<s>
In	O
computing	O
,	O
a	O
line	B-Application
editor	I-Application
is	O
a	O
text	B-Application
editor	I-Application
in	O
which	O
each	O
editing	O
command	O
applies	O
to	O
one	O
or	O
more	O
complete	O
lines	O
of	O
text	O
designated	O
by	O
the	O
user	O
.	O
</s>
<s>
Line	B-Application
editors	I-Application
predate	O
screen-based	O
text	B-Application
editors	I-Application
and	O
originated	O
in	O
an	O
era	O
when	O
a	O
computer	O
operator	O
typically	O
interacted	O
with	O
a	O
teleprinter	O
(	O
essentially	O
a	O
printer	O
with	O
a	O
keyboard	B-Device
)	O
,	O
with	O
no	O
video	O
display	O
,	O
and	O
no	O
ability	O
to	O
move	O
a	O
cursor	O
interactively	O
within	O
a	O
document	O
.	O
</s>
<s>
Line	B-Application
editors	I-Application
were	O
also	O
a	O
feature	O
of	O
many	O
home	O
computers	O
,	O
avoiding	O
the	O
need	O
for	O
a	O
more	O
memory-intensive	O
full-screen	O
editor	O
.	O
</s>
<s>
Line	B-Application
editors	I-Application
are	O
limited	O
to	O
typewriter	O
keyboard	B-Device
text-oriented	O
input	O
and	O
output	O
methods	O
.	O
</s>
<s>
Line	B-Application
editors	I-Application
keep	O
a	O
reference	O
to	O
the	O
"	O
current	O
line	O
"	O
to	O
which	O
the	O
entered	O
commands	O
usually	O
are	O
applied	O
.	O
</s>
<s>
Early	O
line	B-Application
editors	I-Application
included	O
Expensive	B-Application
Typewriter	I-Application
and	O
QED	B-Application
.	O
</s>
<s>
Both	O
pre-dated	O
the	O
advent	O
of	O
UNIX	B-Application
;	O
the	O
former	O
two	O
ran	O
on	O
DEC	B-Device
PDP-1	I-Device
'	O
s	O
,	O
while	O
the	O
latter	O
was	O
a	O
Unisys	O
product	O
.	O
</s>
<s>
Numerous	O
line	B-Application
editors	I-Application
are	O
included	O
with	O
UNIX	B-Application
and	O
Linux	B-Application
:	O
ed	B-Application
is	O
considered	O
the	O
standard	O
UNIX	B-Application
editor	O
,	O
while	O
ex	B-Device
extends	O
it	O
and	O
has	O
more	O
features	O
,	O
and	O
sed	B-Application
was	O
written	O
for	O
pattern-based	O
text	B-Application
editing	I-Application
as	O
part	O
of	O
a	O
shell	B-Language
script	I-Language
.	O
</s>
<s>
For	O
the	O
first	O
10	O
years	O
of	O
the	O
IBM	B-Device
PC	I-Device
,	O
the	O
only	O
editor	O
provided	O
in	O
DOS	B-Device
was	O
the	O
Edlin	B-Application
line	B-Application
editor	I-Application
.	O
</s>
<s>
Line	B-Application
editors	I-Application
are	O
still	O
used	O
non-interactively	O
in	O
shell	B-Language
scripts	I-Language
and	O
when	O
dealing	O
with	O
failing	O
operating	O
systems	O
.	O
</s>
<s>
Update	O
systems	O
such	O
as	O
patch	B-Application
traditionally	O
used	O
diff	B-Application
data	O
converted	O
into	O
a	O
script	O
of	O
ed	B-Application
commands	O
.	O
</s>
<s>
They	O
are	O
also	O
used	O
in	O
many	O
MUD	B-Application
systems	O
,	O
though	O
many	O
people	O
edit	O
text	O
on	O
their	O
own	O
computer	O
using	O
MUD	B-Application
's	O
download	O
and	O
upload	O
features	O
.	O
</s>
