Navigating Linux relies heavily on command-line operations. Mastering directory and file commands is crucial for efficient system management. Here are 20 fundamental commands with practical examples:
### 🗂️ Directory Navigation
1. **pwd** (Print Working Directory)
Shows current directory path
`$ pwd` → `/home/user/documents`
2. **cd** (Change Directory)
Moves between directories
`$ cd /var/log`
`$ cd ..` (go back one level)
3. **ls** (List)
Displays directory contents
`$ ls -l` (detailed list)
`$ ls -a` (show hidden files)
4. **tree**
Shows directory structure visually
`$ tree -L 2` (display 2 levels deep)
### 📁 Directory Management
5. **mkdir** (Make Directory)
Creates new directories
`$ mkdir new_project`
`$ mkdir -p dir1/dir2/dir3` (create nested directories)
6. **rmdir** (Remove Directory)
Deletes EMPTY directories
`$ rmdir old_folder`
### 📄 File Operations
7. **touch**
Creates empty files or updates timestamps
`$ touch file.txt`
8. **cp** (Copy)
Copies files/directories
`$ cp file.txt backup/`
`$ cp -r dir1 dir2` (recursive copy)
9. **mv** (Move)
Moves/renames files
`$ mv old.txt new.txt`
`$ mv file.txt ~/Documents/`
10. **rm** (Remove)
Deletes files/directories
`$ rm temporary.log`
`$ rm -r old_project` (delete recursively)
### 🔍 File Inspection
11. **cat** (Concatenate)
Shows file content
`$ cat config.conf`
12. **less**
Views files page-by-page
`$ less long_file.log` (press `q` to exit)
13. **head**
Displays first 10 lines
`$ head -n 5 file.log` (show first 5 lines)
14. **tail**
Shows last 10 lines
`$ tail -f access.log` (live updates)
### 🔎 Search Operations
15. **find**
Searches for files/directories
`$ find /home -name "*.jpg"`
`$ find . -size +10M`
16. **grep** (Global Regular Expression Print)
Searches text patterns
`$ grep "error" system.log`
`$ grep -r "TODO" ./src/` (recursive search)
### 🛡️ Permissions & Ownership
17. **chmod** (Change Mode)
Modifies file permissions
`$ chmod 755 script.sh`
`$ chmod u+x executable` (add user execute)
18. **chown** (Change Owner)
Changes file ownership
`$ chown user:group file.txt`
### 🔗 File Links
19. **ln** (Link)
Creates file links
`$ ln -s target.txt symlink.txt` (symbolic link)
### ℹ️ File Information
20. **file**
Identifies file type
`$ file unknown.dat` → `unknown.dat: ASCII text`
21. **stat**
Shows detailed file info
`$ stat document.pdf`
22. **du** (Disk Usage)
Checks file/directory size
`$ du -sh *` (human-readable sizes)
### 💡 Pro Tips
- Use `man [command]` for official documentation (e.g., `man ls`)
- Combine commands with pipes: `grep "404" access.log | less`
- Tab completion saves typing: type `cd Dow⇥` to autocomplete `Downloads`
Practice these commands in a safe environment to build confidence. Remember: Linux is case-sensitive and paths matter! Start with basic operations before attempting system-critical tasks. 🐧
