MAN page from Trustix vim-5.7-3tr.i586.rpm


Section: User Commands (1)
Updated: August 1996


xxd- make a hexdump or do the reverse. 


xxd[options] [infile [outfile]]
xxd-r[evert] [options] [infile [outfile]] 


xxdcreates a hex dump of a given file or standard input.It can also convert a hex dump back to its original binary form.Likeuuencode(1)anduudecode(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. 


If noinfileis given, standard input is read.Ifinfileis specified as a`-'character, then input is taken from standard input.If nooutfileis given (or a`-'character is in its place), results are sent to standard output.

Note that a "lazy" parser is used which does not check for more than the firstoption letter, unless the option is followed by a parameter.Spaces between a single option letter and its parameter are optional.Parameters to options can be specified in decimal, hexadecimal or octalnotation.Thus-c8,-c 8,-c 010and-cols 8are all equivalent.

-a | -autoskip
toggle autoskip: A single '*' replaces nul-lines. Default off.
-b | -bits
Switch to bits (binary digits) dump, rather than hexdump.This option writes octets as eight digits "1"s and "0"s instead of a normalhexacecimal dump. Each line is preceded by a line number in hexadecimal andfollowed by an ascii (or ebcdic) representation. The command line switches-r, -p, -i do not work with this mode.
-c cols | -cols cols
-c cols | -cols colsformat<cols>octets per line. Default 16 (-i: 12, -ps: 30, -b: 6). Max 256.
Change the character encoding in the righthand column from ASCII to EBCDIC.This does not change the hexadecimal representation. The option ismeaningless in combinations with -r, -p or -i.
-g bytes | -groupsize bytes
seperate the output of every<bytes>bytes (two hex characters or eight bit-digits each) by a whitespace.Specify-g 0to suppress grouping.<Bytes> defaults to 2in normal mode and 1 in bits mode.Grouping does not apply to postscript or include style.
-h | -help
print a summary of available commands and exit. No hex dumping is performed.
-i | -include
output in C include file style. A complete static array definition is written(named after the input file), unless xxd reads from stdin.
-l len | -len len
stop after writing<len>octets.
-p | -ps | -postscript | -plain
output in postscript continuous hexdump style. Also known as plain hexdumpstyle.
-r | -revert
reverse operation: convert (or patch) hexdump into binary.If not writing to stdout, xxd writes into its output file without truncatingit. Use the combination-r -pto read plain hexadecimal dumps without line number information and without aparticular column layout. Additional Whitespace and line-breaks are allowedanywhere.
-seek offset
When used after-r: revert with<offset>added to file positions found in hexdump.
-s [+][-]seek
start at<seek>bytes abs. (or rel.) infile offset.+ indicates that the seek is relative to the current stdin file position(meaningless when not reading from stdin). - indicates that the seekshould be that many characters from the end of the input (or if combined with + : before the current stdin file position).Without -s option, xxd starts at the current file position.
use upper case hex letters. Default is lower case.
-v | -version
show version string.


xxd -rhas some builtin magic while evaluating line number information.If the ouput file is seekable, then the linenumbers at the start of eachhexdump line may be out of order, lines may be missing, or overlapping. Inthese cases xxd will lseek(2) to the next position. If the output file is notseekable, only gaps are allowed, which will be filled by null-bytes.

xxd -rnever generates parse errors. Garbage is silently skipped.

When editing hexdumps, please note thatxxd -rskips everything on the input line after reading enough columns of hexadecimaldata (see option -c). This also means, that changes to the printable ascii (orebcdic) columns are always ignored. Reverting a plain (or postscript) stylehexdump with xxd -r -p does not depend on the correct number of columns. Here an thing that looks like a pair of hex-digits is interpreted.

Note the difference between
% xxd -i file
% xxd -i < file

xxd -s +seekmay be different fromxxd -s seek, as lseek(2) is used to "rewind" input. A '+'makes a difference if the input source is stdin, and if stdin's file positionis not at the start of the file by the time xxd is started and given its input.The following examples may help to clarify (or further confuse!)...

Rewind stdin before reading; needed because the `cat' has already read to theend of stdin.
% sh -c 'cat > plain_copy; xxd -s 0 > hex_copy' < file

Hexdump from file position 0x480 (=1024+128) onwards.The `+' sign means "relative to the current position", thus the `128' adds tothe 1k where dd left off.
% sh -c 'dd of=plain_snippet bs=1k count=1; xxd -s +128 > hex_snippet' < file

Hexdump from file position 0x100 ( = 1024-768) on.
% sh -c 'dd of=plain_snippet bs=1k count=1; xxd -s +-768 > hex_snippet' < file

However, this is a rare situation and the use of `+' is rarely needed.the author prefers to monitor the effect of xxd with strace(1) or truss(1), whenever -s is used. 


Print everything but the first three lines (hex 0x30 bytes) offile.
% xxd -s 0x30 file

Print 3 lines (hex 0x30 bytes) from the end of
% xxd -s -0x30 file

Print 120 bytes as continuous hexdump with 40 octets per line.
% xxd -l 120 -ps -c 20 xxd.1


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 224d .TH XXD 1 "M
000000c: 616e 7561 6c20 7061 6765 2066 anual page f
0000018: 6f72 2078 7864 220a 2e5c 220a or xxd"..\".
0000024: 2e5c 2220 3231 7374 204d 6179 .\" 21st May
0000030: 2031 3939 360a 2e5c 2220 4d61 1996..\" Ma
000003c: 6e20 7061 6765 2061 7574 686f n page autho
0000048: 723a 0a2e 5c22 2020 2020 546f r:..\" To
0000054: 6e79 204e 7567 656e 7420 3c74 ny Nugent <t
0000060: 6f6e 7940 7363 746e 7567 656e onyAATTsctnugen
000006c: 2e70 7070 2e67 752e 6564 752e

Display just the date from the file xxd.1
% xxd -s 0x28 -l 12 -c 12 xxd.1
0000028: 3231 7374 204d 6179 2031 3939 21st May 199

Copyinput_filetooutput_fileand prepend 100 bytes of value 0x00.
% xxd input_file | xxd -r -s 100 > output_file

Patch the date in the file xxd.1
% echo '0000029: 3574 68' | xxd -r - xxd.1
% xxd -s 0x28 -l 12 -c 12 xxd.1
0000028: 3235 7468 204d 6179 2031 3939 25th May 199

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

Hexdump this file with autoskip.
% xxd -a -c 12 file
0000000: 0000 0000 0000 0000 0000 0000 ............
000fffc: 0000 0000 40 ....A

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 asvim(1)to hexdump a region marked between `a' and `z'.

Use xxd as a filter within an editor such asvim(1)to recover a binary hexdump marked between `a' and `z'.
:'a,'z!xxd -r

Use xxd as a filter within an editor such asvim(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



The following error values are returned:
no errors encountered.
operation not supported (xxd -r -istill impossible).
error while parsing options.
problems with input file.
problems with output file.
desired seek position is unreachable.


uuencode(1), uudecode(1), patch(1)


The tools weirdness matches its creators brain.Use entirely at your own risk. Copy files. Trace it. Become a wizard.


This manual page documents xxd version 1.7 


(c) 1990-1997 by Juergen Weigert

Distribute freely and credit me,
make money and share with me,
lose money and don't ask me.

Manual page started by Tony Nugent
<> <>
Small changes by Bram Moolenaar.Edited by Juergen Weigert.




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