Check Disk Space with the Commands df and du

Use the df utility to review a summary of the available and used disk space on your Linux system. With the -h option, it shows the disk space in human-readable form. The du utility, by contrast, lists space utilization on a directory-and-subdirectory basis.

Output of the df Command

The output of the df command structures the results into six columns:

• Filesystem: The name of the filesystem. Filesystems that aren't temporary (tmpfs) and aren't physically separate sometimes list as being a loopback device, iterated at /dev/loopnn.
• 1K-blocks: The number of kilobyte blocks available to the filesystem.
• Used: The number of blocks used.
• Available: The number of blocks available. If the filesystem dynamically updates, this value will always be zero. Snap packages, for example, grow and shrink as necessary, so df always lists them as fully used.
• Use%: The ration of available-to-used blocks.
• Mounted on: The location where the filesystem is mounted in the system.

Output of the du Command

The du command, on the other hand, shows the disk space used by the files and directories in the current directory. The -h option makes the output easier to understand.

By default, the du command lists all subdirectories to show how much disk space each has occupied. Consolidate the output with the -s option, which only shows a summary. Unless you run sudo du, however, you'll see permission-denied errors for any directories to which the logged-in account lacks read access.

To show the disk usage of a directory other than the current directory, insert that directory name as the last argument.