Gitignore File Configuration Guide: Keep Only What You Need in Your Repository
.gitignore is a core configuration file for Git repositories, used to specify files/folders that are not tracked, preventing repository bloat and sensitive information leaks. It is a text file in the root directory with one rule per line, and can be quickly generated using templates like gitignore.io. Core syntax includes: ignoring specific files/folders (e.g., temp.txt, logs/); using wildcards for batch ignoring (*.log, *.tmp); recursively ignoring subdirectories (**/temp.txt); negative rules (!debug.log); and comments (#). Common scenarios include ignoring node_modules/.env/dist/ in frontend projects, __pycache__/venv/ in Python projects, and system files like .DS_Store/Thumbs.db. If a file has already been tracked, it needs to be removed with `git rm --cached` before committing the .gitignore. Ensure accurate paths, distinguish between directories and files, rules take effect recursively, and avoid excluding the .gitignore file itself. Mastering .gitignore helps maintain a clean and efficient repository, enhancing collaboration experience.
Read MoreUnderstanding Git's HEAD Pointer: The Underlying Logic of Version Rollback
HEAD is a special pointer in Git that marks the current version's position, by default pointing to the latest commit of the current branch, acting as a "coordinate" for the timeline. It is closely associated with branches and by default follows the branch to its latest commit. Version rollback essentially involves modifying the HEAD pointer to jump from the current version to a historical version, at which point the branch will also move accordingly. For example, after rolling back to historical version B, the workspace state updates synchronously, and a new commit will generate a new version, advancing the branch forward. It is important to note the following when performing the operation: avoid rolling back pushed versions to prevent collaboration confusion; directly pointing to a historical commit will put you in a "detached HEAD" state, which requires manual handling. HEAD is a core element of version control, and understanding its role enables clear management of version iterations and rollbacks.
Read MoreGit Common Commands Quick Reference: Pull, Push, and Branch Switching All in One
Git is a version control tool that can record file modifications, revert versions, and support multi - person collaboration. The commonly used commands are as follows: Basic operations: Use `git init` to initialize a local repository, and `git clone 地址` to clone a remote repository. Daily operations: `git status` to check the file status, `git add` to stage modifications (use `git add .` to stage all changes), and `git commit -m "message"` to commit to the local repository. Branch operations: `git branch` to view branches, `git checkout -b 分支名` to create and switch to a branch, and `git merge 分支名` to merge branches. Pull and push: `git pull 远程 分支` to pull code, and `git push 远程 分支` to push (add `-u` for the first time). Undo and recovery: `git checkout -- 文件` to undo uncommitted modifications, and `git reset --soft HEAD~1` to revert the last commit (retaining modifications). Notes: The commit message should be clear, follow the branch naming conventions, always `pull` before collaboration to avoid conflicts, and use `git reset --hard` with caution. Core commands: `init`, `clone`, `add`, `commit`, `status`, `checkout`, `merge`
Read More详解Git暂存区：为何需先执行add再进行commit？
This article introduces Git's staging area and core operation logic. Git consists of three areas: the working directory (where files are manipulated), the staging area (a transfer station), and the local repository (historical versions). The staging area is a critical filter before commits. The core logic is "add first, then commit": the staging area allows step-by-step commits (e.g., dividing a novel into chapters), preventing accidental commits of incomplete work. `git add` adds modifications from the working directory to the staging area, while `git commit` submits the staged content to the local repository to form a version. Key points: Committing directly without adding will prompt "nothing to commit". `git reset HEAD <filename>` can undo changes in the staging area. The staging area enables flexible commits, ensures version clarity, and acts as the "final checkpoint" before Git commits. In summary, the staging area, through filtering and transfer, enables staged commits, modification checks, and flexible adjustments, being a core design to avoid accidental commits and maintain historical clarity.
Read MoreEssential Git Tips for Beginners: 3 Practical Techniques to Resolve Branch Merge Conflicts
Conflicts during Git branch merging are a common issue in collaborative development, and mastering 3 techniques can resolve them effortlessly. **Technique 1: Understand Conflict Markers** Locate the conflicting files by identifying markers like `<<<<<<< HEAD` and `=======`. Modify the files based on business logic to retain the desired code. After resolving, execute `git add` and continue the merging process. **Technique 2: Use Visual Tools** Leverage editors like VS Code to auto-highlight conflict regions. Resolve conflicts quickly via buttons such as "Accept Current Change," "Accept Incoming Change," or "Merge Changes," for a more intuitive experience. **Technique 3: Prevent Conflicts at the Source** Reduce conflicts by first pulling the latest code from the target branch (`git pull`) before merging. Additionally, adopt small-step merging (e.g., merging small features daily) to avoid excessive divergence. **Core Principle**: Resolve conflicts efficiently by first manually understanding markers, then using tools, and finally preparing in advance.
Read MoreGetting Started with Git from Scratch: From Cloning a Repository to Committing Code
This article introduces the core knowledge of Git, a distributed version control system. Git is used to manage code changes, supporting multi - person collaboration and version rollback. To install Git, download the corresponding system version (Windows/macOS/Linux) from the official website and verify it using the command `git --version`. Configure the identity by using `git config --global` to set the name and email. Before cloning a remote repository, copy its URL and execute `git clone` to get it on the local machine. A Git repository is divided into the working area (for editing), the staging area (for pending commits), and the local repository (for versions). The workflow is: make modifications → `git add` to stage → `git commit` to commit → `git push` to push. Common commands include `status` to check the status, `log` to view the history, and `pull` to fetch. The core process is: clone → modify → stage → commit → push. With more practice, you can master it.
Read MoreLinux 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.
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