my $Usage = "usage: volume root_dir subvol timeframe dateformat keep\n";
@ARGV == 6 or die $Usage;  # we need six arguments

my (
  $subvol_to_snapshot_arg, # this
  $snap_root_dir_arg,      # assigns all variables
  $yabsm_subvol_name_arg,  # in one go
  $timeframe_arg,          # and leaves room
  $date_format_arg,        # to comment
  $snaps_to_keep_arg,      # what they are about
) = @ARGV;

##</code><code>##

sub create_snapshot_name { 

  my ($min, $hr, $day, $mon, $yr) = (localtime())[1..5];

  $mon++;      # month count starts at zero. 
  $yr += 1900; # year represents years since 1900. 

  my @fields = 
    $date_format_arg   eq 'mm/dd/yyyy'
    ? ($mon, $day)
    : $date_format_arg eq 'dd/mm/yyyy'
      ? ($day,$mon)
      : die "$date_format_arg is not a valid date format";
      
  sprintf "day=%02d_%02d_%04d,time=%02d:%02d",@fields,$yr,$hr,$min;
}

##</code><code>##

This script should not be used by the end user.

##</code><code>##

exec "pod2man $0" if -t; # display manual page if invoked from terminal