du Command Linux: Display Directory Size and Disk Usage Explained with Examples

The du (disk usage) command in Linux is a powerful tool that allows users to measure directory size, analyze disk usage, and manage storage effectively. Whether you are troubleshooting storage shortages or simply want to analyze large files taking up unnecessary space, du is one of the most essential Linux commands for system administrators and developers alike.

What is the du Command in Linux?

The du command stands for Disk Usage. It estimates and displays the amount of disk space files and directories occupy. Unlike df, which shows overall filesystem space, du drills down into specific directories and files to reveal precise usage details.

Basic Syntax

du [options] [file...]

If no path is provided, du defaults to the current directory.

Commonly Used Options with du

• -h : Human-readable output (e.g., KB, MB, GB).
• -s : Show only the total size of a directory.
• -a : Include both files and directories in the output.
• -c : Display a grand total at the end.
• -d N : Limit the depth of directories displayed.
• --max-depth=N : Equivalent to -d N, useful for controlling directory levels.
• --apparent-size : Show the space a file appears to take, not actual disk blocks.

Practical Examples of du Command

1. Checking Disk Usage of Current Directory

du -h

Output Example:

4.0K    ./scripts
36M     ./logs
120M    ./backups
160M    .

This shows how much space each subdirectory in the current path consumes, followed by the total.

2. Showing Only the Total Size of a Directory

du -sh /var/log

Output Example:

220M    /var/log

Perfect when you only need the size of an entire directory.

3. Getting Disk Usage for All Files and Directories

du -ah /home/username

Output Example:

32K   /home/username/file1.txt
4.0K  /home/username/.bashrc
95M   /home/username/Videos
96M   /home/username

This displays every file’s size along with directory sizes.

4. Displaying a Grand Total

du -ch /var

Output Example:

120K   /var/tmp
150M   /var/www
2.0G   /var/lib
2.15G  total

5. Limiting Directory Depth

du -h --max-depth=1 /etc

Output Example:

2.0M   /etc/ssh
5.5M   /etc/apache2
8.0K   /etc/default
20M    /etc

This shows only one level of subdirectories instead of every nested folder.

6. Sorting Disk Usage by Size

du alone doesn’t sort, so we can pipe it with sort:

du -h --max-depth=1 | sort -hr

Output Example:

500M   ./backups
120M   ./logs
4.0K   ./scripts
620M   .

This helps quickly identify which directories consume the most storage.

7. Finding the Largest Directories

Combine du with head to list only the top results:

du -h --max-depth=1 /home | sort -hr | head -n 5

This efficiently reveals the top 5 space-consuming directories under /home.

Interactive Tip: Monitor Disk Usage Growth

For admins tracking disk usage frequently, wrap du within a watch command:

watch -n 10 'du -sh /var/log'

This displays updated disk usage every 10 seconds – extremely useful for monitoring log growth in real-time.

du vs df Command in Linux

Use du when investigating specific folder/file sizes, and df when you need filesystem-level insights.

Best Practices for Using du Command

• Always use -h for easier readability.
• Combine du with sort to identify storage hogs quickly.
• Limit directory depth with --max-depth to avoid overwhelming outputs.
• Use -c to get precise totals useful in reports.

Conclusion

The du command is a must-know for Linux system administrators, DevOps engineers, and even developers who want fine control over their storage. With its ability to measure and summarize disk usage, combined with sorting and filtering, du helps to quickly identify large directories and optimize disk space usage effectively.

By mastering du with practical options like -h, -s, and --max-depth, you’ll always stay on top of disk space management in Linux environments.