded user experience. Common bottlenecks include CPU, memory, disk I/O, and network, with corresponding diagnostic tools: dstat (comprehensive status), top (CPU/load), free -h (memory), iostat -x 1 (disk I/O), and ss -tuln (network). Targeted tuning strategies: Optimize CPU by managing high - utilization processes; focus on memory caching (the larger the better) and Swap usage; improve disk I/O for random reads/writes (e.g., migrating to SSD); and reduce TIME_WAIT connections and limit connection numbers in the network. System parameters can be temporarily or permanently adjusted via sysctl, which requires testing and verification. Key considerations: Diagnose first before tuning—avoid blind adjustments. Regular monitoring (e.g., with dstat) and continuous iteration are crucial.
Read MoreLinux System Maintenance: Essential Basic Knowledge for Beginners
Maintaining Linux servers is an essential skill in the internet era. Linux, being stable, open-source, and secure, is the mainstream operating system for servers. Beginners can solve common issues such as file permissions and service startup by mastering basic operations. Core skills include: command-line operations (ssh login, basic commands like pwd/ls/cd); file system (root directory and core directory structures such as /etc/var); file operations (touch/mkdir/cp/mv/rm); permission management (rwx permission representation, chmod modification); processes and services (ps/top/kill for viewing and terminating processes, systemctl for managing services); network configuration (ip addr, ping, port checking, and firewall setup); system updates (apt/yum for updates, software installation and uninstallation); and log backup (tar compression, tail for log viewing). Learning suggestions: practice extensively using virtual machines or experimental platforms, utilize tools like Xshell/FinalShell, make good use of the man command for help, back up data before operations, and develop a cautious habit.
Read MoreEssential Linux Command Line Tips for Beginners
This article introduces the learning and use of the Linux command line. The reason for learning the command line is its directness and efficiency, which is suitable for server management, can complete complex tasks, and is more flexible than the graphical interface. Basic file directory operations include ls (list directories, e.g., ls -la shows detailed hidden files), cd (change directory, e.g., cd ~ returns to the home directory), pwd (show current path), mkdir (create directories), touch (create empty files), rm (delete, e.g., rm -rf is used with caution), cp (copy), mv (move/rename), etc. It should be noted that dangerous operations such as rm -rf require special caution. Efficiency tips include: shortcuts (Ctrl+C to interrupt, Ctrl+D to exit, etc.), wildcards (* for batch file matching), pipes | to combine commands (e.g., ls | grep "txt"), background operation &, using --help or man to check help, history commands (history) and Ctrl+R for search. Common problem solutions: For insufficient permissions, use sudo to elevate privileges; check command spelling or consult help if there is an error; exit with exit or Ctrl+D. Summary: The command line is a set of tools that can be mastered with more practice. Platforms like Runoob and Learn Linux Terminal are recommended for learning.
Read MoreDisk Space Management: Storage Optimization for Linux Servers
This article introduces the necessity, methods, and optimization strategies for disk space management on Linux servers. Insufficient disk space can lead to software installation failures, service errors, and even system crashes, thus requiring reasonable management. Core concepts include inodes (which record file metadata and are prone to exhaustion first) and blocks (the smallest unit for data storage). Tools for checking: `df -h` for overall space, `du -sh`/`du -ah` for directory sizes, and `df -i` for inode issues. Common problems and solutions: oversized logs (managed automatically by logrotate or manually cleared), temporary file accumulation (via tmpwatch or deleting files in /tmp), uncleaned large files (using find to locate large files), and unreasonable partitioning (adjusting LVM or separating partitions). For long-term optimization, regular backup cleanup, using external storage to share pressure, and setting up alert monitoring are recommended. Always confirm before deletion to avoid randomly clearing logs. The core principles are regular inspection, proactive cleanup, and long-term planning to ensure server stability.
Read MoreCommon Issues for Beginners: How to Troubleshoot Linux Service Startup Failures
Linux service startup failures are common issues for beginners. Here's a step-by-step troubleshooting guide: First, confirm the status with `systemctl status 服务名` (replace "服务名" with the actual service name); if it shows "failed", further investigation is needed. Next, use `journalctl -u 服务名` or service-specific logs (e.g., Nginx error log at `/var/log/nginx/error.log`) to identify errors, focusing on keywords like "syntax error", "port in use", or "permission denied". If the service is not installed, check with `yum list installed` (for RHEL/CentOS) or `dpkg -l` (for Debian/Ubuntu), then install it via `yum` or `apt`. Key areas to check include: configuration file syntax (e.g., `nginx -t` for Nginx), port conflicts (use `netstat -tuln` to check ports), dependent services (via `systemctl list-dependencies`), and permission issues (adjust ownership and file permissions). Following the order "status → logs → fix configuration/port/dependencies" and combining log analysis with command checks will help resolve issues quickly for beginners.
Read MoreDetailed Explanation of Linux Network Services: From DNS to FTP
This article introduces the basic content of Linux network services, with a focus on DNS and FTP services. Linux network services are core programs that provide network functions (such as domain name resolution and file transfer) for servers, helping to understand network communication logic and manage server maintenance. DNS (Domain Name System), as a "translator", converts domain names (e.g., www.baidu.com) into IP addresses. Its working principle includes local cache queries and recursive/iterative queries to DNS servers (e.g., 114.114.114.114). The Linux configuration file is /etc/resolv.conf, which records DNS server addresses. FTP (File Transfer Protocol), as a "courier", uses the control connection (port 21) to transmit instructions and data connections (port 20 or random ports) to transfer files. vsftpd is commonly used in Linux, and the configuration file vsftpd.conf controls anonymous or user permissions. Common issues: For DNS, check resolv.conf and use nslookup. For FTP, verify the status of vsftpd and the port (21). It is recommended to practice nslookup to test domain name resolution or anonymously connect to public FTP servers to enhance network service management capabilities.
