<s>
is	O
a	O
special	B-Application
file	I-Application
in	O
Unix-like	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
that	O
provides	O
as	O
many	O
null	O
characters	O
(	O
ASCII	B-Protocol
NUL	B-Operating_System
,	O
0x00	O
)	O
as	O
are	O
read	O
from	O
it	O
.	O
</s>
<s>
When	O
is	O
memory-mapped	O
,	O
e.g.	O
,	O
with	O
mmap	B-Operating_System
,	O
to	O
the	O
virtual	O
address	O
space	O
,	O
it	O
is	O
equivalent	O
to	O
using	O
anonymous	O
memory	O
;	O
i.e.	O
</s>
<s>
HP-UX	O
8.x	O
introduced	O
the	O
MAP_ANONYMOUS	O
flag	O
for	O
mmap( )	O
,	O
which	O
maps	O
anonymous	O
memory	O
directly	O
without	O
a	O
need	O
to	O
open	O
.	O
</s>
<s>
The	O
dd	B-Application
Unix	I-Application
utility	O
program	O
reads	O
octet	O
streams	O
from	O
a	O
source	O
to	O
a	O
destination	O
,	O
possibly	O
performing	O
data	O
conversions	O
in	O
the	O
process	O
.	O
</s>
<s>
Destroying	O
existing	O
data	O
on	O
a	O
file	O
system	O
partition	O
(	O
low-level	B-Application
formatting	I-Application
)	O
:	O
</s>
<s>
Note	O
:	O
Instead	O
of	O
creating	O
a	O
real	O
file	O
with	O
only	O
zero	O
bytes	O
,	O
many	O
file	O
systems	O
also	O
support	O
the	O
creation	O
of	O
sparse	B-General_Concept
files	I-General_Concept
which	O
returns	O
zeros	O
upon	O
reading	O
but	O
use	O
less	O
actual	O
space	O
.	O
</s>
