Report file system disk space usage in a human-readable format

$  df -H

sample outputs:

Estimate file space usage in a human-readable format

$  du -H

sample outputs:

How to get the total size of a directory

$  du -hs /path/to/directory

sample outputs:

 

List directory contents

$  ls -a

sample outputs:

Find the Ubuntu Linux distribution version and related information

$ lsb_release -a

sample outputs: