    UPDATE(VIII)                 11/1/73                 UPDATE(VIII)

    NAME
         update - periodically update the super block

    SYNOPSIS
         update

    DESCRIPTION
         Update  is  a program that executes the sync primitive every
         30 seconds.  This insures that the file system is fairly  up
         to date in case of a crash.  This command should not be exe-
         cuted directly, but should be executed out of  the  initial-
         ization shell command file.  See sync(II) for details.

    SEE ALSO
         sync(II), init(VIII)

    BUGS
         With  update  running, if the CPU is halted just as the sync
         is executed, a file system can be damaged.  This is partial-
         ly  due  to DEC hardware that writes zeros when NPR requests
         fail.  A fix would be to have sync temporarily increment the
         system  time by at least 30 seconds to trigger the execution
         of update.  This would give 30 seconds  grace  to  halt  the
         CPU.

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