<s>
The	O
Comprehensive	B-Language
Perl	I-Language
Archive	I-Language
Network	I-Language
(	O
CPAN	B-Language
)	O
is	O
a	O
repository	B-Application
of	O
over	O
250,000	O
software	B-Architecture
modules	I-Architecture
and	O
accompanying	O
documentation	O
for	O
39,000	O
distributions	O
,	O
written	O
in	O
the	O
Perl	B-Language
programming	I-Language
language	I-Language
by	O
over	O
12,000	O
contributors	O
.	O
</s>
<s>
CPAN	B-Language
can	O
denote	O
either	O
the	O
archive	O
network	O
or	O
the	O
Perl	B-Language
program	O
that	O
acts	O
as	O
an	O
interface	O
to	O
the	O
network	O
and	O
as	O
an	O
automated	O
software	O
installer	O
(	O
somewhat	O
like	O
a	O
package	B-Application
manager	I-Application
)	O
.	O
</s>
<s>
Most	O
software	O
on	O
CPAN	B-Language
is	O
free	B-Application
and	I-Application
open	I-Application
source	I-Application
software	I-Application
.	O
</s>
<s>
CPAN	B-Language
was	O
conceived	O
in	O
1993	O
and	O
has	O
been	O
active	O
online	O
since	O
October	O
1995	O
.	O
</s>
<s>
It	O
is	O
based	O
on	O
the	O
CTAN	B-General_Concept
model	O
and	O
began	O
as	O
a	O
place	O
to	O
unify	O
the	O
structure	O
of	O
scattered	O
Perl	B-Language
archives	O
.	O
</s>
<s>
Like	O
many	O
programming	O
languages	O
,	O
Perl	B-Language
has	O
mechanisms	O
to	O
use	O
external	O
libraries	B-Library
of	O
code	O
,	O
making	O
one	O
file	O
contain	O
common	O
routines	O
used	O
by	O
several	O
programs	O
.	O
</s>
<s>
Perl	B-Language
calls	O
these	O
modules	B-Language
.	O
</s>
<s>
Perl	B-Language
modules	I-Language
are	O
typically	O
installed	O
in	O
one	O
of	O
several	O
directories	B-Application
whose	O
paths	B-Application
are	O
placed	O
in	O
the	O
Perl	B-Language
interpreter	I-Language
when	O
it	O
is	O
first	O
compiled	B-Language
;	O
on	O
Unix-like	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
,	O
common	O
paths	B-Application
include	O
/usr/lib/perl5	O
,	O
/usr/local/lib/perl5	O
,	O
and	O
several	O
of	O
their	O
subdirectories	B-Application
.	O
</s>
<s>
Perl	B-Language
comes	O
with	O
a	O
small	O
set	O
of	O
core	O
modules	B-Language
.	O
</s>
<s>
Some	O
of	O
these	O
perform	O
bootstrapping	O
tasks	O
,	O
such	O
as	O
ExtUtils::MakeMaker	O
,	O
which	O
is	O
used	O
to	O
create	O
Makefiles	O
for	O
building	O
and	O
installing	O
other	O
extension	O
modules	B-Language
;	O
others	O
,	O
like	O
List::Util	O
,	O
are	O
merely	O
commonly	O
used	O
.	O
</s>
<s>
CPAN	B-Language
's	O
main	O
purpose	O
is	O
to	O
help	O
programmers	O
locate	O
modules	B-Language
and	O
programs	O
not	O
included	O
in	O
the	O
Perl	B-Language
standard	O
distribution	O
.	O
</s>
<s>
Authors	O
maintain	O
and	O
improve	O
