cp命令：Ubuntu中复制文件的方法
在Ubuntu系统中，`cp`是复制文件/目录的基础命令，不删除源文件。基础格式为`cp 源文件/目录 目标位置`。常用参数：`-i`（覆盖前提示确认）、`-r`（递归复制目录，必加）、`-v`（显示详细过程）。 场景示例：复制单个文件到当前目录（`cp test.txt .`）；复制到指定目录（`cp test.txt docs/`，需`docs`存在）；复制多个文件（`cp file1.txt file2.txt docs/`）；复制目录必须加`-r`（`cp -r docs/ backup/`，自动创建目标目录）；覆盖时用`-i`确认（`cp -i test.txt docs/`）。 注意：目录复制忘加`-r`会失败；目标文件存在时默认覆盖，建议用`-i`；隐藏文件（如`.bashrc`）可直接复制；目标目录不存在时，`-r`会自动创建。 掌握关键点：基础格式、目录加`-r`、`-i`确认覆盖、`-v`查看过程
Read MoreUbuntu rm命令：删除文件/目录的正确姿势
本文介绍Ubuntu系统中`rm`命令的正确使用方法，避免误删重要数据。`rm`是删除文件/目录的核心工具，默认直接删除且不进回收站，删除后难恢复。 基础用法：删除单个文件用`rm 文件名`；删除目录需加`-r`（递归），即`rm -r 目录名`。常用选项：`-i`交互式确认（删除前提示，避免误删）、`-f`强制删除（忽略错误，慎用）、`-v`显示删除过程。 **安全注意**：禁止用`rm *`或`rm -rf *`（会删当前目录所有内容），不删除系统关键目录（如`/etc`），删除目录前用`ls`确认结构，空目录用`rmdir`更安全。误删后可尝试图形回收站（终端删除的文件不进）或工具（如`extundelete`，需安装，且删除后避免写入数据）。 总结：删除前确认目标，优先用`-i`，远离危险命令，确保数据安全。
Read More快速上手：Ubuntu mkdir创建文件夹
本文介绍Ubuntu系统中创建目录的基础命令`mkdir`。`mkdir`（make directory缩写）用于创建空目录，是组织文件的必备工具。基本用法：在当前目录创建单个文件夹，命令格式为`mkdir 文件夹名称`（如`mkdir projects`）。 如需在指定路径（相对或绝对路径）创建，直接指定路径即可（如`mkdir ~/Documents/notes`或`mkdir /tmp/temp_files`）。 若需创建多层嵌套文件夹（如`a/b/c`），普通`mkdir`会因父目录不存在报错，此时需加`-p`选项（`--parents`）自动创建所有父目录（如`mkdir -p workspace/code/python`）。 常见问题：父目录不存在时，用`-p`解决；权限不足则需用`sudo`（谨慎使用）。 总结：`mkdir`核心语法为`mkdir [选项] 路径`，基本创建单个目录，多层目录需`-p`，权限问题用`sudo`。
Read MoreUbuntu必备：pwd命令查看当前路径
在Ubuntu系统中，`pwd`（Print Working Directory）是显示当前工作目录的实用命令，帮助用户明确在文件系统中的位置。文件系统以根目录 `/` 为起点呈树状结构，当前路径即用户在该结构中的具体位置（如用户主目录常用 `~` 表示）。 基本用法简单：打开终端（`Ctrl+Alt+T`）后输入 `pwd`，即可显示当前路径（如 `/home/yourname`）。它还有两个隐藏参数：`-P` 显示物理路径（忽略符号链接，显示真实位置），`-L` 显示符号链接路径（默认选项，显示链接路径而非真实位置）。例如，若 `link_to_docs` 是指向 `~/Documents` 的软链接，`pwd -L` 显示 `~/link_to_docs`，`pwd -P` 则显示 `~/Documents`。 掌握 `pwd` 能避免文件操作错误，配合 `cd` 切换路径可高效管理文件，是文件管理的基础工具。
Read More保姆级教程：Ubuntu下ls命令详解
Ubuntu中ls是查看目录内容的常用命令，基础用法为`ls`（显示当前目录非隐藏文件，按字母排序）。其核心在于选项组合：`-a`显示隐藏文件（含`.`和`..`）；`-l`显示详细信息（含权限、所有者、大小、修改时间等）；`-h`配合`-l`使大小以KB/MB等单位显示；`-t`按修改时间排序，`-r`反向排序，`-S`按大小排序，`-d`仅显示目录名，`--color=auto`用颜色区分文件类型。可组合选项如`-lha`（详细+隐藏+大小）、`-ltr`（详细+时间+反向）。还能查看指定路径（如`ls /home/user/Documents`）。常用组合：`ls -l`（详细）、`ls -a`（隐藏）、`ls -lha`（详细隐藏大小）等。建议用`man ls`获取更多帮助。
Read MoreUbuntu新手入门：cd命令怎么用？
本文介绍Ubuntu系统中cd命令的使用，它是目录切换的核心工具，类似Windows文件夹点击。 **基本用法**：格式为`cd 目标目录`，可直接进入当前目录的子目录（如`cd Documents`），或通过`~用户名`进入其他用户家目录（需权限，如`cd ~root`）。 **路径区分**：相对路径从当前目录出发（`..`表示上一级，如`cd ..`）；绝对路径从根目录`/`出发，可用`~`代指家目录（如`cd ~/Pictures`）或直接写完整路径（如`cd /usr/share/doc`）。 **常用技巧**：`cd -`返回上一次目录，`cd ~`直接回家目录，`cd ..`返回上一级。 **常见问题**：目录不存在/拼写错误（区分大小写，用`ls`检查）；含空格目录需用引号或反斜杠（如`cd "my docs"`）；系统目录需权限时用`sudo`（普通用户优先操作家目录）。 最后，用`pwd`可确认当前目录，掌握路径和技巧即可
Read More实测 Z-Image：6B 参数的高效图像生成模型
Z-Image是6B参数的高效图像生成模型，8步推理（8 NFEs）即可达到甚至超越主流竞品水平，16G VRAM消费级设备可流畅运行。模型分三个变体：Turbo（轻量实时，适用于AIGC应用、小程序）、Base（基础未蒸馏，支持二次微调）、Edit（图像编辑专用），其中Turbo最具落地价值。实测中，1024×1024分辨率生成耗时0.8秒（Flash Attention+模型编译），显存峰值14G。技术上，其S3-DiT架构提升参数效率，Decoupled-DMD蒸馏算法实现8步推理，DMDR融合RL与DMD优化质量。优势场景包括双语文本渲染、写实生成、低显存部署及图像编辑；局限为仅Turbo开放，极端风格化生成和模型编译耗时待优化。Z-Image兼顾性能、效率与落地性，适合中小团队和开发者降低部署门槛。
