[unix-history] / usr / man / man8 / update.8

.TH UPDATE 8 
.SH NAME
update \- periodically update the super block
.SH SYNOPSIS
.B /etc/update
.SH DESCRIPTION
.I Update
is a program that executes
the
.IR 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.
.SH "SEE ALSO"
sync(2), sync(1), init(8)
.SH BUGS
With
.I update
running,
if the CPU is
halted just as
the
.I sync
is executed,
a file system can be damaged.
This is partially due to DEC hardware that
writes zeros when NPR requests fail.
A fix would be to have
.IR sync (1)
temporarily increment the system time by at
least 30 seconds to trigger the execution of
.I update.
This would give 30 seconds grace to halt the CPU.
Commit	Line	Data
aa26a18b KT	1	.TH UPDATE 8
	2	.SH NAME
	3	update \- periodically update the super block
	4	.SH SYNOPSIS
	5	.B /etc/update
	6	.SH DESCRIPTION
	7	.I Update
	8	is a program that executes
	9	the
	10	.IR sync (2)
	11	primitive every 30 seconds.
	12	This insures that the file system
	13	is fairly up to date in case of a crash.
	14	This command should not be executed directly,
	15	but should be executed out of the
	16	initialization shell command file.
	17	.SH "SEE ALSO"
	18	sync(2), sync(1), init(8)
	19	.SH BUGS
	20	With
	21	.I update
	22	running,
	23	if the CPU is
	24	halted just as
	25	the
	26	.I sync
	27	is executed,
	28	a file system can be damaged.
	29	This is partially due to DEC hardware that
	30	writes zeros when NPR requests fail.
	31	A fix would be to have
	32	.IR sync (1)
	33	temporarily increment the system time by at
	34	least 30 seconds to trigger the execution of
	35	.I update.
	36	This would give 30 seconds grace to halt the CPU.