1HEXDUMP(1)                       User Commands                      HEXDUMP(1)
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NAME

6       hexdump - display file contents in hexadecimal, decimal, octal, or
7       ascii
8
9       hexdump options file ...
10
11       hd options file ...
12

DESCRIPTION

14       The hexdump utility is a filter which displays the specified files, or
15       standard input if no files are specified, in a user-specified format.
16

OPTIONS

18       Below, the length and offset arguments may be followed by the
19       multiplicative suffixes KiB (=1024), MiB (=1024*1024), and so on for
20       GiB, TiB, PiB, EiB, ZiB and YiB (the "iB" is optional, e.g., "K" has
21       the same meaning as "KiB"), or the suffixes KB (=1000), MB
22       (=1000*1000), and so on for GB, TB, PB, EB, ZB and YB.
23
24       -b, --one-byte-octal
25           One-byte octal display. Display the input offset in hexadecimal,
26           followed by sixteen space-separated, three-column, zero-filled
27           bytes of input data, in octal, per line.
28
29       -c, --one-byte-char
30           One-byte character display. Display the input offset in
31           hexadecimal, followed by sixteen space-separated, three-column,
32           space-filled characters of input data per line.
33
34       -C, --canonical
35           Canonical hex+ASCII display. Display the input offset in
36           hexadecimal, followed by sixteen space-separated, two-column,
37           hexadecimal bytes, followed by the same sixteen bytes in %_p format
38           enclosed in | characters. Invoking the program as hd implies this
39           option.
40
41       -d, --two-bytes-decimal
42           Two-byte decimal display. Display the input offset in hexadecimal,
43           followed by eight space-separated, five-column, zero-filled,
44           two-byte units of input data, in unsigned decimal, per line.
45
46       -e, --format format_string
47           Specify a format string to be used for displaying data.
48
49       -f, --format-file file
50           Specify a file that contains one or more newline-separated format
51           strings. Empty lines and lines whose first non-blank character is a
52           hash mark (#) are ignored.
53
54       -L, --color[=when]
55           Accept color units for the output. The optional argument when can
56           be auto, never or always. If the when argument is omitted, it
57           defaults to auto. The colors can be disabled; for the current
58           built-in default see the --help output. See also the Colors
59           subsection and the COLORS section below.
60
61       -n, --length length
62           Interpret only length bytes of input.
63
64       -o, --two-bytes-octal
65           Two-byte octal display. Display the input offset in hexadecimal,
66           followed by eight space-separated, six-column, zero-filled,
67           two-byte quantities of input data, in octal, per line.
68
69       -s, --skip offset
70           Skip offset bytes from the beginning of the input.
71
72       -v, --no-squeezing
73           The -v option causes hexdump to display all input data. Without the
74           -v option, any number of groups of output lines which would be
75           identical to the immediately preceding group of output lines
76           (except for the input offsets), are replaced with a line comprised
77           of a single asterisk.
78
79       -x, --two-bytes-hex
80           Two-byte hexadecimal display. Display the input offset in
81           hexadecimal, followed by eight space-separated, four-column,
82           zero-filled, two-byte quantities of input data, in hexadecimal, per
83           line.
84
85       -h, --help
86           Display help text and exit.
87
88       -V, --version
89           Print version and exit.
90
91       For each input file, hexdump sequentially copies the input to standard
92       output, transforming the data according to the format strings specified
93       by the -e and -f options, in the order that they were specified.
94