Read MoreNginx Port and Domain Binding: Easily Achieve Domain Access to the Server
This article explains how to bind ports and domains in Nginx to achieve hosting multiple websites/services on a single server. The core is to distinguish different sites by "port + domain name". Nginx configures virtual hosts through the `server` block, with key directives including `listen` (port), `server_name` (domain name), `root` (file path), and `index` (home page). Prerequisites: The server needs Nginx installed, the domain name should be registered and resolved to a public IP, and the server should be tested to be accessible. Practical cases are divided into two scenarios: 1. The same domain name with different ports (e.g., binding 80 and 443 ports for `www.myblog.com`, with HTTPS certificate required for the latter); 2. Different domain names with different ports (e.g., `www.myblog.com` using port 80, `blog.myblog.com` using port 8080). Configuration files are stored in `/etc/nginx/conf.d/`, and examples should include `listen` and `server_name`. Verification: Execute `nginx -t` to check syntax, use `systemctl restart nginx` to apply changes, and verify access via a browser. Common issues: Configuration errors (check syntax), unapplied domain resolution (wait for DNS or use `nslookup`), port conflicts (change port or ...).
Read MoreCommon Nginx Commands: Essential Start, Stop, Restart, and Configuration Check for Beginners
This article introduces the core commands for Nginx daily management to help beginners get started quickly. There are two ways to start Nginx: using `nginx` for source code installation, and `sudo systemctl start nginx` for system services installed via yum/apt. Verification can be done by `ps aux | grep nginx` or accessing the test page. For stopping, there are quick stop (`nginx -s stop`, which may interrupt ongoing requests) and graceful stop (`nginx -s quit`, recommended, waiting for current requests to complete). The difference lies in whether the service is interrupted. For restarting, there are two methods: reloading the configuration (`nginx -s reload`, essential after configuration changes without interruption) and full restart (`systemctl restart`, which may cause brief interruption). Configuration checks require first verifying syntax with `nginx -t`, then applying changes with `nginx -s reload`. `nginx -T` can display the complete configuration. Common commands for beginners include start/stop, reload, and syntax checking. Note permissions, configuration paths, and log troubleshooting. Mastering these commands enables efficient daily Nginx operation and maintenance.
