ls flags:   * denotes interesting ones                                          
  -A *  Lists all entries except . (dot) and .. (dot-dot).                      
  -c    Uses the time of last modification of the i-node for either             
        sorting (when used with the -t flag) or for displaying (when            
        used with the -l flag).                                                 
  -d *  Displays only the information for the directory named.                  
        Directories are treated like files, which is helpful when using         
        the -l flag to get the status of a directory.                           
  -l *  Displays the mode, number of links, owner, group, size (in              
        bytes), and time of last modification for each file.                    
  -R    Lists all subdirectories recursively.                                   
  -r    Reverses the order of the sort.                                         
  -t *  Sorts by time of last modification instead of by name.                  
  -u    Uses the time of the last access, instead of the time of the            
        last modification, for either sorting (when used with the  -t           
        flag) or for displaying (when used with the  -l flag).                  
  -1    Put output 1 file per line (instead of multi-column).
        This is the default if piped to a file.