their	O
own	O
modules	B-Language
.	O
</s>
<s>
Forking	O
,	O
and	O
creating	O
competing	O
modules	B-Language
for	O
the	O
same	O
task	O
or	O
purpose	O
,	O
is	O
common	O
.	O
</s>
<s>
There	O
is	O
a	O
third-party	O
bug	O
tracking	O
system	O
that	O
is	O
automatically	O
set	O
up	O
for	O
any	O
uploaded	O
distribution	O
,	O
but	O
authors	O
may	O
opt	O
to	O
use	O
a	O
different	O
bug	O
tracking	O
system	O
such	O
as	O
GitHub	B-Application
.	O
</s>
<s>
Similarly	O
,	O
though	O
GitHub	B-Application
is	O
a	O
popular	O
location	O
to	O
store	O
the	O
source	O
for	O
distributions	O
,	O
it	O
may	O
be	O
stored	O
anywhere	O
the	O
author	O
prefers	O
,	O
or	O
may	O
not	O
be	O
publicly	O
accessible	O
at	O
all	O
.	O
</s>
<s>
Maintainers	O
may	O
grant	O
permissions	O
to	O
others	O
to	O
maintain	O
or	O
take	O
over	O
their	O
modules	B-Language
,	O
and	O
permissions	O
may	O
be	O
granted	O
by	O
admins	O
for	O
those	O
wishing	O
to	O
take	O
over	O
abandoned	O
modules	B-Language
.	O
</s>
<s>
Previous	O
versions	O
of	O
updated	O
distributions	O
are	O
retained	O
on	O
CPAN	B-Language
until	O
deleted	O
by	O
the	O
uploader	O
,	O
and	O
a	O
secondary	O
mirror	O
network	O
called	O
BackPAN	O
retains	O
distributions	O
even	O
if	O
they	O
are	O
deleted	O
from	O
CPAN	B-Language
.	O
</s>
<s>
Also	O
,	O
the	O
complete	O
history	O
of	O
the	O
CPAN	B-Language
and	O
all	O
its	O
modules	B-Language
is	O
available	O
as	O
the	O
GitPAN	O
project	O
,	O
allowing	O
to	O
easily	O
see	O
the	O
complete	O
history	O
for	O
all	O
the	O
modules	B-Language
and	O
for	O
easy	O
maintenance	O
of	O
forks	O
.	O
</s>
<s>
CPAN	B-Language
is	O
also	O
used	O
to	O
distribute	O
new	O
versions	O
of	O
Perl	B-Language
,	O
as	O
well	O
as	O
related	O
projects	O
,	O
such	O
as	O
Parrot	B-Language
and	O
Raku	B-Application
.	O
</s>
<s>
Files	O
on	O
the	O
CPAN	B-Language
are	O
referred	O
to	O
as	O
distributions	O
.	O
</s>
<s>
A	O
distribution	O
may	O
consist	O
of	O
one	O
or	O
more	O
modules	B-Language
,	O
documentation	O
files	O
,	O
or	O
programs	O
packaged	O
in	O
a	O
common	O
archiving	O
format	O
,	O
such	O
as	O
a	O
gzipped	O
tar	B-Application
archive	I-Application
or	O
a	O
ZIP	B-General_Concept
file	I-General_Concept
.	O
</s>
<s>
New	O
distributions	O
are	O
uploaded	O
to	O
the	O
Perl	B-Language
Authors	O
Upload	O
Server	O
,	O
or	O
PAUSE	O
(	O
see	O
the	O
section	O
Uploading	O
distributions	O
with	O
PAUSE	O
)	O
.	O
</s>
<s>
In	O
2003	O
,	O
distributions	O
started	O
to	O
include	O
metadata	O
files	O
,	O
called	O
META.yml	O
,	O
indicating	O
the	O
distribution	O
's	O
name	O
,	O
version	O
,	O
dependencies	B-Application
,	O
and	O
other	O
useful	O
