<s>
On	O
Unix-like	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
,	O
rdate	B-Protocol
is	O
a	O
tool	O
for	O
querying	O
the	O
current	O
time	O
from	O
a	O
network	O
server	O
and	O
,	O
optionally	O
,	O
setting	O
the	O
system	B-Operating_System
time	I-Operating_System
.	O
</s>
<s>
Rdate	B-Protocol
uses	O
the	O
Time	B-Protocol
Protocol	I-Protocol
.	O
</s>
<s>
The	O
Time	B-Protocol
Protocol	I-Protocol
is	O
generally	O
considered	O
obsolete	O
and	O
has	O
been	O
replaced	O
by	O
the	O
Network	B-Protocol
Time	I-Protocol
Protocol	I-Protocol
(	O
NTP	O
)	O
.	O
</s>
<s>
When	O
used	O
to	O
set	O
the	O
local	O
system	B-Operating_System
time	I-Operating_System
,	O
rdate	B-Protocol
operates	O
by	O
changing	O
system	B-Operating_System
time	I-Operating_System
immediately	O
to	O
the	O
time	O
and	O
date	O
returned	O
by	O
the	O
server	O
.	O
</s>
<s>
This	O
led	O
to	O
the	O
development	O
of	O
the	O
Network	B-Protocol
Time	I-Protocol
Protocol	I-Protocol
,	O
which	O
gradually	O
changes	O
the	O
system	B-Operating_System
time	I-Operating_System
and	O
does	O
not	O
skip	O
ticks	O
.	O
</s>
<s>
Due	O
to	O
the	O
problems	O
described	O
above	O
,	O
rdate	B-Protocol
is	O
generally	O
used	O
only	O
on	O
systems	O
where	O
NTP	O
is	O
not	O
available	O
,	O
or	O
in	O
specialized	O
circumstances	O
where	O
it	O
is	O
required	O
that	O
system	B-Operating_System
time	I-Operating_System
be	O
set	O
correctly	O
as	O
soon	O
as	O
possible	O
during	O
initial	O
setup	O
,	O
before	O
services	O
which	O
may	O
be	O
vulnerable	O
to	O
abrupt	O
time-changes	O
have	O
started	O
.	O
</s>
