du — Check disk usage

💬 "du command"

• Concept: An essential Linux command for checking disk usage. It is used to find the culprit folders and files when server storage is full.
• Output structure: The default command prints all sub-items in complex detail in KB units, making it hard to read.
• Recommended practical output: When you type du -sh *, capacity units are summarized in an easy-to-read format such as 45M or 2.3G.
• Left column: Shows the total capacity actually occupied by the file or folder.
• Right column: Shows the name of the target using that capacity.

3 Essential Command Combinations

• du -sh — Summarize only the total combined capacity of the current folder in a single line
• du -sh * — Check the capacity of each item directly under the current folder individually
• du -sh * | sort -h — Sort the output so the largest folders appear at the bottom

💬 "Also tell me one way to apply this"

Scenario: How to resolve a situation where log files explode to GB sizes and the server disk becomes full.

Step 1: Track down the culprit folder

Move to the log directory and sort the folders by size.

cd /var/log && du -sh * | sort -h

Step 2: Target huge files

After entering the culprit folder, dig down to the file level and filter out only files larger than 1GB.

du -ah * | grep -E '^[0-9.]+[G]'

Step 3: Free up space safely (key point)

If you delete a running log file with rm, the process keeps holding onto it and the disk space is not returned. Use the command below to truncate the file contents to 0 bytes and reclaim space immediately.

cat /dev/null > user-activity.log

Actual Execution Screen

This is the result of actually creating a folder on this PC and running du -sh * | sort -h. The items get larger toward the bottom, and at the very bottom logs is the largest at 2.3G.

!Result of du -sh * | sort -h: sorted by size from 2.4M src to 2.3G logs

Server in actual operation

This is the result of filtering only files larger than 1GB inside that logs folder. user-activity.log is taking up 1.9G.

![Result of du -ah . | grep -E '^[0-9.]+[G]': 1.9G user-activity.log](https://games.aidebatehub.com/assets/du-logs.png)

Source (HTML): https://games.aidebatehub.com/programs/linux/filesystem/du.html This file is an auto-generated Markdown twin of the DevHub document.