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cbookview

cbookview is a terminal application to explore commonly played chess openings.

If no file is passed at the command line, cbookview will show its internal (default) opening book. Passing a polyglot opening book file (with extension .bin) on the command line will allow you to explore the plies contained in that book file interactively. You can also open a PGN file (extension .pgn) which will be presented like it was an opening book. In other words, all the moves played in that PGN file will be merged into a single forest of plies. When exporing PGN files, no particular order of plies is imposed. When exploring a polyglot file the most popular moves will always come first.

For example, lets assume you want to examine blacks replies to the Ruy lopez. Use the cursor keys to navigate to the move after bishop b5. Here is what the interface will show:

a6         ┌─────────────────┐
Nf6       1│ R +   K Q B N R │        1.e4 e5 2.Nf3 Nc6 3.Bb5 a6
g6        2│ P P P   P P P P │
f5        3│   + N +   +   + │
Nge7      4│ +   + P +   +   │
Bc5       5│   +   p   + B + │
d6        6│ +   +   + n + p │
Nd4       7│ p p p + p p p + │
Bb4       8│ r n b k q b + r │
Bd6        └─────────────────┘
Qf6          h g f e d c b a
f6



Up/Down (kj) = change ply, Left/Right (hl) = back/forward                 ESC = Quit

Moving the cursor down the list of book moves will also update the position and game history. As already mentioned, the moves in polyglot book files are ordered according to popularity. So pawn to a6 is actually the most popular line of the Ruy Lopez.

Speaking about popular lines, you can use the Home key to move to the first ply, and the End key to move to the last ply of the current line. So if you press End directly after starting cbookview you will actually see the most popular variation of the currently loaded book.

The easteregg: Poor mans chessboard

If you press a (for "All moves") cbookview will switch to the tree of all possible moves. This is a poor mans way for following games and abusing cbookview as a two-player board. Pressing d (for "Default book") will load the internal polyglot book.