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hexdump.1 (11021B)


      1 .\"	$OpenBSD: hexdump.1,v 1.24 2011/05/06 18:11:43 otto Exp $
      2 .\"	$NetBSD: hexdump.1,v 1.14 2001/12/07 14:46:24 bjh21 Exp $
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     31 .\"	from: @(#)hexdump.1	8.2 (Berkeley) 4/18/94
     32 .\"
     33 .Dd $Mdocdate: May 6 2011 $
     34 .Dt HEXDUMP 1
     35 .Os
     36 .Sh NAME
     37 .Nm hexdump
     38 .Nd ascii, decimal, hexadecimal, octal dump
     39 .Sh SYNOPSIS
     40 .Nm hexdump
     41 .Bk -words
     42 .Op Fl bCcdovx
     43 .Op Fl e Ar format_string
     44 .Op Fl f Ar format_file
     45 .Op Fl n Ar length
     46 .Op Fl s Ar offset
     47 .Op Ar
     48 .Ek
     49 .Sh DESCRIPTION
     50 The
     51 .Nm
     52 utility is a filter which displays the specified files, or
     53 the standard input, if no files are specified, in a user-specified
     54 format.
     55 .Pp
     56 The options are as follows:
     57 .Bl -tag -width Ds
     58 .It Fl b
     59 .Em One-byte octal display .
     60 Display the input offset in hexadecimal, followed by sixteen
     61 space-separated, three column, zero-filled, bytes of input data,
     62 in octal, per line.
     63 .It Fl C
     64 .Em Canonical hex+ASCII display .
     65 Display the input offset in hexadecimal, followed by sixteen
     66 space-separated, two column, hexadecimal bytes, followed by the
     67 same sixteen bytes in %_p format enclosed in ``|'' characters.
     68 .It Fl c
     69 .Em One-byte character display .
     70 Display the input offset in hexadecimal, followed by sixteen
     71 space-separated, three column, space-filled, characters of input
     72 data per line.
     73 .It Fl d
     74 .Em Two-byte decimal display .
     75 Display the input offset in hexadecimal, followed by eight
     76 space-separated, five column, zero-filled, two-byte units
     77 of input data, in unsigned decimal, per line.
     78 .It Fl e Ar format_string
     79 Specify a format string to be used for displaying data.
     80 .It Fl f Ar format_file
     81 Specify a file that contains one or more newline separated format strings.
     82 Empty lines and lines whose first non-blank character is a hash mark
     83 .Pq Ql #
     84 are ignored.
     85 .It Fl n Ar length
     86 Interpret only
     87 .Ar length
     88 bytes of input.
     89 By default,
     90 .Ar length
     91 is interpreted as a decimal number.
     92 With a leading
     93 .Cm 0x
     94 or
     95 .Cm 0X ,
     96 .Ar length
     97 is interpreted as a hexadecimal number,
     98 otherwise, with a leading
     99 .Cm 0 ,
    100 .Ar length
    101 is interpreted as an octal number.
    102 .It Fl o
    103 .Em Two-byte octal display .
    104 Display the input offset in hexadecimal, followed by eight
    105 space-separated, six column, zero-filled, two byte quantities of
    106 input data, in octal, per line.
    107 .It Fl s Ar offset
    108 Skip
    109 .Ar offset
    110 bytes from the beginning of the input.
    111 By default,
    112 .Ar offset
    113 is interpreted as a decimal number.
    114 With a leading
    115 .Cm 0x
    116 or
    117 .Cm 0X ,
    118 .Ar offset
    119 is interpreted as a hexadecimal number,
    120 otherwise, with a leading
    121 .Cm 0 ,
    122 .Ar offset
    123 is interpreted as an octal number.
    124 Appending the character
    125 .Cm b ,
    126 .Cm k ,
    127 or
    128 .Cm m
    129 to
    130 .Ar offset
    131 causes it to be interpreted as a multiple of
    132 .Li 512 ,
    133 .Li 1024 ,
    134 or
    135 .Li 1048576 ,
    136 respectively.
    137 .It Fl v
    138 The
    139 .Fl v
    140 option causes hexdump to display all input data.
