<s>
In	O
software	B-General_Concept
engineering	I-General_Concept
and	O
computer	B-General_Concept
science	I-General_Concept
,	O
clobbering	B-General_Concept
a	O
file	B-Operating_System
,	O
processor	B-General_Concept
register	I-General_Concept
or	O
a	O
region	O
of	O
computer	B-General_Concept
memory	I-General_Concept
is	O
the	O
process	O
of	O
overwriting	O
its	O
contents	O
completely	O
,	O
whether	O
intentionally	O
or	O
unintentionally	O
,	O
or	O
to	O
indicate	O
that	O
such	O
an	O
action	O
will	O
likely	O
occur	O
.	O
</s>
<s>
Memory	O
or	O
file	B-Operating_System
overwrites	O
in	O
POSIX	O
systems	O
,	O
as	O
well	O
as	O
in	O
shells	O
such	O
as	O
Bash	B-Operating_System
,	O
often	O
happen	O
unintentionally	O
-	O
such	O
as	O
using	O
the	O
>	O
redirection	B-Device
operator	I-Device
.	O
</s>
<s>
Therefore	O
,	O
to	O
prevent	O
unintentional	O
clobbering	B-General_Concept
,	O
various	O
means	O
can	O
be	O
used	O
-	O
for	O
example	O
,	O
setting	O
the	O
shell	O
parameter	O
set	O
-o	O
noclobber	B-General_Concept
(	O
bash	B-Operating_System
,	O
ksh	B-Language
)	O
or	O
set	O
noclobber	B-General_Concept
(	O
csh	B-Operating_System
,	O
tcsh	B-Language
)	O
will	O
prevent	O
>	O
from	O
clobbering	B-General_Concept
by	O
making	O
it	O
issue	O
an	O
error	B-Error_Name
message	I-Error_Name
instead	O
:	O
</s>
<s>
The	O
default	O
behavior	O
of	O
the	O
mv	O
and	O
cp	B-Application
commands	O
is	O
to	O
clobber	B-General_Concept
their	O
destination	O
file	B-Operating_System
if	O
it	O
already	O
exists	O
.	O
</s>
<s>
This	O
behavior	O
may	O
be	O
overridden	O
by	O
invoking	O
or	O
aliasing	B-Device
the	O
commands	O
with	O
the	O
-i	O
switch	O
,	O
causing	O
the	O
commands	O
to	O
prompt	O
the	O
user	O
before	O
overwriting	O
the	O
destination	O
file	B-Operating_System
,	O
or	O
-n	O
to	O
not	O
transfer	O
source	O
files	O
with	O
a	O
naming	O
conflict	O
.	O
</s>
<s>
In	O
makefiles	O
,	O
a	O
common	O
target	O
clobber	B-General_Concept
means	O
complete	O
cleanup	O
of	O
all	O
unnecessary	O
files	O
and	O
directories	O
produced	O
by	O
previous	O
invocations	O
of	O
the	O
make	B-Application
command	B-Application
.	O
</s>
<s>
It	O
is	O
a	O
more	O
severe	O
target	O
than	O
clean	O
and	O
is	O
commonly	O
used	O
to	O
uninstall	B-Application
software	O
.	O
</s>
<s>
Some	O
make-related	O
commands	O
invoke	O
"	O
make	B-Application
clobber	B-General_Concept
"	O
during	O
their	O
execution	O
.	O
</s>
<s>
They	O
check	O
the	O
CLOBBER	B-General_Concept
environment	O
variable	O
.	O
</s>
<s>
If	O
it	O
is	O
set	O
to	O
OFF	O
then	O
clobbering	B-General_Concept
is	O
not	O
done	O
.	O
</s>
<s>
In	O
assembler	B-Language
programming	I-Language
-	O
including	O
as	O
supported	O
in	O
C	B-Language
and	O
C++	B-Language
through	O
GCC	B-Application
-	O
the	O
term	O
clobbered	B-General_Concept
registers	I-General_Concept
is	O
often	O
used	O
to	O
denote	O
any	O
registers	O
whose	O
value	O
may	O
be	O
overwritten	O
during	O
the	O
course	O
of	O
executing	O
an	O
instruction	O
or	O
instructions	O
.	O
</s>
