🐧 Linux File and Directory Management

The directory structure of the Linux system is tree-like, with the top level being the root directory <span>/</span>. All files and directories start from <span>/</span> and are added to the system tree through “mounting”.

📂 1. Path Basics: Absolute Path and Relative Path

Before operating the Linux file system, it is essential to understand the two representations of paths:

🧭 1. Absolute Path

A complete path that starts from the root directory <span>/</span>. No matter where you are in the system, this path can accurately locate the target file or directory.

These paths begin with <span>/</span>, indicating a downward navigation from the top level of the file system (the root directory).

💡 Understanding Tip:

Just like writing an address in real life, from “Country → Province → City → Street → House Number” layer by layer, an absolute path always starts from the root directory, writing out the complete “address” of the file.

🧩 2. Relative Path

A path that does not start from the root directory <span>/</span>, but describes the target file’s location relative to the current working directory.

Common Symbols:

.  : represents the current directory.. : represents the parent directory~  : represents the current user's home directory (e.g., /root or /home/username)

🧭 2. Overview of Common Directory Handling Commands

The common file and directory operation commands are as follows:

• <span>ls</span>: list directories and files (list files)

• <span>cd</span>: change directory (change directory)

• <span>pwd</span>: display the current directory (print working directory)

• <span>mkdir</span>: create directory (make directory)

• <span>rmdir</span>: remove empty directory (remove directory)

• <span>cp</span>: copy file or directory (copy file)

• <span>rm</span>: remove file or directory (remove)

• <span>mv</span>: move or rename file, directory (move file)

You can use <span>man [command]</span> to view detailed documentation for each command. For example:<span>man cp</span>

📑 3. Detailed Explanation of Directory Operation Commands

1️⃣ <span><span>ls</span></span> — List Directory Contents

Syntax:

ls [-aAdfFhilnrRSt] [directory name]ls [--color={never,auto,always}]ls [--full-time]

Common Parameter Descriptions:

• <span>-a</span>: display all files (including hidden files)

• <span>-d</span>: display only the directory itself, not its contents

• <span>-l</span>: output in long format, including permissions, owner, size, time, etc.

Example:

[root@www ~]# ls -al ~

2️⃣ <span><span>cd</span></span> — Change Directory

Syntax:

cd [relative path or absolute path]

Common Examples:

# Using absolute pathcd /root/runoob/# Using relative pathcd ./runoob/# Return to home directorycd ~# Return to parent directorycd ..

💡 Tip: Repeatedly practicing the switching of <span>cd</span> with relative and absolute paths helps to understand the hierarchical structure of the Linux file system.

3️⃣ <span><span>pwd</span></span> — Display Current Directory

Syntax:

pwd [-P]

Parameter Descriptions:

• <span>-P</span>: display the real path (if the current path is a symbolic link, it shows the target path)

Example:

[root@www ~]# cd /var/mail[root@www mail]# pwd /var/mail[root@www mail]# pwd -P /var/spool/mail

✨ <span>pwd -P</span> can avoid confusion from symbolic link paths, and it is recommended to use it in scripts.

4️⃣ <span><span>mkdir</span></span> — Create Directory

Syntax:

mkdir [-mp] directory name

Parameter Descriptions:

• <span>-m</span>: directly specify permissions (not restricted by <span>umask</span>)

• <span>-p</span>: recursively create multi-level directories

Example:

mkdir -p test1/test2/test3/test4mkdir -m 711 secure_dir

If there is no <span>-p</span> parameter, the system will not automatically create the parent directories.

5️⃣ <span><span>rmdir</span></span> — Remove Empty Directory

Syntax:

rmdir [-p] directory name

Parameter Descriptions:

• <span>-p</span>: recursively remove multi-level empty directories

Example:

rmdir testdirmdir -p test1/test2/test3/test4

⚠️ Note:<span>rmdir</span> can only remove empty directories. If there are files in the directory, please use <span>rm -r</span>.

