shell_cmds/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 .Cm m ,
 117 or
 118 .Cm g
 119 to
 120 .Ar offset
 121 causes it to be interpreted as a multiple of
 122 .Li 512 ,
 123 .Li 1024 ,
 124 .Li 1048576 ,
 125 or
 126 .Li 1073741824 ,
 127 respectively.
 128 .It Fl v
 129 Cause
 130 .Nm
 131 to display all input data.
 132 Without the
 133 .Fl v
 134 option, any number of groups of output lines, which would be
 135 identical to the immediately preceding group of output lines (except
 136 for the input offsets), are replaced with a line comprised of a
 137 single asterisk.
 138 .It Fl x
 139 .Em Two-byte hexadecimal display .
 140 Display the input offset in hexadecimal, followed by eight, space
 141 separated, four column, zero-filled, two-byte quantities of input
 142 data, in hexadecimal, per line.
 143 .El
 144 .Pp
 145 For each input file,
 146 .Nm
 147 sequentially copies the input to standard output, transforming the
 148 data according to the format strings specified by the
 149 .Fl e
 150 and
 151 .Fl f
 152 options, in the order that they were specified.
 153 .Ss Formats
 154 A format string contains any number of format units, separated by
 155 whitespace.
 156 A format unit contains up to three items: an iteration count, a byte
 157 count, and a format.
 158 .Pp
 159 The iteration count is an optional positive integer, which defaults to
 160 one.
 161 Each format is applied iteration count times.
 162 .Pp
 163 The byte count is an optional positive integer.
 164 If specified it defines the number of bytes to be interpreted by
 165 each iteration of the format.
 166 .Pp
 167 If an iteration count and/or a byte count is specified, a single slash
 168 must be placed after the iteration count and/or before the byte count
 169 to disambiguate them.
 170 Any whitespace before or after the slash is ignored.
 171 .Pp
 172 The format is required and must be surrounded by double quote
 173 (" ") marks.
 174 It is interpreted as a fprintf-style format string (see
 175 .Xr fprintf 3 ) ,
 176 with the
 177 following exceptions:
 178 .Bl -bullet -offset indent
 179 .It
 180 An asterisk (*) may not be used as a field width or precision.
 181 .It
 182 A byte count or field precision
 183 .Em is
 184 required for each ``s'' conversion
 185 character (unlike the
 186 .Xr fprintf 3
 187 default which prints the entire string if the precision is unspecified).
 188 .It
 189 The conversion characters ``h'', ``l'', ``n'', ``p'' and ``q'' are
 190 not supported.
 191 .It
 192 The single character escape sequences
 193 described in the C standard are supported:
 194 .Bd -ragged -offset indent -compact
 195 .Bl -column <alert_character>
 196 .It "NUL        \e0
 197 .It "<alert character>  \ea
 198 .It "<backspace>        \eb
 199 .It "<form-feed>        \ef
 200 .It "<newline>  \en
 201 .It "<carriage return>  \er
 202 .It "<tab>      \et
 203 .It "<vertical tab>     \ev
 204 .El
 205 .Ed
 206 .El
 207 .Pp
 208 The
 209 .Nm
 210 utility also supports the following additional conversion strings:
 211 .Bl -tag -width Fl
 212 .It Cm \&_a Ns Op Cm dox
 213 Display the input offset, cumulative across input files, of the
 214 next byte to be displayed.
 215 The appended characters
 216 .Cm d ,
 217 .Cm o ,
 218 and
 219 .Cm x
 220 specify the display base
 221 as decimal, octal or hexadecimal respectively.
 222 .It Cm \&_A Ns Op Cm dox
 223 Identical to the
 224 .Cm \&_a
 225 conversion string except that it is only performed
 226 once, when all of the input data has been processed.
 227 .It Cm \&_c
 228 Output characters in the default character set.
 229 Nonprinting characters are displayed in three character, zero-padded
 230 octal, except for those representable by standard escape notation
 231 (see above),
 232 which are displayed as two character strings.
 233 .It Cm _p
 234 Output characters in the ASCII character set.
 235 Non-ASCII characters are displayed as a single
 236 .Dq Cm \&. .
 237 .It Cm _u
 238 Output US
 239 .Tn ASCII
 240 characters, with the exception that control characters are
 241 displayed using the following, lower-case, names.
 242 Characters greater than 0xff, hexadecimal, are displayed as hexadecimal
 243 strings.
