<s>
Red	B-Operating_System
Hat	I-Operating_System
Enterprise	I-Operating_System
Linux	I-Operating_System
derivatives	I-Operating_System
are	O
Linux	B-Application
distributions	I-Application
that	O
are	O
based	O
on	O
the	O
source	O
code	O
of	O
Red	O
Hat	O
Enterprise	O
Linux	O
(	O
RHEL	O
)	O
.	O
</s>
<s>
Red	O
Hat	O
Linux	O
was	O
one	O
of	O
the	O
first	O
and	O
most	O
popular	O
Linux	B-Application
distributions	I-Application
.	O
</s>
<s>
Red	O
Hat	O
does	O
not	O
make	O
a	O
compiled	B-Language
version	O
of	O
its	O
Enterprise	O
Linux	O
product	O
available	O
for	O
free	O
download	O
.	O
</s>
<s>
However	O
,	O
as	O
the	O
license	O
terms	O
on	O
which	O
it	O
is	O
mostly	O
based	O
explicitly	O
stipulate	O
,	O
Red	O
Hat	O
has	O
made	O
the	O
entire	O
source	O
code	O
available	O
in	O
RPM	B-Application
format	O
via	O
their	O
network	O
of	O
servers	O
.	O
</s>
<s>
The	O
availability	O
of	O
the	O
complete	O
source	O
code	O
of	O
the	O
distribution	O
in	O
RPM	B-Application
format	O
makes	O
it	O
relatively	O
easy	O
to	O
recompile	B-Language
the	O
entire	O
distribution	O
.	O
</s>
<s>
Several	O
distributions	B-Application
were	O
created	O
that	O
took	O
Red	O
Hat	O
's	O
source	O
code	O
,	O
recompiled	B-Language
it	O
,	O
and	O
released	O
it	O
.	O
</s>
<s>
The	O
Red	B-Operating_System
Hat	I-Operating_System
Enterprise	I-Operating_System
Linux	I-Operating_System
derivatives	I-Operating_System
generally	O
include	O
the	O
union	O
set	O
,	O
which	O
is	O
included	O
in	O
the	O
different	O
versions	O
of	O
RHEL	O
.	O
</s>
<s>
The	O
version	O
numbers	O
are	O
typically	O
identical	O
to	O
the	O
ones	O
featured	O
in	O
RHEL	O
;	O
as	O
such	O
,	O
the	O
free	O
versions	O
maintain	O
binary	B-General_Concept
compatibility	I-General_Concept
with	O
the	O
paid-for	O
version	O
,	O
which	O
means	O
software	O
intended	O
for	O
RHEL	O
typically	O
runs	O
just	O
as	O
well	O
on	O
a	O
free	O
version	O
.	O
</s>
<s>
Relatively	O
few	O
changes	O
need	O
to	O
be	O
made	O
to	O
the	O
distributions	B-Application
.	O
</s>
<s>
However	O
,	O
RHEL	O
used	O
to	O
use	O
Red	O
Hat	O
's	O
own	O
Up2date	B-Application
technology	O
for	O
providing	O
updates	O
.	O
</s>
<s>
For	O
convenience	O
,	O
several	O
of	O
the	O
free	O
alternatives	O
ship	O
with	O
yum	B-Application
replacing	O
up2date	B-Application
,	O
something	O
that	O
makes	O
providing	O
mirrors	O
for	O
upgrades	O
significantly	O
easier	O
.	O
</s>
<s>
Red	O
Hat	O
Enterprise	O
Linux	O
5	O
and	O
above	O
releases	O
use	O
yum	B-Application
as	O
their	O
native	O
system	O
for	O
providing	O
updates	O
,	O
with	O
up2date	B-Application
being	O
just	O
its	O
front	O
end	O
.	O
</s>
<s>
Free	O
redistributions	O
are	O
expressly	O
permitted	O
by	O
the	O
GNU	B-License
General	I-License
Public	I-License
License	I-License
upon	O
which	O
Red	O
Hat	O
's	O
distributions	B-Application
are	O
based	O
.	O
</s>
<s>
Where	O
distributions	B-Application
(	O
e.g.	O
,	O
CentOS	O
)	O
have	O
not	O
been	O
deemed	O
sufficiently	O
thorough	O
in	O
removing	O
references	O
to	O
Red	O
Hat	O
,	O
they	O
have	O
received	O
warnings	O
from	O
Red	O
Hat	O
's	O
legal	O
counsel	O
.	O
</s>
<s>
ClefOS	O
–	O
a	O
port	O
of	O
CentOS	O
for	O
IBM	B-Device
Z	I-Device
by	O
Sine	O
Nomine	O
Associates	O
.	O
</s>
<s>
EulerOS	O
–	O
certified	O
to	O
The	B-Application
Open	I-Application
Group	I-Application
's	O
UNIX	O
03	O
standard	O
.	O
</s>
<s>
Previous	O
versions	O
were	O
built	O
on	O
top	O
of	O
Scientific	B-Application
Linux	I-Application
.	O
</s>
<s>
Inspur	O
K-UX	O
–	O
certified	O
to	O
The	B-Application
Open	I-Application
Group	I-Application
's	O
UNIX	O
03	O
standard	O
.	O
</s>
<s>
MIRACLE	O
LINUX	O
–	O
an	O
enterprise	O
Linux	B-Application
distribution	I-Application
developed	O
by	O
Cybertrust	O
Japan	O
.	O
</s>
<s>
Oracle	O
Linux	O
–	O
free	O
to	O
download	O
,	O
distribute	O
and	O
use	O
with	O
public	O
access	O
to	O
the	O
latest	O
errata	O
and	O
patches	O
from	O
the	O
Oracle	O
Linux	O
yum	B-Application
server	O
.	O
</s>
<s>
Springdale	O
Linux	O
–	O
formerly	O
PUIAS	O
Linux	O
is	O
a	O
complete	O
operating	O
system	O
for	O
desktops	O
and	O
servers	O
,	O
built	O
by	O
compiling	B-Language
the	O
source	O
packages	O
for	O
Red	O
Hat	O
Enterprise	O
Linux	O
.	O
</s>
<s>
Distributions	B-Application
which	O
have	O
ceased	O
production	O
or	O
outdated	O
:	O
</s>
