<s>
rn	B-Protocol
(	O
short	O
for	O
Read	O
News	O
)	O
is	O
a	O
news	B-Protocol
client	I-Protocol
(	O
or	O
'	O
newsreader	B-Protocol
 '	O
)	O
written	O
by	O
Larry	O
Wall	O
and	O
originally	O
released	O
in	O
1984	O
.	O
</s>
<s>
It	O
was	O
one	O
of	O
the	O
first	O
newsreaders	B-Protocol
to	O
take	O
full	O
advantage	O
of	O
character-addressable	O
CRT	O
terminals	O
(	O
vnews	O
,	O
by	O
Kenneth	O
Almquist	O
was	O
first	O
)	O
.	O
</s>
<s>
Previous	O
newsreaders	B-Protocol
,	O
such	O
as	O
readnews	O
,	O
were	O
mostly	O
line-oriented	O
and	O
designed	O
for	O
use	O
on	O
the	O
printing	O
terminals	O
which	O
were	O
common	O
on	O
the	O
early	O
Unix	B-Application
minicomputers	B-Architecture
where	O
the	O
Usenet	B-Application
software	O
and	O
network	O
originated	O
.	O
</s>
<s>
Later	O
variants	O
of	O
the	O
original	O
rn	B-Protocol
program	O
included	O
rrn	O
,	O
trn	O
,	O
and	O
strn	O
.	O
</s>
<s>
rn	B-Protocol
was	O
also	O
notable	O
for	O
three	O
other	O
features	O
it	O
introduced	O
:	O
KILL	B-Application
files	I-Application
,	O
"	O
do	O
the	O
right	O
thing	O
"	O
,	O
and	O
automatic	O
configuration	O
.	O
</s>
<s>
The	O
KILL	B-Application
file	I-Application
was	O
a	O
file	O
(	O
called	O
,	O
obviously	O
enough	O
,	O
)	O
containing	O
regular	B-Language
expressions	I-Language
matched	O
against	O
the	O
subjects	O
of	O
news	O
articles	O
in	O
each	O
group	O
;	O
if	O
an	O
article	O
matched	O
,	O
it	O
would	O
be	O
marked	O
as	O
having	O
already	O
been	O
read	O
.	O
</s>
<s>
This	O
feature	O
proved	O
essential	O
as	O
the	O
growth	O
of	O
the	O
Usenet	B-Application
made	O
it	O
impossible	O
to	O
read	O
every	O
article	O
in	O
even	O
a	O
limited	O
selection	O
of	O
newsgroups	O
.	O
</s>
<s>
Most	O
Unix	B-Application
programs	O
,	O
and	O
in	O
particular	O
all	O
of	O
the	O
Usenet	B-Application
software	O
,	O
were	O
distributed	O
in	O
source	O
code	O
form	O
.	O
</s>
<s>
Because	O
different	O
vendors	O
of	O
Unix	B-Application
systems	I-Application
(	O
and	O
in	O
many	O
cases	O
,	O
different	O
versions	O
of	O
the	O
Unix	B-Application
software	O
)	O
implemented	O
slightly	O
different	O
behavior	O
and	O
names	O
for	O
important	O
functions	O
,	O
a	O
system	O
administrator	O
was	O
required	O
to	O
have	O
sufficient	O
programming	O
expertise	O
to	O
edit	O
the	O
source	O
code	O
before	O
building	O
the	O
program	O
executables	O
to	O
account	O
for	O
these	O
differences	O
.	O
</s>
<s>
rn	B-Protocol
changed	O
that	O
by	O
including	O
a	O
script	O
called	O
,	O
which	O
had	O
enough	O
intelligence	O
on	O
its	O
own	O
to	O
examine	O
the	O
computer	O
system	O
it	O
was	O
running	O
on	O
and	O
determine	O
,	O
of	O
those	O
functions	O
and	O
interfaces	O
known	O
to	O
behave	O
differently	O
,	O
which	O
behavior	O
the	O
system	O
implemented	O
.	O
</s>
<s>
Today	O
,	O
most	O
open	B-Application
source	I-Application
software	I-Application
is	O
distributed	O
with	O
a	O
similar	O
script	O
,	O
such	O
as	O
autoconf	B-Application
.	O
</s>
<s>
Like	O
all	O
of	O
the	O
original	O
newsreaders	B-Protocol
and	O
the	O
Usenet	B-Application
software	O
itself	O
,	O
rn	B-Protocol
was	O
designed	O
for	O
the	O
environment	O
of	O
a	O
large	O
time-shared	B-General_Concept
minicomputer	B-Architecture
,	O
which	O
users	O
connected	O
to	O
using	O
terminals	O
wired	O
directly	O
to	O
the	O
machine	O
,	O
and	O
where	O
the	O
only	O
networks	O
available	O
were	O
accessed	O
by	O
slow	O
and	O