information	O
;	O
however	O
,	O
not	O
all	O
distributions	O
contain	O
metadata	O
.	O
</s>
<s>
In	O
2010	O
,	O
version	O
2	O
of	O
this	O
specification	O
was	O
created	O
to	O
be	O
used	O
via	O
a	O
new	O
file	O
called	O
META.json	O
,	O
with	O
the	O
YAML	B-Protocol
format	O
file	O
often	O
also	O
included	O
for	O
backward	B-General_Concept
compatibility	I-General_Concept
.	O
</s>
<s>
With	O
thousands	O
of	O
distributions	O
,	O
CPAN	B-Language
needs	O
to	O
be	O
structured	O
to	O
be	O
useful	O
.	O
</s>
<s>
Authors	O
often	O
place	O
their	O
modules	B-Language
in	O
the	O
natural	O
hierarchy	O
of	O
Perl	B-Language
module	I-Language
names	O
(	O
such	O
as	O
Apache::DBI	O
or	O
Lingua::EN::Inflect	O
)	O
according	O
to	O
purpose	O
or	O
domain	O
,	O
though	O
this	O
is	O
not	O
enforced	O
.	O
</s>
<s>
CPAN	B-Language
module	B-Language
distributions	O
usually	O
have	O
names	O
in	O
the	O
form	O
of	O
CGI-Application-3.1	O
(	O
where	O
the	O
::	O
used	O
in	O
the	O
module	B-Language
's	O
name	O
has	O
been	O
replaced	O
with	O
a	O
dash	O
,	O
and	O
the	O
version	O
number	O
has	O
been	O
appended	O
to	O
the	O
name	O
)	O
,	O
but	O
this	O
is	O
only	O
a	O
convention	O
;	O
many	O
prominent	O
distributions	O
break	O
the	O
convention	O
,	O
especially	O
those	O
that	O
contain	O
multiple	O
modules	B-Language
.	O
</s>
<s>
The	O
distribution	O
infrastructure	O
of	O
CPAN	B-Language
consists	O
of	O
its	O
worldwide	O
network	O
of	O
more	O
than	O
250	O
mirrors	O
in	O
more	O
than	O
60	O
countries	O
.	O
</s>
<s>
Most	O
mirrors	O
update	O
themselves	O
hourly	O
,	O
daily	O
or	O
bidaily	O
from	O
the	O
CPAN	B-Language
master	O
site	O
.	O
</s>
<s>
Some	O
sites	O
are	O
major	O
FTP	B-Protocol
servers	O
which	O
mirror	O
lots	O
of	O
other	O
software	O
,	O
but	O
others	O
are	O
simply	O
servers	O
owned	O
by	O
companies	O
that	O
use	O
Perl	B-Language
heavily	O
.	O
</s>
<s>
Several	O
search	O
engines	O
have	O
been	O
written	O
to	O
help	O
Perl	B-Language
programmers	O
sort	O
through	O
the	O
CPAN	B-Language
.	O
</s>
<s>
The	O
official	O
includes	O
textual	O
search	O
,	O
a	O
browsable	O
index	O
of	O
modules	B-Language
,	O
and	O
extracted	O
copies	O
of	O
all	O
distributions	O
currently	O
on	O
the	O
CPAN	B-Language
.	O
</s>
<s>
On	O
16	O
May	O
2018	O
,	O
the	O
Perl	B-Language
Foundation	O
announced	O
that	O
search.cpan.org	O
would	O
be	O
shut	O
down	O
on	O
29	O
June	O
2018	O
(	O
after	O
19	O
years	O
of	O
operation	O
)	O
,	O
due	O
to	O
its	O
aging	O
codebase	O
and	O
maintenance	O
burden	O
.	O
</s>
<s>
Users	O
will	O
be	O
transitioned	O
and	O
redirected	O
to	O
the	O
third-party	O
alternative	O
MetaCPAN	B-Language