Read MoreNginx Beginner's Guide: Configuring an Accessible Web Server
### A Beginner's Guide to Nginx Nginx is a high-performance, lightweight web server/reverse proxy, ideal for high-concurrency scenarios. It features low resource consumption, flexible configuration, and ease of use. **Installation**: On mainstream Linux systems (Ubuntu/Debian/CentOS/RHEL), install via `apt` or `dnf`. Start and enable Nginx with `systemctl start/ enable nginx`, then verify with `systemctl status nginx` or by accessing the server's IP address. **Core Configuration**: Configuration files are located in `/etc/nginx/`, where `nginx.conf` is the main configuration file and `conf.d/` stores virtual host configurations. Create a website directory (e.g., `/var/www/html`), write an `index.html` file, and add a `server` block in `conf.d/` (specifying port 80 listening and the website directory). **Testing & Management**: After modifying configurations, use `nginx -t` to check syntax and `systemctl reload` to apply changes. Ensure port 80 is open (firewall settings) and file permissions are correct for testing access. Common commands include `start/stop/restart/reload nginx` and status checks. **Summary**
Read MoreNginx Dynamic and Static Content Separation: Speed Up and Stabilize Your Website Loading
Nginx static-dynamic separation separates static resources (images, CSS, JS, etc.) from dynamic resources (PHP, APIs, etc.). Nginx focuses on quickly returning static resources, while backend servers handle dynamic requests. This approach can improve page loading speed, reduce backend pressure, and enhance scalability (static resources can be deployed on CDNs, and dynamic requests can use load balancing). The core of implementation is distinguishing requests using Nginx's `location` directive: static resources (e.g., `.jpg`, `.js`) are directly returned using the `root` directive with specified paths; dynamic requests (e.g., `.php`) are forwarded to the backend (e.g., PHP-FPM) via `fastcgi_pass` or similar. In practice, within the `server` block of the Nginx configuration file, use `~*` to match static suffixes and set paths, and `~` to match dynamic requests and forward them to the backend. After verification, restart Nginx to apply the changes and optimize website performance.
Read MoreIntroduction to Nginx Caching: Practical Tips for Improving Website Access Speed
Nginx caching temporarily stores frequently accessed content to "trade space for time," enhancing access speed, reducing backend pressure, and saving bandwidth. It mainly includes two types: proxy caching (for static resources in reverse proxy scenarios, with origin requests to the backend) and web caching (HTTP caching, relying on the backend `Cache-Control` headers for browser local caching). Dynamic content and frequently changing content (e.g., user information, real-time data) are not recommended for caching. Configuring proxy caching requires defining paths (e.g., `proxy_cache_path`) and parameters (e.g., cache size, key rules), enabling them in `location` (e.g., `proxy_cache my_cache`), and restarting Nginx after verifying the configuration. Management involves checking cache status (logging `HIT/MISS`), clearing caches (manually deleting cache files or using the `ngx_cache_purge` module), and optimization (caching only static resources, setting `max-age` reasonably). Common issues: For cache misses, check configuration, backend headers, or permissions; for stale content, verify `Cache-Control` headers. Key points: Cache only static content, monitor hit status via logs, and prohibit caching dynamic content.
Read MoreConfiguring HTTPS in Nginx: A Step-by-Step Guide to Achieving Secure Website Access
This article introduces the necessity and practical methods of configuring HTTPS for websites. HTTPS ensures data transmission security through SSL/TLS encryption, preventing user information from being stolen. It also improves search engine rankings and user trust (since browser "insecure" prompts can affect experience), making it an essential configuration for modern websites. The core of configuration is using Let's Encrypt free certificates (obtained via the Certbot tool). On Ubuntu/Debian systems, execute `apt install certbot python3-certbot-nginx` to install Certbot and the Nginx plugin. Then, use `certbot --nginx -d example.com -d www.example.com` to obtain the certificate by specifying the domain name. Certbot will automatically configure Nginx (listening on port 443, setting SSL certificate paths, and redirecting HTTP to HTTPS). Verification methods include checking certificate status (`certbot certificates`) and accessing the HTTPS site via a browser to check the small lock icon. It is important to note certificate path, permissions, and firewall port configurations. Let's Encrypt certificates auto-renew every 90 days, which can be tested with `certbot renew --dry-run`. In summary, HTTPS configuration is simple and can enhance security, SEO, and user experience, making it an essential skill for modern websites.
