<s>
ex	O
,	O
short	O
for	O
EXtended	O
,	O
is	O
a	O
line	B-Application
editor	I-Application
for	O
Unix	B-Application
systems	I-Application
originally	O
written	O
by	O
Bill	O
Joy	O
in	O
1976	O
,	O
beginning	O
with	O
an	O
earlier	O
program	O
written	O
by	O
Charles	O
Haley	O
.	O
</s>
<s>
The	O
original	O
Unix	B-Application
editor	O
,	O
distributed	O
with	O
the	O
Bell	B-Operating_System
Labs	I-Operating_System
versions	I-Operating_System
of	O
the	O
operating	O
system	O
in	O
the	O
1970s	O
,	O
was	O
the	O
rather	O
user-unfriendly	O
ed	B-Application
.	O
</s>
<s>
George	O
Coulouris	O
of	O
Queen	O
Mary	O
College	O
,	O
London	O
,	O
which	O
had	O
installed	O
Unix	B-Application
in	O
1973	O
,	O
developed	O
an	O
improved	O
version	O
called	O
em	O
in	O
1975	O
that	O
could	O
take	O
advantage	O
of	O
video	O
terminals	O
.	O
</s>
<s>
While	O
visiting	O
Berkeley	O
,	O
Coulouris	O
presented	O
his	O
program	O
to	O
Bill	O
Joy	O
,	O
who	O
modified	O
it	O
to	O
be	O
less	O
demanding	O
on	O
the	O
processor	O
;	O
Joy	O
's	O
version	O
became	O
ex	O
and	O
got	O
included	O
in	O
the	O
Berkeley	B-Operating_System
Software	I-Operating_System
Distribution	I-Operating_System
.	O
</s>
<s>
ex	O
was	O
eventually	O
given	O
a	O
full-screen	O
visual	O
interface	O
(	O
adding	O
to	O
its	O
command	O
line	O
oriented	O
operation	O
)	O
,	O
thereby	O
becoming	O
the	O
vi	B-Application
text	B-Application
editor	I-Application
.	O
</s>
<s>
In	O
recent	O
times	O
,	O
ex	O
is	O
implemented	O
as	O
a	O
personality	O
of	O
the	O
vi	B-Application
program	O
;	O
most	O
variants	O
of	O
vi	B-Application
still	O
have	O
an	O
"	O
ex	B-Device
mode	I-Device
"	O
,	O
which	O
is	O
invoked	O
using	O
the	O
command	O
ex	O
,	O
or	O
from	O
within	O
vi	B-Application
for	O
one	O
command	O
by	O
typing	O
the	O
:	O
(	O
colon	O
)	O
character	O
.	O
</s>
<s>
Although	O
there	O
is	O
overlap	O
between	O
ex	O
and	O
vi	B-Application
functionality	O
,	O
some	O
things	O
can	O
only	O
be	O
done	O
with	O
ex	O
commands	O
,	O
so	O
it	O
remains	O
useful	O
when	O
using	O
vi	B-Application
.	O
</s>
<s>
The	O
core	O
ex	O
commands	O
which	O
relate	O
to	O
search	O
and	O
replace	O
are	O
essential	O
to	O
vi	B-Application
.	O
</s>
<s>
For	O
instance	O
,	O
the	O
ex	O
command	O
replaces	O
every	O
instance	O
of	O
with	O
,	O
and	O
works	O
in	O
vi	B-Application
too	O
.	O
</s>
<s>
ex	O
 [ -rR ] 	O
 [ -s|-v ] 	O
[	O
-c	O
command ]	O
[	O
-t	O
tagstring ]	O
[	O
-w	O
size ]	O
file	O
...	O
</s>
<s>
-c	O
command	O
Execute	O
command	O
on	O
first	O
buffer	O
loaded	O
from	O
file	O
.	O
</s>
