<s>
A	O
software	B-Application
repository	I-Application
,	O
or	O
repo	O
for	O
short	O
,	O
is	O
a	O
storage	O
location	O
for	O
software	B-Application
packages	I-Application
.	O
</s>
<s>
A	O
software	B-Application
repository	I-Application
is	O
typically	O
managed	O
by	O
source	O
or	O
version	B-Architecture
control	I-Architecture
,	O
or	O
repository	O
managers	O
.	O
</s>
<s>
Package	B-Application
managers	I-Application
allow	O
automatically	O
installing	O
and	O
updating	O
repositories	O
,	O
sometimes	O
called	O
"	O
packages	O
"	O
.	O
</s>
<s>
Repositories	O
may	O
be	O
solely	O
for	O
particular	O
programs	O
,	O
such	O
as	O
CPAN	B-Language
for	O
the	O
Perl	B-Language
programming	I-Language
language	I-Language
,	O
or	O
for	O
an	O
entire	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
Operators	O
of	O
such	O
repositories	O
typically	O
provide	O
a	O
package	B-Application
management	I-Application
system	I-Application
,	O
tools	O
intended	O
to	O
search	O
for	O
,	O
install	O
and	O
otherwise	O
manipulate	O
software	B-Application
packages	I-Application
from	O
the	O
repositories	O
.	O
</s>
<s>
For	O
example	O
,	O
many	O
Linux	B-Application
distributions	I-Application
use	O
Advanced	B-Application
Packaging	I-Application
Tool	I-Application
(	O
APT	B-Application
)	O
,	O
commonly	O
found	O
in	O
Debian	O
based	O
distributions	O
,	O
or	O
Yellowdog	B-Application
Updater	I-Application
,	I-Application
Modified	I-Application
(	O
yum	B-Application
)	O
found	O
in	O
Red	O
Hat	O
based	O
distributions	O
.	O
</s>
<s>
There	O
are	O
also	O
multiple	O
independent	O
package	B-Application
management	I-Application
systems	I-Application
,	O
such	O
as	O
pacman	O
,	O
used	O
in	O
Arch	O
Linux	O
and	O
equo	O
,	O
found	O
in	O
Sabayon	O
Linux	O
.	O
</s>
<s>
As	O
software	B-Application
repositories	I-Application
are	O
designed	O
to	O
include	O
useful	O
packages	O
,	O
major	O
repositories	O
are	O
designed	O
to	O
be	O
malware	O
free	O
.	O
</s>
<s>
As	O
a	O
side	O
effect	O
,	O
many	O
systems	O
that	O
have	O
these	O
abilities	O
do	O
not	O
need	O
anti-malware	B-Application
software	O
such	O
as	O
antivirus	B-Application
software	I-Application
.	O
</s>
<s>
Most	O
major	O
Linux	B-Application
distributions	I-Application
have	O
many	O
repositories	O
around	O
the	O
world	O
that	O
mirror	O
the	O
main	O
repository	O
.	O
</s>
<s>
In	O
an	O
enterprise	O
environment	O
,	O
a	O
software	B-Application
repository	I-Application
is	O
usually	O
used	O
to	O
store	O
artifacts	O
,	O
or	O
to	O
mirror	O
external	O
repositories	O
which	O
may	O
be	O
inaccessible	O
due	O
to	O
security	O
restrictions	O
.	O
</s>
<s>
At	O
client	O
side	O
,	O
a	O
package	B-Application
manager	I-Application
helps	O
installing	O
from	O
and	O
updating	O
the	O
repositories	O
.	O
</s>
<s>
At	O
server	O
side	O
,	O
a	O
software	B-Application
repository	I-Application
is	O
typically	O
managed	O
by	O
source	B-Architecture
control	I-Architecture
or	O
repository	O
managers	O
.	O
</s>
<s>
A	O
package	B-Application
management	I-Application
system	I-Application
is	O
different	O
from	O
a	O
package	B-Application
development	I-Application
process	I-Application
.	O
</s>
<s>
A	O
typical	O
use	O
of	O
a	O
package	B-Application
management	I-Application
system	I-Application
is	O
to	O
facilitate	O
the	O
integration	O
of	O
code	O
from	O
possibly	O
different	O
sources	O
into	O
a	O
coherent	O
stand-alone	O
operating	O
unit	O
.	O
</s>
<s>
Thus	O
,	O
a	O
package	B-Application
management	I-Application
system	I-Application
might	O
be	O
used	O
to	O
produce	O
a	O
distribution	B-Application
of	I-Application
Linux	I-Application
,	O
possibly	O
a	O
distribution	O
tailored	O
to	O
a	O
specific	O
restricted	O
application	O
.	O
</s>
<s>
A	O
package	B-Application
development	I-Application
process	I-Application
,	O
by	O
contrast	O
,	O
is	O
used	O
to	O
manage	O
the	O
co-development	O
of	O
code	O
and	O
documentation	O
of	O
a	O
collection	O
of	O
functions	O
or	O
routines	O
with	O
a	O
common	O
theme	O
,	O
producing	O
thereby	O
a	O
package	O
of	O
software	O
functions	O
that	O
typically	O
will	O
not	O
be	O
complete	O
and	O
usable	O
by	O
themselves	O
.	O
</s>
<s>
A	O
