Check Folder Size and Disk Space in Linux (du and df)

Why check

Find big files and folders that eat your space.
Free space before the disk is full.
Spot a folder that grows for no reason. That can point to logs gone wild or even malware.

Use du for folders and df for whole disks.

Basic use:

du /path/to/directory

The numbers are hard to read. Add -h to see KB, MB or GB:

du -h ~/Documents

Show only the first level of subfolders with --max-depth=1:

du -h --max-depth=1

Show only the total of a folder with -s:

du -sh

The dot . means the current folder. Give a path to check another one: du -sh /var/log.

Find what fills the disk. This lists the first-level folders from big to small:

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

Go into the biggest folders one by one and run the command again.

df

Add -h for readable sizes:

df -h

Check one partition:

df -h /dev/sda2

Show the file system type with -T:

df -T

Check inodes (the number of files) with -i. A disk can be "full" because it ran out of inodes:

df -i

Combine the options:

df -hT