Каков самый простой способ проверить, установлен ли webmin?

tree - еще одна полезная команда для этого задания:

Просто установите его через sudo apt-get install tree и введите следующее:

tree --du -h /path/to/directory
...
...

33.7M used in 0 directories, 25 files

Из дерева man: [!d2 ]

-h    Print  the size of each file but in a more human readable way, e.g. appending a size letter for kilo‐
      bytes (K), megabytes (M), gigabytes (G), terabytes (T), petabytes (P) and exabytes (E).

--du  For each directory report its size as the accumulation of sizes of all its files and  sub-directories
      (and their files, and so on). The total amount of used space is also given in the final report (like
      the 'du -c' command.)