<s>
od	B-Device
is	O
a	O
command	B-Application
on	O
various	O
operating	B-General_Concept
systems	I-General_Concept
for	O
displaying	O
(	O
"	O
dumping	O
"	O
)	O
data	O
in	O
various	O
human-readable	B-General_Concept
output	O
formats	O
.	O
</s>
<s>
The	O
od	B-Device
program	O
can	O
display	O
output	O
in	O
a	O
variety	O
of	O
formats	O
,	O
including	O
octal	O
,	O
hexadecimal	O
,	O
decimal	B-Application
,	O
and	O
ASCII	B-Protocol
.	O
</s>
<s>
It	O
is	O
useful	O
for	O
visualizing	O
data	O
that	O
is	O
not	O
in	O
a	O
human-readable	B-General_Concept
format	I-General_Concept
,	O
like	O
the	O
executable	B-Application
code	I-Application
of	O
a	O
program	O
,	O
or	O
where	O
the	O
primary	O
form	O
is	O
ambiguous	O
(	O
e.g.	O
</s>
<s>
od	B-Device
is	O
one	O
of	O
the	O
earliest	O
Unix	B-Application
programs	O
,	O
having	O
appeared	O
in	O
version	O
1	O
AT&T	B-Operating_System
Unix	I-Operating_System
.	O
</s>
<s>
The	O
implementation	O
for	O
od	B-Device
used	O
on	O
Linux	B-Application
systems	O
is	O
usually	O
provided	O
by	O
GNU	B-Application
Core	I-Application
Utilities	I-Application
.	O
</s>
<s>
Since	O
it	O
predates	O
the	B-Device
Bourne	I-Device
shell	I-Device
,	O
its	O
existence	O
causes	O
an	O
inconsistency	O
in	O
the	O
do	O
loop	O
syntax	O
.	O
</s>
<s>
if	O
...	O
fi	O
and	O
case	O
...	O
esac	O
,	O
but	O
od	B-Device
's	O
existence	O
necessitates	O
do	O
...	O
done	O
.	O
</s>
<s>
The	O
command	B-Application
is	O
available	O
as	O
a	O
separate	O
package	O
for	O
Microsoft	B-Application
Windows	I-Application
as	O
part	O
of	O
the	O
UnxUtils	B-Application
collection	O
of	O
native	B-Language
Win32	B-Library
ports	O
of	O
common	O
GNU	O
Unix-like	B-Operating_System
utilities	O
.	O
</s>
<s>
The	O
command	B-Application
has	O
also	O
been	O
ported	O
to	O
the	O
IBM	B-Application
i	I-Application
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
Normally	O
a	O
dump	O
of	O
an	O
executable	B-Application
file	I-Application
is	O
very	O
long	O
.	O
</s>
<s>
The	O
head	B-Device
program	O
prints	O
out	O
the	O
first	O
few	O
lines	O
of	O
the	O
output	O
.	O
</s>
<s>
Here	O
is	O
an	O
example	O
of	O
a	O
dump	O
of	O
the	O
"	O
Hello	O
world	O
"	O
program	O
,	O
piped	O
through	O
head	B-Device
.	O
</s>
<s>
Here	O
is	O
an	O
example	O
of	O
od	B-Device
used	O
to	O
diagnose	O
the	O
output	O
of	O
echo	B-Application
where	O
the	O
user	O
types	O
and	O
after	O
writing	O
"	O
Hello	O
"	O
to	O
literal	O
insert	O
a	O
tab	O
and	O
^C	B-Device
character	O
:	O
</s>