Read MoreNginx Virtual Hosts: Deploying Multiple Websites on a Single Server
This article introduces the Nginx virtual host feature, which allows a single server to host multiple websites, thereby reducing costs. The core is to simulate multiple virtual servers through technology. There are three implementation methods in Nginx: domain name-based (the most common, where different domains correspond to different websites), port-based (distinguished by different ports, suitable for scenarios without additional domains), and IP-based (for servers with multiple IPs, where different IPs correspond to different websites). Before configuration, Nginx needs to be installed, website content prepared (e.g., directories `/var/www/site1` and `/var/www/site2` with homepages), and domain name resolution or test domains (optional) should be ensured. Taking the domain name-based method as an example, the steps are: create the configuration file `/etc/nginx/sites-available/site1.com`, write a `server` block (listening on port 80, matching the domain name, specifying the root directory), configure the second website similarly, create a soft link to `sites-enabled`, test with `nginx -t`, and restart Nginx. For other methods: the port-based method requires specifying a different port (e.g., 8080) in the `server` block; the IP-based method requires the server to bind multiple IPs, with the `listen` directive in the configuration file specifying the IP and port. Common issues include permissions, configuration errors, and domain name resolution, which require checking directory permissions, syntax, and confirming that the domain name points to the server's IP. In summary, Nginx's virtual host feature is a cost-effective solution for hosting multiple websites on a single server, with flexible configuration options based on domain names, ports, or IPs to meet various deployment needs.
Read MoreNginx Static Resource Service: Rapid Setup for Image/File Access
Nginx is suitable for hosting static resources such as images and CSS due to its high performance, lightness, stability, and strong concurrency capabilities, which enhances access speed and saves server resources. For installation, run `sudo apt install nginx` on Ubuntu/Debian and `sudo yum install nginx` on CentOS/RHEL. After startup, access `localhost` to verify. For core configuration, create `static.conf` in `/etc/nginx/conf.d/`. Example: Listen on port 80, use `location` to match paths (e.g., `/images/` and `/files/`), specify the resource root directory with `root`, and enable directory browsing with `autoindex on` (with options to set size and time display). During testing, create `images` and `files` directories under `/var/www/static`, place files in them, run `nginx -t` to check configuration, and reload Nginx with `systemctl reload nginx` to apply changes. Then test access via `localhost/images/xxx.jpg` or `localhost/files/xxx.pdf`. Key considerations include Nginx user permissions and configuration reload effectiveness. Setting up Nginx for static resource service is simple, with core configuration paths and directory browsing functionality, ideal for rapid static resource hosting. It can be extended with features like image compression and anti-leeching.
Read MoreNginx Load Balancing: Simple Configuration for Multi-Server Traffic Distribution
This article introduces Nginx load balancing configuration to solve the problem of excessive load on a single server. At least two backend servers running the same service are required, with Nginx installed and the backend ports open. The core configuration consists of two steps: first, define the backend server group using `upstream` (supporting round-robin, weight, and health checks, e.g., `server 192.168.1.100:8080 weight=2;` or `max_fails=2 fail_timeout=10s`); second, configure `proxy_pass` to this group in the `server` block, passing the client's `Host` and real IP (`proxy_set_header Host $host; proxy_set_header X-Real-IP $remote_addr;`). Verification involves running `nginx -t` to check syntax, `nginx -s reload` to restart, and testing access to confirm request distribution. Common issues such as unresponsive backends or configuration errors can be resolved by checking firewalls and logs. Advanced strategies include IP hashing (`ip_hash`) and URL hashing (requires additional module).
Read MoreIntroduction to Nginx Reverse Proxy: Easily Achieve Frontend-Backend Separation
In a web front-end and back-end separation architecture, Nginx reverse proxy can solve problems such as cross-origin issues, complex domain name management, and back-end exposure. The reverse proxy acts as an intermediary server, so users access the back-end real service by visiting Nginx, which is transparent to users. When front-end and back-end are separated, reverse proxy can unify domain names (users only need to remember one domain name), hide the back-end address (enhancing security), and distribute requests by path (e.g., `/` for the front-end and `/api` for the back-end). Nginx is simple to install (Ubuntu uses `apt install nginx`, CentOS uses `yum install nginx`). The core of configuration is the `location` block: the front-end static files use `root` and `index` to point to the front-end directory, while the back-end API uses `proxy_pass` to forward to the real address, with `proxy_set_header` to pass header information. In practice, place the front-end files in the Nginx directory. After the back-end service is started, use `location` to distinguish paths. Nginx intercepts requests and forwards them, allowing users to complete front-end and back-end interaction by accessing a single domain name. Reverse proxy also supports extended functions such as load balancing and caching, making it a key tool in front-end and back-end separation architectures.
