<s>
In	O
Unix	B-Application
,	O
graph	O
is	O
a	O
command-line	B-Application
utility	O
used	O
to	O
draw	O
plots	O
from	O
tabular	O
data	O
.	O
</s>
<s>
The	O
graph	O
utility	O
,	O
written	O
by	O
Douglas	O
McIlroy	O
,	O
was	O
present	O
in	O
the	O
first	O
version	O
of	O
Unix	B-Application
,	O
and	O
every	O
later	O
version	O
,	O
for	O
instance	O
:	O
</s>
<s>
Its	O
output	O
is	O
a	O
sequence	O
of	O
commands	O
for	O
the	O
plot	B-Application
utility	O
,	O
which	O
creates	O
plots	O
using	O
ASCII	O
graphics	O
.	O
</s>
<s>
This	O
design	O
demonstrates	O
the	B-Operating_System
Unix	I-Operating_System
philosophy	I-Operating_System
:	O
defining	O
the	O
plot	B-Application
(	O
graph	O
)	O
and	O
drawing	O
it	O
(	O
plot	B-Application
)	O
are	O
separate	O
tools	O
,	O
so	O
they	O
can	O
be	O
recombined	O
with	O
other	O
tools	O
.	O
</s>
<s>
For	O
instance	O
,	O
plot	B-Application
can	O
be	O
substituted	O
with	O
a	O
different	O
utility	O
,	O
that	O
accepts	O
the	O
same	O
plot	B-Application
commands	O
,	O
but	O
creates	O
the	O
plot	B-Application
in	O
a	O
graphics	O
file	O
format	O
,	O
or	O
sends	O
it	O
to	O
a	O
plotter	B-Operating_System
.	O
</s>
<s>
Unix	B-Application
v7	O
also	O
provided	O
device	O
drivers	O
for	O
plotting	O
the	O
results	O
to	O
various	O
graphics	O
devices	O
;	O
</s>
<s>
The	O
GNU	B-Application
plotutils	I-Application
package	O
provides	O
a	O
free	O
non-exact	O
reimplementation	O
,	O
available	O
for	O
Linux	B-Application
and	O
many	O
other	O
systems	O
.	O
</s>
<s>
In	O
its	O
simplest	O
use	O
,	O
the	O
graph	O
utility	O
takes	O
a	O
textfile	O
containing	O
pairs	O
of	O
numbers	O
,	O
indicating	O
the	O
points	O
of	O
a	O
line	O
plot	B-Application
.	O
</s>
<s>
It	O
outputs	O
the	O
line	O
plot	B-Application
.	O
</s>
<s>
These	O
screenshots	O
demonstrate	O
basic	O
operation	O
on	O
SunOS	O
5.10	O
,	O
on	O
which	O
graph	O
and	O
plot	B-Application
come	O
preinstalled	O
.	O
</s>
<s>
The	O
example	O
input	O
is	O
from	O
the	O
first	O
example	O
in	O
the	O
GNU	B-Application
plotutils	I-Application
manual	O
.	O
</s>
<s>
These	O
screenshots	O
demonstrate	O
the	O
GNU	B-Application
plotutils	I-Application
version	O
of	O
graph	O
when	O
run	O
in	O
an	O
xterm	B-Language
,	O
exploiting	O
xterm	B-Language
's	O
ability	O
to	O
emulate	O
a	O
Tektronix	B-General_Concept
4010	I-General_Concept
plotter	B-Operating_System
.	O
</s>
<s>
This	O
demo	O
was	O
run	O
on	O
Ubuntu	B-Operating_System
,	O
which	O
makes	O
GNU	B-Application
plotutils	I-Application
available	O
as	O
an	O
optional	O
package	O
;	O
many	O
other	O
Linux	B-Application
distributions	O
and	O
other	O
Unix-like	B-Operating_System
systems	I-Operating_System
do	O
the	O
same	O
.	O
</s>