.	O
</s>
<s>
CPAN	B-Language
Testers	O
are	O
a	O
group	O
of	O
volunteers	O
,	O
who	O
will	O
download	O
and	O
test	O
distributions	O
as	O
they	O
are	O
uploaded	O
to	O
CPAN	B-Language
.	O
</s>
<s>
This	O
enables	O
the	O
authors	O
to	O
have	O
their	O
modules	B-Language
tested	O
on	O
many	O
platforms	O
and	O
environments	O
that	O
they	O
would	O
otherwise	O
not	O
have	O
access	O
to	O
,	O
thus	O
helping	O
to	O
promote	O
portability	O
,	O
as	O
well	O
as	O
a	O
degree	O
of	O
quality	O
.	O
</s>
<s>
Smoke	O
testers	O
send	O
reports	O
,	O
which	O
are	O
then	O
collated	O
and	O
used	O
for	O
a	O
variety	O
of	O
presentation	O
websites	O
,	O
including	O
the	O
main	O
reports	O
site	O
,	O
statistics	O
and	O
dependencies	B-Application
.	O
</s>
<s>
Authors	O
can	O
upload	O
new	O
distributions	O
to	O
the	O
CPAN	B-Language
through	O
the	O
Perl	B-Language
Authors	O
Upload	O
Server	O
(	O
PAUSE	O
)	O
.	O
</s>
<s>
Once	O
registered	O
,	O
they	O
may	O
use	O
a	O
web	O
interface	O
at	O
,	O
or	O
an	O
FTP	B-Protocol
interface	O
to	O
upload	O
files	O
to	O
their	O
directory	B-Application
and	O
delete	O
them	O
.	O
</s>
<s>
Modules	B-Language
in	O
the	O
upload	O
will	O
only	O
be	O
indexed	O
as	O
canonical	O
if	O
the	O
module	B-Language
name	O
has	O
not	O
been	O
used	O
before	O
(	O
granting	O
first-come	O
permission	O
to	O
the	O
uploader	O
)	O
,	O
or	O
if	O
the	O
uploader	O
has	O
permission	O
for	O
that	O
name	O
,	O
and	O
if	O
the	O
module	B-Language
is	O
a	O
higher	O
version	O
than	O
any	O
existing	O
entry	O
.	O
</s>
<s>
There	O
is	O
also	O
a	O
Perl	B-Language
core	O
module	B-Language
named	O
CPAN	B-Language
;	O
it	O
is	O
usually	O
differentiated	O
from	O
the	O
repository	B-Application
itself	O
by	O
using	O
the	O
name	O
CPAN.pm	O
.	O
</s>
<s>
CPAN.pm	O
is	O
mainly	O
an	O
interactive	O
shell	O
which	O
can	O
be	O
used	O
to	O
search	O
for	O
,	O
download	O
,	O
and	O
install	O
distributions	O
.	O
</s>
<s>
An	O
interactive	O
shell	O
called	O
is	O
also	O
provided	O
in	O
the	O
Perl	B-Language
core	O
,	O
and	O
is	O
the	O
usual	O
way	O
of	O
running	O
CPAN.pm	O
.	O
</s>
<s>
After	O
a	O
short	O
configuration	O
process	O
and	O
mirror	O
selection	O
,	O
it	O
uses	O
tools	O
available	O
on	O
the	O
user	O
's	O
computer	O
to	O
automatically	O
download	O
,	O
unpack	O
,	O
compile	B-Language
,	O
test	O
,	O
and	O
install	O
modules	B-Language
.	O
</s>
<s>
An	O
effort	O
to	O
replace	O
CPAN.pm	O
with	O
something	O
cleaner	O
and	O
more	O
modern	O
resulted	O
in	O
the	O
CPANPLUS	B-Language
(	O
or	O
CPAN++	O
)	O
set	O
of	O
modules	B-Language
.	O
</s>
<s>
CPANPLUS	B-Language
separates	O
the	O
back-end	O
work	O