Read MoreDetailed Explanation of Nginx Configuration Files: Server Block and Location for Beginners
The core of Nginx configuration lies in Server blocks (virtual hosts) and location blocks (path distribution). The main configuration file (nginx.conf) includes the global context (with directives like worker_processes), the events context (with worker_connections), and the http context (which contains multiple Server blocks). A Server block defines a website using directives such as listen (port), server_name (domain name), root (root directory), and index (homepage). Location blocks match requests based on paths, supporting prefix, exact, regular expression, and other types, with priority order: exact match > prefix with ^~ > ordinary prefix > regular expression > default. After configuration, use `nginx -t` to verify syntax and `nginx -s reload` to apply changes. After mastering basic configurations (port, domain name, static path), beginners can progressively learn advanced features like dynamic request forwarding and caching.
Read MoreLearn Nginx from Scratch: A Step-by-Step Guide to Installation and Startup
This article introduces the basics of learning Nginx, emphasizing its lightweight, efficient, and flexible configuration, making it suitable for web server setup. The content includes: Nginx supports Windows and Linux systems. Installation is explained using Ubuntu/Debian and CentOS/RHEL as examples: for Ubuntu, run `apt update` followed by `apt install nginx`; for CentOS, first install the EPEL repository and then use `yum install nginx`. After starting with `systemctl start nginx`, access `localhost` to verify a successful default welcome page display. The core configuration files are located in `/etc/nginx/`, where the `default` configuration file defines listening on port 80, the root directory `/var/www/html`, etc. Common commands include starting/stopping, reloading, and syntax checking. It also mentions common troubleshooting (port conflicts, configuration errors) and methods for customizing the homepage. For Windows installation, download, extract, and start via command line. Finally, it encourages hands-on practice to master advanced features.
Read MoreNode.js File System: Quick Reference Guide for Common fs Module APIs
# Node.js File System: Quick Reference for the fs Module This article introduces the core APIs of the `fs` module in Node.js, helping beginners quickly get started with file operations. The `fs` module provides both synchronous and asynchronous APIs: synchronous methods (e.g., `readFileSync`) block execution and are suitable for simple scripts, while asynchronous methods (e.g., `readFile`) are non-blocking and handle results via callbacks, making them ideal for high-concurrency scenarios. Common APIs include: reading files with `readFile` (asynchronous) or `readFileSync` (synchronous); writing with `writeFile` (overwrite mode); creating directories with `mkdir` (supports recursive creation); deleting files/directories with `unlink`/`rmdir` (non-empty directories require `fs.rm` with `recursive: true`); reading directories with `readdir`; getting file information with `stat`; and checking existence with `existsSync`. Advanced tips: Use the `path` module for path handling; always check for errors in asynchronous operations; optimize memory usage for large files with streams; and be mindful of file permissions. Mastering the basic APIs will cover most common scenarios, with further learning needed for complex operations like stream processing.
Read MoreNon-blocking I/O in Node.js: Underlying Principles for High-Concurrency Scenarios
This article focuses on explaining Node.js non-blocking I/O and its advantages. Traditional synchronous blocking I/O causes programs to wait for I/O completion, leaving the CPU idle and resulting in extremely low efficiency under high concurrency. Non-blocking I/O, by contrast, initiates a request without waiting, immediately executing other tasks, and notifies completion through callback functions, which are uniformly scheduled by the event loop. Node.js implements non-blocking I/O through the event loop and the libuv library: asynchronous I/O requests are handed over to the kernel (e.g., Linux epoll) by libuv. The kernel monitors I/O completion status, and upon completion, the corresponding callback is added to the task queue. The main thread is not blocked and can continue processing other tasks. Its high concurrency capability arises from: a single-threaded JS engine that does not block, with a large number of I/O requests waiting concurrently. The total time consumed is only the average time per single request, not the sum. libuv abstracts cross-platform I/O models and maintains an event loop (handling microtasks, macrotasks, and I/O callbacks) to uniformly schedule callbacks. Non-blocking I/O enables Node.js to excel in scenarios such as web servers, real-time communication, and I/O-intensive data processing. It is the core of Node.js's high concurrency handling, efficiently supporting tasks like front-end engineering and API services.