Read MoreShell Scripting Basics: An Introduction to Linux Automation Tasks
The Shell is an interface program for Linux command-line interaction (e.g., bash), and a script is a text file of commands for automating tasks. Learning Shell enhances operational efficiency (batch processing, scheduled tasks), system maintenance (monitoring, deployment), and is cross-platform and general-purpose with simple, easy-to-learn syntax. Basic syntax includes: variables (starting with letters/underscores, no spaces in assignment, referenced with $), common commands (echo, pwd, ls, etc.), comments (# for single line), conditional judgment (if-else), and loops (for/while). For advanced use, tools like grep and awk can be combined. Improve proficiency by modifying examples, practicing complex scenarios (e.g., crontab), and using set -x for debugging.
Read MoreBeginner's Guide: Configuring Environment Variables in Linux
This article introduces the knowledge of Linux environment variables. Environment variables are information carriers for the system or programs (e.g., PATH records command paths). Their role is to allow programs to be found by the system and to set running parameters. To view environment variables, you can use `printenv`/`env` (for all variables) or `echo $VariableName` (for a single variable). For temporary configuration, use `export VariableName=Value`, which only takes effect in the current terminal session. For permanent configuration, modify the configuration files: for the user-level, edit `~/.bashrc` or `~/.zshrc` (effective for the current user); for the system-level, edit `/etc/profile` (effective for all users). After modification, use `source` to load the changes. Verification can be done by checking the newly added path with `echo $PATH` or testing relevant tools. Common issues include: forgetting to use `source` which leads to configuration not taking effect, path errors, and requiring `sudo` privileges for system-level configurations. In summary: use `export` for temporary settings, modify configuration files for permanence, and mastering environment variables can enhance efficiency.
Read MoreBeginner's Must-Know: Linux Log File Viewing Commands
This article introduces 5 essential log viewing commands for Linux server beginners, applicable to daily problem diagnosis and monitoring. The core commands and their uses are as follows: 1. **tail**: View the end of a file. Use `-n 数字` to specify the number of lines, `-f` for real-time monitoring (e.g., website access logs), and `-q` to suppress the filename display. 2. **head**: View the start of a file. The `-n 数字` parameter specifies the number of lines, suitable for initial logs (e.g., system startup logs). 3. **cat**: Quickly view the entire content of small files. Use `-n`/`-b` to display line numbers. Not recommended for large files (risk of screen overflow). 4. **less**: Page through large files. Supports up/down navigation, search (`/关键词`), and `+G` to jump to the end. 5. **grep**: Filter content by keyword. Use `-n` to show line numbers, `-i` for case-insensitive matching, and `-v` for inverse filtering. Often combined with `tail` (e.g., `tail -f log | grep error`). Combination tips: For example, `tail -n 100 log | grep error` quickly locates errors, and `less +G log` jumps to the end of the log.
Read MoreData Backup Strategy: Ensuring Data Security for Linux Servers
The data on Linux servers (such as website files, business logs, etc.) is crucial and requires reliable backup to mitigate risks of data loss caused by hardware failures, misoperations, and other issues. The core of backup involves formulating a strategy that combines frequency (real-time data with daily increments, critical data with daily increments plus full backups), type (recommended for beginners: full + incremental combination), and storage locations (local + offsite). Common tools include rsync (incremental synchronization), tar (file archiving), and cron (scheduled tasks). Beginner strategies: Basic version (local hard drive + USB flash drive, daily increments + weekly full backups, executed via cron); Advanced version (offsite cloud storage, daily increments + full backups, multi-copy protection). Key best practices: Regularly test restoration, encrypt sensitive data, implement multi-copy storage, manage permissions, and monitor backup status to ensure backups are effective and accessible.
Read MoreLinux Server Security Hardening: 5 Essential Tasks for Beginners
This article addresses Linux server security issues and summarizes 5 simple hardening steps for beginners: 1. **System Update and Patch Management**: Regularly update system packages (use `apt update` + `upgrade` + `autoremove` for Ubuntu/Debian, and `yum`/`dnf update` for CentOS) to fix known vulnerabilities. 2. **Strengthen User Permissions and Authentication**: Disable direct root login, create regular users with sudo privileges, and recommend SSH key-based login (generate key pairs locally and upload public keys to the server). 3. **Configure Firewall**: Only open necessary ports (e.g., SSH, HTTP/HTTPS). For Ubuntu, use `ufw` (enable and allow specified services); for CentOS, use `firewalld` (reload after opening ports), with default rejection of other connections. 4. **Close Unnecessary Services and Ports**: Disable insecure services like FTP and Telnet. Check open ports with `ss -tuln` and remove non-business-essential ports/services. 5. **Log Auditing and Monitoring**: Monitor critical logs such as `/var/log/auth.log` and use `tail -f` for real-time login attempt tracking. Install `fail2ban` to automatically ban repeatedly failed IPs.
Read MoreBeginner's Guide: Linux Disk Space Cleaning Tips
When the disk space on a Linux server is insufficient, you can resolve it by following these steps: First, execute `df -h` to check partition usage, focusing on the root directory or system directories like `/var`. Next, use `du -sh` to locate large directories (e.g., `/var/cache`), and `find / -type f -size +100M 2>/dev/null` to search for large files. For targeted cleanup: Logs in `/var/log` can be rotated using logrotate or old compressed packages deleted; temporary cache files in `/tmp` and `/var/tmp` can be cleared after running `sync`, or system cache can be released by `echo 3 > /proc/sys/vm/drop_caches`; uninstall unnecessary software packages (via `yum` or `apt`); and large files in user directories (e.g., under `/home`) can be directly deleted. **Note**: Do not delete system-critical files. Confirm no programs are using files before deletion, and follow the procedures for safe and efficient operation.
