<s>
Uptime	B-Device
is	O
a	O
measure	O
of	O
system	O
reliability	O
,	O
expressed	O
as	O
the	O
percentage	O
of	O
time	B-Operating_System
a	O
machine	O
,	O
typically	O
a	O
computer	O
,	O
has	O
been	O
working	O
and	O
available	O
.	O
</s>
<s>
Uptime	B-Device
is	O
the	O
opposite	O
of	O
downtime	O
.	O
</s>
<s>
It	O
is	O
often	O
used	O
as	O
a	O
measure	O
of	O
computer	B-General_Concept
operating	I-General_Concept
system	I-General_Concept
reliability	O
or	O
stability	O
,	O
in	O
that	O
this	O
time	B-Operating_System
represents	O
the	O
time	B-Operating_System
a	O
computer	O
can	O
be	O
left	O
unattended	O
without	O
crashing	B-General_Concept
,	O
or	O
needing	O
to	O
be	O
rebooted	B-Operating_System
for	O
administrative	O
or	O
maintenance	O
purposes	O
.	O
</s>
<s>
Conversely	O
,	O
long	O
uptime	B-Device
may	O
indicate	O
negligence	O
,	O
because	O
some	O
critical	O
updates	O
can	O
require	O
reboots	O
on	O
some	O
platforms	O
.	O
</s>
<s>
In	O
2005	O
,	O
Novell	O
reported	O
a	O
server	O
with	O
a	O
6-year	O
uptime	B-Device
.	O
</s>
<s>
Netcraft	O
maintains	O
the	O
uptime	B-Device
records	O
for	O
many	O
thousands	O
of	O
web	O
hosting	O
computers	O
.	O
</s>
<s>
A	O
server	O
running	O
Novell	B-Operating_System
NetWare	I-Operating_System
has	O
been	O
reported	O
to	O
have	O
been	O
shut	O
down	O
after	O
16	O
years	O
of	O
uptime	B-Device
due	O
to	O
a	O
failing	O
hard	O
disk	O
.	O
</s>
<s>
A	O
Cisco	O
router	B-Protocol
has	O
been	O
reported	O
to	O
have	O
been	O
running	O
continuously	O
for	O
21	O
years	O
.	O
</s>
<s>
Some	O
versions	O
of	O
Microsoft	B-Application
Windows	I-Application
include	O
an	O
uptime	B-Device
field	O
in	O
Windows	O
Task	O
Manager	O
,	O
under	O
the	O
"	O
Performance	O
"	O
tab	O
.	O
</s>
<s>
The	O
output	O
of	O
the	O
systeminfo	B-Application
command	O
includes	O
a	O
"	O
System	O
Up	B-Device
Time	I-Device
"	O
or	O
"	O
System	B-Operating_System
Boot	I-Operating_System
Time	B-Operating_System
"	O
field	O
.	O
</s>
<s>
The	O
time	B-Operating_System
given	O
by	O
systeminfo	B-Application
is	O
not	O
reliable	O
.	O
</s>
<s>
It	O
does	O
not	O
take	O
into	O
account	O
time	B-Operating_System
spent	O
in	O
sleep	O
or	O
hibernation	O
.	O
</s>
<s>
Thus	O
,	O
the	O
boot	B-Operating_System
time	I-Operating_System
will	O
drift	O
forward	O
every	O
time	B-Operating_System
the	O
computer	O
sleeps	O
or	O
hibernates	O
.	O
</s>
<s>
The	O
NET	B-Device
command	O
with	O
its	O
STATISTICS	O
sub-command	O
provides	O
the	O
date	O
and	O
time	B-Operating_System
the	O
computer	O
started	O
,	O
for	O
both	O
the	O
NET	B-Device
STATISTICS	O
WORKSTATION	O
and	O
NET	B-Device
STATISTICS	O
SERVER	O
variants	O
.	O
</s>
<s>
The	O
command	O
NET	B-Device
STATS	O
SRV	O
is	O
shorthand	O
for	O
NET	B-Device
STATISTICS	O
SERVER	O
.	O
</s>
<s>
Uptime	B-Device
can	O
be	O
determined	O
via	O
Windows	B-Library
Management	I-Library
Instrumentation	I-Library
(	O
WMI	O
)	O
,	O
by	O
querying	O
the	O
LastBootUpTime	O
property	O
of	O
the	O
Win32_OperatingSystem	O
class	O
.	O
</s>
<s>
