Difference between revisions of "Xxd"

Revision as of 02:28, 31 May 2012

xxd' is a Linux command that creates a hex dump of a given file or standard input. It can also convert a hex dump back to its original binary form. Like uuencode(1) and uudecode(1) it allows the transmission of binary data in a 'mail-safe' ASCII representation, but has the advantage of decoding to standard output. Moreover, it can be used to perform binary file patching.

Examples

Note: The following are taken directly from the man pages (with some extra additions by me).

• Print everything but the first three lines (hex 0x30 bytes) of file.

% xxd -s 0x30 file

• Print 3 lines (hex 0x30 bytes) from the end of file.

% xxd -s -0x30 file

• Print 120 bytes as continuous hexdump with 20 octets per line.

% xxd -l 120 -ps -c 20 xxd.1
2e54482058584420312022417567757374203139
39362220224d616e75616c207061676520666f72
20787864220a2e5c220a2e5c222032317374204d
617920313939360a2e5c22204d616e2070616765
20617574686f723a0a2e5c2220202020546f6e79
204e7567656e74203c746f6e79407363746e7567

• Hexdump the first 120 bytes of this man page with 12 octets per line.

% xxd -l 120 -c 12 xxd.1
0000000: 2e54 4820 5858 4420 3120 2241 .TH XXD 1 "A
000000c: 7567 7573 7420 3139 3936 2220 ugust 1996"
0000018: 224d 616e 7561 6c20 7061 6765 "Manual page
0000024: 2066 6f72 2078 7864 220a 2e5c for xxd"..\
0000030: 220a 2e5c 2220 3231 7374 204d "..\" 21st M
000003c: 6179 2031 3939 360a 2e5c 2220 ay 1996..\"
0000048: 4d61 6e20 7061 6765 2061 7574 Man page aut
0000054: 686f 723a 0a2e 5c22 2020 2020 hor:..\"
0000060: 546f 6e79 204e 7567 656e 7420 Tony Nugent
000006c: 3c74 6f6e 7940 7363 746e 7567 <tony@sctnug

• Display just the date from the file xxd.1

% xxd -s 0x36 -l 13 -c 13 xxd.1
0000036: 3231 7374 204d 6179 2031 3939 36 21st May 1996

• Copy input_file to output_file and prepend 100 bytes of value 0x00.

% xxd input_file | xxd -r -s 100 > output_file

• Patch the date in the file xxd.1

% echo "0000037: 3574 68" | xxd -r - xxd.1
% xxd -s 0x36 -l 13 -c 13 xxd.1
0000036: 3235 7468 204d 6179 2031 3939 36 25th May 1996

• Create a 65537 byte file with all bytes 0x00, except for the last one which is 'A' (hex 0x41).

% echo "010000: 41" | xxd -r > file

• Create a 1 byte file containing a single 'A' character. The number after '-r -s' adds to the linenumbers found in the file; in effect, the leading bytes are suppressed.

% echo "010000: 41" | xxd -r -s -0x10000 > file

• Use xxd as a filter within an editor such as vim(1) to hexdump a region marked between 'a' and 'z'.

:'a,'z!xxd

• Use xxd as a filter within an editor such as vim(1) to recover a binary hexdump marked between 'a' and 'z'.

:'a,'z!xxd -r

• Use xxd as a filter within an editor such as vim(1) to recover one line of a hexdump. Move the cursor over the line and type:

!!xxd -r

• Read single characters from a serial line

% xxd -c1 < /dev/term/b &
% stty < /dev/term/b -echo -opost -isig -icanon min 1
% echo -n foo > /dev/term/b

Miscellaneous

• Convert tab characters into groups of space characters:

$ echo -e "foo\tbar" | expand | xxd -g 1 -u
0000000: 66 6F 6F 20 20 20 20 20 62 61 72 0A              foo     bar.
$ echo -e "foo\tbar" | xxd -g 1 -u
0000000: 66 6F 6F 09 62 61 72 0A                          foo.bar.
$

• Convert groups of space characters into tab characters:

$ echo "                 asdf sdf" | unexpand | od -c
0000000  \t  \t       a   s   d   f       s   d   f  \n
0000014
$ echo "                 asdf sdf" | od -c
0000000
0000020       a   s   d   f       s   d   f  \n
0000032

See also

• uuencode
• hexdump
• od
• Coreutils

External links

• xxd man page