Read MoreLinux User Management: Creation, Deletion, and Permission Assignment
Linux user management is fundamental to system maintenance, distinguishing permissions through user (UID) and group (GID) identifiers to ensure security and resource isolation. Core operations include: User creation requires administrative privileges, using `useradd -m username` (-m creates a home directory) followed by `passwd username` to set a password. Viewing user information uses `id`, and switching users is done with `su -`. User deletion is performed via `userdel -r username` (-r removes the home directory). Permission management is achieved through `chmod` (letter/numeric method), `chown`/`chgrp` (change owner/group), with the `-R` flag for recursive directory permission changes. Temporary privilege elevation with `sudo` requires adding the user to the `wheel` (CentOS) or `sudo` (Ubuntu) group using `usermod -aG`. Caution is advised during operations to avoid accidental user deletion or incorrect permission assignments.
Read MoreSystem Monitoring Tools: A Guide to Linux Server Performance Viewing
This article introduces 6 essential performance monitoring tools for Linux server beginners, helping them quickly grasp the "health status" of servers. System monitoring is crucial for ensuring service stability, requiring regular checks of CPU, memory, disk, and other resources. Core tools include: `top` for real-time monitoring of CPU, memory, and processes; sort by P/M to quickly identify high resource-consuming processes. `vmstat` analyzes overall system performance, focusing on the number of runnable processes (r), IO blocking processes (b), and swap partition usage (swpd). `iostat` specializes in disk IO, using tps and %util to determine bottlenecks. `free -h` provides a quick view of memory usage and available space. `df -h` and `du -sh` monitor disk partition space and directory/file sizes respectively. Tool selection scenarios: Use `top` for a quick overview, `free` when memory is tight, `iostat` to diagnose disk IO bottlenecks, `df` when space is insufficient, and `du` to locate large files. Mastering these tools enables timely detection and resolution of resource issues through targeted monitoring, ensuring stable server operation.
Read MoreMounting Linux File Systems: Essential Steps for Beginners
Mounting in Linux is a crucial operation to connect external storage devices (such as hard drives and USB flash drives) to the directory structure, enabling the system to read data from external devices as if they were local files. Since Linux directories follow a tree structure, external devices must be attached to the system's directory tree through a mount point (an empty directory). **Core Concepts**: Device name (e.g., `/dev/sdb1`) and mount point (e.g., `/mnt/usb`). Before operation, confirm the device name using `lsblk` or `fdisk -l`, and create the mount point with `sudo mkdir`. **Mounting Steps**: 1. Execute `sudo mount [device name] [mount point]`; 2. Verify success with `df -h` or `mount`; 3. Unmount using `sudo umount [mount point]`, ensuring no programs are accessing the device. **Common Issues**: Non-existent mount points, incorrect device names, and "device busy" during unmounting. Solutions include creating the directory, confirming the device, and exiting programs using the device. Temporary mounts are not persistent across reboots; permanent mounts require modifying `/etc/fstab`. **Summary**: By mastering device names, mount points, and the `mount/umount` commands, combined with `lsblk` to verify devices, you can successfully mount and access external storage.
Read MoreNginx Reverse Proxy: An Introduction to Load Balancing on Linux Servers
### Introduction to Nginx Reverse Proxy and Load Balancing **Core Functions**: Reverse proxy hides backend servers and unifies user access; load balancing distributes pressure across multiple servers to avoid single-point overload. **Reverse Proxy**: Similar to a "front desk receptionist," it receives user requests and forwards them to backend servers. Users need not know the specific backend servers, enhancing security and management efficiency. **Load Balancing**: When there are multiple backend servers, Nginx uses the `upstream` module to distribute requests. The default "round-robin" strategy can be adjusted as needed: - **Weighted Round-Robin**: Distributes requests by `weight` (e.g., `server 192.168.1.101 weight=5`); - **IP Hash**: Fixes user requests to a specific server (`ip_hash` directive). **Configuration Steps**: 1. Define backend server group: `upstream backend_servers { server 192.168.1.101; server 192.168.1.102; }`; 2. Configure reverse proxy: `proxy_pass http://backend_servers;` with `proxy_set_header` to forward request headers; 3. Test configuration.
Read MoreApache Virtual Host Configuration: Setting Up Multiple Websites on Linux
### Guide to Virtual Hosting and Apache Multi-Site Configuration This article introduces configuring virtual hosts on Linux servers using Apache to run multiple websites on a single server, which saves resources and is suitable for individuals/small teams. Virtual hosts are divided into domain-based and IP-based, with a core focus on domain-based configuration. Steps: 1. **Install Apache** (Ubuntu: `sudo apt install apache2`; CentOS: `sudo yum install httpd`), then start and enable auto-start on boot; 2. **Create website directories and files** (e.g., `/var/www/site1/public`), and write a test homepage; 3. **Configure virtual hosts**: Create an independent configuration file (e.g., `site1.conf`) in Apache's configuration directory (e.g., Ubuntu's `/etc/apache2/sites-available`), setting parameters like `ServerName` and `DocumentRoot`; 4. **Enable the configuration** (e.g., `a2ensite` for Ubuntu), then restart Apache to apply changes. Testing: Locally simulate domain access by modifying the `hosts` file; publicly, resolve the domain to the server IP via DNS. Common issues like insufficient permissions or configuration errors can be resolved through permission settings or syntax checks. Summary: After completing installation, directory creation, virtual host configuration, and testing, multiple sites can run in isolation.
