du: show disk usage of files and directories

Updated November 2026

du adds up how much disk space files and directories use. When a disk is full, df tells you which file system, and du tells you which directories are responsible.

Common options

Examples

du -sh /var/log                      # total size of one directory
du -sh *                             # size of everything in the current directory
du -h -d 1 /var | sort -h            # each directory in /var, smallest to largest
sudo du -xh -d 1 / | sort -h | tail -15   # the biggest top-level directories on /
du -ah /srv/uploads | sort -h | tail -20  # the 20 biggest files and directories
du -sh --exclude='*.iso' ~/Downloads

sort -h understands sizes such as 1.5G and 300M; see sort.

Hunting down a full disk

1. df -h to see which file system is full.
2. sudo du -xh -d 1 /mountpoint | sort -h to find the biggest directory.
3. Repeat one level deeper until you find the culprit: usually logs, caches, old backups, core dumps or container images.
4. For big single files: sudo find /mountpoint -xdev -type f -size +1G -exec ls -lh {} +.

For interactive browsing, install ncdu: sudo ncdu -x / lets you walk through directories sorted by size and delete from inside the tool.

When du and df disagree

• Deleted files still open: a program keeps writing to a log you removed. df counts the space, du cannot see the file. Find them with sudo lsof +L1 and restart the program.
• Files hidden under a mount point: data written to /data before a disk was mounted there is invisible to du but uses space on the parent file system.
• Reserved blocks: ext4 reserves 5% for root by default, which df does not show as available.
• Snapshots and compression on btrfs and ZFS: use btrfs filesystem du or zfs list -o space for accurate numbers.

macOS and BSD du support -h, -s, -d and -x but not the GNU long options.