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recover(6) - recover - recover a NetHack game interrupted by disaster - man 6 recover

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RECOVER(6)                                                          RECOVER(6)



NAME
       recover - recover a NetHack game interrupted by disaster

SYNOPSIS
       recover [ -d directory ] base1 base2 ...

DESCRIPTION
       Occasionally,  a  NetHack game will be interrupted by disaster when the
       game or the system crashes.  Prior to NetHack v3.1,  these  games  were
       lost  because  various information like the player's inventory was kept
       only in(1,8) 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.

       The base options tell recover which files to process.  Each base option
       specifies recovery of a separate game.

       The -d option, which must be the first argument if(3,n) it appears, supplies
       a directory which is the NetHack playground.  It  overrides  the  value
       from NETHACKDIR, HACKDIR, or the directory specified by the game admin-
       istrator during compilation (usually /usr/games/lib/nethackdir).

       For recovery to be possible, nethack must have been compiled  with  the
       INSURANCE  option,  and  the  run-time option checkpoint must also have
       been on.  NetHack normally writes out files for levels  as  the  player
       leaves them, so they will be ready for return visits.  When checkpoint-
       ing, NetHack also writes out the level entered  and  the  current  game
       state  on  every level change.  This naturally slows level changes down
       somewhat.

       The level file(1,n) names are of the form base.nn, where nn is  an  internal
       bookkeeping  number  for  the  level.  The file(1,n) 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.
       Microcomputers use the character name, possibly truncated and  modified
       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(3,n)  the number of concurrent players is being limited.  It
       may be necessary to look(1,8,3 Search::Dict) in(1,8) the playground to  find  the  correct  base
       name of the interrupted game.  recover will transform these level files
       into a save file(1,n) of the same name as nethack would have used.

       Since recover must be able to read(2,n,1 builtins) and delete files from the playground
       and create files in(1,8) the save directory, it has interesting interactions
       with game security.  Giving ordinary players access(2,5) 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 the microcomputer ports install recover by default.

       For a multi-user system, the game administrator may want to arrange for
       all  .0  files  in(1,8)  the  playground  to be fed to recover when the host(1,5)
       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 savefiles of the
       same name.  Savefiles created by recover are uncompressed; they may  be
       compressed  afterwards if(3,n) desired, but even a compression-using nethack
       will find them in(1,8) the uncompressed form.

SEE ALSO
       nethack(6)

BUGS
       recover makes no attempt to find out if(3,n) a base name specifies a game in(1,8)
       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.



4th Berkeley Distribution       9 January 1993                      RECOVER(6)

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