Read MoreCommon Issues for Beginners: Methods to Update Linux Systems
### Why Update the Linux System? Updates fix security vulnerabilities, add new features (e.g., support for new hardware), optimize performance, and enhance system security and usability. ### Pre-Update Preparation 1. **Backup Data**: Back up important files in advance (e.g., via USB copy). 2. **Identify the Distribution**: - For Ubuntu/Debian-based systems: Use `lsb_release -a` or `cat /etc/os-release`. - For CentOS/RHEL-based systems: Use `cat /etc/redhat-release`. ### General Update Steps (Mainstream Distributions) - **Ubuntu/Debian-based**: - `sudo apt update` (Update package lists) → - `sudo apt upgrade` (Upgrade software); use `full-upgrade` for complex dependencies. - **CentOS/RHEL-based**: `sudo dnf update` (yum is also supported, but dnf is recommended). ### Common Issues and Solutions - **Insufficient Permissions**: Add `sudo` before commands. - **Download Failures**: Switch to a domestic mirror source (e.g., Alibaba Cloud) or check the network. - **Black Screen After Update**: Restart; if ineffective, boot into recovery mode for repair. - **Rollback**: Ubuntu
Read MoreSetting Environment Variables in Linux: A Beginner's Guide
This article introduces the core knowledge of Linux environment variables. Environment variables are variables that store system or program runtime information, such as software paths, language settings, etc. They allow the system to "remember" configurations without repeatedly entering complex information. Setting environment variables is mainly used to enable the system to locate executable programs (such as the PATH variable) or to control language, user information, etc. To view variables: use `echo $VARIABLE_NAME` for a single variable, and `env` or `printenv` for all variables. Temporary settings (valid only in the current terminal) use `export VARIABLE_NAME=value`, for example, `export MY_VAR="hello"`. For permanent settings, there are user-level configurations (modify `~/.bashrc` or `~/.profile` and require `source` to take effect) and system-level configurations (requires `sudo` to modify files like `/etc/profile`, applicable to all users). The `PATH` variable is critical, as it lists the paths the system searches for executable files. To temporarily add a path, use `export PATH=$PATH:/new/path`, and permanent configuration follows the same logic. Common variables also include `HOME` (home directory), `LANG` (language), etc. Note: Use `export` for temporary settings and configuration files for permanent ones; `sudo` is required for system-level modifications; variable values... (Note: The original text ends abruptly here.)
Read MoreIntroduction to Server Security: Fundamentals of Linux Firewalls
**Summary:** This article introduces Linux firewalls, which act as the "gatekeepers" of servers to restrict network access and primarily protect servers from attacks. The mainstream tools are categorized into three types: ufw (for Ubuntu/Debian, simple and based on iptables), firewalld (for CentOS/RHEL, supporting dynamic rules and zone management), and iptables (low-level, suitable for advanced users). In basic operations, ufw uses `enable` to turn on and `allow` to open ports; for firewalld, `--permanent` must be added to ensure rule persistence, and `reload` is required to apply changes. Common pitfalls for beginners include forgetting to add `--permanent` (resulting in temporary rule失效), setting the default policy to "deny inbound" for enhanced security, and only allowing specific IPs to access high-risk ports (e.g., 22). Conclusion: Firewalls are a security barrier; it is essential to clarify requirements, configure rules, ensure persistence, and conduct regular checks. （注：原文中“规则忘加`--permanent`会临时失效”中的“失效”翻译为“rule invalidation”更精准，已修正。） **Final Translation:** **Summary:** This article introduces Linux firewalls, which act as the "gatekeepers" of servers to restrict network access and primarily protect servers from attacks. The mainstream tools are categorized into three types: ufw (for Ubuntu/Debian, simple and based on iptables), firewalld (for CentOS/RHEL, supporting dynamic rules and zone management), and iptables (low-level, suitable for advanced users). In basic operations, ufw uses `enable` to turn on and `allow` to open ports; for firewalld, `--permanent` must be added to ensure rule persistence, and `reload` is required to apply changes. Common pitfalls for beginners include forgetting to add `--permanent` (resulting in temporary rule invalidation), setting the default policy to "deny inbound" for enhanced security, and only allowing specific IPs to access high-risk ports (e.g., 22). Conclusion: Firewalls are a security barrier; it is essential to clarify requirements, configure rules, ensure persistence, and conduct regular checks.
Read MoreEssential for Beginners: Basics of Linux Network Configuration
This article introduces the necessity and practical methods of Linux network configuration. For newcomers, mastering network configuration is fundamental for using servers and setting up services. They need to first understand four key elements: IP address (the "ID" of a device), subnet mask (network segment identifier), gateway (entrance/exit between internal and external networks), and DNS (domain name translation). Common commands to check network status include: `ip addr` to view IP addresses, `route -n` to check routes, and `ping` to test connectivity (including local loopback and external network verification). For dynamic IP configuration (DHCP), use the `nmcli` tool to modify connection parameters and activate them. For static IP configuration, prepare parameters such as IP, subnet mask, gateway, and DNS in advance. On CentOS, set static IPs in the `/etc/sysconfig/network-scripts/ifcfg-eth0` file, while Ubuntu uses `netplan` to configure the `01-netcfg.yaml` file. After configuration, verification steps include: using `ip addr` to confirm the IP, `ping` to test local/gateway/external network connectivity, and `nslookup` to test DNS. Common issues like IP conflicts or failure to ping the gateway can be troubleshooted by following the steps: "check IP → verify routes → ping tests". The core lies in understanding the four key elements and practicing commands like `ip` and `ping` regularly.
