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

6       hexdump  -  display  file  contents  in ascii, decimal, hexadecimal, or
7       octal
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SYNOPSIS

10       hexdump [options] file [...]
11

DESCRIPTION

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.
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OPTIONS

17       The  length  and offset arguments may be followed by the multiplicative
18       suffixes KiB=1024, MiB=1024*1024, and so on for GiB, TiB, PiB, EiB, ZiB
19       and  YiB (the "iB" is optional, e.g. "K" has the same meaning as "KiB")
20       or the suffixes KB=1000, MB=1000*1000, and so on for GB, TB, PB, EB, ZB
21       and YB.
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23       -b     One-byte  octal  display.  Display the input offset in hexadeci‐
24              mal, followed by sixteen  space-separated,  three-column,  zero-
25              filled bytes of input data, in octal, per line.
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27       -c     One-byte  character  display.  Display the input offset in hexa‐
28              decimal,  followed  by  sixteen  space-separated,  three-column,
29              space-filled characters of input data per line.
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31       -C     Canonical  hex+ASCII display.  Display the input offset in hexa‐
32              decimal, followed by sixteen space-separated, two-column,  hexa‐
33              decimal  bytes, followed by the same sixteen bytes in %_p format
34              enclosed in '|' characters.
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36       -d     Two-byte decimal display.  Display the input offset in hexadeci‐
37              mal,  followed  by  eight  space-separated,  five-column,  zero-
38              filled, two-byte units of input data, in unsigned  decimal,  per
39              line.
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41       -e format_string
42              Specify a format string to be used for displaying data.
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44       -f format_file
45              Specify  a file that contains one or more newline separated for‐
46              mat strings.  Empty lines and lines whose first non-blank  char‐
47              acter is a hash mark (#) are ignored.
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49       -n length
50              Interpret only length bytes of input.
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52       -o     Two-byte  octal  display.  Display the input offset in hexadeci‐
53              mal, followed by eight space-separated, six-column, zero-filled,
54              two-byte quantities of input data, in octal, per line.
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56       -s offset
57              Skip offset bytes from the beginning of the input.
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59       -v     The -v option causes hexdump to display all input data.  Without
60              the -v option, any number of groups of output lines which  would
61              be  identical to the immediately preceding group of output lines
62              (except for the input offsets), are replaced with  a  line  com‐
63              prised of a single asterisk.
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65       -x     Two-byte hexadecimal display.  Display the input offset in hexa‐
66              decimal, followed by eight space-separated,  four-column,  zero-
67              filled,  two-byte  quantities of input data, in hexadecimal, per
68              line.
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70       For each input file, hexdump sequentially copies the input to  standard
71       output, transforming the data according to the format strings specified
72       by the -e and -f options, in the order that they were specified.
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FORMATS

