`od`

Dump a file in various formats (POSIX)

Syntax:

od [-v] [-A format] [-t fmtstr]  [-N count]
   [-j skip] [file]...

Options:

-A format

Display the file offset field in one of the following formats:

d -- decimal, 9 digits
n -- none (omit this field)
o -- octal, 10 digits
x -- hexadecimal, 7 digits.

The default is o.

-j skip

Ignore the first skip bytes of data. You can add a trailing character to specify units of blocks (b), kilobytes (k), or megabytes (m).

-N count

Display only count bytes of input. You can add a trailing character to specify units of blocks (b), kilobytes (k), or megabytes (m).

-t format

Display data field using this format specification; see "Output formats," below.

The default format is oS.

-v

Be verbose. If you don't specify the -v option, od folds multiple identical lines into a single line that contains an asterisk (*).

file

The pathname of an input file. If you don't specify any files, od reads from standard input.

Description:

Use the od utility to display a file in various forms, including decimal, hex, octal, and ASCII. The name "od" (octal dump) is derived from the default output format.

The od utility processes input in 16-byte units that are formatted into a line. In the default output format:

the file offset field is displayed in octal, 10 digits
a space separates the file offset field from the data
the data is displayed as four space-separated objects in octal

For example:

$ echo "abcdefghijklmnopqrstuvwxyz01234" | od
0000000000 14430661141 15031663145 15432665151 16033667155
0000000020 16434671161 17035673165 06114075171 01215031462
0000000040

To exclude part of the input, use the -N and -j options. You can specify the arguments to these options in hex (using a 0x prefix) or octal (using a 0 prefix). The default units for these options are bytes, but you can specify different units as follows:

To specify:	Add this suffix:
Blocks (512 bytes)	`b`
Kilobytes (1024 bytes)	`k`
Megabytes (1048576 bytes)	`m`

Output formats

To specify the output format, use the -t option. The format argument -- which you can specify in decimal, hex, or octal -- tells od which format to use for presenting the output:

a

Named characters. Display printable characters as themselves, and nonprintable characters as a single dot (.).

c

Characters. Display printable characters as themselves; display all other characters as 2-digit hex values, except for the following:

ASCII mnemonic	Value	Representation
`NUL`	00	\0
<alert>	07	\a
<backspace>	08	\b
<tab>	09	\t
<newline>	0a	\n
<vertical tab>	0b	\v
<formfeed>	0c	\f
<carriage return>	0d	\r

d[1|2|4|C|S|I|L]

Decimal, in objects the size of an int by default.

f[4|8|F|D|L]

Floating point, in objects the size of an float by default.

o[1|2|4|C|S|I|L]

Octal, in objects the size of an int by default.

u[1|2|4|C|S|I|L]

Unsigned decimal, in objects the size of an int by default.

x[1|2|4|C|S|I|L]

Hexadecimal, in objects the size of an int by default.

The input, processed in 16-byte units formatted into a line, is displayed according to the size you choose:

To display input as:	Choose:
Sixteen 1-byte objects	`1`
Eight 2-byte objects	`2`
Four 4-byte values per line	`4`
Two 8-byte values per line	`8`
`char`	`C`
`double`	`D`
`float`	`F`
`int`	`I`
`long` or `long double` (depending on the format)	`L`
`short`	`S`

Examples:

Display the second to eleventh sectors of the hard disk, /dev/hd0:

od -j 1b -N 10b /dev/hd0

Exit status:

0: All input files were processed successfully.
>0: An error occurred.