Read MoreA Comprehensive Guide to Starting and Stopping Linux Services
This article introduces the core methods for managing Linux services. Services are background - running programs, and management is fundamental to system maintenance. Modern Linux uses the systemctl tool of systemd for management. The core operations include: starting a service with `sudo systemctl start <service name>`, stopping it with `stop`, restarting with `restart`, and checking the status with `status`; setting it to start automatically at boot with `enable` and disabling it with `disable`. The self - starting status can be viewed through `list - unit - files`. Practical operations include: reloading the configuration (without restarting) with `reload` and viewing logs with `journalctl -u <service name>`. Precautions: `sudo` privilege elevation is required, the service name must be accurate (e.g., Nginx is `nginx`), and ensure the service is installed before operation. `stop` will forcefully terminate the service and may lose data; `restart` or `reload` (safer) is preferred. Mastering these can meet basic operation and maintenance needs.
Read MoreLinux Server Data Backup: Simple and Practical Strategies
The core of Linux server backup is to create data copies to mitigate risks such as accidental deletion and system failures. Backups are categorized by content into three types: full (copies all data), incremental (only new/modified data), and differential (data added/modified since the last full backup). Efficient data replication is key. For beginners, recommended tools include `tar` for archiving and compression (e.g., `tar -czvf backup.tar.gz /data`), and `rsync` for incremental synchronization (local or cross-server, e.g., `rsync -av /data/ /backup/`). Strategies should be selected based on needs: individuals/small servers can use weekly full backups + daily incremental backups; enterprises require daily full backups + offsite storage (e.g., cloud storage) with encryption for sensitive data. Automation is achieved via `crontab` to execute scripts regularly. Post-backup verification is essential (e.g., restore testing or `rsync --dry-run`). Key considerations include encryption, offsite storage, regular recovery testing, and permission control (e.g., directory permissions set to 700). Core principle: Prioritize simplicity and practicality, selecting a solution that matches your data volume and specific use case.
Read MoreLearn Linux Disk Partitioning and Mounting in 5 Minutes
Partitioning and mounting disks in Linux are fundamental operations for managing storage, analogous to closet organization and entry points. The steps are as follows: 1. **Check Disks**: Use `lsblk` or `sudo fdisk -l` to identify hard drives/partitions, and `df -h` to view currently mounted partitions. 2. **Create Partition**: Enter the tool with `sudo fdisk /dev/sdb`, input `n` to create a new primary partition, specify the size (e.g., `+20G`), and save with `w`. 3. **Format**: Format with `sudo mkfs.ext4 /dev/sdb1` (e.g., using the ext4 filesystem). **Always back up data before formatting**. 4. **Temporary Mount**: Create a mount point with `sudo mkdir /mnt/mynewdisk`, then mount with `sudo mount /dev/sdb1 /mnt/mynewdisk`. 5. **Permanent Mount**: Use `sudo blkid` to get the UUID, edit `/etc/fstab` to add an entry (format: `UUID=... 挂载点 ext4 defaults 0 0`), and verify with `sudo mount -a`. Key points: Partition → Format → Mount → Persistence. Back up data before operations, and use `umount` for unmounting.
Read MoreEssential for Beginners: Methods to Open Ports in Linux Firewall
This article introduces the necessity and common methods for opening ports on Linux servers, helping beginners get started quickly. Opening ports is fundamental for services to communicate externally (e.g., Web on port 80, SSH on port 22); otherwise, connection refusals will occur. Common tools are categorized into three types: UFW is suitable for Ubuntu/Debian with minimal operations, following steps: installation, allowing ports (e.g., `allow 22/tcp`), enabling, and verification; firewalld applies to CentOS/RHEL with zone management, steps: checking status, adding port rules (specify a zone like `public`), reloading, and verification; iptables is a universal underlying tool with powerful functions but complex syntax, requiring adding rules, saving (to avoid loss after restart), and verification. Port openness can be verified using telnet, nc (netcat), or curl. Beginners should note: prefer UFW/firewalld, avoid opening high-risk ports, ensure rules take permanent effect, and confirm the service is running.
Read MoreNTP Time Synchronization: Linux Server Clock Configuration
Linux server time synchronization is a fundamental and critical task. The Network Time Protocol (NTP) is the core tool that addresses issues such as log chaos, service authentication failures, and data conflicts. NTP achieves time synchronization through a hierarchical structure (Stratum 1-16, where lower strata are more authoritative). Common tools include NTPD (classic but resource-intensive) and Chrony (lightweight, fast to start, suitable for servers with limited memory). Taking NTPD as an example for installation: For CentOS/RHEL (below 7.9), use `yum install ntp -y`. For Ubuntu/Debian, use `apt install ntp -y` (Note: CentOS 7+ requires uninstalling Chrony first). Configure `/etc/ntp.conf` by adding authoritative servers (e.g., `ntp.aliyun.com`), and open the UDP 123 port in the firewall. Start the service with `systemctl start ntpd && enable`. Verify synchronization status using `ntpq -p`, and perform manual synchronization with `ntpdate -u`. Chrony follows a similar basic configuration and startup process; verification is done via `chronyc sources`. Common issues like service startup failures or slow synchronization can be resolved by checking ports, network connectivity, or replacing servers. Time synchronization is essential for server
Read MoreDetailed Explanation of Linux System User and User Group Management
This article introduces the core knowledge of Linux user and user group management, aiming to achieve permission control and resource isolation. Users are categorized into root (UID 0, highest privilege), system users (UID 1-999, for running services), and ordinary users (UID ≥ 1000, for daily operations). Groups include primary groups (default ownership) and supplementary groups (additional memberships). Key configuration files: `/etc/passwd` stores user information (UID, GID, home directory, etc.), `/etc/group` stores group information (GID, members), and `/etc/shadow` stores encrypted passwords. Common commands: User management commands include `useradd` (-m to create home directory), `usermod` (-g to change primary group, -aG to add supplementary group), `userdel` (-r to delete home directory), and `passwd` (to set password); group management commands include `groupadd` and `groupdel`. Practical operation examples: Creating an ordinary user and adding them to a group, setting up a shared directory with the group ownership and assigning group read/write permissions. Note that for multi-user sharing, users should be in the same group, and when deleting a user while preserving files, manually clean the home directory after removing the user.