6️⃣ <span><span>cp</span></span> — Copy File or Directory

Syntax:

cp [-adfilprsu] source file target filecp [options] source1 source2 ... target directory

Common Parameter Descriptions:

• <span>-a</span>: equivalent to <span>-pdr</span><span>,</span> preserves attributes, recursively copies, does not dereference links

• <span>-i</span>: prompt before overwrite (interactive mode)

• <span>-r</span>: recursively copy directories

• <span>-p</span>: preserve file permissions and timestamps

• <span>-u</span>: copy only if the source file is newer

Example:

cp ~/.bashrc /tmp/bashrccp -i ~/.bashrc /tmp/bashrc

7️⃣ <span><span>rm</span></span> — Remove File or Directory

Syntax:

rm [-fir] file or directory

Parameter Descriptions:

• <span>-f</span>: force delete, do not prompt for errors

• <span>-i</span>: interactive mode (prompt before deletion)

• <span>-r</span>: recursively delete directories and contents

Example:

rm -i bashrcrm -rf testdir

⚠️ Dangerous Operation Warning!<span>rm -rf /</span> will directly delete the entire system, please confirm the path before operating!

8️⃣ <span><span>mv</span></span> — Move or Rename File

Syntax:

mv [-fiu] source file target filemv [options] source1 source2 ... target directory

Parameter Descriptions:

• <span>-f</span>: overwrite directly, do not ask

• <span>-i</span>: prompt before overwrite

• <span>-u</span>: move only if the source file is newer

Example:

mv bashrc mvtest/mv mvtest mvtest2

📜 4. File Content Viewing Commands

Common file viewing commands in the Linux system include:

• <span>cat</span>: display file content from the first line

• <span>tac</span>: display file content from the last line (reverse of cat)

• <span>nl</span>: display line numbers

• <span>more</span>: display in pages, can scroll down

• <span>less</span>: enhanced version of more, can scroll up and down

• <span>head</span>: display the first few lines of a file

• <span>tail</span>: display the last few lines of a file or monitor file changes in real-time

You can also use <span>man [command]</span> to view complete explanations.

1️⃣ <span><span>cat</span></span> / <span><span>tac</span></span> — Display File in Order or Reverse

Syntax:

cat [options] filetac [options] file

Example:

cat /etc/issuetac /etc/issue

<span>cat</span> displays from the first line; <span>tac</span> displays from the last line. Suitable for quickly viewing short files.

2️⃣ <span><span>nl</span></span> — Display File Content with Line Numbers

Syntax:

nl [-bnw] file

Parameter Descriptions:

• <span>-b a</span>: number all lines

• <span>-b t</span>: ignore empty lines (default)

• <span>-n ln</span>: line numbers displayed on the left

• <span>-w</span>: set line number width

Example:

nl /etc/issue

3️⃣ <span><span>more</span></span> — View File in Pages

Common Operation Keys:

• Space: scroll down one page

• Enter: scroll down one line

• <span>/keyword</span>: search for keywords downwards

• <span>b</span> or <span>Ctrl + b</span>: scroll up one page

• <span>q</span>: exit

Example:

more /etc/man_db.config

4️⃣ <span><span>less</span></span> — Enhanced File Viewer

Common Operation Keys:

• Space or PageDown: scroll down one page

• PageUp: scroll up one page

• <span>/keyword</span>: search downwards

• <span>?keyword</span>: search upwards

• <span>n</span> / <span>N</span>: repeat last search (in the opposite direction)

• <span>q</span>: exit

Example:

less /etc/man.config

5️⃣ <span><span>head</span></span> / <span><span>tail</span></span> — View the First or Last Few Lines of a File

Syntax:

head [-n number] filetail [-n number] file

Parameter Descriptions:

• <span>-n</span>: specify the number of lines to display

• <span>-f</span>: <span>tail</span> continuously monitors file changes (commonly used for logs)

Example:

head -n 20 /etc/man.configtail -f /var/log/messages

🧩 <span>tail -f</span> is commonly used for real-time log output viewing, such as Nginx, system logs, etc.

🎯 Summary

File and directory management in Linux is the foundation of daily operations and development. Mastering commands like <span>ls</span>, <span>cd</span>, <span>pwd</span>, <span>mkdir</span>, <span>rm</span>, <span>cp</span>, <span>mv</span>, etc., will make you proficient in system operations.

It is recommended to practice more hands-on and combine with <span>man</span> documentation to deepen understanding.