75       A format string contains any  number  of  format  units,  separated  by
76       whitespace.   A  format  unit  contains up to three items: an iteration
77       count, a byte count, and a format.
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79       The iteration count is an optional positive integer, which defaults  to
80       one.  Each format is applied iteration count times.
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82       The  byte  count  is  an  optional  positive  integer.  If specified it
83       defines the number of bytes to be interpreted by each iteration of  the
84       format.
85
86       If  an iteration count and/or a byte count is specified, a single slash
87       must be placed after the iteration count and/or before the  byte  count
88       to  disambiguate  them.   Any  whitespace  before or after the slash is
89       ignored.
90
91       The format is required and must be surrounded by  double  quote  ("  ")
92       marks.   It  is  interpreted  as  a  fprintf-style  format  string (see
93       fprintf(3), with the following exceptions:
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95       1.     An asterisk (*) may not be used as a field width or precision.
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97       2.     A byte count or field precision is required for each  s  conver‐
98              sion  character  (unlike the fprintf(3) default which prints the
99              entire string if the precision is unspecified).
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101       3.     The conversion characters h, l, n, p, and q are not supported.
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103       4.     The single character escape sequences described in the  C  stan‐
104              dard are supported:
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106                    NULL                 \0
107                    <alert character>    \a
108                    <backspace>          \b
109                    <form-feed>          \f
110                    <newline>            \n
111                    <carriage return>    \r
112                    <tab>                \t
113                    <vertical tab>       \v
114
115   Conversion strings
116       The  hexdump  utility also supports the following additional conversion
117       strings.
118
119       _a[dox]
120              Display the input offset, cumulative across input files, of  the
121              next  byte to be displayed.  The appended characters d, o, and x
122              specify the  display  base  as  decimal,  octal  or  hexadecimal
123              respectively.
124
125       _A[dox]
126              Identical  to  the  _a  conversion string except that it is only
127              performed once, when all of the input data has been processed.
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129       _c     Output characters in the  default  character  set.   Nonprinting
130              characters  are displayed in three-character, zero-padded octal,
131              except for those representable by standard escape notation  (see
132              above), which are displayed as two-character strings.
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134       _p     Output  characters  in  the  default character set.  Nonprinting
135              characters are displayed as a single '.'.
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137       _u     Output US ASCII characters,  with  the  exception  that  control
138              characters are displayed using the following, lower-case, names.
139              Characters greater than  0xff,  hexadecimal,  are  displayed  as
140              hexadecimal strings.
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142                 000 nul  001 soh  002 stx  003 etx  004 eot  005 enq
143                 006 ack  007 bel  008 bs   009 ht   00A lf   00B vt
144                 00C ff   00D cr   00E so   00F si   010 dle  011 dc1
145                 012 dc2  013 dc3  014 dc4  015 nak  016 syn  017 etb
146                 018 can  019 em   01A sub  01B esc  01C fs   01D gs
147                 01E rs   01F us   0FF del
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149   Counters
150       The default and supported byte counts for the conversion characters are
151       as follows:
152
153       %_c, %_p, %_u, %c
154              One byte counts only.
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156       %d, %i, %o, %u, %X, %x
157              Four byte default, one, two and four byte counts supported.
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159       %E, %e, %f, %G, %g
160              Eight byte default, four byte counts supported.
161
162       The amount of data interpreted by each format string is the sum of  the
163       data  required  by each format unit, which is the iteration count times
164       the byte count, or the  iteration  count  times  the  number  of  bytes
165       required by the format if the byte count is not specified.
166
167       The  input  is  manipulated  in blocks, where a block is defined as the
168       largest amount of data specified by any format string.  Format  strings
169       interpreting  less than an input block's worth of data, whose last for‐
170       mat unit both interprets some number of bytes and does not have a spec‐
171       ified  iteration  count, have the iteration count incremented until the
172       entire input block has been processed  or  there  is  not  enough  data
173       remaining in the block to satisfy the format string.
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175       If,  either  as a result of user specification or hexdump modifying the
176       iteration count as described above, an iteration count is greater  than
177       one, no trailing whitespace characters are output during the last iter‐
178       ation.
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180       It is an error to specify a byte count as well as  multiple  conversion
181       characters  or  strings unless all but one of the conversion characters
182       or strings is _a or _A.
183
184       If, as a result of the specification of the -n  option  or  end-of-file
185       being reached, input data only partially satisfies a format string, the
186       input block is zero-padded sufficiently to display all  available  data
187       (i.e.  any  format  units overlapping the end of data will display some
188       number of the zero bytes).
189
190       Further output by such format strings is replaced by an equivalent num‐
191       ber of spaces.  An equivalent number of spaces is defined as the number
192       of spaces output by an s conversion character with the same field width
193       and precision as the original conversion character or conversion string
194       but with any '+', ´ ´, '#' conversion flag characters removed, and ref‐
195       erencing a NULL string.
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197       If  no  format strings are specified, the default display is equivalent
198       to specifying the -x option.
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EXIT STATUS

201       hexdump exits 0 on success and >0 if an error occurred.
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EXAMPLES

204       Display the input in perusal format:
205          "%06.6_ao "  12/1 "%3_u "
206          "\t\t" "%_p "
207          "\n"
208
209       Implement the -x option:
210          "%07.7_Ax\n"
211          "%07.7_ax  " 8/2 "%04x " "\n"
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STANDARDS

214       The hexdump utility is expected to be IEEE Std 1003.2 ("POSIX.2")  com‐
215       patible.
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AVAILABILITY

218       The  hexdump command is part of the util-linux package and is available
219       from Linux Kernel  Archive  ⟨ftp://ftp.kernel.org/pub/linux/utils/util-
220       linux/⟩.
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224util-linux                      September 2011                      HEXDUMP(1)
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