Read MoreHow to Configure SSH Key-based Login (Passwordless Login) on Linux
SSH key-based login (passwordless login) ensures security through asymmetric encryption and eliminates the need to enter passwords, making it suitable for Linux server management. Traditional password login is vulnerable to brute-force attacks, while key-based login is more reliable and convenient. Prerequisites: The client must have an SSH tool installed (Linux/macOS have it pre-installed; Windows needs Git Bash/PuTTY). The server must have the SSH service installed (check with `ssh -V`). Steps: 1. Generate a key pair on the client: Run `ssh-keygen -t rsa -b 4096` to create `id_rsa` (private key, keep it secret with permissions set to 600) and `id_rsa.pub` (public key, can be shared). 2. Copy the public key to the server: For Linux/macOS, use `ssh-copy-id -i ~/.ssh/id_rsa.pub username@server-IP`; for Windows, manually paste the public key content into the server's `~/.ssh/authorized_keys` and set permissions `chmod 600 authorized_keys`. 3. Configure the server: Edit `sshd_config` to ensure `PubkeyAuthentication yes`, then restart `sshd`. 4. Test the connection: Directly execute `ssh username@
Read MoreIntroduction to Linux Log Analysis: Tools for System Fault Diagnosis
Linux logs are the "system diaries" that record system operation events and anomalies, serving as the core clue for fault diagnosis (e.g., web service failures can be located via logs for 404 errors or connection failures). Core log files include: /var/log/messages (system routine events and errors), /var/log/auth.log (authentication, login, and permission changes), /var/log/dmesg (kernel hardware initialization and driver errors), and application-specific service logs. Commonly used viewing commands are: tail -f for real-time tracking, grep for filtering keywords (e.g., "error"), and cat/less for file processing. Fault diagnosis follows the process: "phenomenon → locate logs → keyword analysis": for user login failure, check auth.log (keyword "Failed password"); for web service startup failure, check service error logs (keyword "port occupied"); for system lag, check messages/dmesg (keywords "out of memory" or "IO error"). Key points to master: selecting the right log, filtering keywords, and paying attention to timestamps. Advanced tools include journalctl and the ELK Stack.
Read MoreMust-Know: Quick Reference for Linux Process Management Commands
This article introduces the core process management commands in the Linux system, helping beginners quickly solve daily problems. **Viewing Processes**: The `ps` command lists process statuses. A common usage is `ps -aux`, with key columns including PID (Process ID), USER (user), %CPU/%MEM (resource usage), STAT (status, e.g., R for running, S for sleeping), and COMMAND (start command). **Real-time Monitoring**: `top` dynamically updates process information. Press `P`/`M` to sort by CPU/memory usage, `k` to terminate a process, and `q` to exit. **Terminating Processes**: `kill` terminates processes by PID (e.g., `kill 1234`, use `-9` for forceful termination), and `killall` terminates by process name (e.g., `killall -9 firefox`). **Other Tools**: `pstree` displays process relationships in a tree structure. `jobs`/`bg`/`fg` manage background jobs (e.g., after pausing with `Ctrl+Z`, `bg %1` resumes background execution, and `fg %1` brings it back to the foreground). **Note for Beginners**: Avoid terminating
Read MoreYum/Apt Package Managers: Powerful Tools for Linux Software Installation
To install software on Linux, Yum or Apt package managers are required, which automatically handle downloading, dependencies, and updates. Yum is used for RHEL/CentOS/Fedora, managing .rpm packages. Its core commands include: `sudo yum install/search/remove/clean all`. Software sources are located in `/etc/yum.repos.d/`, and additional sources can be added via `epel-release`. Apt is for Debian/Ubuntu, managing .deb packages. Its commands are: `sudo apt install/search/remove/clean`. Before using `upgrade`, the sources must be updated with `update` first. Software sources are in `/etc/apt/sources.list` and `/etc/apt/sources.list.d/`, and Ubuntu users can switch to domestic mirror sources. Both managers rely on correct software sources. Beginners should first run `cat /etc/os-release` to confirm the distribution. If dependency issues occur, update the sources first; if software sources are incorrect, back them up and test. In summary: Use Yum for RHEL/CentOS/Fedora and Apt for Debian/Ubuntu. Familiarity is achieved through practice.
Read MoreIntroduction to Shell Scripting: Automating Tasks on Linux Servers
Shell scripts are automated execution tools in Linux that write commands into a text file in sequence to replace repetitive manual operations and improve efficiency. They are essential skills for server management. Their basic syntax includes variable assignment (no spaces around the equals sign), conditional judgment (if-else), and loops (for/while). The first "Hello World" script requires defining variables, adding execution permissions (chmod +x), and running the script. Practical scripts, such as disk monitoring, extract the root partition usage rate using commands like `df -h` and trigger an alert when it exceeds 80%. Precautions: Execute permission must be granted before running, no spaces in variable assignment, and use `./` to specify the current directory when executing. Learning can start with basic exercises, and after mastering variables, conditions, and loops, one can advance to learning `crontab` for scheduled tasks to achieve automated operations and maintenance.