of	O
downloading	O
,	O
compiling	B-Language
,	O
and	O
installing	O
modules	B-Language
from	O
the	O
interactive	O
shell	O
used	O
to	O
issue	O
commands	O
.	O
</s>
<s>
Finally	O
,	O
CPANPLUS	B-Language
can	O
uninstall	O
a	O
distribution	O
.	O
</s>
<s>
CPANPLUS	B-Language
was	O
added	O
to	O
the	O
Perl	B-Language
core	O
in	O
version	O
5.10.0	O
,	O
and	O
removed	O
from	O
it	O
in	O
version	O
5.20.0	O
.	O
</s>
<s>
A	O
smaller	O
,	O
leaner	O
modern	O
alternative	O
to	O
these	O
CPAN	B-Language
installers	O
was	O
developed	O
called	O
cpanminus	O
.	O
</s>
<s>
cpanminus	O
was	O
designed	O
to	O
have	O
a	O
much	O
smaller	O
memory	O
footprint	O
as	O
often	O
required	O
in	O
limited	O
memory	O
environments	O
,	O
and	O
to	O
be	O
usable	O
as	O
a	O
standalone	O
script	O
such	O
that	O
it	O
can	O
even	O
install	O
itself	O
,	O
requiring	O
only	O
the	O
expected	O
set	O
of	O
core	O
Perl	B-Language
modules	I-Language
to	O
be	O
available	O
.	O
</s>
<s>
It	O
is	O
also	O
available	O
from	O
CPAN	B-Language
as	O
the	O
module	B-Language
App::cpanminus	O
,	O
which	O
installs	O
the	O
script	O
.	O
</s>
<s>
It	O
recognizes	O
the	O
cpanfile	O
format	O
for	O
specifying	O
prerequisites	O
,	O
useful	O
in	O
ad-hoc	O
Perl	B-Language
projects	O
that	O
may	O
not	O
be	O
designed	O
for	O
CPAN	B-Language
installation	O
.	O
</s>
<s>
Each	O
of	O
these	O
modules	B-Language
can	O
check	O
a	O
distribution	O
's	O
dependencies	B-Application
and	O
recursively	O
install	O
any	O
prerequisites	O
,	O
either	O
automatically	O
or	O
with	O
individual	O
user	O
approval	O
.	O
</s>
<s>
Each	O
support	O
FTP	B-Protocol
and	O
HTTP	O
and	O
can	O
work	O
through	O
firewalls	O
and	O
proxies	O
.	O
</s>
<s>
Experienced	O
Perl	B-Language
programmers	O
often	O
comment	O
that	O
half	O
of	O
Perl	B-Language
's	O
power	O
is	O
in	O
the	O
CPAN	B-Language
.	O
</s>
<s>
It	O
has	O
been	O
called	O
Perl	B-Language
's	O
killer	O
app	O
.	O
</s>
<s>
It	O
is	O
roughly	O
equivalent	O
to	O
Composer	B-Application
for	O
PHP	B-Application
;	O
the	O
PyPI	B-Language
(	O
Python	B-Language
Package	I-Language
Index	I-Language
)	O
repository	B-Application
for	O
Python	B-Language
;	O
RubyGems	B-Application
for	O
Ruby	B-Language
;	O
CRAN	O
for	O
R	B-Language
;	O
npm	B-Language
for	O
Node.js	B-Language
;	O
LuaRocks	B-Language
for	O
Lua	B-Language
;	O
Maven	B-Language
for	O
Java	B-Language
;	O
and	O
Hackage	B-Library
for	O
Haskell	B-Language
.	O
</s>
<s>
CPAN	B-Language
's	O
use	O
of	O
arbitrated	O
name	O
spaces	O
,	O
a	O
testing	O
regime	O
and	O
a	O
well	O
defined	O
documentation	O
style	O
makes	O
it	O
unique	O
.	O
</s>
<s>
Given	O
its	O
importance	O
