hexdump/hexdump.1

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  32 .\"     @(#)hexdump.1   8.2 (Berkeley) 4/18/94
  33 .\" $FreeBSD: src/usr.bin/hexdump/hexdump.1,v 1.21 2004/07/10 13:11:00 tjr Exp $
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  35 .Dd July 10, 2004
  36 .Dt HEXDUMP 1
  37 .Os
  38 .Sh NAME
  39 .Nm hexdump
  40 .Nd ASCII, decimal, hexadecimal, octal dump
  41 .Sh SYNOPSIS
  42 .Nm
  43 .Op Fl bcCdovx
  44 .Op Fl e Ar format_string
  45 .Op Fl f Ar format_file
  46 .Op Fl n Ar length
  47 .Bk -words
  48 .Op Fl s Ar skip
  49 .Ek
  50 .Ar
  51 .Sh DESCRIPTION
  52 The
  53 .Nm
  54 utility is a filter which displays the specified files, or
  55 the standard input, if no files are specified, in a user specified
  56 format.
  57 .Pp
  58 The options are as follows:
  59 .Bl -tag -width indent
  60 .It Fl b
  61 .Em One-byte octal display .
  62 Display the input offset in hexadecimal, followed by sixteen
  63 space-separated, three column, zero-filled, bytes of input data,
  64 in octal, per line.
  65 .It Fl C
  66 .Em Canonical hex+ASCII display .
  67 Display the input offset in hexadecimal, followed by sixteen
  68 space-separated, two column, hexadecimal bytes, followed by the
  69 same sixteen bytes in %_p format enclosed in ``|'' characters.
  70 .It Fl c
  71 .Em One-byte character display .
  72 Display the input offset in hexadecimal, followed by sixteen
  73 space-separated, three column, space-filled, characters of input
  74 data per line.
  75 .It Fl d
  76 .Em Two-byte decimal display .
  77 Display the input offset in hexadecimal, followed by eight
  78 space-separated, five column, zero-filled, two-byte units
  79 of input data, in unsigned decimal, per line.
  80 .It Fl e Ar format_string
  81 Specify a format string to be used for displaying data.
  82 .It Fl f Ar format_file
  83 Specify a file that contains one or more newline separated format strings.
  84 Empty lines and lines whose first non-blank character is a hash mark
  85 .Pf ( Cm \&# )
  86 are ignored.
  87 .It Fl n Ar length
  88 Interpret only
  89 .Ar length
  90 bytes of input.
  91 .It Fl o
  92 .Em Two-byte octal display .
  93 Display the input offset in hexadecimal, followed by eight
  94 space-separated, six column, zero-filled, two byte quantities of
  95 input data, in octal, per line.
  96 .It Fl s Ar offset
  97 Skip
  98 .Ar offset
  99 bytes from the beginning of the input.
 100 By default,
 101 .Ar offset
 102 is interpreted as a decimal number.
 103 With a leading
 104 .Cm 0x
 105 or
 106 .Cm 0X ,
 107 .Ar offset
 108 is interpreted as a hexadecimal number,
 109 otherwise, with a leading
 110 .Cm 0 ,
 111 .Ar offset
 112 is interpreted as an octal number.
 113 Appending the character
 114 .Cm b ,
 115 .Cm k ,
 116 or
 117 .Cm m
 118 to
 119 .Ar offset
 120 causes it to be interpreted as a multiple of
 121 .Li 512 ,
 122 .Li 1024 ,
 123 or
 124 .Li 1048576 ,
 125 respectively.
 126 .It Fl v
 127 Cause
 128 .Nm
 129 to display all input data.
 130 Without the
 131 .Fl v
 132 option, any number of groups of output lines, which would be
 133 identical to the immediately preceding group of output lines (except
 134 for the input offsets), are replaced with a line comprised of a
 135 single asterisk.
 136 .It Fl x
 137 .Em Two-byte hexadecimal display .
 138 Display the input offset in hexadecimal, followed by eight, space
 139 separated, four column, zero-filled, two-byte quantities of input
 140 data, in hexadecimal, per line.