Read MoreFTP Service Setup: A Guide to File Transfer on Linux Servers
This article introduces the method of setting up an vsftpd FTP server on Linux systems. FTP is a standard protocol for network file transfer, and vsftpd has become a popular choice for Linux due to its security and stability. The steps include: 1. Preparation: A Linux server (e.g., CentOS/Ubuntu), administrator privileges, and network configuration are required. 2. Installation: For CentOS, use `sudo yum install vsftpd -y`, and for Ubuntu, use `sudo apt install vsftpd -y`. 3. Start the service and set it to start on boot: `systemctl start/ enable vsftpd`. 4. Firewall configuration: Open port 21 (control connection) and passive ports 50000-60000 (data transfer). 5. Create FTP users: Root login is prohibited. Use `useradd` to set the home directory, and `chown`/`chmod` to modify permissions. 6. Configure vsftpd.conf: Enable local user login and write permissions, restrict users to their own home directories, and specify the passive port range. 7. Testing: Connect locally using `ftp localhost`, or remotely with tools like FileZilla. Common issues such as connection timeouts and permission errors require checking the firewall, service status, and directory permissions. The above steps can complete the basic setup.
Read MoreDNS Resolution Principle and Linux Server Configuration Practice
This article introduces the principles, Linux configuration, and setup methods of DNS (Domain Name System). DNS, often referred to as the "phone book" of the Internet, translates domain names (e.g., baidu.com) into IP addresses, enabling domain-name-to-IP mapping. Its resolution process consists of six steps: local cache query (checking the hosts file), local DNS server query, root domain server query, top-level domain server query, authoritative domain server query, and finally returning the IP address to the operating system. In Linux, local DNS configuration is implemented through two key files: `/etc/hosts`, acting as a local "mini-address book" with the highest priority; and `/etc/resolv.conf`, which specifies DNS servers (e.g., 114.114.114.114), though it may be dynamically overwritten. Taking BIND as an example for DNS server setup, the steps include installing the software, configuring the main file `/etc/named.conf`, creating forward and reverse zone data files, starting the service, and testing. Common issues include configuration syntax errors, firewall blocking the 53 port (DNS default port), and inability for other devices to resolve names. Troubleshooting involves checking configurations, logs, and permissions. DNS is fundamental to network communication. Mastering its principles and configuration allows efficient management of domain name resolution services.
Read MoreSetting IP Addresses on Linux Servers: A Beginner's Guide
The IP address of a Linux server is the foundation for device communication (like a "house number"). IPv4 consists of 4 groups of numbers ranging from 0 to 255 (e.g., 192.168.1.100) and is used to locate devices. IP configuration supports two methods: dynamic (via DHCP, automatic acquisition for temporary testing) and static (manual specification for production environments). To view the IP address: Use `ip addr` (recommended) or `ifconfig` (requires installation on some systems). Identify the network interface name (e.g., eth0/ens33) and the assigned IP address. For static configuration (CentOS example): Confirm the network interface name, modify `/etc/sysconfig/network-scripts/ifcfg-ens33`, set `BOOTPROTO=static`, specify `IPADDR`, `NETMASK`, `GATEWAY`, and `DNS`, then restart the network service with `systemctl restart network` and verify the IP. For dynamic configuration: Change the configuration file's `BOOTPROTO=dhcp`, restart the network, and verify. For Ubuntu, use Netplan; configuration files are located in `/etc/netplan/`, apply changes with `netplan apply`. Common issues: IP conflicts, incorrect gateway/DNS settings. Troubleshoot using tools like `ping`.
Read MoreA Step-by-Step Guide to Configuring Linux Firewall (iptables)
This article introduces the configuration of Linux firewall (iptables) with the core objective of protecting server security. iptables is a packet filtering tool that manages traffic through tables (primarily filter), chains (INPUT/OUTPUT/FORWARD), and rules (match conditions + actions). Before configuration, existing rules should be checked (`iptables -L -n`) and cleared (`-F`/`-X`). Key steps include: allowing traffic on the local loopback interface (lo), setting default policies (DROP for inbound, ACCEPT for outbound), opening necessary ports (e.g., SSH, 80/443 for web services), and finally saving the rules (using `service iptables save` for CentOS and installing `iptables-persistent` for Ubuntu). Security considerations: prioritize rule order, apply the principle of least privilege, avoid directly exposing port 22 to the public internet, and regularly audit rules. Common operations include viewing, deleting, and clearing rules. By following these steps, a basic firewall can be quickly configured to meet the security needs of most servers.
Read MoreEssential for Beginners: A Detailed Explanation of Linux User Permission Management
Linux permission management is the core of security and collaboration in multi-user systems, aiming to protect system security (preventing misoperations and malicious behaviors) and enable division of labor and collaboration (different users obtaining permissions as needed). Core concepts include three types of users (ordinary users, system users, root), user groups (for unified permission management), and file/directory permissions divided into three categories: owner, group, and others. Each category corresponds to three operations: read (r), write (w), and execute (x) (e.g., a directory requires x permission to be entered). To view permissions, use `ls -l`. To modify permissions, use `chmod` (numerical method: r=4, w=2, x=1; e.g., 754 represents rwxr-xr--; symbolic method: `+/-/=` to add/remove/set permissions, e.g., `u+x` adds execute permission to the owner). Ownership or group can be changed via `chown`/`chgrp`. Common issues to note: Files cannot be modified mostly due to permission or ownership problems; directories cannot be accessed without x permission; ordinary users use `sudo` to escalate privileges. Security recommendations: Minimize root usage, do not grant write permissions to others, and regularly check permissions. Master `ls -l`, `chmod`, and `chown`.
