To display the aggregate size of each file or subdirectory (including hidden files and subdirectories) contained within the current directory, sorted by size (largest first), run the following command:
du -sk * .??* | sort -nr
What is the meaning of symbols after
-sk and before pipe,
As a bonus question, where/how can I find this kind of thing (a combination of special characters in a command line in Linux) using Google? I tried searching, but I couldn't find much since they are just punctuation.