1HEXDUMP(1) User Commands HEXDUMP(1)
2
6 hexdump - display file contents in hexadecimal, decimal, octal, or
7 ascii
8
10 hexdump [options] file...
11
13 The hexdump utility is a filter which displays the specified files, or
14 standard input if no files are specified, in a user-specified format.
15
17 Below, the length and offset arguments may be followed by the multi‐
18 plicative suffixes KiB (=1024), MiB (=1024*1024), and so on for GiB,
19 TiB, PiB, EiB, ZiB and YiB (the "iB" is optional, e.g. "K" has the same
20 meaning as "KiB"), or the suffixes KB (=1000), MB (=1000*1000), and so
21 on for GB, TB, PB, EB, ZB and YB.
22 -b, --one-byte-octal
24 One-byte octal display. Display the input offset in hexadeci‐
25 mal, followed by sixteen space-separated, three-column, zero-
26 filled bytes of input data, in octal, per line.
27 -c, --one-byte-char
29 One-byte character display. Display the input offset in hexa‐
30 decimal, followed by sixteen space-separated, three-column,
31 space-filled characters of input data per line.
32 -C, --canonical
34 Canonical hex+ASCII display. Display the input offset in hexa‐
35 decimal, followed by sixteen space-separated, two-column, hexa‐
36 decimal bytes, followed by the same sixteen bytes in %_p format
37 enclosed in '|' characters.
38 -d, --two-bytes-decimal
40 Two-byte decimal display. Display the input offset in hexadeci‐
41 mal, followed by eight space-separated, five-column, zero-
42 filled, two-byte units of input data, in unsigned decimal, per
43 line.
44 -e, --format format_string
46 Specify a format string to be used for displaying data.
47 -f, --format-file file
49 Specify a file that contains one or more newline-separated for‐
50 mat strings. Empty lines and lines whose first non-blank char‐
51 acter is a hash mark (#) are ignored.
52 -L, --color[=when]
54 Accept color units for the output. The optional argument when
55 can be auto, never or always. If the when argument is omitted,
56 it defaults to auto. The colors can be disabled; for the cur‐
57 rent built-in default see the --help output. See also the Col‐
58 ors subsection and the COLORS section below.
59 -n, --length length
61 Interpret only length bytes of input.
62 -o, --two-bytes-octal
64 Two-byte octal display. Display the input offset in hexadeci‐
65 mal, followed by eight space-separated, six-column, zero-filled,
66 two-byte quantities of input data, in octal, per line.
67 -s, --skip offset
69 Skip offset bytes from the beginning of the input.
70 -v, --no-squeezing
72 The -v option causes hexdump to display all input data. Without
73 the -v option, any number of groups of output lines which would
74 be identical to the immediately preceding group of output lines
75 (except for the input offsets), are replaced with a line com‐
76 prised of a single asterisk.
77 -x, --two-bytes-hex
79 Two-byte hexadecimal display. Display the input offset in hexa‐
80 decimal, followed by eight space-separated, four-column, zero-
81 filled, two-byte quantities of input data, in hexadecimal, per
82 line.
83 -V, --version
85 Display version information and exit.
86 -h, --help
88 Display help text and exit.
89 For each input file, hexdump sequentially copies the input to standard
91 output, transforming the data according to the format strings specified
92 by the -e and -f options, in the order that they were specified.
93
95 A format string contains any number of format units, separated by
96 whitespace. A format unit contains up to three items: an iteration
97 count, a byte count, and a format.
98 The iteration count is an optional positive integer, which defaults to
100 one. Each format is applied iteration count times.
101 The byte count is an optional positive integer. If specified it
103 defines the number of bytes to be interpreted by each iteration of the
104 format.
105 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 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 1. An asterisk (*) may not be used as a field width or precision.
116 2. A byte count or field precision is required for each s conver‐
118 sion character (unlike the fprintf(3) default which prints the
119 entire string if the precision is unspecified).
120 3. The conversion characters h, l, n, p, and q are not supported.
122 4. The single character escape sequences described in the C stan‐
124 dard are supported:
125 NULL \0
127 <alert character> \a
128 <backspace> \b
129 <form-feed> \f
130 <newline> \n
131 <carriage return> \r
132 <tab> \t
133 <vertical tab> \v
134 Conversion strings
136 The hexdump utility also supports the following additional conversion
137 strings.
138 _a[dox]
140 Display the input offset, cumulative across input files, of the
141 next byte to be displayed. The appended characters d, o, and x
142 specify the display base as decimal, octal or hexadecimal
143 respectively.
144 _A[dox]
146 Identical to the _a conversion string except that it is only
147 performed once, when all of the input data has been processed.
148 _c Output characters in the default character set. Non-printing
150 characters are displayed in three-character, zero-padded octal,
151 except for those representable by standard escape notation (see
152 above), which are displayed as two-character strings.
