Master Linux: From OS Basics to Command-Line Power Tools

Operating System Overview

An operating system (OS) is the fundamental software that manages hardware and software resources, running directly on the hardware and enabling other software to operate.

Linux OS Installation

https://blog.csdn.net/huaijiu123/article/details/82083452

Linux Filesystem

/var

: Stores variable data such as logs, spools, and temporary files. /home: Contains user files and personal settings; a directory is created for each user. /proc: Virtual files representing kernel and process information, not stored on disk. /bin: Essential binary executables required for system boot. /etc: Configuration files for the system and services. /root: Home directory of the root (superuser). /dev: Device files that abstract hardware as files.

Linux Command Operations

Show current directory: pwd Change directory: cd [directory], cd ~ (home), cd .. (parent), cd - (previous), cd / (root)

List files: ls, ls -l (detailed), ls -a (including hidden), ls -la (both)

Create directories: mkdir folder, mkdir -p path/to/folder Remove directories: rmdir folder, rmdir -p folder Delete files/directories: rm -rf target (force), rm -ri target (interactive)

Copy files/directories: cp source target, cp -r dir1 dir2, cp -ri dir1 dir2 Move/rename: mv old new Create empty file: touch filename Edit files: vi filename View file content: cat filename, cat > filename Show file start: head filename, head -n N filename Show file end: tail filename, tail -f filename,

tail -n N filename

Linux Permission Management

Linux defines read ( r), write ( w), and execute ( x) permissions for owner, group, and others. Use ls -l to view them. drwxr-xr-x 2 root root 4096 Sep 23 2011 bin Permission bits are represented as: d: directory rwx: owner has read, write, execute r-x: group has read and execute r-x: others have read and execute

Change permissions with chmod. Two modes are supported:

Symbolic mode: chmod u=rwx,g=rw,o=rw file Numeric mode: chmod 753 file (owner 7=rwx, group 5=r-x, others 3=-wx)

Linux Process Management

View running processes with ps and filter with grep: ps -ef | grep process_name Terminate a process using kill -9 PID.

Common Linux Commands

clear

: clear the terminal screen man: view command manual pages mnt: mount filesystems

SSH service control: service sshd start, service sshd restart, service sshd stop Run a Java JAR in background:

nohup java -jar jar-0.0.1-SNAPSHOT.jar &

Linux System Software Installation

Three common installation methods:

tar : extract source packages ( tar -zxvf file.tar.gz, tar -jxvf file.tar.bz2, tar -xvf file.tar)

rpm : Red Hat package manager; install, query, or remove packages (e.g., rpm -ivh package.rpm, rpm -qa | grep name, rpm -e package)

yum : Front‑end to rpm that resolves dependencies automatically.