FORMATS

96       A format string contains any number of format units, separated by
97       whitespace. A format unit contains up to three items: an iteration
98       count, a byte count, and a format.
99
100       The iteration count is an optional positive integer, which defaults to
101       one. Each format is applied iteration count times.
102
103       The byte count is an optional positive integer. If specified it defines
104       the number of bytes to be interpreted by each iteration of the format.
105
106       If an iteration count and/or a byte count is specified, a single slash
107       must be placed after the iteration count and/or before the byte count
108       to disambiguate them. Any whitespace before or after the slash is
109       ignored.
110
111       The format is required and must be surrounded by double quote (" ")
112       marks. It is interpreted as a fprintf-style format string (see
113       fprintf(3)), with the following exceptions:
114
115       1.
116           An asterisk (*) may not be used as a field width or precision.
117
118       2.
119           A byte count or field precision is required for each s conversion
120           character (unlike the fprintf(3) default which prints the entire
121           string if the precision is unspecified).
122
123       3.
124           The conversion characters h, l, n, p, and q are not supported.
125
126       4.
127           The single character escape sequences described in the C standard
128           are supported:
129
130          ┌──────────────────┬────┐
131          │                  │    │
132          │NULL              │ \0 │
133          ├──────────────────┼────┤
134          │                  │    │
135          │<alert character> │ \a │
136          ├──────────────────┼────┤
137          │                  │    │
138          │<backspace>       │ \b │
139          ├──────────────────┼────┤
140          │                  │    │
141          │<form-feed>       │ \f │
142          ├──────────────────┼────┤
143          │                  │    │
144          │<newline>         │ \n │
145          ├──────────────────┼────┤
146          │                  │    │
147          │<carriage return> │ \r │
148          ├──────────────────┼────┤
149          │                  │    │
150          │<tab>             │ \t │
151          ├──────────────────┼────┤
152          │                  │    │
153          │<vertical tab>    │ \v │
154          └──────────────────┴────┘
155
156   Conversion strings
157       The hexdump utility also supports the following additional
158       conversion strings.
159
160       _a[dox]
161           Display the input offset, cumulative across input files, of
162           the next byte to be displayed. The appended characters d, o,
163           and x specify the display base as decimal, octal or
164           hexadecimal respectively.
165
166       _A[dox]
167           Almost identical to the _a conversion string except that it
168           is only performed once, when all of the input data has been
169           processed.
170
171       _c
172           Output characters in the default character set. Non-printing
173           characters are displayed in three-character, zero-padded
174           octal, except for those representable by standard escape
175           notation (see above), which are displayed as two-character
176           strings.
177
178       _p
179           Output characters in the default character set. Non-printing
180           characters are displayed as a single '.'.
181
182       _u
183           Output US ASCII characters, with the exception that control
184           characters are displayed using the following, lower-case,
185           names. Characters greater than 0xff, hexadecimal, are
186           displayed as hexadecimal strings.
187
188          ┌────────┬─────────┬─────────┬─────────┬─────────┬─────────┐
189          │        │         │         │         │         │         │
190          │000 nul │ 001 soh │ 002 stx │ 003 etx │ 004 eot │ 005 enq │
191          ├────────┼─────────┼─────────┼─────────┼─────────┼─────────┤
192          │        │         │         │         │         │         │
193          │006 ack │ 007 bel │ 008 bs  │ 009 ht  │ 00A lf  │ 00B vt  │
194          ├────────┼─────────┼─────────┼─────────┼─────────┼─────────┤
195          │        │         │         │         │         │         │
196          │00C ff  │ 00D cr  │ 00E so  │ 00F si  │ 010 dle │ 011 dc1 │
197          ├────────┼─────────┼─────────┼─────────┼─────────┼─────────┤
198          │        │         │         │         │         │         │
199          │012 dc2 │ 013 dc3 │ 014 dc4 │ 015 nak │ 016 syn │ 017 etb │
200          ├────────┼─────────┼─────────┼─────────┼─────────┼─────────┤
201          │        │         │         │         │         │         │
202          │018 can │ 019 em  │ 01A sub │ 01B esc │ 01C fs  │ 01D gs  │
203          ├────────┼─────────┼─────────┼─────────┼─────────┼─────────┤
204          │        │         │         │         │         │         │
205          │01E rs  │ 01F us  │ 0FF del │         │         │         │
206          └────────┴─────────┴─────────┴─────────┴─────────┴─────────┘
207
208   Colors
209       When put at the end of a format specifier, hexdump
210       highlights the respective string with the color specified.
211       Conditions, if present, are evaluated prior to
212       highlighting.
213
214       _L[color_unit_1,color_unit_2,...,color_unit_n]
215
216       The full syntax of a color unit is as follows:
217
218       [!]COLOR[:VALUE][@OFFSET_START[-END]]
219
220       !
221           Negate the condition. Please note that it only makes
222           sense to negate a unit if both a value/string and an
223           offset are specified. In that case the respective
224           output string will be highlighted if and only if the
225           value/string does not match the one at the offset.
226
227       COLOR
228           One of the 8 basic shell colors.
229
230       VALUE
231           A value to be matched specified in hexadecimal, or
232           octal base, or as a string. Please note that the usual
233           C escape sequences are not interpreted by hexdump
234           inside the color_units.
235
236       OFFSET
237           An offset or an offset range at which to check for a
238           match. Please note that lone OFFSET_START uses the same
239           value as END offset.
240
241   Counters
242       The default and supported byte counts for the conversion
243       characters are as follows:
244
245       %_c, %_p, %_u, %c
246           One byte counts only.
247
248       %d, %i, %o, %u, %X, %x
249           Four byte default, one, two and four byte counts
250           supported.
251
252       %E, %e, %f, %G, %g
253           Eight byte default, four byte counts supported.
254
255       The amount of data interpreted by each format string is the
256       sum of the data required by each format unit, which is the
257       iteration count times the byte count, or the iteration
258       count times the number of bytes required by the format if
259       the byte count is not specified.
260
261       The input is manipulated in blocks, where a block is
262       defined as the largest amount of data specified by any
263       format string. Format strings interpreting less than an
264       input block’s worth of data, whose last format unit both
265       interprets some number of bytes and does not have a
266       specified iteration count, have the iteration count
267       incremented until the entire input block has been processed
268       or there is not enough data remaining in the block to
269       satisfy the format string.
270
271       If, either as a result of user specification or hexdump
272       modifying the iteration count as described above, an
273       iteration count is greater than one, no trailing whitespace
274       characters are output during the last iteration.
275
276       It is an error to specify a byte count as well as multiple
277       conversion characters or strings unless all but one of the
278       conversion characters or strings is _a or _A.
279
280       If, as a result of the specification of the -n option or
281       end-of-file being reached, input data only partially
282       satisfies a format string, the input block is zero-padded
283       sufficiently to display all available data (i.e., any
284       format units overlapping the end of data will display some
285       number of the zero bytes).
286
287       Further output by such format strings is replaced by an
288       equivalent number of spaces. An equivalent number of spaces
289       is defined as the number of spaces output by an s
290       conversion character with the same field width and
291       precision as the original conversion character or
292       conversion string but with any '+', ' ', '#' conversion
293       flag characters removed, and referencing a NULL string.
294
295       If no format strings are specified, the default display is
296       very similar to the -x output format (the -x option causes
297       more space to be used between format units than in the
298       default output).
299