    141 Without the
    142 .Fl v
    143 option, any number of groups of output lines, which would be
    144 identical to the immediately preceding group of output lines (except
    145 for the input offsets), are replaced with a line comprised of a
    146 single asterisk
    147 .Pq Ql * .
    148 .It Fl x
    149 .Em Two-byte hexadecimal display .
    150 Display the input offset in hexadecimal, followed by eight, space
    151 separated, four column, zero-filled, two-byte quantities of input
    152 data, in hexadecimal, per line.
    153 .El
    154 .Pp
    155 For each input file,
    156 .Nm
    157 sequentially copies the input to standard output, transforming the
    158 data according to the format strings specified by the
    159 .Fl e
    160 and
    161 .Fl f
    162 options, in the order that they were specified.
    163 .Ss Formats
    164 A format string contains any number of format units, separated by
    165 whitespace.
    166 A format unit contains up to three items: an iteration count, a byte
    167 count, and a format.
    168 .Pp
    169 The iteration count is an optional positive integer, which defaults to
    170 one.
    171 Each format is applied iteration count times.
    172 .Pp
    173 The byte count is an optional positive integer.
    174 If specified it defines the number of bytes to be interpreted by
    175 each iteration of the format.
    176 .Pp
    177 If an iteration count and/or a byte count is specified, a single slash
    178 .Pq Sq /
    179 must be placed after the iteration count and/or before the byte count
    180 to disambiguate them.
    181 Any whitespace before or after the slash is ignored.
    182 .Pp
    183 The format is required and must be surrounded by double quote
    184 .Pq \&"\& \&"
    185 marks
    186 (the quote mark is a special character in many shell programs,
    187 and may have to be escaped from the shell).
    188 It is interpreted as a fprintf-style format string (see
    189 .Xr fprintf 3 ) ,
    190 with the
    191 following exceptions:
    192 .Bl -bullet -offset indent
    193 .It
    194 An asterisk (*) may not be used as a field width or precision.
    195 .It
    196 A byte count or field precision
    197 .Em is
    198 required for each
    199 .Sq s
    200 conversion character (unlike the
    201 .Xr fprintf 3
    202 default which prints the entire string if the precision is unspecified).
    203 .It
    204 The conversion characters
    205 .Sq h ,
    206 .Sq l ,
    207 .Sq n ,
    208 .Sq p ,
    209 and
    210 .Sq q
    211 are not supported.
    212 .It
    213 The single character escape sequences
    214 described in the C standard are supported:
    215 .Pp
    216 .Bl -tag -width "Xalert characterXXX" -offset indent -compact
    217 .It NUL
    218 \e0
    219 .It Aq alert character
    220 \ea
    221 .It Aq backspace
    222 \eb
    223 .It Aq form-feed
    224 \ef
    225 .It Aq newline
    226 \en
    227 .It Aq carriage return
    228 \er
    229 .It Aq tab
    230 \et
    231 .It Aq vertical tab
    232 \ev
    233 .El
    234 .El
    235 .Pp
    236 .Nm
    237 also supports the following additional conversion strings:
    238 .Bl -tag -width Fl
    239 .It Cm \&_a Ns Op Cm dox
    240 Display the input offset, cumulative across input files, of the
    241 next byte to be displayed.
    242 The appended characters
    243 .Cm d ,
    244 .Cm o ,
    245 and
    246 .Cm x
    247 specify the display base
    248 as decimal, octal or hexadecimal respectively.
    249 .It Cm \&_A Ns Op Cm dox
    250 Identical to the
    251 .Cm \&_a
    252 conversion string except that it is only performed
    253 once, when all of the input data has been processed.
    254 .It Cm \&_c
    255 Output characters in the default character set.
    256 Nonprinting characters are displayed in three character, zero-padded
    257 octal, except for those representable by standard escape notation
    258 (see above),
    259 which are displayed as two character strings.
    260 .It Cm _p
    261 Output characters in the default character set.
    262 Nonprinting characters are displayed as a single dot
    263 .Ql \&. .
    264 .It Cm _u
    265 Output US ASCII characters, with the exception that control characters are
    266 displayed using the following, lower-case, names.