to	O
the	O
Perl	B-Language
developer	O
community	O
,	O
the	O
CPAN	B-Language
both	O
shapes	O
and	O
is	O
shaped	O
by	O
Perl	B-Language
's	O
culture	O
.	O
</s>
<s>
Its	O
"	O
self-appointed	O
master	O
librarian	O
"	O
,	O
Jarkko	O
Hietaniemi	O
,	O
often	O
takes	O
part	O
in	O
the	O
April	O
Fools	O
 '	O
Day	O
jokes	O
;	O
on	O
1	O
April	O
2002	O
the	O
site	O
was	O
temporarily	O
named	O
to	O
CJAN	B-Language
,	O
where	O
the	O
"	O
J	O
"	O
stood	O
for	O
"	O
Java	B-Language
"	O
.	O
</s>
<s>
In	O
2003	O
,	O
the	O
www.cpan.org	O
domain	O
name	O
was	O
redirected	O
to	O
Matt	B-Language
's	I-Language
Script	I-Language
Archive	I-Language
,	O
a	O
site	O
infamous	O
in	O
the	O
Perl	B-Language
community	O
for	O
having	O
badly	O
written	O
code	O
.	O
</s>
<s>
Some	O
of	O
the	O
distributions	O
on	O
the	O
CPAN	B-Language
are	O
distributed	O
as	O
jokes	O
.	O
</s>
<s>
The	O
Acme::	O
hierarchy	O
is	O
reserved	O
for	O
joke	O
modules	B-Language
;	O
for	O
instance	O
,	O
Acme::Don	O
'	O
t	O
adds	O
a	O
do	O
n't	O
function	O
that	O
does	O
n't	O
run	O
the	O
code	O
given	O
to	O
it	O
(	O
to	O
complement	O
the	O
do	O
built-in	O
,	O
which	O
does	O
)	O
.	O
</s>
<s>
Even	O
outside	O
the	O
Acme::	O
hierarchy	O
,	O
some	O
modules	B-Language
are	O
still	O
written	O
largely	O
for	O
amusement	O
;	O
one	O
example	O
is	O
Lingua::Romana::Perligata	O
,	O
which	O
can	O
be	O
used	O
to	O
write	O
Perl	B-Language
programs	O
in	O
a	O
subset	O
of	O
Latin	O
.	O
</s>
<s>
In	O
2005	O
,	O
a	O
group	O
of	O
Perl	B-Language
developers	O
who	O
also	O
had	O
an	O
interest	O
in	O
JavaScript	O
got	O
together	O
to	O
create	O
JSAN	O
,	O
the	O
JavaScript	O
Archive	O
Network	O
.	O
</s>
<s>
The	O
JSAN	O
is	O
a	O
near-direct	O
port	O
of	O
the	O
CPAN	B-Language
infrastructure	O
for	O
use	O
with	O
the	O
JavaScript	O
language	O
,	O
which	O
for	O
most	O
of	O
its	O
lifespan	O
did	O
not	O
have	O
a	O
cohesive	O
"	O
community	O
"	O
.	O
</s>
<s>
In	O
2008	O
,	O
after	O
a	O
chance	O
meeting	O
with	O
CPAN	B-Language
admin	O
Adam	O
Kennedy	O
at	O
the	O
Open	O
Source	O
Developers	O
Conference	O
,	O
Linux	O
kernel	O
developer	O
Rusty	O
Russell	O
created	O
the	O
CCAN	O
,	O
the	O
Comprehensive	O
C	B-Language
Archive	O
Network	O
.	O
</s>
<s>
The	O
CCAN	O
is	O
a	O
direct	O
port	O
of	O
the	O
CPAN	B-Language
architecture	O
for	O
use	O
with	O
the	O
C	B-Language
language	I-Language
.	O
</s>
<s>
CRAN	O
,	O
the	O
Comprehensive	O
R	B-Language
Archive	O
Network	O
,	O
is	O
a	O
set	O
of	O
mirrors	O
hosting	O
the	O
R	B-Language
programming	I-Language
language	I-Language
distribution(s )	O
,	O
documentation	O
,	O
and	O
contributed	O
extensions	O
.	O
</s>
