od(1)

NAME

od, xd — octal and hexadecimal dump

SYNOPSIS

od [-v] [-A address_base] [-j skip] [-N count] [-t type_string] ... [file ...]

xd [-v] [-A address_base] [-j skip] [-N count] [-t type_string] ... [file ...]

Supported Pre-POSIX Usage

od [-bcdosx] [file] [[+][0x]offset [.][b]]

xd [-bcdosx] [file] [[+][0x]offset [.][b]]

DESCRIPTION

od and xd concatenate one or more input files and write their contents to standard output in a user-specified format. If file is not specified, the standard input is used.

Options and Arguments

od and xd recognize the following options and command-line arguments:

-A address_base

Specify the input offset base. address_base is a single character that defines which format the offset base is written in:

d: Decimal format.
o: Octal format.
x: Hexadecimal format.
n: Do not write the offset.

-j skip

Jump over skip bytes from the beginning of the input. od seeks past the first skip bytes in the concatenated input files. If the combined input is not at least skip bytes long, od writes a diagnostic message to standard error and exits with a non-zero exit status. By default, skip is interpreted as a decimal number. If skip has a leading 0x or 0X, it is interpreted as a hexadecimal number; a leading 0 indicates that skip is an octal number.

If the value of skip is followed by a b, k, or m, it is interpreted as a multiple of 512, 1024, or 1048576, respectively.

-N count

Format no more than count bytes of input.

By default, count is interpreted as a decimal number. A leading 0x or 0X indicates that count is a hexadecimal number; a leading 0 identifies an octal value.

If count bytes of input are not available (after successfully skipping if -jskip is specified), the input that is available is formatted.

-t type_string

type_string is a string defining the types to be used when writing the input data.

The string can contain any of the following type-specification characters:

a: named character ,
c: character ,
d: signed decimal ,
f: floating point ,
o: octal ,
u: unsigned decimal ,
x: hexadecimal ,

Type specification characters d, f, o, u, and x can be followed by an optional unsigned decimal integer specifying the number of bytes to be transformed by each instance of the output type, or by an optional C, S, I, or L indicating that the conversion should be applied to an item of type char, short, int, or long, respectively.

Type specification character f can be followed by an optional F, D, or L indicating that the conversion should be applied to an item of type float, double, or long double, respectively.

Multiple types can be concatenated within the same type_string and multiple -t options can be specified. Output lines are written for each type specified in the order in which the type specification characters appear.

-v

Write all input data. Without the -v option, any number of groups of output lines, that would be identical to the immediately preceding group of output lines (except for the byte offsets), are replaced with a line containing only an asterisk (*).

file

Pathname of one or more input files to be processed. If file is not specified, the standard input is used.

Input files can be any file type.

DESCRIPTION OF PRE-POSIX USAGE

od and xd dump file in one or more formats as selected by the first argument. If the first argument is missing, the default is -o for od; -x for xd. An offset field is inserted at the beginning of each line. For od, the offset is in octal, for xd, the offset is in hexadecimal.

Options

od and xd recognize the following format options:

-b: Interpret bytes in octal (hexadecimal).
-c: Interpret bytes in ASCII. Certain non-graphic characters appear as C escapes: null=\0, backspace=\b, form-feed=\f, new-line=\n, return=\r, tab=\t; others appear as 3-digit octal numbers.
-d: Interpret 16-bit words in decimal.
-o: Interpret 16-bit words in octal.
-s: Interpret 16-bit words in signed decimal.
-x: Interpret 16-bit words in hexadecimal.

file specifies which file is to be dumped. If file is not specified, the standard input is used.

offset specifies the offset in the file where dumping is to commence, and is normally interpreted as octal bytes. Interpretation can be altered as follows:

offset must be preceded by + if the file argument is omitted.
offset preceded by 0x is interpreted in hexadecimal.
offset followed by . is interpreted in decimal.
offset followed by b is interpreted in blocks of 512 bytes.

Dumping continues until end-of-file.

EXAMPLES

Write hexadecimal bytes and the corresponding octal values to the standard output in blocks of 16 bytes in one line, by transforming the data from the input file file1:

od -tx1oC file1 

The following commands write one line each of the types character, signed decimal integer, and float, in the order given, transforming 100 bytes of data starting from fifteenth byte offset in the file file1:

od -j14 -N100 -tc -tdfF file1 
od -j0xe -N100 -tcd4fF file1 

Write one line each of the types unsigned integer, named character, and long double, with the offsets written in hexadecimal and forcing a write, even on lines that are identical to the immediately preceding group of output lines:

od -v -Ax -tuafL file1 

WARNINGS

When the output format is of floating-point type (using the -t fD, -t fL, or -t f options), the following actions occur:

If the input bytes cannot be transformed into a valid floating point number, a floating point exception might occur. In that case, the output is printed as a string containing some non-numeric characters and program execution continues.
When the number of input bytes used for transformation is set to 1 with the type specifier characters d, o, u, or x, only the least-significant seven bits of each byte are used.
When one or more of the -A, -j, -N, or -t options is specified, an operand starting with the first character as a plus-sign (+) or the first character as numeric is interpreted as a file name.

(UNIX Standard only, see standards(5). Multiple types can be specified by using multiple -bcdox options. Output lines are written for each type specified in the order in which the types are specified.)

EXTERNAL INFLUENCES

For information about the UNIX standard environment, see standards(5).

Environment Variables

LANG provides a default value for the internationalization variables that are unset or null. If LANG is unset or null, the default value of "C" (see lang(5)) is used. If any of the internationalization variables contains an invalid setting, od will behave as if all internationalization variables are set to "C". See environ(5).

LC_ALL If set to a non-empty string value, overrides the values of all the other internationalization variables.

LC_CTYPE determines the interpretation of text as single and/or multi-byte characters, the classification of characters as printable, and the characters matched by character class expressions in regular expressions.

LC_MESSAGES determines the locale that should be used to affect the format and contents of diagnostic messages written to standard error and informative messages written to standard output.

NLSPATH determines the location of message catalogues for the processing of LC_MESSAGES.

International Code Set Support

Single- and multi-byte character code sets are supported. Multi-byte data is displayed as multi-byte values.

RETURN VALUE

Exit values are:

0: Successful completion.
>0: Error condition occurred.

STANDARDS CONFORMANCE

od: SVID2, SVID3, XPG2, XPG3, XPG4, POSIX.2