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Display files in decimal, hex, octal, or ASCII (UNIX)
hd [-8] [-A format] [-n count] [-s skip]
[-t format[fmt_string]] [-v] [file...]
QNX Neutrino, Microsoft Windows
- -8
- Use 8-bit ASCII characters (default 7).
- -A format
- Display the file offset field in the specified format. Valid formats are:
- d — decimal, 9 digits
- n — none (omit this field)
- o — octal, 10 digits
- x — hexadecimal, 7 digits.
- -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).
- -s 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).
- -t format[fmt_string]
- Use this output/display format; see
“Output formats,”
below.
The default format is x1.
- -v
- Be verbose.
If you don't specify the -v option, hd 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, hd reads from standard input.
If a file is a hyphen
(-), hd reads from the standard input at
that point in the sequence.
The hd utility displays data in decimal, hex,
octal, or ASCII. The name “hd” (hex dump) is
derived from the default output format.
The hd 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 hex, 7 digits
- a space separates the file offset field from the data
- the data is displayed as 16 space-separated bytes in hex
- the same data is also displayed in ASCII, if printable;
unprintable data appears as dots.
For example:
$ echo "abcdefghijklmnopqrstuvwxyz01234" | hd
0000000: 61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f 70 abcdefghijklmnop
0000010: 71 72 73 74 75 76 77 78 79 7a 30 31 32 33 34 0a qrstuvwxyz01234.
To exclude part of the input, use the -n and
-s 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 |
To specify the output format, use the -t option. The
format argument — which you can specify in decimal, hex,
or octal — tells hd 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 |
Display the second to eleventh sectors of the hard disk,
/dev/hd0:
hd -s 1b -n 10b /dev/hd0
- 0
- All input files were processed successfully.
- >0
- An error occurred.
od
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