Linux du Command: Check File and Directory Disk Usage

The du (disk usage) command estimates how much disk space files and directories occupy. It’s the go-to tool when you need to find what’s consuming space—whether that’s a single file, a project folder, or an entire filesystem. This guide covers the syntax, the options you’ll actually use, and practical examples with their output.

Syntax

du [OPTIONS] [FILE|DIRECTORY...]

With no arguments, du reports the usage of the current directory and every subdirectory beneath it.

The most useful options

Option	Meaning
-h, --human-readable	Human-readable sizes (1K, 234M, 2G)
-s, --summarize	Show only a total for each argument
-a, --all	Report files as well as directories
-c, --total	Print a grand total at the end
-d N, --max-depth=N	Limit how many directory levels are shown
--apparent-size	Show apparent size instead of disk usage
-x, --one-file-system	Skip directories on other filesystems
--exclude=PATTERN	Skip files/directories matching a pattern
--time	Show the last modification time
-t SIZE, --threshold=SIZE	Only show entries at least (or at most) SIZE

Basic usage

Size of a single file

du -h /etc/passwd

Output:

4.0K    /etc/passwd

Size of a directory (recursive listing)

Without -s, du prints every subdirectory:

du -h /var/log

Output:

16K     /var/log/apt
4.0K    /var/log/private
2.3M    /var/log/journal/9f2a
2.3M    /var/log/journal
12M     /var/log

Total size only with -s

The -s (summarize) flag collapses everything into one line—the most efficient way to size a directory:

du -sh /var/log

Output:

12M     /var/log

Common recipes

Size of everything in the current directory

du -sh *

Output:

1.2G    Downloads
340M    Pictures
28K     notes.txt
4.0K    todo.md

Include hidden files, and add a grand total

du -sch .[!.]* * | tail -n 1

Or more simply, get one total for the whole current directory:

du -sh .

Output:

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1.6G    .

Limit the depth

Show only the top level of /usr, one directory deep, with a grand total:

du -h --max-depth=1 /usr | sort -rh

Output:

3.9G    /usr
2.1G    /usr/lib
1.2G    /usr/share
480M    /usr/bin
120M    /usr/include

Find the largest items, biggest first

Pipe du into sort -rh (reverse, human-numeric) to rank by size:

du -sh * | sort -rh | head -n 5

Output:

1.2G    Downloads
340M    Pictures
96M     projects
28K     notes.txt
4.0K    todo.md

Show every file, not just directories

du -ah /etc/lvm

Output:

96K     /etc/lvm/lvm.conf
4.0K    /etc/lvm/profile/default.profile
8.0K    /etc/lvm/profile
108K    /etc/lvm

Exclude files by pattern

Skip .log files when sizing a directory:

du -sh --exclude="*.log" /var/www

Stay on one filesystem

Useful when a directory contains mount points you don’t want to descend into:

du -sh -x /

Only show entries above a size threshold

Report only items larger than 100 MB:

du -h --threshold=100M /home/user

Output:

1.2G    /home/user/Downloads
340M    /home/user/Pictures

Apparent size vs disk usage

By default, du reports disk usage—the actual number of allocated blocks, which is rounded up to the filesystem block size. --apparent-size reports the file’s logical size instead. The two differ for small files and, dramatically, for sparse files:

du -h --apparent-size sparse.img
du -h sparse.img

Output:

1.0G    sparse.img
4.0K    sparse.img

The first line is what you’d read out of the file; the second is what it actually occupies on disk. When you care about real storage consumed, use the default (disk usage), not --apparent-size.

Reporting in specific units

du -k /etc/hosts      # size in kilobytes (1K blocks)
du -m /var/log        # size in megabytes
du -b /etc/hostname   # apparent size in bytes
du --si -s /var       # powers of 1000 (kB/MB/GB) instead of 1024

Output:

4       /etc/hosts
12      /var/log
26      /etc/hostname
13M     /var

Note the difference between -h (base 1024: KiB/MiB) and --si (base 1000: kB/MB). A directory shown as 12M by -h may read as 13M under --si.

Extract just the size in a script

du puts the size in the first column, so pull it out with awk or cut:

filesize=$(du -sh /etc/passwd | awk '{print $1}')
echo "$filesize"

Output:

4.0K

du vs df

These two are easy to confuse:

• du works bottom-up, adding up the space used by files and directories you point it at. Answer: “How much space is this directory using?”
• df reads filesystem-level accounting from the superblock. Answer: “How much space is free on this filesystem?”

They can disagree—for example, a deleted file still held open by a running process no longer appears to du, but its blocks are still counted by df until the process closes it.

df -h /

Output:

Filesystem      Size  Used Avail Use% Mounted on
/dev/nvme0n1p2  468G  210G  234G  48% /

Summary

• Use du -sh dir for a quick total of a directory.
• Use du -h --max-depth=1 dir | sort -rh to see where space goes, one level down, largest first.
• Use du -sh * | sort -rh | head to rank the biggest items in a folder.
• Remember that du reports disk usage by default; add --apparent-size only when you want logical file sizes.
• Reach for df (not du) when you want free space on a whole filesystem.