Read MoreNode.js REPL Environment: An Efficient Tool for Interactive Programming
The Node.js REPL (Read-Eval-Print Loop) is an interactive programming environment that provides immediate feedback through an input-execute-output loop, making it suitable for learning and debugging. To start, install Node.js and enter `node` in the terminal, where you'll see the `>` prompt. Basic operations include simple calculations (e.g., `1+1`), variable definition (`var message = "Hello"`), and testing functions/APIs (e.g., `add(2,3)` or the array `map` method). Common commands are `.help` (view commands), `.exit` (quit), `.clear` (clear), `.save`/`.load` (file operations), with support for arrow key history navigation and Tab auto-completion. The REPL enables quick debugging, API testing (e.g., `fs` module), and temporary script execution. Note that variables are session-specific, making it ideal for rapid validation rather than large-scale project development. It serves as an efficient tool for Node.js learning, accelerating code verification and debugging.
Read MoreBuilding RESTful APIs with Node.js: Routing and Response Implementation
This article introduces the core process of building a RESTful API using Node.js and Express. Node.js is well-suited for high-concurrency services due to its non-blocking I/O and single-threaded model, and when paired with the lightweight and efficient Express framework, it is ideal for beginners. For preparation, install Node.js (recommended LTS version) and initialize the project. Install the Express framework via `npm install express`. The core involves creating a service with Express: importing the framework, instantiating it, and defining routes. Use methods like `app.get()` to handle different HTTP requests (GET/POST/PUT/DELETE), with the `express.json()` middleware to parse JSON request bodies. Each method corresponds to different operations: GET retrieves resources, POST creates, PUT updates, and DELETE removes. Data is passed using route parameters and request bodies, with status codes such as 200, 201, and 404 returned in results. Advanced content includes route modularization (splitting route files) and 404 handling. Finally, test the API using Postman or curl. After mastering this, you can connect to a database to extend functionality and complete the construction of a basic API.
Read MoreFrontend Developers Learning Node.js: The Mindset Shift from Browser to Server
This article introduces the necessity and core points for front-end developers to learn Node.js. Based on Google Chrome's V8 engine, Node.js enables JavaScript to run on the server-side, overcoming the limitations of front-end developers in building back-end services and enabling full-stack development. Its core features include "non-blocking I/O" (handling concurrent requests through the event loop), "full-access" environment (capable of operating on files and ports), and the "CommonJS module system". For front-end developers transitioning to back-end roles, mindset shifts are required: changing from the sandboxed (API-limited) runtime environment to a full-access environment; transforming asynchronous programming from an auxiliary task (e.g., setTimeout) to a core design principle (to avoid server blocking); and adjusting from ES Modules to CommonJS (require/module.exports) for module systems. The learning path includes: mastering foundational modules (fs, http), understanding asynchronous programming (callbacks/Promise/async), developing APIs with frameworks like Express, and exploring the underlying principles of tools such as Webpack and Babel. In summary, Node.js empowers front-end developers to build full-stack capabilities without switching programming languages, enabling them to understand server-side logic and expand career horizons. It is a key tool for bridging the gap between front-end and back-end development.
Read MoreNode.js Buffer: An Introduction to Handling Binary Data
In Node.js, when dealing with binary data such as images and network transmission data, the Buffer is a core tool for efficiently storing and manipulating byte streams. It is a fixed-length array of bytes, where each element is an integer between 0 and 255. Buffer cannot be dynamically expanded and serves as the foundation for I/O operations. There are three ways to create a Buffer: `Buffer.alloc(size)` (specifies the length and initializes it to 0), `Buffer.from(array)` (converts an array to a Buffer), and `Buffer.from(string, encoding)` (converts a string to a Buffer, requiring an encoding like utf8 to be specified). A Buffer can read and write bytes via indices, obtain its length using the `length` property, convert to a string with `buf.toString(encoding)`, and concatenate Buffers using `Buffer.concat([buf1, buf2])`. Common methods include `write()` (to write a string) and `slice()` (to extract a portion). Applications include file processing, network communication, and database BLOB operations. It is important to note encoding consistency (e.g., matching utf8 and base64 conversions), avoid overflow (values exceeding 255 will be truncated), and manage off-heap memory reasonably to prevent leaks. Mastering Buffer is crucial for understanding Node.js binary data processing.
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