<s>
(	O
R	O
)	O
?	O
ex	O
or	O
simply	O
Rex	B-Language
is	O
an	O
open	B-Application
source	I-Application
remote	O
execution	O
,	O
configuration	B-General_Concept
management	I-General_Concept
and	O
software	B-Application
deployment	I-Application
tool	O
.	O
</s>
<s>
It	O
combines	O
Perl	B-Language
and	O
Secure	B-Protocol
Shell	I-Protocol
(	O
SSH	B-Protocol
)	O
for	O
a	O
portable	O
,	O
centralistic	O
approach	O
to	O
its	O
problem	O
domain	O
.	O
</s>
<s>
Rex	B-Language
is	O
an	O
acronym	O
for	O
"	O
Remote	O
Execution	O
"	O
.	O
</s>
<s>
Rex	B-Language
originated	O
from	O
the	O
need	O
of	O
a	O
flexible	O
,	O
parallel	O
remote	O
execution	O
application	O
with	O
software	B-Application
deployment	I-Application
and	O
configuration	B-General_Concept
management	I-General_Concept
capabilities	O
.	O
</s>
<s>
Unsatisfied	O
with	O
available	O
implementations	O
in	O
2010	O
,	O
the	O
author	O
of	O
Rex	B-Language
,	O
Jan	O
Gehring	O
,	O
decided	O
to	O
implement	O
a	O
Perl-based	O
tool	O
to	O
cope	O
with	O
his	O
requirements	O
.	O
</s>
<s>
Rex	B-Language
is	O
a	O
stand-alone	O
application	O
executing	O
either	O
a	O
single	O
command	O
or	O
so-called	O
tasks	O
.	O
</s>
<s>
It	O
is	O
defined	O
via	O
a	O
small	O
DSL	B-Language
,	O
but	O
is	O
essentially	O
a	O
Perl	B-Language
script	O
.	O
</s>
<s>
Therefore	O
,	O
it	O
can	O
contain	O
arbitrary	O
Perl	B-Language
as	O
well	O
.	O
</s>
<s>
For	O
code	O
reuse	O
,	O
configuration	O
instructions	O
are	O
placed	O
in	O
modules	B-Application
which	O
can	O
be	O
included	O
by	O
a	O
Rexfile	O
.	O
</s>
<s>
For	O
Rex	B-Language
to	O
be	O
able	O
to	O
work	O
,	O
the	O
managed	O
targets	O
must	O
provide	O
a	O
running	O
SSH	B-Protocol
server	O
and	O
a	O
Perl	B-Language
5	O
interpreter	O
.	O
</s>
<s>
Rex	B-Language
serves	O
a	O
variety	O
of	O
applications	O
.	O
</s>
<s>
Examples	O
are	O
user	O
&	O
group	O
,	O
cron	B-General_Concept
,	O
filesystem	B-Application
,	O
kernel	B-Application
module	I-Application
,	O
process	O
and	O
virtual	B-Architecture
machine	I-Architecture
management	O
.	O
</s>
<s>
Rex	B-Language
is	O
discussed	O
on	O
conferences	O
and	O
in	O
related	O
press	O
releases	O
.	O
</s>
<s>
It	O
was	O
voted	O
under	O
the	O
Best	O
Open	B-Application
Source	I-Application
solutions	O
2013	O
by	O
.	O
</s>