 141 .El
 142 .Pp
 143 For each input file,
 144 .Nm
 145 sequentially copies the input to standard output, transforming the
 146 data according to the format strings specified by the
 147 .Fl e
 148 and
 149 .Fl f
 150 options, in the order that they were specified.
 151 .Ss Formats
 152 A format string contains any number of format units, separated by
 153 whitespace.
 154 A format unit contains up to three items: an iteration count, a byte
 155 count, and a format.
 156 .Pp
 157 The iteration count is an optional positive integer, which defaults to
 158 one.
 159 Each format is applied iteration count times.
 160 .Pp
 161 The byte count is an optional positive integer.
 162 If specified it defines the number of bytes to be interpreted by
 163 each iteration of the format.
 164 .Pp
 165 If an iteration count and/or a byte count is specified, a single slash
 166 must be placed after the iteration count and/or before the byte count
 167 to disambiguate them.
 168 Any whitespace before or after the slash is ignored.
 169 .Pp
 170 The format is required and must be surrounded by double quote
 171 (" ") marks.
 172 It is interpreted as a fprintf-style format string (see
 173 .Xr fprintf 3 ) ,
 174 with the
 175 following exceptions:
 176 .Bl -bullet -offset indent
 177 .It
 178 An asterisk (*) may not be used as a field width or precision.
 179 .It
 180 A byte count or field precision
 181 .Em is
 182 required for each ``s'' conversion
 183 character (unlike the
 184 .Xr fprintf 3
 185 default which prints the entire string if the precision is unspecified).
 186 .It
 187 The conversion characters ``h'', ``l'', ``n'', ``p'' and ``q'' are
 188 not supported.
 189 .It
 190 The single character escape sequences
 191 described in the C standard are supported:
 192 .Bd -ragged -offset indent -compact
 193 .Bl -column <alert_character>
 194 .It "NUL        \e0
 195 .It "<alert character>  \ea
 196 .It "<backspace>        \eb
 197 .It "<form-feed>        \ef
 198 .It "<newline>  \en
 199 .It "<carriage return>  \er
 200 .It "<tab>      \et
 201 .It "<vertical tab>     \ev
 202 .El
 203 .Ed
 204 .El
 205 .Pp
 206 The
 207 .Nm
 208 utility also supports the following additional conversion strings:
 209 .Bl -tag -width Fl
 210 .It Cm \&_a Ns Op Cm dox
 211 Display the input offset, cumulative across input files, of the
 212 next byte to be displayed.
 213 The appended characters
 214 .Cm d ,
 215 .Cm o ,
 216 and
 217 .Cm x
 218 specify the display base
 219 as decimal, octal or hexadecimal respectively.
 220 .It Cm \&_A Ns Op Cm dox
 221 Identical to the
 222 .Cm \&_a
 223 conversion string except that it is only performed
 224 once, when all of the input data has been processed.
 225 .It Cm \&_c
 226 Output characters in the default character set.
 227 Nonprinting characters are displayed in three character, zero-padded
 228 octal, except for those representable by standard escape notation
 229 (see above),
 230 which are displayed as two character strings.
 231 .It Cm _p
 232 Output characters in the ASCII character set.
 233 Non-ASCII characters are displayed as a single
 234 .Dq Cm \&. .
 235 .It Cm _u
 236 Output US
 237 .Tn ASCII
 238 characters, with the exception that control characters are
 239 displayed using the following, lower-case, names.
 240 Characters greater than 0xff, hexadecimal, are displayed as hexadecimal
 241 strings.
