sub get_df {
 my (@headers,@rows);
 # put each line the command returns into an array
 my @df = `df -Ph`;
 # the first element of the array contains the headers
 my $temp_df = shift @df;
 @headers = split (/\s+/, $temp_df);
 foreach (@df) {
  my @parsed_row = split (/\s+/, $_);
  unshift @rows, \@parsed_row;
 }
 return (\@headers, \@rows);
}