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HEXDUMP(1)                BSD General Commands Manual               HEXDUMP(1)

NAME
     hexdump -- ASCII, decimal, hexadecimal, octal dump

SYNOPSIS
     hexdump [-bcCdovx] [-e format_string] [-f format_file] [-n length] [-s skip] file ...

DESCRIPTION
     The hexdump utility is a filter which displays the specified files, or the standard input, if no files
     are specified, in a user specified format.

     The options are as follows:

     -b      One-byte octal display.  Display the input offset in hexadecimal, followed by sixteen space-separated, spaceseparated,
             separated, three column, zero-filled, bytes of input data, in octal, per line.

     -C      Canonical hex+ASCII display.  Display the input offset in hexadecimal, followed by sixteen
             space-separated, two column, hexadecimal bytes, followed by the same sixteen bytes in %_p for-mat format
             mat enclosed in ``|'' characters.

     -c      One-byte character display.  Display the input offset in hexadecimal, followed by sixteen
             space-separated, three column, space-filled, characters of input data per line.

     -d      Two-byte decimal display.  Display the input offset in hexadecimal, followed by eight space-separated, spaceseparated,
             separated, five column, zero-filled, two-byte units of input data, in unsigned decimal, per
             line.

     -e format_string
             Specify a format string to be used for displaying data.

     -f format_file
             Specify a file that contains one or more newline separated format strings.  Empty lines and
             lines whose first non-blank character is a hash mark (#) are ignored.

     -n length
             Interpret only length bytes of input.

     -o      Two-byte octal display.  Display the input offset in hexadecimal, followed by eight space-sepa-rated, space-separated,
             rated, six column, zero-filled, two byte quantities of input data, in octal, per line.

     -s offset
             Skip offset bytes from the beginning of the input.  By default, offset is interpreted as a dec-imal decimal
             imal number.  With a leading 0x or 0X, offset is interpreted as a hexadecimal number, other-wise, otherwise,
             wise, with a leading 0, offset is interpreted as an octal number.  Appending the character b,
             k, or m to offset causes it to be interpreted as a multiple of 512, 1024, or 1048576, respec-tively. respectively.
             tively.

     -v      Cause hexdump to display all input data.  Without the -v option, any number of groups of output
             lines, which would be identical to the immediately preceding group of output lines (except for
             the input offsets), are replaced with a line comprised of a single asterisk.

     -x      Two-byte hexadecimal display.  Display the input offset in hexadecimal, followed by eight,
             space separated, four column, zero-filled, two-byte quantities of input data, in hexadecimal,
             per line.

     For each input file, hexdump sequentially copies the input to standard output, transforming the data
     according to the format strings specified by the -e and -f options, in the order that they were speci-fied. specified.
     fied.

   Formats
     A format string contains any number of format units, separated by whitespace.  A format unit contains
     up to three items: an iteration count, a byte count, and a format.

     The iteration count is an optional positive integer, which defaults to one.  Each format is applied
     iteration count times.

     The byte count is an optional positive integer.  If specified it defines the number of bytes to be
     interpreted by each iteration of the format.

     If an iteration count and/or a byte count is specified, a single slash must be placed after the itera-tion iteration
     tion count and/or before the byte count to disambiguate them.  Any whitespace before or after the slash
     is ignored.

     The format is required and must be surrounded by double quote (" ") marks.  It is interpreted as a
     fprintf-style format string (see fprintf(3)), with the following exceptions:

           •   An asterisk (*) may not be used as a field width or precision.

           •   A byte count or field precision is required for each ``s'' conversion character (unlike the
               fprintf(3) default which prints the entire string if the precision is unspecified).

           •   The conversion characters ``h'', ``l'', ``n'', ``p'' and ``q'' are not supported.

           •   The single character escape sequences described in the C standard are supported:

                     NUL                  \0
                     <alert character>    \a
                     <backspace>          \b
                     <form-feed>          \f
                     <newline>            \n
                     <carriage return>    \r
                     <tab>                \t
                     <vertical tab>       \v

     The hexdump utility also supports the following additional conversion strings:

     _a[dox]     Display the input offset, cumulative across input files, of the next byte to be displayed.
                 The appended characters d, o, and x specify the display base as decimal, octal or hexadeci-mal hexadecimal
                 mal respectively.

     _A[dox]     Identical to the _a conversion string except that it is only performed once, when all of
                 the input data has been processed.

     _c          Output characters in the default character set.  Nonprinting characters are displayed in
                 three character, zero-padded octal, except for those representable by standard escape nota-tion notation
                 tion (see above), which are displayed as two character strings.

     _p          Output characters in the ASCII character set.  Non-ASCII characters are displayed as a sin-gle single
                 gle ``.''.

     _u          Output US ASCII characters, with the exception that control characters are displayed using
                 the following, lower-case, names.  Characters greater than 0xff, hexadecimal, are displayed
                 as hexadecimal strings.

                 000 NUL  001 SOH  002 STX  003 ETX  004 EOT  005 ENQ
                 006 ACK  007 BEL  008 BS   009 HT   00A LF   00B VT
                 00C FF   00D CR   00E SO   00F SI   010 DLE  011 DC1
                 012 DC2  013 DC3  014 DC4  015 NAK  016 SYN  017 ETB
                 018 CAN  019 EM   01A SUB  01B ESC  01C FS   01D GS
                 01E RS   01F US   0FF DEL

     The default and supported byte counts for the conversion characters are as follows:

           %_c, %_p, %_u, %c       One byte counts only.

           %d, %i, %o, %u, %X, %x  Four byte default, one, two and four byte counts supported.

           %E, %e, %f, %G, %g      Eight byte default, four and twelve byte counts supported.

     The amount of data interpreted by each format string is the sum of the data required by each format
     unit, which is the iteration count times the byte count, or the iteration count times the number of
     bytes required by the format if the byte count is not specified.

     The input is manipulated in ``blocks'', where a block is defined as the largest amount of data speci-fied specified
     fied by any format string.  Format strings interpreting less than an input block's worth of data, whose
     last format unit both interprets some number of bytes and does not have a specified iteration count,
     have the iteration count incremented until the entire input block has been processed or there is not
     enough data remaining in the block to satisfy the format string.

     If, either as a result of user specification or hexdump modifying the iteration count as described
     above, an iteration count is greater than one, no trailing whitespace characters are output during the
     last iteration.

     It is an error to specify a byte count as well as multiple conversion characters or strings unless all
     but one of the conversion characters or strings is _a or _A.

     If, as a result of the specification of the -n option or end-of-file being reached, input data only
     partially satisfies a format string, the input block is zero-padded sufficiently to display all avail-able available
     able data (i.e., any format units overlapping the end of data will display some number of the zero
     bytes).

     Further output by such format strings is replaced by an equivalent number of spaces.  An equivalent
     number of spaces is defined as the number of spaces output by an s conversion character with the same
     field width and precision as the original conversion character or conversion string but with any ``+'',
     `` '', ``#'' conversion flag characters removed, and referencing a NULL string.

     If no format strings are specified, the default display is a one-byte hexadecimal display.

DIAGNOSTICS
     The hexdump utility exits 0 on success, and >0 if an error occurs.

EXAMPLES
     Note that the following format strings, used with -e, must be enclosed in single quotes.

     Display the input in perusal format:

           "%06.6_ao "  12/1 "%3_u "
           "\t\t" "%_p "
           "\n"

     Implement the -x option:

           "%07.7_Ax\n"
           "%07.7_ax  " 8/2 "%04x " "\n"

SEE ALSO
     gdb(1), od(1)

BSD                              July 10, 2004                             BSD