UPDATE(8) UPDATE(8)
NAME
update - periodically update the super block
SYNOPSIS
/etc/update
DESCRIPTION
Update is a program that executes the sync(2) 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 executed directly, but should be executed out of the
initialization shell command file.
SEE ALSO
sync(2), sync(1), init(8)
BUGS
With update running, if the CPU is halted just as the sync
is executed, a file system can be damaged. This is par-
tially due to DEC hardware that writes zeros when NPR
requests fail. A fix would be to have sync(1) 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.