See: http://ostermiller.org/qqwing/

qqwing <options>
Sudoku solver and generator.
  --generate <num>     Generate new puzzles
  --solve              Solve all the puzzles from standard input
  --difficulty <diff>  Generate only simple, easy, intermediate, expert, or any
  --symmetry <sym>     Symmetry: none, rotate90, rotate180, mirror, flip, or random
  --puzzle             Print the puzzle (default when generating)
  --nopuzzle           Do not print the puzzle (default when solving)
  --solution           Print the solution (default when solving)
  --nosolution         Do not print the solution (default when generating)
  --stats              Print statistics about moves used to solve the puzzle
  --nostats            Do not print statistics (default)
  --timer              Print time to generate or solve each puzzle
  --notimer            Do not print solve or generation times (default)
  --count-solutions    Count the number of solutions to puzzles
  --nocount-solutions  Do not count the number of solutions (default)
  --history            Print trial and error used when solving
  --nohistory          Do not print trial and error to solve (default)
  --instructions       Print the steps (at least 81) needed to solve the puzzle
  --noinstructions     Do not print steps to solve (default)
  --log-history        Print trial and error to solve as it happens
  --nolog-history      Do not print trial and error  to solve as it happens
  --one-line           Print puzzles on one line of 81 characters
  --compact            Print puzzles on 9 lines of 9 characters
  --readable           Print puzzles in human readable form (default)
  --csv                Ouput CSV format with one line puzzles
  --help               Print this message
  --about              Author and license information
  --version            Display current version number
