File: coreutils.info,  Node: od invocation,  Next: base32 invocation,  Prev: nl invocation,  Up: Output of entire files

3.4 ‘od’: Write files in octal or other formats
===============================================

‘od’ writes an unambiguous representation of each FILE (‘-’ means
standard input), or standard input if none are given.  Synopses:

     od [OPTION]... [FILE]...
     od [-abcdfilosx]... [FILE] [[+]OFFSET[.][b]]
     od [OPTION]... --traditional [FILE] [[+]OFFSET[.][b] [[+]LABEL[.][b]]]

   Each line of output consists of the offset in the input, followed by
groups of data from the file.  By default, ‘od’ prints the offset in
octal, and each group of file data is a C ‘short int’’s worth of input
printed as a single octal number.

   If OFFSET is given, it specifies how many input bytes to skip before
formatting and writing.  By default, it is interpreted as an octal
number, but the optional trailing decimal point causes it to be
interpreted as decimal.  If no decimal is specified and the offset
begins with ‘0x’ or ‘0X’ it is interpreted as a hexadecimal number.  If
there is a trailing ‘b’, the number of bytes skipped will be OFFSET
multiplied by 512.

   If a command is of both the first and second forms, the second form
is assumed if the last operand begins with ‘+’ or (if there are two
operands) a digit.  For example, in ‘od foo 10’ and ‘od +10’ the ‘10’ is
an offset, whereas in ‘od 10’ the ‘10’ is a file name.

   The program accepts the following options.  Also see *note Common
options::.

‘-A RADIX’
‘--address-radix=RADIX’
     Select the base in which file offsets are printed.  RADIX can be
     one of the following:

     ‘d’
          decimal;
     ‘o’
          octal;
     ‘x’
          hexadecimal;
     ‘n’
          none (do not print offsets).

     The default is octal.

‘--endian=ORDER’
     Reorder input bytes, to handle inputs with differing byte orders,
     or to provide consistent output independent of the endian
     convention of the current system.  Swapping is performed according
     to the specified ‘--type’ size and endian ORDER, which can be
     ‘little’ or ‘big’.

‘-j BYTES’
‘--skip-bytes=BYTES’
     Skip BYTES input bytes before formatting and writing.  If BYTES
     begins with ‘0x’ or ‘0X’, it is interpreted in hexadecimal;
     otherwise, if it begins with ‘0’, in octal; otherwise, in decimal.
     BYTES may be, or may be an integer optionally followed by, one of
     the following multiplicative suffixes:
          ‘b’  =>            512 ("blocks")
          ‘KB’ =>           1000 (KiloBytes)
          ‘K’  =>           1024 (KibiBytes)
          ‘MB’ =>      1000*1000 (MegaBytes)
          ‘M’  =>      1024*1024 (MebiBytes)
          ‘GB’ => 1000*1000*1000 (GigaBytes)
          ‘G’  => 1024*1024*1024 (GibiBytes)
     and so on for ‘T’, ‘P’, ‘E’, ‘Z’, ‘Y’, ‘R’, and ‘Q’.  Binary
     prefixes can be used, too: ‘KiB’=‘K’, ‘MiB’=‘M’, and so on.

‘-N BYTES’
‘--read-bytes=BYTES’
     Output at most BYTES bytes of the input.  Prefixes and suffixes on
     ‘bytes’ are interpreted as for the ‘-j’ option.

‘-S BYTES’
‘--strings[=BYTES]’
     Instead of the normal output, output only “string constants”: at
     least BYTES consecutive ASCII graphic characters, followed by a
     zero byte (ASCII NUL). Prefixes and suffixes on BYTES are
     interpreted as for the ‘-j’ option.

     If BYTES is omitted with ‘--strings’, the default is 3.

‘-t TYPE’
‘--format=TYPE’
     Select the format in which to output the file data.  TYPE is a
     string of one or more of the below type indicator characters.  If
     you include more than one type indicator character in a single TYPE
     string, or use this option more than once, ‘od’ writes one copy of
     each output line using each of the data types that you specified,
     in the order that you specified.

     Adding a trailing “z” to any type specification appends a display
     of the single byte character representation of the printable
     characters to the output line generated by the type specification.

     ‘a’
          named character, ignoring high-order bit
     ‘c’
          printable single byte character, C backslash escape or a 3
          digit octal sequence
     ‘d’
          signed decimal
     ‘f’
          floating point (*note Floating point::)
     ‘o’
          octal
     ‘u’
          unsigned decimal
     ‘x’
          hexadecimal

     The type ‘a’ outputs things like ‘sp’ for space, ‘nl’ for newline,
     and ‘nul’ for a zero byte.  Only the least significant seven bits
     of each byte is used; the high-order bit is ignored.  Type ‘c’
     outputs ‘ ’, ‘\n’, and ‘\0’, respectively.

     Except for types ‘a’ and ‘c’, you can specify the number of bytes
     to use in interpreting each number in the given data type by
     following the type indicator character with a decimal integer.
     Alternately, you can specify the size of one of the C compiler’s
     built-in data types by following the type indicator character with
     one of the following characters.  For integers (‘d’, ‘o’, ‘u’,
     ‘x’):

     ‘C’
          char
     ‘S’
          short
     ‘I’
          int
     ‘L’
          long

     For floating point (‘f’):

     F
          float
     D
          double
     L
          long double

‘-v’
‘--output-duplicates’
     Output consecutive lines that are identical.  By default, when two
     or more consecutive output lines would be identical, ‘od’ outputs
     only the first line, and puts just an asterisk on the following
     line to indicate the elision.

‘-w[N]’
‘--width[=N]’
     Dump ‘n’ input bytes per output line.  This must be a multiple of
     the least common multiple of the sizes associated with the
     specified output types.

     If this option is not given at all, the default is 16.  If N is
     omitted, the default is 32.

   The next several options are shorthands for format specifications.
GNU ‘od’ accepts any combination of shorthands and format specification
options.  These options accumulate.

‘-a’
     Output as named characters.  Equivalent to ‘-t a’.

‘-b’
     Output as octal bytes.  Equivalent to ‘-t o1’.

‘-c’
     Output as printable single byte characters, C backslash escapes or
     3 digit octal sequences.  Equivalent to ‘-t c’.

‘-d’
     Output as unsigned decimal two-byte units.  Equivalent to ‘-t u2’.

‘-f’
     Output as floats.  Equivalent to ‘-t fF’.

‘-i’
     Output as decimal ints.  Equivalent to ‘-t dI’.

‘-l’
     Output as decimal long ints.  Equivalent to ‘-t dL’.

‘-o’
     Output as octal two-byte units.  Equivalent to ‘-t o2’.

‘-s’
     Output as decimal two-byte units.  Equivalent to ‘-t d2’.

‘-x’
     Output as hexadecimal two-byte units.  Equivalent to ‘-t x2’.

‘--traditional’
     Recognize the non-option label argument that traditional ‘od’
     accepted.  The following syntax:

          od --traditional [FILE] [[+]OFFSET[.][b] [[+]LABEL[.][b]]]

     can be used to specify at most one file and optional arguments
     specifying an offset and a pseudo-start address, LABEL.  The LABEL
     argument is interpreted just like OFFSET, but it specifies an
     initial pseudo-address.  The pseudo-addresses are displayed in
     parentheses following any normal address.

   An exit status of zero indicates success, and a nonzero value
indicates failure.