    267 Other non-printable characters are displayed as hexadecimal strings.
    268 .Bd -literal -offset 3n
    269 000 nul  001 soh  002 stx  003 etx  004 eot  005 enq
    270 006 ack  007 bel  008 bs   009 ht   00A lf   00B vt
    271 00C ff   00D cr   00E so   00F si   010 dle  011 dc1
    272 012 dc2  013 dc3  014 dc4  015 nak  016 syn  017 etb
    273 018 can  019 em   01A sub  01B esc  01C fs   01D gs
    274 01E rs   01F us   07F del
    275 .Ed
    276 .El
    277 .Pp
    278 The default and supported byte counts for the conversion characters
    279 are as follows:
    280 .Bl -tag -width  "Xc,_Xc,_Xc,_Xc,_Xc,_Xc" -offset indent
    281 .It Li \&%_c , \&%_p , \&%_u , \&%c
    282 One byte counts only.
    283 .It Xo
    284 .Li \&%d , \&%i , \&%o ,
    285 .Li \&%u , \&%X , \&%x
    286 .Xc
    287 Four byte default, one, two, four and eight byte counts supported.
    288 .It Xo
    289 .Li \&%E , \&%e , \&%f ,
    290 .Li \&%G , \&%g
    291 .Xc
    292 Eight byte default, four byte counts supported.
    293 .El
    294 .Pp
    295 The amount of data interpreted by each format string is the sum of the
    296 data required by each format unit, which is the iteration count times the
    297 byte count, or the iteration count times the number of bytes required by
    298 the format if the byte count is not specified.
    299 .Pp
    300 The input is manipulated in
    301 .Dq blocks ,
    302 where a block is defined as the
    303 largest amount of data specified by any format string.
    304 Format strings interpreting less than an input block's worth of data,
    305 whose last format unit both interprets some number of bytes and does
    306 not have a specified iteration count, have the iteration count
    307 incremented until the entire input block has been processed or there
    308 is not enough data remaining in the block to satisfy the format string.
    309 .Pp
    310 If, either as a result of user specification or hexdump modifying
    311 the iteration count as described above, an iteration count is
    312 greater than one, no trailing whitespace characters are output
    313 during the last iteration.
    314 .Pp
    315 It is an error to specify a byte count as well as multiple conversion
    316 characters or strings unless all but one of the conversion characters
    317 or strings is
    318 .Cm \&_a
    319 or
    320 .Cm \&_A .
    321 .Pp
    322 If, as a result of the specification of the
    323 .Fl n
    324 option or end-of-file being reached, input data only partially
    325 satisfies a format string, the input block is zero-padded sufficiently
    326 to display all available data (i.e., any format units overlapping the
    327 end of data will display some number of the zero bytes).
    328 .Pp
    329 Further output by such format strings is replaced by an equivalent
    330 number of spaces.
    331 An equivalent number of spaces is defined as the number of spaces
    332 output by an
    333 .Cm s
    334 conversion character with the same field width
    335 and precision as the original conversion character or conversion
    336 string but with any
    337 .Ql + ,
    338 .Ql \&\ \& ,
    339 .Ql #
    340 conversion flag characters
    341 removed, and referencing a NULL string.
    342 .Pp
    343 If no format strings are specified, the default display is equivalent
    344 to specifying the
    345 .Fl x
    346 option.
    347 .Sh EXIT STATUS
    348 .Ex -std hexdump
    349 .Sh EXAMPLES
    350 Display characters using a fieldwidth of 4,
    351 and using special names for control characters:
    352 .Pp
    353 .Dl $ hexdump -e '"%4_u"' file
    354 .Pp
    355 An example file for use with the
    356 .Fl f
    357 option, to display the input in perusal format:
    358 .Bd -literal -offset indent
    359 "%06.6_ao "  12/1 "%3_u "
    360 "\et\et" "%_p "
    361 "\en"
    362 .Ed
    363 .Pp
    364 An example file for use with the
    365 .Fl f
    366 option, which implements the equivalent of the
    367 .Fl x
    368 option:
    369 .Bd -literal -offset indent
    370 "%07.7_Ax\en"
    371 "%07.7_ax " 8/2 "   %04x " "\en"
    372 .Ed
    373 .Sh SEE ALSO
    374 .Xr od 1