<s>
A	O
zero-byte	B-Application
file	I-Application
or	O
zero-length	B-Application
file	I-Application
is	O
a	O
computer	B-Operating_System
file	I-Operating_System
containing	O
no	O
data	O
;	O
that	O
is	O
,	O
it	O
has	O
a	O
length	O
or	O
size	O
of	O
zero	O
bytes	O
.	O
</s>
<s>
There	O
are	O
many	O
ways	O
that	O
could	O
manually	O
create	O
a	O
zero-byte	B-Application
file	I-Application
,	O
for	O
example	O
,	O
saving	O
empty	O
content	O
in	O
a	O
text	B-Application
editor	I-Application
,	O
using	O
utilities	O
provided	O
by	O
operating	B-General_Concept
systems	I-General_Concept
,	O
or	O
programming	O
to	O
create	O
it	O
.	O
</s>
<s>
On	O
Unix-like	B-Operating_System
systems	I-Operating_System
,	O
the	O
shell	O
command	O
$	O
touch	B-Application
filename	B-Device
results	O
in	O
a	O
zero-byte	B-Application
file	I-Application
.	O
</s>
<s>
Zero-byte	B-Application
files	I-Application
may	O
arise	O
in	O
cases	O
where	O
a	O
program	O
creates	O
a	O
file	O
but	O
aborts	O
or	O
is	O
interrupted	O
prematurely	O
while	O
writing	O
to	O
it	O
.	O
</s>
<s>
Because	O
writes	O
are	O
cached	B-General_Concept
in	O
memory	B-Architecture
and	O
only	O
flushed	O
to	O
disk	O
at	O
a	O
later	O
time	O
(	O
page	B-General_Concept
cache	I-General_Concept
)	O
,	O
a	O
program	O
that	O
does	O
not	O
flush	O
its	O
writes	O
to	O
disk	O
or	O
terminate	O
normally	O
may	O
result	O
in	O
a	O
zero-byte	B-Application
file	I-Application
.	O
</s>
<s>
When	O
the	O
zero-byte	B-Application
file	I-Application
is	O
made	O
,	O
file	B-Application
system	I-Application
does	O
not	O
record	O
the	O
file	O
's	O
content	O
on	O
storage	O
,	O
but	O
only	O
updates	O
its	O
index	O
table	O
.	O
</s>
<s>
Even	O
a	O
file	O
describing	O
an	O
empty	O
word	B-General_Concept
processor	I-General_Concept
document	O
,	O
an	O
image	O
file	O
with	O
zero-by-zero	O
dimensions	O
,	O
or	O
an	O
audio	O
file	O
of	O
length	O
zero	O
seconds	O
usually	O
still	O
contains	O
metadata	O
identifying	O
the	O
file	O
format	O
and	O
describing	O
some	O
basic	O
attributes	O
of	O
the	O
file	O
;	O
it	O
results	O
in	O
the	O
file	O
with	O
some	O
positive	O
size	O
.	O
</s>
<s>
Some	O
very	O
simple	O
formats	O
do	O
not	O
use	O
metadata	O
,	O
such	O
as	O
ASCII	B-Protocol
text	I-Protocol
files	I-Protocol
;	O
these	O
may	O
validly	O
be	O
zero	O
bytes	O
(	O
a	O
common	O
convention	O
terminates	O
text	B-General_Concept
files	I-General_Concept
with	O
a	O
one	O
-	O
or	O
two-byte	O
newline	O
,	O
however	O
)	O
.	O
</s>
<s>
Conversely	O
,	O
zero-byte	B-Application
files	I-Application
must	O
use	O
some	O
disk	O
space	O
to	O
be	O
indexed	O
by	O
a	O
filesystem	B-Application
,	O
though	O
none	O
for	O
content	O
.	O
</s>
<s>
Zero-byte	B-Application
files	I-Application
cannot	O
be	O
loaded	O
or	O
used	O
by	O
most	O
applications	O
.	O
</s>
<s>
In	O
some	O
cases	O
,	O
zero-byte	B-Application
files	I-Application
may	O
be	O
used	O
to	O
convey	O
information	O
like	O
file	O
metadata	O
(	O
for	O
example	O
,	O
its	O
filename	B-Device
may	O
contain	O
an	O
instruction	O
to	O
a	O
user	O
viewing	O
a	O
directory	O
listing	O
such	O
as	O
,	O
etc	O
.	O
</s>
<s>
)	O
;	O
or	O
to	O
put	O
in	O
a	O
directory	O
to	O
ensure	O
that	O
it	O
is	O
nonempty	O
,	O
since	O
some	O
tools	O
such	O
as	O
backup	O
and	O
revision	B-Architecture
control	I-Architecture
software	I-Architecture
may	O
ignore	O
the	O
empty	O
directories	O
.	O
</s>