 242 .Bl -column \&000_nu \&001_so \&002_st \&003_et \&004_eo
 243 .It "\&000\ NUL\t001\ SOH\t002\ STX\t003\ ETX\t004\ EOT\t005\ ENQ
 244 .It "\&006\ ACK\t007\ BEL\t008\ BS\t009\ HT\t00A\ LF\t00B\ VT
 245 .It "\&00C\ FF\t00D\ CR\t00E\ SO\t00F\ SI\t010\ DLE\t011\ DC1
 246 .It "\&012\ DC2\t013\ DC3\t014\ DC4\t015\ NAK\t016\ SYN\t017\ ETB
 247 .It "\&018\ CAN\t019\ EM\t01A\ SUB\t01B\ ESC\t01C\ FS\t01D\ GS
 248 .It "\&01E\ RS\t01F\ US\t0FF\ DEL
 249 .El
 250 .El
 251 .Pp
 252 The default and supported byte counts for the conversion characters
 253 are as follows:
 254 .Bl -tag -width  "Xc,_Xc,_Xc,_Xc,_Xc,_Xc" -offset indent
 255 .It Li \&%_c , \&%_p , \&%_u , \&%c
 256 One byte counts only.
 257 .It Xo
 258 .Li \&%d , \&%i , \&%o ,
 259 .Li \&%u , \&%X , \&%x
 260 .Xc
 261 Four byte default, one, two and four byte counts supported.
 262 .It Xo
 263 .Li \&%E , \&%e , \&%f ,
 264 .Li \&%G , \&%g
 265 .Xc
 266 Eight byte default, four and twelve byte counts supported.
 267 .El
 268 .Pp
 269 The amount of data interpreted by each format string is the sum of the
 270 data required by each format unit, which is the iteration count times the
 271 byte count, or the iteration count times the number of bytes required by
 272 the format if the byte count is not specified.
 273 .Pp
 274 The input is manipulated in ``blocks'', where a block is defined as the
 275 largest amount of data specified by any format string.
 276 Format strings interpreting less than an input block's worth of data,
 277 whose last format unit both interprets some number of bytes and does
 278 not have a specified iteration count, have the iteration count
 279 incremented until the entire input block has been processed or there
 280 is not enough data remaining in the block to satisfy the format string.
 281 .Pp
 282 If, either as a result of user specification or
 283 .Nm
 284 modifying
 285 the iteration count as described above, an iteration count is
 286 greater than one, no trailing whitespace characters are output
 287 during the last iteration.
 288 .Pp
 289 It is an error to specify a byte count as well as multiple conversion
 290 characters or strings unless all but one of the conversion characters
 291 or strings is
 292 .Cm \&_a
 293 or
 294 .Cm \&_A .
 295 .Pp
 296 If, as a result of the specification of the
 297 .Fl n
 298 option or end-of-file being reached, input data only partially
 299 satisfies a format string, the input block is zero-padded sufficiently
 300 to display all available data (i.e., any format units overlapping the
 301 end of data will display some number of the zero bytes).
 302 .Pp
 303 Further output by such format strings is replaced by an equivalent
 304 number of spaces.
 305 An equivalent number of spaces is defined as the number of spaces
 306 output by an
 307 .Cm s
 308 conversion character with the same field width
 309 and precision as the original conversion character or conversion
 310 string but with any
 311 .Dq Li \&+ ,
 312 .Dq \&\ \& ,
 313 .Dq Li \&#
 314 conversion flag characters
 315 removed, and referencing a NULL string.
 316 .Pp
 317 If no format strings are specified, the default display is a
 318 one-byte hexadecimal display.
 319 .Sh DIAGNOSTICS
 320 .Ex -std
 321 .Sh EXAMPLES
 322 Note that the following format strings, used with
 323 .Fl e ,
 324 must be enclosed in single quotes.
 325 .Pp
 326 Display the input in perusal format:
 327 .Bd -literal -offset indent
 328 "%06.6_ao "  12/1 "%3_u "
 329 "\et\et" "%_p "
 330 "\en"
 331 .Ed
 332 .Pp
 333 Implement the \-x option:
 334 .Bd -literal -offset indent
 335 "%07.7_Ax\en"
 336 "%07.7_ax  " 8/2 "%04x " "\en"
 337 .Ed
 338 .Sh SEE ALSO
 339 .Xr gdb 1 ,
 340 .Xr od 1