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Linux in a Nutshell

This directory of Linux commands is from Linux in a Nutshell, 5th Edition.

Click on any of the 687 commands below to get a description and list of available options. All links in the command summaries point to the online version of the book on Safari Bookshelf.

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hexdump [options] file

Display specified file or input in hexadecimal, octal, decimal, or ASCII format. Option flags are used to specify the display format.



Use a one-byte octal display, meaning the input offset is in hexadecimal and is followed by 16 three-column octal data bytes, filled in with zeroes and separated by spaces.


Use a one-byte character display, meaning the input offset is in hexadecimal and is followed by 16 three-column entries, filled in with zeroes and separated with spaces.


Canonical mode. Display hexadecimal offset, two sets of eight columns of hexadecimal bytes, then a | followed by the ASCII representation of those same bytes.


Use a two-byte decimal display. The input offset is again in hexadecimal, but the display has only eight entries per line, of five columns each, containing two bytes of unsigned decimal format.

-e format_string

Choose a format string to be used to transform the output data. Format strings consist of:

Iteration count

The iteration count is optional. It determines the number of times to use the transformation string. The number should be followed by a slash character (/) to distinguish it from the byte count.

Byte count

The number of bytes to be interpreted by the conversion string. It should be preceded by a slash character to distinguish it from the iteration count.

Format characters

The actual format characters should be surrounded by quotation marks and are interpreted as fprintf (see printf) formatting strings, although the *, h, l, n, p, and q options will not work as expected. Format string usage is discussed at greater length in the hexdump manpage.

-f filename

Choose a file that contains several format strings. The strings should be separated by newlines; the # character marks a line as a comment.

-n length

Limit the number of bytes of input to be interpreted.


Two-byte octal display, meaning a hexadecimal offset followed by eight five-column data entries of two bytes each, in octal format.

-s offset

Skip to specified offset. The offset number is assumed to be decimal unless it starts with 0x or 0X (hexadecimal), or O (octal). Numbers may also be designated in megabytes, kilobytes, or half-kilobytes with the addition of m, k, or b at the end of the number.


Display all input data, even if it is the same as the previous line. Normally, a duplicate line is replaced by an asterisk (*).


Display data in a two-byte hexadecimal format. The offset is, as usual, in hexadecimal, and is followed by eight space-separated entries, each of which contains four-column, two-byte chunks of data in hexadecimal format.

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