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 example):
ls -alr > output The exercice is to write a perl which take as input a file generated by the previous command and displays:
The sorted list of all owners (without duplicates) according their name
A sorted list of all filenames for which several files exists with the same filename (you should display the number of occurences too).
A sorted list of files according their size.
A sorted list of files according the last writing time .