153 _p Output characters in the default character set. Non-printing
155 characters are displayed as a single '.'.
156 _u Output US ASCII characters, with the exception that control
158 characters are displayed using the following, lower-case, names.
159 Characters greater than 0xff, hexadecimal, are displayed as
160 hexadecimal strings.
161 000 nul 001 soh 002 stx 003 etx 004 eot 005 enq
163 006 ack 007 bel 008 bs 009 ht 00A lf 00B vt
164 00C ff 00D cr 00E so 00F si 010 dle 011 dc1
165 012 dc2 013 dc3 014 dc4 015 nak 016 syn 017 etb
166 018 can 019 em 01A sub 01B esc 01C fs 01D gs
167 01E rs 01F us 0FF del
168 Colors
170 When put at the end of a format specifier, hexdump highlights the
171 respective string with the color specified. Conditions, if present,
172 are evaluated prior to highlighting.
173 _L[color_unit_1,color_unit_2,...,color_unit_n]
175 The full syntax of a color unit is as follows:
177 [!]COLOR[:VALUE][@OFFSET_START[-END]]
179 ! Negate the condition. Please note that it only makes sense to
181 negate a unit if both a value/string and an offset are speci‐
182 fied. In that case the respective output string will be high‐
183 lighted if and only if the value/string does not match the one
184 at the offset.
185 COLOR One of the 8 basic shell colors.
187 VALUE A value to be matched specified in hexadecimal, or octal base,
189 or as a string. Please note that the usual C escape sequences
190 are not interpreted by hexdump inside the color_units.
191 OFFSET An offset or an offset range at which to check for a match.
193 Please note that lone OFFSET_START uses the same value as END
194 offset.
195 Counters
197 The default and supported byte counts for the conversion characters are
198 as follows:
199 %_c, %_p, %_u, %c
201 One byte counts only.
202 %d, %i, %o, %u, %X, %x
204 Four byte default, one, two and four byte counts supported.
205 %E, %e, %f, %G, %g
207 Eight byte default, four byte counts supported.
208 The amount of data interpreted by each format string is the sum of the
210 data required by each format unit, which is the iteration count times
211 the byte count, or the iteration count times the number of bytes
212 required by the format if the byte count is not specified.
213 The input is manipulated in blocks, where a block is defined as the
215 largest amount of data specified by any format string. Format strings
216 interpreting less than an input block's worth of data, whose last for‐
217 mat unit both interprets some number of bytes and does not have a spec‐
218 ified iteration count, have the iteration count incremented until the
219 entire input block has been processed or there is not enough data
220 remaining in the block to satisfy the format string.
221 If, either as a result of user specification or hexdump modifying the
223 iteration count as described above, an iteration count is greater than
224 one, no trailing whitespace characters are output during the last iter‐
225 ation.
226 It is an error to specify a byte count as well as multiple conversion
228 characters or strings unless all but one of the conversion characters
229 or strings is _a or _A.
230 If, as a result of the specification of the -n option or end-of-file
232 being reached, input data only partially satisfies a format string, the
233 input block is zero-padded sufficiently to display all available data
234 (i.e. any format units overlapping the end of data will display some
235 number of the zero bytes).
236 Further output by such format strings is replaced by an equivalent num‐
238 ber of spaces. An equivalent number of spaces is defined as the number
239 of spaces output by an s conversion character with the same field width
240 and precision as the original conversion character or conversion string
241 but with any '+', ´ ´, '#' conversion flag characters removed, and ref‐
242 erencing a NULL string.
243 If no format strings are specified, the default display is very similar
245 to the -x output format (the -x option causes more space to be used
246 between format units than in the default output).
247
249 hexdump exits 0 on success and >0 if an error occurred.
250
252 Display the input in perusal format:
253 "%06.6_ao " 12/1 "%3_u "
254 "\t\t" "%_p "
255 "\n"
256 Implement the -x option:
258 "%07.7_Ax\n"
259 "%07.7_ax " 8/2 "%04x " "\n"
260 MBR Boot Signature example: Highlight the addresses cyan and the bytes at
262 offsets 510 and 511 green if their value is 0xAA55, red otherwise.
263 "%07.7_Ax_L[cyan]\n"
264 "%07.7_ax_L[cyan] " 8/2 " %04x_L[green:0xAA55@510-511,!red:0xAA55@510-511] " "\n"
265
267 Implicit coloring can be disabled by an empty file /etc/terminal-col‐
268 ors.d/hexdump.disable.
269 See terminal-colors.d(5) for more details about colorization configura‐
271 tion.
272
274 The hexdump utility is expected to be IEEE Std 1003.2 ("POSIX.2") com‐
275 patible.
276
278 The hexdump command is part of the util-linux package and is available
279 from Linux Kernel Archive ⟨https://www.kernel.org/pub/linux/utils/util-
280 linux/⟩.
281util-linux April 2013 HEXDUMP(1)