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Cold04 Technical Notes

website·Indexed 32 days ago

https://note.cold04.com/

A collection of technical documentation and tutorials covering Linux system administration (CentOS 7), Shell scripting, SQL Server database management, WLAN and IEEE 802.11 protocols, network configuration (VTP, STP, NAT, Static Routing), and LNMP stack deployment including distributed web server setups and WordPress installation.

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What's inside Cold04 Notes

  1. Introduction to Regular Expressions for Text Pattern Matching

    Regular expressions (regex) are special character sequences used for pattern matching and searching text. They consist of literal characters (e.g., letters a-z) and special characters known as "metacharacters." A single regex string can describe and match a series of strings that follow specific syntactic rules, making them a powerful tool for validating if a string matches a particular pattern.

  2. Overview of Regular Expressions (Regex)

    Regular expressions are special sequences of characters used for pattern matching and searching within text. They consist of literal characters (e.g., letters a-z) and special characters known as 'metacharacters'. Regex allows a developer to describe a set of strings that follow a specific syntactic rule using a single string pattern.

  3. Introduction to Shell Scripting

    A Shell script is a plain text document containing a series of commands that a Shell interpreter reads and executes line by line. They are typically used to automate the batch execution of Linux system commands or user-defined commands. Shell scripts usually end with the .sh extension.

  4. Overview of SQL Server Stored Procedures

    A stored procedure is a compiled set of SQL statements stored in the database to perform a specific function. They can accept input parameters and return output parameters. Stored procedures improve execution efficiency, enhance security, and simplify complex operations by encapsulating logic on the server side.

  5. Overview of SQL Server Views

    A view is a virtual table whose contents are defined by a query. Unlike a standard table, a view does not store data values physically in the database (unless it is an indexed view). Instead, the rows and columns are dynamically generated from the tables referenced in the view's defining query whenever the view is accessed.

  6. Understand the fundamentals of Distributed Systems

    A distributed system consists of a group of computer nodes that communicate over a network and coordinate their work to achieve a common goal. Key characteristics include the absence of shared memory or disk storage, relying instead on message passing for communication. Critical challenges in distributed systems include concurrency, lack of a global clock, independent node failures, network partitioning, software errors, and security attacks.

  7. Understand Huawei FAT AP (Autonomous) Architecture

    The FAT AP (Autonomous) architecture allows the Access Point (AP) to implement all wireless access functions independently without requiring an Access Controller (AC). While this provides high independence and ease of deployment for homes or small businesses, it creates high operational and maintenance costs for large enterprises because each AP must be configured and upgraded individually.

  8. Understand Huawei AC + FIT AP (Thin AP) Architecture

    The AC + FIT AP architecture, also known as the 'Thin AP' architecture, separates the control plane from the radio plane. The FIT AP provides the wireless radio signal but lacks management and control capabilities. All management, security processing, and control functions are centralized in the Wireless Access Controller (AC), significantly improving security and management efficiency compared to FAT APs.

  9. Understand Linux disk device naming and basics

    In Linux, disks are represented as device files located in /dev/sd[a-z]. For example, /dev/sda is the first disk and /dev/sdb is the second. These are binary files and should not be edited with text editors. A raw disk must be partitioned and formatted before it can be mounted and used to store files.

  10. Deploy WordPress files to distributed Nginx and PHP servers

    In a distributed architecture, the WordPress source files must be present on both the Nginx (web server) and PHP (application server) nodes. Upload the WordPress archive and extract it to the /var/www/html directory on both servers.
    tar -zxvf wordpress-4.9.1-zh_CN.tar.gz -C /var/www/html/

  11. Understand LVM (Logical Volume Manager) architecture

    LVM provides a flexible way to manage disk space by abstracting physical storage into logical volumes. The hierarchy and creation order is:

    1. Physical Volume (PV): The base layer (disk partition, RAID, etc.).
    2. Volume Group (VG): A pool created from one or more PVs.
    3. Logical Volume (LV): The top layer created from a VG, which is then formatted and mounted.

    Management Order:

    • Creation: PV $\rightarrow$ VG $\rightarrow$ LV
    • Deletion: LV $\rightarrow$ VG $\rightarrow$ PV

  12. Understand Huawei AC + FIT AP (Thin AP) Architecture

    The AC + FIT AP architecture, also known as the 'Thin AP' architecture, splits functions between a Wireless Controller (AC) and Fit APs. The Fit AP provides the wireless radio frequency (RF) signal but lacks management and control capabilities; all control and management functions are centralized on the AC.