EXIT STATUS

301       hexdump exits 0 on success and > 0 if an error occurred.
302

CONFORMING TO

304       The hexdump utility is expected to be IEEE Std 1003.2
305       ("POSIX.2") compatible.
306

EXAMPLES

308       Display the input in perusal format:
309
310              "%06.6_ao "  12/1 "%3_u "
311              "\t" "%_p "
312              "\n"
313
314       Implement the -x option:
315
316              "%07.7_Ax\n"
317              "%07.7_ax  " 8/2 "%04x " "\n"
318
319       MBR Boot Signature example: Highlight the addresses cyan
320       and the bytes at offsets 510 and 511 green if their value
321       is 0xAA55, red otherwise.
322
323              "%07.7_Ax_L[cyan]\n"
324              "%07.7_ax_L[cyan]  " 8/2 "   %04x_L[green:0xAA55@510-511,!red:0xAA55@510-511] " "\n"
325

COLORS

327       The output colorization is implemented by
328       terminal-colors.d(5) functionality. Implicit coloring can
329       be disabled by an empty file
330
331          /etc/terminal-colors.d/hexdump.disable
332
333       for the hexdump command or for all tools by
334
335          /etc/terminal-colors.d/disable
336
337       The user-specific $XDG_CONFIG_HOME/terminal-colors.d or
338       $HOME/.config/terminal-colors.d overrides the global
339       setting.
340
341       Note that the output colorization may be enabled by
342       default, and in this case terminal-colors.d directories do
343       not have to exist yet.
344

REPORTING BUGS

346       For bug reports, use the issue tracker at
347       https://github.com/util-linux/util-linux/issues.
348

AVAILABILITY

350       The hexdump command is part of the util-linux package which
351       can be downloaded from Linux Kernel Archive
352       <https://www.kernel.org/pub/linux/utils/util-linux/>.
353
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356util-linux 2.39.2                 2023-08-17                        HEXDUMP(1)
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