expensive	O
dial-up	O
modem	O
connections	O
.	O
</s>
<s>
All	O
of	O
the	O
articles	O
in	O
all	O
of	O
the	O
newsgroups	O
were	O
stored	O
in	O
files	O
on	O
the	O
local	O
disk	O
(	O
known	O
as	O
the	O
"	O
news	O
spool	O
"	O
)	O
,	O
and	O
rn	B-Protocol
could	O
simply	O
read	O
those	O
files	O
directly	O
when	O
presenting	O
them	O
to	O
the	O
user	O
.	O
</s>
<s>
When	O
local	B-General_Concept
area	I-General_Concept
networks	I-General_Concept
became	O
widespread	O
,	O
it	O
was	O
natural	O
that	O
administrators	O
and	O
users	O
would	O
desire	O
remote	O
access	O
to	O
the	O
news	O
spool	O
,	O
and	O
NNTP	B-Protocol
,	O
the	O
Network	B-Protocol
News	I-Protocol
Transfer	I-Protocol
Protocol	I-Protocol
,	O
was	O
developed	O
to	O
serve	O
that	O
need	O
.	O
</s>
<s>
While	O
working	O
at	O
Baylor	O
College	O
of	O
Medicine	O
,	O
Stan	O
O	O
.	O
Barber	O
developed	O
remote	O
rn	B-Protocol
(	O
rrn	O
)	O
,	O
a	O
set	O
of	O
patches	B-Application
to	O
rn	B-Protocol
which	O
allowed	O
it	O
to	O
communicate	O
with	O
an	O
NNTP	B-Protocol
server	O
over	O
a	O
local-area	O
(	O
or	O
even	O
wide-area	O
)	O
network	O
.	O
</s>
<s>
Barber	O
later	O
took	O
over	O
maintenance	O
responsibility	O
for	O
rn	B-Protocol
itself	O
from	O
Larry	O
Wall	O
.	O
</s>
<s>
As	O
news	O
volumes	O
continued	O
to	O
increase	O
,	O
it	O
became	O
apparent	O
that	O
even	O
KILL	B-Application
files	I-Application
could	O
not	O
possibly	O
keep	O
up	O
with	O
the	O
sheer	O
number	O
of	O
users	O
and	O
articles	O
.	O
</s>
<s>
A	O
new	O
concept	O
,	O
the	O
threaded	O
newsreader	B-Protocol
,	O
was	O
needed	O
as	O
users	O
gradually	O
switched	O
from	O
a	O
"	O
read	O
most	O
,	O
kill	O
few	O
"	O
model	O
to	O
"	O
ignore	O
most	O
,	O
read	O
few	O
"	O
.	O
</s>
<s>
By	O
organizing	O
the	O
articles	O
in	O
a	O
newsgroup	O
according	O
to	O
threads	O
of	O
discussion	O
,	O
using	O
headers	O
that	O
had	O
long	O
been	O
present	O
in	O
Usenet	B-Application
articles	O
but	O
practically	O
unused	O
,	O
a	O
threaded	O
newsreader	B-Protocol
would	O
allow	O
users	O
to	O
keep	O
up	O
with	O
topics	O
and	O
discussions	O
they	O
were	O
interested	O
without	O
having	O
to	O
explicitly	O
deselect	O
uninteresting	O
threads	O
.	O
</s>
<s>
Kim	O
F	O
.	O
Storm	O
's	O
nn	O
newsreader	B-Protocol
was	O
the	O
first	O
to	O
implement	O
this	O
new	O
model	O
,	O
and	O
it	O
looked	O
for	O
a	O
while	O
as	O
if	O
nn	O
would	O
do	O
to	O
rn	B-Protocol
what	O
rn	B-Protocol
did	O
to	O
readnews	O
.	O
</s>
<s>
This	O
fate	O
was	O
averted	O
when	O
Wayne	O
Davison	O
developed	O
trn	O
,	O
a	O
set	O
of	O
patches	B-Application
to	O
rn	B-Protocol
which	O
gave	O
it	O
both	O
threading	O
at	O
the	O
article	O
level	O
and	O
a	O
new	O
user	O
interface	O
that	O
would	O
allow	O
users	O
to	O
select	O
only	O
the	O
threads	O
they	O
desired	O
,	O
while	O
remaining	O
true	O
to	O
the	O
original	O
rn	B-Protocol
interface	O
philosophy	O
of	O
do	O
the	O
right	O
thing	O
.	O
</s>
<s>
An	O
even	O
more	O
recent	O
addition	O
to	O
the	O
rn	B-Protocol
family	O
has	O
been	O
the	O
addition	O
of	O
scoring	O
,	O
which	O
allows	O
a	O
more	O
complex	O
method	O
of	O
evaluating	O
articles	O
to	O
determine	O
whether	O
the	O
user	O
wishes	O
to	O
read	O
them	O
;	O
originally	O
this	O
was	O
implemented	O
in	O
a	O
code	B-Application
fork	I-Application
of	O
trn	O
called	O
strn	O
,	O
but	O
later	O
this	O
was	O
integrated	O
into	O
the	O
official	O
trn	O
distribution	O
.	O
</s>