good	O
package	B-Application
development	I-Application
process	I-Application
will	O
help	O
users	O
conform	O
to	O
good	O
documentation	O
and	O
coding	O
practices	O
,	O
integrating	O
some	O
level	O
of	O
unit	O
testing	O
.	O
</s>
<s>
Very	O
few	O
people	O
have	O
the	O
ability	O
to	O
test	O
their	O
software	O
under	O
multiple	O
operating	B-General_Concept
systems	I-General_Concept
with	O
different	O
versions	O
of	O
the	O
core	O
code	O
and	O
with	O
other	O
contributed	O
packages	O
they	O
may	O
use	O
.	O
</s>
<s>
For	O
the	O
R	B-Language
programming	I-Language
language	I-Language
,	O
the	O
Comprehensive	O
R	B-Language
Archive	O
Network	O
(	O
CRAN	O
)	O
runs	O
tests	O
routinely	O
.	O
</s>
<s>
At	O
more	O
or	O
less	O
regular	O
intervals	O
,	O
CRAN	O
tests	O
Sally	O
's	O
contribution	O
under	O
a	O
dozen	O
combinations	O
of	O
operating	B-General_Concept
systems	I-General_Concept
and	O
versions	O
of	O
the	O
core	O
R	B-Language
language	I-Language
software	O
.	O
</s>
<s>
This	O
example	O
exposes	O
both	O
a	O
strength	O
and	O
a	O
weakness	O
in	O
the	O
R	B-Language
contributed-package	O
system	O
:	O
CRAN	O
supports	O
this	O
kind	O
of	O
automated	B-Application
testing	I-Application
of	O
contributed	O
packages	O
,	O
but	O
packages	O
contributed	O
to	O
CRAN	O
need	O
not	O
specify	O
the	O
versions	O
of	O
other	O
contributed	O
packages	O
that	O
they	O
use	O
.	O
</s>
<s>
If	O
Sally	O
(	O
in	O
the	O
example	O
above	O
)	O
gets	O
an	O
error	O
message	O
she	O
does	O
not	O
understand	O
or	O
thinks	O
is	O
inappropriate	O
,	O
especially	O
from	O
a	O
development	O
version	O
of	O
the	O
language	O
,	O
she	O
can	O
(	O
and	O
often	O
does	O
with	O
R	B-Language
)	O
ask	O
the	O
core	O
development-team	O
for	O
the	O
language	O
for	O
help	O
.	O
</s>
<s>
pear	B-Application
install	O
<package>	O
Python	B-Language
Setuptools	B-Application
PyPI	B-Language
pip	B-Application
,	O
EasyInstall	O
,	O
PyPM	B-Language
,	O
Anaconda	B-Application
R	B-Language
R	B-Language
CMD	O
check	O
process	O
CRAN	O
install.packagesremotesGitHub	O
Often	O
on	O
12	O
platforms	O
or	O
combinations	O
of	O
different	O
versions	O
of	O
R	B-Language
(	O
devel	O
,	O
prerel	O
,	O
patched	O
,	O
release	O
)	O
on	O
different	O
operating	B-General_Concept
systems	I-General_Concept
(	O
different	O
versions	O
of	O
Linux	O
,	O
Windows	O
,	O
macOS	O
,	O
and	O
Solaris	O
)	O
.	O
</s>
<s>
Many	O
other	O
programming	O
languages	O
,	O
among	O
them	O
C	B-Language
,	O
C++	B-Language
,	O
and	O
Fortran	B-Application
,	O
do	O
not	O
possess	O
a	O
central	O
software	B-Application
repository	I-Application
with	O
universal	O
scope	O
.	O
</s>
<s>
Netlib	B-Application
,	O
mainly	O
mathematical	O
routines	O
for	O
Fortran	B-Application
and	O
C	B-Language
,	O
historically	O
one	O
of	O
the	O
first	O
open	O
software	B-Application
repositories	I-Application
;	O
</s>
<s>
Boost	B-Language
,	O
a	O
strictly	O
curated	O
collection	O
of	O
high-quality	O
libraries	O
for	O
C++	B-Language
;	O
some	O
code	O
developed	O
in	O
Boost	B-Language
later	O
became	O
part	O
of	O
the	O
C++	B-Language
standard	O
library	O
.	O
</s>
<s>
Package	B-Application
managers	I-Application
help	O
manage	O
repositories	O
and	O
the	O
distribution	O
of	O
them	O
.	O
</s>
<s>
If	O
a	O
repository	O
is	O
updated	O
,	O
a	O
package	B-Application
manager	I-Application
will	O
typically	O
allow	O
the	O
user	O
to	O
update	O
that	O
repository	O
through	O
the	O
package	B-Application
manager	I-Application
.	O
</s>
<s>
They	O
also	O
help	O
with	O
managing	O
things	O
such	O
as	O
dependencies	O
between	O
other	O
software	B-Application
repositories	I-Application
.	O
</s>
<s>
Some	O
examples	O
of	O
Package	B-Application
Managers	I-Application
include	O
:	O
</s>
<s>
This	O
may	O
interact	O
with	O
a	O
binary	B-Application
repository	I-Application
manager	I-Application
much	O
like	O
a	O
developer	O
would	O
by	O
getting	O
artifacts	O
from	O
the	O
repositories	O
and	O
pushing	O
builds	O
there	O
.	O
</s>
<s>
JAR	O
,	O
WAR	O
,	O
DLLS	O
,	O
RPM	B-Application
etc	O
.	O
)	O
</s>
<s>
NuGet	B-Application
)	O
that	O
contain	O
files	O
appropriate	O
for	O
the	O
package	O
type	O
(	O
ex	O
.	O
</s>
