Example 4-2. words

  #!/usr/bin/perl -w
  # words - gather lines, present in columns
  
  use strict;
  
  my ($item, $cols, $rows, $maxlen);
  my ($xpixel, $ypixel, $mask, @data);
  
  getwinsize( );
  
  # first gather up every line of input,
  # remembering the longest line length seen
  $maxlen = 1;        
  while (<>) {
      my $mylen;
      s/\s+$//;
      $maxlen = $mylen if (($mylen = length) > $maxlen);
      push(@data, $_);
  }
  
  $maxlen += 1;               # to make extra space
  
  # determine boundaries of screen
  $cols = int($cols / $maxlen) || 1;
  $rows = int(($#data+$cols) / $cols);
  
  # pre-create mask for faster computation
  $mask = sprintf("%%-%ds ", $maxlen-1);
  
  # subroutine to check whether at last item on line
  sub EOL { ($item+1) % $cols =  = 0 }  
  
  # now process each item, picking out proper piece for this position
  for ($item = 0; $item < $rows * $cols; $item++) {
      my $target =  ($item % $cols) * $rows + int($item/$cols);
      my $piece = sprintf($mask, $target < @data ? $data[$target] : "");
      $piece =~ s/\s+$// if EOL( );  # don't blank-pad to EOL
      print $piece;
      print "\n" if EOL( );
  }
  
  # finish up if needed
  print "\n" if EOL( );
  
  # not portable -- linux only
  sub getwinsize {
      my $winsize = "\0" x 8;
      my $TIOCGWINSZ = 0x40087468;
      if (ioctl(STDOUT, $TIOCGWINSZ, $winsize)) {
          ($rows, $cols, $xpixel, $ypixel) = unpack('S4', $winsize);
      } else {
          $cols = 80;
      }
  }