1 .TH RECOVER 6 "9 January 1993"
4 recover \- recover a NetHack game interrupted by disaster
14 Occasionally, a NetHack game will be interrupted by disaster
15 when the game or the system crashes.
16 Prior to NetHack v3.1, these games were lost because various information
17 like the player's inventory was kept only in memory.
18 Now, all pertinent information can be written out to disk,
19 so such games can be recovered at the point of the last level change.
25 which files to process.
26 Each base option specifies recovery of a separate game.
30 option, which must be the first argument if it appears,
31 supplies a directory which is the NetHack playground.
32 It overrides the value from NETHACKDIR, HACKDIR, or the directory
33 specified by the game administrator during compilation
34 (usually /usr/games/lib/nethackdir).
36 For recovery to be possible,
38 must have been compiled with the INSURANCE option, and the run-time option
40 must also have been on.
41 NetHack normally writes out files for levels as the player leaves them,
42 so they will be ready for return visits.
43 When checkpointing, NetHack also writes out the level entered and
44 the current game state on every level change.
45 This naturally slows level changes down somewhat.
47 The level file names are of the form base.nn, where nn is an internal
48 bookkeeping number for the level.
49 The file base.0 is used for game identity, locking, and, when checkpointing,
51 Various OSes use different strategies for constructing the base name.
52 Microcomputers use the character name, possibly truncated and modified
53 to be a legal filename on that system.
54 Multi-user systems use the (modified) character name prefixed
55 by a user number to avoid conflicts,
56 or "xlock" if the number of concurrent players is being limited.
57 It may be necessary to look in the playground to find the correct
58 base name of the interrupted game.
60 will transform these level files into a save file of the same name as
66 must be able to read and delete files from the playground
67 and create files in the save directory,
68 it has interesting interactions with game security.
69 Giving ordinary players access to
71 through setuid or setgid is tantamount to leaving the playground
73 with respect to both cheating and messing up other players.
74 For a single-user system, this of course does not change anything,
75 so some of the microcomputer ports install
79 For a multi-user system,
80 the game administrator may want to arrange for all .0 files in the
81 playground to be fed to recover when the host machine boots,
82 and handle game crashes individually.
83 If the user population is sufficiently trustworthy,
85 can be installed with the same permissions the
90 is easily compiled from the distribution utility directory.
97 will overwrite existing savefiles of the same name.
101 they may be compressed afterwards if desired,
102 but even a compression-using
104 will find them in the uncompressed form.
110 makes no attempt to find out if a base name specifies a game in progress.
111 If multiple machines share a playground, this would be impossible to
115 should be taught to use the nethack playground locking mechanism to