Read MoreBeginner's Guide to Nginx: From Installation to Reverse Proxy Configuration
Nginx is a high-performance HTTP and reverse proxy server, lightweight and stable, suitable for scenarios such as website building and load balancing. Installation is divided into Ubuntu/Debian (`sudo apt install nginx`) and CentOS/RHEL (`sudo yum install nginx`). Verification is done with `nginx -v`. Start the service (`sudo systemctl start nginx`) and set it to start automatically (`sudo systemctl enable nginx`). Management commands include start/stop, restart, and reload configuration (`reload`). For core reverse proxy configuration: Create a site configuration file (e.g., `myapp.conf`) in `/etc/nginx/conf.d/`. Example configuration: The `server` listens on port 80, `server_name` is set to the domain name/IP, `location /` forwards to the backend port (e.g., `127.0.0.1:3000`) via `proxy_pass`, and passes Host and real IP through `proxy_set_header`. After configuration, check syntax with `nginx -t`, and `reload` to apply changes, then test access to the backend content. Notes: Open ports 80/443 in the firewall, ensure the backend service is running, and `proxy_pass` must start with `http://`/`https://`.
Read MoreSetting up Apache on Linux Servers: Quick Deployment of Websites
### Apache Web Server Setup Guide Apache is an open-source, free, and mainstream web server suitable for Linux, Windows, and other systems, making it the first choice for beginners in website building. The setup process is as follows: **Prerequisites**: A Linux server (e.g., Alibaba Cloud CentOS/Ubuntu), basic command-line operation skills, and root/sudo privileges. **Installation**: For CentOS, use `sudo yum install httpd -y`; for Ubuntu, use `sudo apt install apache2 -y`. **Start and Enable Auto-Start**: On CentOS, run `sudo systemctl start httpd` and `enable` it for boot auto-start; Ubuntu uses `apache2` instead. Check the running status with `systemctl status` (success if it shows `active (running)`). **Firewall Configuration**: Open port 80 (default for HTTP). For CentOS: `firewall-cmd --add-port=80/tcp --permanent` and reload. For Ubuntu: `ufw allow 80/tcp`. **Website Deployment**: The website root directory is `/var/www/html`. Create `index.html` (e.g., with content "Hello, Linux Server!"). After restarting Apache, access the server IP via a browser. **Advanced**: Virtual hosts enable multi-site hosting, requiring configuration of `/etc
Read MoreUnderstanding Linux SSH Service: A Complete Guide to Configuration and Usage
SSH is a secure remote management protocol for Linux servers, replacing insecure services like Telnet by ensuring data security through encrypted transmission. Its advantages include high security (default AES/RSA encryption), cross-platform compatibility, and rich features such as file transfer. It consists of the server-side `sshd` (listening on port 22) and the client-side `ssh`. Installation varies: for Ubuntu/Debian, install and start `sshd` via `apt`; for CentOS/RHEL, use `yum`. Verification involves checking service status and port availability. Basic client login is done with `ssh username@IP`. Passwordless login requires generating a key pair and copying the public key to the server. Server configuration is managed via `sshd_config`, allowing modifications such as changing the port, disabling direct root login, or password-based authentication. After configuration changes, restart the service. Common issues require checking service operation, port accessibility, and firewall settings. SSH is a must-have skill for system administrators, requiring mastery of installation, configuration, and basic usage.
Read MoreZero to Hero: A Guide to Installing Linux on a Server
This article introduces a Linux server installation guide suitable for beginners. Linux servers are secure, efficient, and ideal for high-concurrency tasks, making them fundamental for operations and maintenance. Before installation, the appropriate scenario should be chosen: either a local virtual machine (requiring software like VirtualBox and an Ubuntu Server ISO) or a cloud server (e.g., Alibaba Cloud ECS). Ubuntu Server 22.04 LTS is recommended. For local virtual machine installation: Create a virtual machine (with at least 2GB RAM and a 20GB dynamically allocated hard disk), mount the ISO for booting, select English for installation, use automatic partitioning, set a username and password, check the OpenSSH server option, and verify login after reboot. For cloud server installation: Create an instance on Alibaba Cloud (1 core, 2GB RAM, Ubuntu image) and connect via SSH (using keys for enhanced security). Post-installation verification includes executing `lsb_release -a` to check the version, using `ping` to test network connectivity, and running `sudo apt update` to verify permissions. Beginners should note password security, bridged networking for virtual machines, and installing tools like `vim`. Mastering minimal installation, remote connection, and permission management will enable smooth entry-level operations following the step-by-step instructions.
Read MoreEssential for Beginners: 5 Basic Linux Server Commands
This article introduces 5 basic core commands for Linux servers to help beginners quickly get started. The `ls` command is used to view directory files, displaying the current directory by default. Common parameters include `ls -l` (detailed information), `ls -a` (including hidden files), and `ls [path]` (specifying a directory). The `cd` command switches directories: `cd [directory name]` enters a subdirectory, `cd ..` returns to the parent directory, `cd ~` goes to the home directory, and `cd /` navigates to the root directory. The `pwd` command directly displays the current path, preventing operational errors. `mkdir` creates directories: `mkdir [directory name]` creates a single-level directory, while `mkdir -p [multi-level]` builds nested directories. `df -h` checks disk space, with `-h` converting to human-readable units to view partition sizes and usage rates. These 5 "foundation" commands are fundamental for server management. Practicing parameters (e.g., `ls -l/a`, `mkdir -p`) and familiarizing with the "parameter + target" mode will help beginners gradually advance their skills.
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