<s>
It	O
may	O
be	O
issued	O
via	O
a	O
command-line	B-Application
interface	I-Application
,	O
such	O
as	O
a	O
shell	B-Operating_System
,	O
or	O
as	O
input	O
to	O
a	O
network	O
service	O
as	O
part	O
of	O
a	O
network	O
protocol	O
,	O
or	O
as	O
an	O
event	O
in	O
a	O
graphical	B-Application
user	I-Application
interface	I-Application
triggered	O
by	O
the	O
user	O
selecting	O
an	O
option	O
in	O
a	O
menu	O
.	O
</s>
<s>
Specifically	O
,	O
the	O
term	O
command	O
is	O
used	O
in	O
imperative	B-Application
computer	B-Language
languages	I-Language
.	O
</s>
<s>
The	O
name	O
arises	O
because	O
statements	O
in	O
these	O
languages	O
are	O
usually	O
written	O
in	O
a	O
manner	O
similar	O
to	O
the	O
imperative	B-Application
mood	O
used	O
in	O
many	O
natural	O
languages	O
.	O
</s>
<s>
If	O
one	O
views	O
a	O
statement	O
in	O
an	O
imperative	B-Application
language	I-Application
as	O
being	O
like	O
a	O
sentence	O
in	O
a	O
natural	O
language	O
,	O
then	O
a	O
command	O
is	O
generally	O
like	O
a	O
verb	O
in	O
such	O
a	O
language	O
.	O
</s>
<s>
Here	O
are	O
some	O
commands	O
given	O
to	O
a	O
command-line	B-Application
interpreter	O
(	O
Unix	B-Application
shell	I-Application
)	O
.	O
</s>
<s>
The	O
following	O
command	O
changes	O
the	O
user	O
's	O
working	O
position	O
in	O
the	O
directory	B-Application
tree	I-Application
to	O
the	O
directory	B-Application
/home/pete	O
.	O
</s>
<s>
The	O
utility	O
program	O
is	O
cd	B-Application
and	O
the	O
argument	O
is	O
/home/pete	O
:	O
</s>
<s>
The	O
program	O
name	O
is	O
echo	B-Application
and	O
the	O
argument	O
is	O
"	O
Hello	O
World	O
"	O
.	O
</s>
<s>
They	O
list	O
files	O
in	O
the	O
directory	B-Application
/bin	B-Application
.	O
</s>
<s>
The	O
program	O
is	O
ls	B-Application
,	O
having	O
three	O
flags	O
(	O
l	O
,	O
t	O
,	O
r	O
)	O
,	O
and	O
the	O
argument	O
is	O
the	O
directory	B-Application
/bin	B-Application
:	O
</s>
<s>
The	O
program	O
name	O
is	O
cat	B-Device
,	O
having	O
two	O
file	O
name	O
arguments	O
:	O
</s>
<s>
Here	O
are	O
some	O
commands	O
for	O
the	O
DOS	B-Device
,	O
OS/2	B-Application
and	O
Microsoft	B-Application
Windows	I-Application
command	B-Device
prompt	I-Device
processor	O
.	O
</s>
<s>
The	O
program	O
name	O
is	O
type	B-Device
and	O
the	O
argument	O
is	O
readme.txt	O
.	O
</s>
<s>
The	O
following	O
command	O
lists	O
the	O
contents	O
of	O
the	O
current	O
directory	B-Application
.	O
</s>
<s>
The	O
program	O
name	O
is	O
dir	B-Device
,	O
and	O
Q	O
is	O
a	O
flag	O
requesting	O
that	O
the	O
owner	O
of	O
each	O
file	O
also	O
be	O
listed	O
.	O
</s>
