RECOVER(6) Games Manual RECOVER(6) NAME recover - recover a NetHack game interrupted by disaster SYNOPSIS recover [-d playground-directory] base ... DESCRIPTION Occasionally, a NetHack game is interrupted by disaster when the pro- gram or the system crashes. Prior to NetHack v3.1, these games were lost because information like the player's inventory was kept only in memory. Now, all pertinent information can be written out to disk, so such games can be recovered at the point of the last level change. Base operands tell recover which files to process. Each base specifies recovery of a separate game. The -d option, which must be the first argument if it appears, supplies the directory housing the NetHack playground. It overrides the value of the environment variables NETHACKDIR and HACKDIR, and the directory specified by the game administrator during compilation (usually /usr/games/lib/nethackdir). nethack(6) normally writes out files for levels as the player leaves them, so they will be ready for return vis- its. When checkpointing, it also writes out the level entered and the current game state on every level change. This procedure slows level changes. The level file names are of the form base.nn,where nn is an internal bookkeeping number for the level. The file base.0 is used for game identity, locking, and, when checkpointing, for the game state. Vari- ous OSes use different strategies for constructing the base name. Sin- gle-user systems use the character name, possibly truncated and modi- fied to be a legal filename on that system. Multi-user systems use the (modified) character name prefixed by a user number to avoid conflicts, or xlock if the number of concurrent players is being limited. It may be necessary to look in the playground to find the correct base name of the interrupted game. recover transforms these level files into a save file of the same name that nethack would have used. Since recover must be able to read and delete files from the playground and create files in the save directory, it has interesting interactions with game security. Giving ordinary players access to recover through setuid or setgid is tantamount to leaving the playground world- writable, with respect to both cheating and messing up other players. For a single-user system, this of course does not change anything, so some of these ports install recover by default. For a multi-user system, the game administrator may want to arrange for all .0 files in the playground to be fed to recover when the host machine boots, and handle game crashes individually. If the user popu- lation is sufficiently trustworthy, recover can be installed with the same permissions the nethack executable has. In either case, recover is easily compiled from the distribution utility directory. NOTES Like nethack itself, recover will overwrite existing save files of the same name. Savefiles created by recover are uncompressed; they may be compressed afterwards if desired, but even a compression-using nethack will find them in the uncompressed form. SEE ALSO nethack(6) BUGS recover makes no attempt to find out if a base name specifies a game in progress. If multiple machines share a playground, this would be impossible to determine. recover should be taught to use the nethack playground locking mecha- nism to avoid conflicts. COPYRIGHT This file is Copyright (C) Kenneth Lorber, 2024 for version NetHack-5:1.12. NetHack may be freely redistributed. See license for details. NETHACK 26 April 2026 RECOVER(6)