For human-readable output use the following command:
du -sh /* | sort -h
Use this command to find the directories taking up the most space:
du -k | sort -nr | more
The du command along with the -k switch lists all directories and their respective size in kilobytes. The sort command sorts the output so that the largest directory is shown first in the list. The -nr switch reverses the list and uses only numbers when sorting.
Here’s an example of the output:
12939451 . 1814892 ./abcdef 1219582 ./abcde 839586 ./abcd 718330 ./abc 695610 ./ab 690380 ./a