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XXD(1)									XXD(1)

NAME
       xxd - make a hexdump or do the reverse.

SYNOPSIS
       xxd -h[elp]
       xxd [options] [infile [outfile]]
       xxd -r[evert] [options] [infile [outfile]]

DESCRIPTION
       xxd  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	 stan-
       dard output.  Moreover, it can be used to perform binary	file patching.

OPTIONS
       If no infile is given, standard input is	read.  If infile is  specified
       as  a  `-'  character,  then input is taken from	standard input.	 If no
       outfile is 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 first option	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 octal
       notation.  Thus -c8, -c 8, -c 010 and -cols 8 are 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
	      normal hexadecimal dump. Each line is preceded by	a line	number
	      in  hexadecimal and followed by an ascii (or ebcdic) representa-
	      tion. The	command	line switches -r, -p, -i do not	work with this
	      mode.

       -c cols | -cols cols
	      format  <cols> octets per	line. Default 16 (-i: 12, -ps: 30, -b:
	      6). Max 256.

       -E | -EBCDIC
	      Change the character encoding in the righthand column from ASCII
	      to EBCDIC.  This does not	change the hexadecimal representation.
	      The option is meaningless	in combinations	with -r, -p or -i.

       -e     Switch to	little-endian hexdump.	This option treats byte	groups
	      as words in little-endian	byte order.  The default grouping of 4
	      bytes may	be changed using -g.  This option only applies to hex-
	      dump,  leaving  the  ASCII (or EBCDIC) representation unchanged.
	      The command line switches	-r, -p,	-i do not work with this mode.

       -g bytes	| -groupsize bytes
	      separate	the  output of every <bytes> bytes (two	hex characters
	      or eight bit-digits each)	by a whitespace.  Specify -g 0 to sup-
	      press grouping.  <Bytes> defaults	to 2 in	normal mode, 4 in lit-
	      tle-endian 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  defini-
	      tion  is	written	(named after the input file), unless xxd reads
	      from stdin.

       -l len |	-len len
	      stop after writing <len> octets.

       -o offset
	      add <offset> to the displayed file position.

       -p | -ps	| -postscript |	-plain
	      output in	postscript continuous hexdump  style.  Also  known  as
	      plain hexdump style.

       -r | -revert
	      reverse  operation:  convert (or patch) hexdump into binary.  If
	      not writing to stdout, xxd writes	into its output	 file  without
	      truncating it. Use the combination -r -p to read plain hexadeci-
	      mal dumps	without	line number information	and without a particu-
	      lar  column  layout.  Additional	Whitespace and line-breaks are
	      allowed anywhere.

       -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
	      seek should 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.

       -u     use upper	case hex letters. Default is lower case.

       -v | -version
	      show version string.

CAVEATS
       xxd -r has some builtin magic while evaluating line number information.
       If  the	output	file is	seekable, then the linenumbers at the start of
       each hexdump line may be	out of order, lines may	be missing,  or	 over-
       lapping.	 In these cases	xxd will lseek(2) to the next position.	If the
       output file is not seekable, only  gaps	are  allowed,  which  will  be
       filled by null-bytes.

       xxd -r never generates parse errors. Garbage is silently	skipped.

       When  editing hexdumps, please note that	xxd -r skips everything	on the
       input line after	reading	enough columns of hexadecimal data (see	option
       -c).  This  also	means, that changes to the printable ascii (or ebcdic)
       columns are always ignored. Reverting a	plain  (or  postscript)	 style
       hexdump	with  xxd  -r -p does not depend on the	correct	number of col-
       umns. Here anything that	looks like a  pair  of	hex-digits  is	inter-
       preted.

       Note the	difference between
       % xxd -i	file
       and
       % xxd -i	_ file

       xxd  -s +seek may be different from xxd -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  position	is 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 the end 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 to	the 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.

EXAMPLES
       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

       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 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

RETURN VALUES
       The following error values are returned:

       0      no errors	encountered.

       -1     operation	not supported (	xxd -r -i still	impossible).

       1      error while parsing options.

       2      problems with input file.

       3      problems with output file.

       4,5    desired seek position is unreachable.

SEE ALSO
       uuencode(1), uudecode(1), patch(1)

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

VERSION
       This manual page	documents xxd version 1.7

AUTHOR
       (c) 1990-1997 by	Juergen	Weigert
       <jnweiger@informatik.uni-erlangen.de>

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

       Manual page started by Tony Nugent
       <tony@sctnugen.ppp.gu.edu.au> <T.Nugent@sct.gu.edu.au>
       Small changes by	Bram Moolenaar.	 Edited	by Juergen Weigert.

Manual page for	xxd		  August 1996				XXD(1)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | CAVEATS | EXAMPLES | RETURN VALUES | SEE ALSO | WARNINGS | VERSION | AUTHOR

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