Any idea how to solve an old exercice?

The linux command ls -alR produce informations about files contained in the current directory and
its subdirectories. You can save its output by using redirections (in the file output in the following

ls -alr > output
The exercice is to write a perl which take as input a file generated by the previous command and displays:

  1. The sorted list of all owners (without duplicates) according their name

  2. A sorted list of all filenames for which several files exists with the same filename (you should display the number of occurences too).

  3. A sorted list of files according their size.

  4. A sorted list of files according the last writing time .

Hi tony75,
How would you write it please?