At	O
the	O
command	B-Device
prompt	I-Device
,	O
this	O
can	O
be	O
done	O
using	O
the	O
wmic	O
command	O
:	O
</s>
<s>
WMI	O
can	O
also	O
be	O
queried	O
using	O
a	O
variety	O
of	O
application	B-Application
programming	I-Application
interfaces	I-Application
,	O
including	O
VBScript	B-Application
or	O
PowerShell	B-Application
.	O
</s>
<s>
Microsoft	O
formerly	O
provided	O
a	O
downloadable	O
utility	O
called	O
Uptime.exe	O
,	O
which	O
reports	O
elapsed	O
time	B-Operating_System
in	O
days	O
,	O
hours	O
,	O
minutes	O
,	O
and	O
seconds	O
.	O
</s>
<s>
The	O
time	B-Operating_System
given	O
by	O
Uptime.exe	O
is	O
not	O
reliable	O
.	O
</s>
<s>
It	O
does	O
not	O
take	O
into	O
account	O
time	B-Operating_System
spent	O
in	O
sleep	O
or	O
hibernation	O
.	O
</s>
<s>
Thus	O
,	O
the	O
boot	B-Operating_System
time	I-Operating_System
will	O
drift	O
forward	O
every	O
time	B-Operating_System
the	O
computer	O
sleeps	O
or	O
hibernates	O
.	O
</s>
<s>
The	O
uptime	B-Device
command	O
is	O
also	O
available	O
for	O
FreeDOS	B-Application
.	O
</s>
<s>
Users	O
of	O
Linux	B-Application
systems	O
can	O
use	O
the	O
BSD	B-Operating_System
uptime	B-Device
utility	O
,	O
which	O
also	O
displays	O
the	O
system	O
load	O
averages	O
for	O
the	O
past	O
1	O
,	O
5	O
and	O
15	O
minute	O
intervals	O
:	O
</s>
<s>
The	O
second	O
number	O
is	O
how	O
much	O
of	O
that	O
time	B-Operating_System
the	O
machine	O
has	O
spent	O
idle	O
,	O
in	O
seconds	O
.	O
</s>
<s>
On	O
multi	O
core	O
systems	O
(	O
and	O
some	O
Linux	B-Application
versions	O
)	O
the	O
second	O
number	O
is	O
the	O
sum	O
of	O
the	O
idle	O
time	B-Operating_System
accumulated	O
by	O
each	O
CPU	O
.	O
</s>
<s>
BSD-based	O
operating	B-General_Concept
systems	I-General_Concept
such	O
as	O
FreeBSD	B-Operating_System
,	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
and	O
SySVr4	O
have	O
the	O
uptime	B-Device
command	O
(	O
See	O
)	O
.	O
</s>
<s>
The	O
uptime	B-Device
program	O
on	O
BSD	B-Operating_System
is	O
a	O
Hard	B-Application
link	I-Application
to	O
the	O
w	O
program	O
.	O
</s>
<s>
The	O
w	O
program	O
is	O
based	O
on	O
the	O
RSTS/E	B-Operating_System
,	O
TOPS-10	B-Operating_System
and	O
TOPS-20	B-Operating_System
SYSTAT	O
program	O
.	O
</s>
<s>
There	O
is	O
also	O
a	O
method	O
of	O
using	O
sysctl	O
to	O
call	O
the	O
system	O
's	O
last	O
boot	B-Operating_System
time	I-Operating_System
:	O
</s>
<s>
On	O
OpenVMS	B-Operating_System
systems	O
,	O
the	O
show	O
system	O
command	O
can	O
be	O
used	O
at	O
the	O
DCL	B-Operating_System
command	I-Operating_System
prompt	I-Operating_System
to	O
obtain	O
the	O
system	O
uptime	B-Device
.	O
</s>
<s>
The	O
first	O
line	O
of	O
the	O
resulting	O
display	O
includes	O
the	O
system	O
's	O
uptime	B-Device
,	O
displayed	O
as	O
days	O
followed	O
by	O
hours:minutes:seconds	O
.	O
</s>
<s>
The	O
command	O
output	O
above	O
shows	O
that	O
node	O
JACK	O
on	O
29	O
January	O
2008	O
at	O
16:32:04.67	O
has	O
uptime	B-Device
:	O
894	O
days	O
22	O
hours	O
28	O
minutes	O
and	O
52	O
seconds	O
.	O
</s>
