<s>
The	O
Unix	B-Application
philosophy	O
,	O
originated	O
by	O
Ken	O
Thompson	O
,	O
is	O
a	O
set	O
of	O
cultural	O
norms	O
and	O
philosophical	O
approaches	O
to	O
minimalist	B-Device
,	O
modular	B-Architecture
software	I-Architecture
development	O
.	O
</s>
<s>
It	O
is	O
based	O
on	O
the	O
experience	O
of	O
leading	O
developers	O
of	O
the	O
Unix	B-Application
operating	I-Application
system	I-Application
.	O
</s>
<s>
Early	O
Unix	B-Application
developers	O
were	O
important	O
in	O
bringing	O
the	O
concepts	O
of	O
modularity	B-Architecture
and	O
reusability	O
into	O
software	B-General_Concept
engineering	I-General_Concept
practice	O
,	O
spawning	O
a	O
"	O
software	B-Application
tools	I-Application
"	O
movement	O
.	O
</s>
<s>
Over	O
time	O
,	O
the	O
leading	O
developers	O
of	O
Unix	B-Application
(	O
and	O
programs	O
that	O
ran	O
on	O
it	O
)	O
established	O
a	O
set	O
of	O
cultural	O
norms	O
for	O
developing	O
software	O
;	O
these	O
norms	O
became	O
as	O
important	O
and	O
influential	O
as	O
the	O
technology	O
of	O
Unix	B-Application
itself	O
,	O
and	O
have	O
been	O
termed	O
the	O
"	O
Unix	B-Application
philosophy.	O
"	O
</s>
<s>
The	O
Unix	B-Application
philosophy	O
emphasizes	O
building	O
simple	O
,	O
compact	O
,	O
clear	O
,	O
modular	B-Architecture
,	O
and	O
extensible	B-Architecture
code	O
that	O
can	O
be	O
easily	O
maintained	O
and	O
repurposed	O
by	O
developers	O
other	O
than	O
its	O
creators	O
.	O
</s>
<s>
The	O
Unix	B-Application
philosophy	O
favors	O
composability	O
as	O
opposed	O
to	O
monolithic	B-General_Concept
design	I-General_Concept
.	O
</s>
<s>
The	O
Unix	B-Application
philosophy	O
is	O
documented	O
by	O
Doug	O
McIlroy	O
in	O
the	O
Bell	O
System	O
Technical	O
Journal	O
from	O
1978	O
:	O
</s>
<s>
Design	O
and	O
build	O
software	O
,	O
even	O
operating	B-General_Concept
systems	I-General_Concept
,	O
to	O
be	O
tried	O
early	O
,	O
ideally	O
within	O
weeks	O
.	O
</s>
<s>
It	O
was	O
later	O
summarized	O
by	O
Peter	O
H	O
.	O
Salus	O
in	O
A	O
Quarter-Century	O
of	O
Unix	B-Application
(	O
1994	O
)	O
:	O
</s>
<s>
Write	O
programs	O
to	O
handle	O
text	B-Operating_System
streams	I-Operating_System
,	O
because	O
that	O
is	O
a	O
universal	O
interface	O
.	O
</s>
<s>
In	O
their	O
award-winning	O
Unix	B-Application
paper	O
of	O
1974	O
,	O
Ritchie	O
and	O
Thompson	O
quote	O
the	O
following	O
design	O
considerations	O
:	O
</s>
<s>
Interactive	O
use	O
instead	O
of	O
batch	B-General_Concept
processing	I-General_Concept
.	O
</s>
<s>
Self-supporting	O
system	O
:	O
all	O
Unix	B-Application
software	O
is	O
maintained	O
under	O
Unix	B-Application
.	O
</s>
<s>
In	O
their	O
preface	O
to	O
the	O
1984	O
book	O
,	O
The	O
UNIX	B-Application
Programming	O
Environment	O
,	O
Brian	O
Kernighan	O
and	O
Rob	O
Pike	O
,	O
both	O
from	O
Bell	O
Labs	O
,	O
give	O
a	O
brief	O
description	O
of	O
the	O
Unix	B-Application
design	O
and	O
the	O
Unix	B-Application
philosophy	O
:	O
</s>
<s>
The	O
authors	O
further	O
write	O
that	O
their	O
goal	O
for	O
this	O
book	O
is	O
"	O
to	O
communicate	O
the	O
UNIX	B-Application
programming	O
philosophy.	O
"	O
</s>
<s>
In	O
October	O
1984	O
,	O
Brian	O
Kernighan	O
and	O
Rob	O
Pike	O
published	O
a	O
paper	O
called	O
Program	O
Design	O
in	O
the	O
UNIX	B-Application
Environment	O
.	O
</s>
<s>
In	O
this	O
paper	O
,	O
they	O
criticize	O
the	O
accretion	O
of	O
program	O
options	O
and	O
features	O
found	O
in	O
some	O
