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du

The du (disk usage) command estimates file space usage. While df tells you how much space is left on a whole partition, du is used to find out which specific directories and files are consuming that space.

Basic Syntax​

du [OPTIONS] [FILE or DIRECTORY]

Common Flags/Options​

OptionDescription
-h, --human-readablePrint sizes in human-readable format (e.g., 1K, 234M, 2G).
-s, --summarizeDisplay only a grand total for each specified argument (don't list subdirectories).
-c, --totalProduce a grand total at the very end.
-a, --allWrite counts for all files, not just directories.
--max-depth=NPrint the total for a directory only if it is N or fewer levels below the command line argument.

Real-world Examples​

1. Check the total size of a directory​

If you want to know exactly how much space the /var/log directory takes up, without seeing every single file inside it:

du -sh /var/log

Output Example:

1.2G    /var/log

2. Find the largest directories​

A very common task is finding what is eating up disk space. You can combine du with sort. Note: We use -h for du and -h for sort so the sorting understands Megabytes vs Gigabytes.

sudo du -sh /* | sort -h

3. Analyze usage up to a specific depth​

If you are in the root directory / and want to see how much space each top-level folder uses, but you don't want a massive list of all subfolders:

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

(In some Unix systems or BSD, the equivalent flag is -d 1).

4. Get a grand total of multiple items​

If you want to know the combined size of two different directories:

du -shc /var/log /var/cache

Output Example:

1.2G    /var/log
500M    /var/cache
1.7G    total