Basic usage with null

du ${null}

Display help message

du --help

With 'root' privileges, use du(1), sort(1), and head(1) to display a list of the top 20 space-consuming files in whichever storage medium '/' is mounted. Here, du(1) is using the `-x` flag to keep to the one filesystem, which is important for getting accurate results on the filesystem on which you might, for example, be needing to free space. In order to sort the human-readable file sizes, sort(1) is using the `-h` flag, the `-k` flag to specify the column to sort (first), and its using the `-r` flag to reverse the sorting, so we see the highest size first. To then show the top-20 lines, we use head(1) and specify the number of lines via the `-n` flag. The default number of lines displayed by head(1) and tail(1) is 10. Root privileges are gained for this task by using sudo(8) on bash(1) in order to have a new root-owned BASH session, which then executes the commands proceeding the `-c` flag.

sudo bash -c 'du -xh / | sort -rhk 1 | head -n 20'

Display just the total human-readable size of the current working directory.

du -sh

Display the total human-readable size of the three provided directories, as well as the grand total of the combined directories.

du -chs ~/Desktop ~/Pictures ~/Videos

You could potentially make this task a bit easier with BASH brace expansion.

du -chs ~/{Desktop,Pictures,Videos}