newer	O
Unix	B-Application
systems	I-Application
such	O
as	O
4.2BSD	O
and	O
System	B-Operating_System
V	I-Operating_System
,	O
and	O
explain	O
the	O
Unix	B-Application
philosophy	O
of	O
software	B-Application
tools	I-Application
,	O
each	O
performing	O
one	O
general	O
function	O
:	O
</s>
<s>
The	O
authors	O
contrast	O
Unix	B-Application
tools	O
such	O
as	O
with	O
larger	O
program	O
suites	O
used	O
by	O
other	O
systems	O
.	O
</s>
<s>
McIlroy	O
,	O
then	O
head	O
of	O
the	O
Bell	O
Labs	O
Computing	O
Sciences	O
Research	O
Center	O
,	O
and	O
inventor	O
of	O
the	O
Unix	B-Operating_System
pipe	I-Operating_System
,	O
summarized	O
the	O
Unix	B-Application
philosophy	O
as	O
follows	O
:	O
</s>
<s>
Beyond	O
these	O
statements	O
,	O
he	O
has	O
also	O
emphasized	O
simplicity	O
and	O
minimalism	B-Device
in	O
Unix	B-Application
programming	O
:	O
</s>
<s>
Conversely	O
,	O
McIlroy	O
has	O
criticized	O
modern	O
Linux	B-Application
as	O
having	O
software	O
bloat	O
,	O
remarking	O
that	O
,	O
"	O
adoring	O
admirers	O
have	O
fed	O
Linux	B-Application
goodies	O
to	O
a	O
disheartening	O
state	O
of	O
obesity.	O
"	O
</s>
<s>
He	O
contrasts	O
this	O
with	O
the	O
earlier	O
approach	O
taken	O
at	O
Bell	O
Labs	O
when	O
developing	O
and	O
revising	O
Research	B-Operating_System
Unix	I-Operating_System
:	O
</s>
<s>
As	O
stated	O
by	O
McIlroy	O
,	O
and	O
generally	O
accepted	O
throughout	O
the	O
Unix	B-Application
community	O
,	O
Unix	B-Application
programs	O
have	O
always	O
been	O
expected	O
to	O
follow	O
the	O
concept	O
of	O
DOTADIW	O
,	O
or	O
"	O
Do	O
One	O
Thing	O
And	O
Do	O
It	O
Well.	O
"	O
</s>
<s>
There	O
are	O
limited	O
sources	O
for	O
the	O
acronym	O
DOTADIW	O
on	O
the	O
Internet	O
,	O
but	O
it	O
is	O
discussed	O
at	O
length	O
during	O
the	O
development	O
and	O
packaging	O
of	O
new	O
operating	B-General_Concept
systems	I-General_Concept
,	O
especially	O
in	O
the	O
Linux	B-Application
community	O
.	O
</s>
<s>
Patrick	O
Volkerding	O
,	O
the	O
project	O
lead	O
of	O
Slackware	B-Application
Linux	I-Application
,	O
invoked	O
this	O
design	O
principle	O
in	O
a	O
criticism	O
of	O
the	O
systemd	B-Application
architecture	O
,	O
stating	O
that	O
,	O
"	O
attempting	O
to	O
control	O
services	O
,	O
sockets	O
,	O
devices	O
,	O
mounts	O
,	O
etc.	O
,	O
all	O
within	O
one	O
daemon	B-Operating_System
flies	O
in	O
the	O
face	O
of	O
the	O
Unix	B-Application
concept	O
of	O
doing	O
one	O
thing	O
and	O
doing	O
it	O
well.	O
"	O
</s>
<s>
In	O
his	O
book	O
The	O
Art	O
of	O
Unix	B-Application
Programming	O
that	O
was	O
first	O
published	O
in	O
2003	O
,	O
Eric	O
S	O
.	O
Raymond	O
(	O
open	O
source	O
advocate	O
and	O
programmer	O
)	O
summarizes	O
the	O
Unix	B-Application
philosophy	O
as	O
KISS	O
Principle	O
of	O
"	O
Keep	O
it	O
Simple	O
,	O
Stupid.	O
"	O
</s>
<s>
Make	O
the	O
program	O
and	O
protocols	O
extensible	B-Architecture
.	O
</s>
<s>
In	O
1994	O
,	O
Mike	O
Gancarz	O
,	O
a	O
member	O
of	O
Digital	O
Equipment	O
Corporation	O
's	O
Unix	B-Application
Engineering	O
Group	O
(	O
UEG	O
)	O
,	O
published	O
The	O
UNIX	B-Application
Philosophy	O
based	O
on	O
his	O
own	O
Unix	B-Application
(	O
Ultrix	B-Operating_System
)	O
port	O
development	O
at	O
DEC	O
in	O
the	O
1980s	O
and	O
discussions	O
with	O
colleagues	O
.	O
</s>
<s>
He	O
is	O
also	O
a	O
member	O
of	O
the	O
X	B-Operating_System
Window	I-Operating_System
System	I-Operating_System
development	O
team	O
and	O
author	O