 244 .Bl -column \&000_nu \&001_so \&002_st \&003_et \&004_eo
 245 .It "\&000\ NUL\t001\ SOH\t002\ STX\t003\ ETX\t004\ EOT\t005\ ENQ
 246 .It "\&006\ ACK\t007\ BEL\t008\ BS\t009\ HT\t00A\ LF\t00B\ VT
 247 .It "\&00C\ FF\t00D\ CR\t00E\ SO\t00F\ SI\t010\ DLE\t011\ DC1
 248 .It "\&012\ DC2\t013\ DC3\t014\ DC4\t015\ NAK\t016\ SYN\t017\ ETB
 249 .It "\&018\ CAN\t019\ EM\t01A\ SUB\t01B\ ESC\t01C\ FS\t01D\ GS
 250 .It "\&01E\ RS\t01F\ US\t0FF\ DEL
 251 .El
 252 .El
 253 .Pp
 254 The default and supported byte counts for the conversion characters
 255 are as follows:
 256 .Bl -tag -width  "Xc,_Xc,_Xc,_Xc,_Xc,_Xc" -offset indent
 257 .It Li \&%_c , \&%_p , \&%_u , \&%c
 258 One byte counts only.
 259 .It Xo
 260 .Li \&%d , \&%i , \&%o ,
 261 .Li \&%u , \&%X , \&%x
 262 .Xc
 263 Four byte default, one, two and four byte counts supported.
 264 .It Xo
 265 .Li \&%E , \&%e , \&%f ,
 266 .Li \&%G , \&%g
 267 .Xc
 268 Eight byte default, four and twelve byte counts supported.
 269 .El
 270 .Pp
 271 The amount of data interpreted by each format string is the sum of the
 272 data required by each format unit, which is the iteration count times the
 273 byte count, or the iteration count times the number of bytes required by
 274 the format if the byte count is not specified.
 275 .Pp
 276 The input is manipulated in ``blocks'', where a block is defined as the
 277 largest amount of data specified by any format string.
 278 Format strings interpreting less than an input block's worth of data,
 279 whose last format unit both interprets some number of bytes and does
 280 not have a specified iteration count, have the iteration count
 281 incremented until the entire input block has been processed or there
 282 is not enough data remaining in the block to satisfy the format string.
 283 .Pp
 284 If, either as a result of user specification or
 285 .Nm
 286 modifying
 287 the iteration count as described above, an iteration count is
 288 greater than one, no trailing whitespace characters are output
 289 during the last iteration.
 290 .Pp
 291 It is an error to specify a byte count as well as multiple conversion
 292 characters or strings unless all but one of the conversion characters
 293 or strings is
 294 .Cm \&_a
 295 or
 296 .Cm \&_A .
 297 .Pp
 298 If, as a result of the specification of the
 299 .Fl n
 300 option or end-of-file being reached, input data only partially
 301 satisfies a format string, the input block is zero-padded sufficiently
 302 to display all available data (i.e., any format units overlapping the
 303 end of data will display some number of the zero bytes).
 304 .Pp
 305 Further output by such format strings is replaced by an equivalent
 306 number of spaces.
 307 An equivalent number of spaces is defined as the number of spaces
 308 output by an
 309 .Cm s
 310 conversion character with the same field width
 311 and precision as the original conversion character or conversion
 312 string but with any
 313 .Dq Li \&+ ,
 314 .Dq \&\ \& ,
 315 .Dq Li \&#
 316 conversion flag characters
 317 removed, and referencing a NULL string.
 318 .Pp
 319 If no format strings are specified, the default display is a
 320 one-byte hexadecimal display.
 321 .Sh DIAGNOSTICS
 322 .Ex -std
 323 .Sh EXAMPLES
 324 Note that the following format strings, used with
 325 .Fl e ,
 326 must be enclosed in single quotes.
 327 .Pp
 328 Display the input in perusal format:
 329 .Bd -literal -offset indent
 330 "%06.6_ao "  12/1 "%3_u "
 331 "\et\et" "%_p "
 332 "\en"
 333 .Ed
 334 .Pp
 335 Implement the \-x option:
 336 .Bd -literal -offset indent
 337 "%07.7_Ax\en"
 338 "%07.7_ax  " 8/2 "%04x " "\en"
 339 .Ed
 340 .Sh SEE ALSO
 341 .Xr gdb 1 ,
 342 .Xr od 1