<s>
Windows	B-Application
,	O
and	O
ReactOS	B-Application
used	O
to	O
schedule	O
commands	O
to	O
be	O
executed	O
once	O
,	O
at	O
a	O
particular	O
time	B-Operating_System
in	O
the	O
future	O
.	O
</s>
<s>
On	O
Unix-like	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
,	O
at	O
reads	O
a	O
series	O
of	O
commands	O
from	O
standard	O
input	O
and	O
collects	O
them	O
into	O
one	O
"	O
at-job	O
"	O
which	O
is	O
carried	O
out	O
at	O
a	O
later	O
date	O
.	O
</s>
<s>
The	O
job	O
inherits	O
the	O
current	O
environment	O
,	O
so	O
that	O
it	O
is	O
executed	O
in	O
the	O
same	O
working	B-Application
directory	I-Application
and	O
with	O
the	O
same	O
environment	O
variables	O
set	O
as	O
when	O
it	O
was	O
scheduled	O
.	O
</s>
<s>
It	O
differs	O
from	O
cron	B-General_Concept
,	O
which	O
is	O
used	O
for	O
recurring	O
executions	O
(	O
e.g.	O
</s>
<s>
As	O
with	O
cron	B-General_Concept
,	O
many	O
Unix	O
systems	O
allow	O
the	O
administrator	O
to	O
restrict	O
access	O
to	O
the	O
at	O
command	B-Application
.	O
</s>
<s>
at	O
can	O
be	O
made	O
to	O
mail	O
a	O
user	O
when	O
done	O
carrying	O
out	O
a	O
scheduled	O
job	O
,	O
can	O
use	O
more	O
than	O
one	O
job	B-General_Concept
queue	I-General_Concept
,	O
and	O
can	O
read	O
a	O
list	O
of	O
jobs	O
to	O
carry	O
out	O
from	O
a	O
file	B-Operating_System
instead	O
of	O
standard	O
input	O
.	O
</s>
<s>
The	O
Linux	O
at	O
command	B-Application
was	O
mostly	O
written	O
by	O
Thomas	O
Koenig	O
.	O
</s>
<s>
In	O
addition	O
to	O
the	O
graphical	B-Application
user	I-Application
interface	I-Application
for	O
Windows	B-Application
Task	O
Scheduler	O
in	O
Control	O
Panel	O
,	O
Windows	B-Application
provides	O
an	O
at.exe	O
command	B-Application
that	O
schedules	O
commands	O
and	O
programs	O
to	O
run	O
on	O
a	O
computer	O
at	O
a	O
specified	O
time	B-Operating_System
and	O
date	O
(	O
similar	O
to	O
cron	B-General_Concept
)	O
.	O
</s>
<s>
It	O
is	O
available	O
since	O
Windows	B-Device
NT	I-Device
,	O
but	O
is	O
now	O
deprecated	O
in	O
favor	O
of	O
schtasks	O
.	O
</s>
<s>
The	O
ReactOS	B-Application
implementation	O
is	O
based	O
on	O
the	O
Windows	B-Application
variant	O
.	O
</s>
<s>
A	O
sample	O
command	B-Application
to	O
compile	O
a	O
C	B-Language
program	I-Language
at	O
11:45	O
a	O
.	O
m	O
.	O
on	O
January	O
31	O
would	O
be	O
:	O
</s>
<s>
In	O
some	O
Unix-like	B-Operating_System
computer	B-General_Concept
operating	I-General_Concept
systems	I-General_Concept
,	O
it	O
uses	O
a	O
daemon	B-Operating_System
,	O
atd	O
,	O
which	O
waits	O
in	O
the	O
background	O
periodically	O
checking	O
the	O
list	O
of	O
jobs	O
to	O
do	O
and	O
executing	O
those	O
at	O
their	O
scheduled	O
time	B-Operating_System
on	O
behalf	O
of	O
at	O
.	O
</s>
<s>
The	O
command	B-Application
can	O
be	O
used	O
instead	O
of	O
at	O
to	O
only	O
run	O
scheduled	O
jobs	O
if	O
the	O
system	O
's	O
load	B-Operating_System
average	I-Operating_System
is	O
below	O
a	O
certain	O
value	O
.	O
</s>
<s>
The	O
command-syntax	O
is	O
:	O
</s>
<s>
ID	B-Application
–	O
This	O
parameter	O
specifies	O
the	O
identification	O
number	O
assigned	O
to	O
a	O
scheduled	O
command	B-Application
.	O
</s>
<s>
/delete	O
–	O
This	O
parameter	O
cancels	O
a	O
scheduled	O
command	B-Application
.	O
</s>
<s>
If	O
ID	B-Application
is	O
omitted	O
,	O
all	O
of	O
the	O
scheduled	O
commands	O
on	O
the	O
computer	O
are	O
canceled	O
.	O
</s>
<s>
hours	O
:	O
minutes	O
–	O
This	O
parameter	O
specifies	O
the	O
time	B-Operating_System
when	O
to	O
run	O
the	O
command	B-Application
.	O
</s>
<s>
/interactive	O
–	O
This	O
parameter	O
allows	O
the	O
given	O
command	B-Application
to	O
interact	O
with	O
the	O
desktop	O
of	O
the	O
user	O
who	O
is	O
logged	O
on	O
at	O
the	O
time	B-Operating_System
command	B-Application
runs	O
.	O
</s>
<s>
/every	O
:	O
–	O
This	O
parameter	O
runs	O
the	O
given	O
command	B-Application
on	O
every	O
specified	O
day	O
or	O
days	O
of	O
the	O
week	O
or	O
month	O
.	O
</s>
<s>
date	O
–	O
This	O
parameter	O
specifies	O
the	O
date	O
when	O
to	O
run	O
the	O
given	O
command	B-Application
.	O
</s>
<s>
/next	O
:	O
–	O
This	O
parameter	O
runs	O
command	B-Application
on	O
the	O
next	O
occurrence	O
of	O
the	O
day	O
.	O
</s>
<s>
command	B-Application
–	O
This	O
parameter	O
specifies	O
the	O
Windows	B-Application
command	B-Application
,	O
program	O
(	O
that	O
is	O
,	O
.exe	O
or	O
.com	O
file	B-Operating_System
)	O
,	O
or	O
batch	B-Device
program	O
(	O
that	O
is	O
,	O
.bat	O
or	O
.cmd	O
file	B-Operating_System
)	O
that	O
will	O
be	O
run	O
.	O
</s>
<s>
–	O
Displays	O
help	O
for	O
the	O
command	B-Application
.	O
</s>