of	O
Ultrix	B-Device
Window	I-Device
Manager	I-Device
(	O
uwm	B-Device
)	O
.	O
</s>
<s>
The	O
book	O
focuses	O
on	O
porting	O
UNIX	B-Application
to	O
different	O
computers	O
during	O
the	O
UNIX	B-Application
wars	O
of	O
the	O
1980s	O
and	O
describes	O
his	O
philosophy	O
that	O
portability	O
should	O
be	O
more	O
important	O
than	O
the	O
efficiency	O
of	O
using	O
non-standard	O
interfaces	O
for	O
hardware	O
and	O
graphics	O
devices	O
.	O
</s>
<s>
Store	O
data	O
in	O
flat	O
text	B-General_Concept
files	I-General_Concept
.	O
</s>
<s>
Use	O
shell	B-Language
scripts	I-Language
to	O
increase	O
leverage	O
and	O
portability	O
.	O
</s>
<s>
Richard	O
P	O
.	O
Gabriel	O
suggests	O
that	O
a	O
key	O
advantage	O
of	O
Unix	B-Application
was	O
that	O
it	O
embodied	O
a	O
design	O
philosophy	O
he	O
termed	O
"	O
worse	O
is	O
better	O
"	O
,	O
in	O
which	O
simplicity	O
of	O
both	O
the	O
interface	O
and	O
the	O
implementation	O
are	O
more	O
important	O
than	O
any	O
other	O
attributes	O
of	O
the	O
system	O
—	O
including	O
correctness	O
,	O
consistency	O
,	O
and	O
completeness	O
.	O
</s>
<s>
For	O
example	O
,	O
in	O
the	O
early	O
days	O
Unix	B-Application
used	O
a	O
monolithic	B-Operating_System
kernel	I-Operating_System
(	O
which	O
means	O
that	O
user	O
processes	O
carried	O
out	O
kernel	O
system	O
calls	O
all	O
on	O
the	O
user	O
stack	O
)	O
.	O
</s>
<s>
If	O
a	O
signal	O
was	O
delivered	O
to	O
a	O
process	O
while	O
it	O
was	O
blocked	O
on	O
a	O
long-term	O
I/O	B-General_Concept
in	O
the	O
kernel	O
,	O
then	O
what	O
should	O
be	O
done	O
?	O
</s>
<s>
Should	O
the	O
signal	O
be	O
delayed	O
,	O
possibly	O
for	O
a	O
long	O
time	O
(	O
maybe	O
indefinitely	O
)	O
while	O
the	O
I/O	B-General_Concept
completed	O
?	O
</s>
<s>
The	O
Unix	B-Application
system	I-Application
would	O
occasionally	O
return	O
early	O
from	O
a	O
system	O
call	O
with	O
an	O
error	O
stating	O
that	O
it	O
had	O
done	O
nothing	O
—	O
the	O
"	O
Interrupted	O
System	O
Call	O
"	O
,	O
or	O
an	O
error	O
number	O
4	O
(	O
EINTR	B-Error_Name
)	O
in	O
today	O
's	O
systems	O
.	O
</s>
<s>
On	O
the	O
plus	O
side	O
,	O
this	O
made	O
the	O
I/O	B-General_Concept
system	O
many	O
times	O
simpler	O
to	O
design	O
and	O
understand	O
.	O
</s>
<s>
For	O
the	O
few	O
other	O
programs	O
—	O
things	O
like	O
shells	O
or	O
text	O
editors	O
that	O
respond	O
to	O
job	O
control	O
key	O
presses	O
—	O
small	O
wrappers	O
could	O
be	O
added	O
to	O
system	O
calls	O
so	O
as	O
to	O
retry	O
the	O
call	O
right	O
away	O
if	O
this	O
EINTR	B-Error_Name
error	O
was	O
raised	O
.	O
</s>
<s>
In	O
a	O
1981	O
article	O
entitled	O
"	O
The	O
truth	O
about	O
Unix	B-Application
:	O
The	O
user	O
interface	O
is	O
horrid	O
"	O
published	O
in	O
Datamation	O
,	O
Don	O
Norman	O
criticized	O
the	O
design	O
philosophy	O
of	O
Unix	B-Application
for	O
its	O
lack	O
of	O
concern	O
for	O
the	O
user	O
interface	O
.	O
</s>
<s>
Writing	O
from	O
his	O
background	O
in	O
cognitive	O
science	O
and	O
from	O
the	O
perspective	O
of	O
the	O
then-current	O
philosophy	O
of	O
cognitive	O
engineering	O
,	O
he	O
focused	O
on	O
how	O
end-users	O
comprehend	O
and	O
form	O
a	O
personal	O
cognitive	O
model	O
of	O
systemsor	O
,	O
in	O
the	O
case	O
of	O
Unix	B-Application
,	O
fail	O
to	O
understand	O
,	O
with	O
the	O
result	O
that	O
disastrous	O
mistakes	O
(	O
such	O
as	O
losing	O
an	O
hour	O
's	O
worth	O
of	O
work	O
)	O
are	O
all	O
too	O
easy	O
.	O
</s>
