XXD(1) General Commands Manual 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 standard output. Moreover, it can be used to per‐
form 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 stan‐
dard 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 hexadeci‐
mal and followed by an ascii (or ebcdic) representation. 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.
-g bytes | -groupsize bytes
separate the output of every <bytes> bytes (two hex characters or eight bit-digits each) by a white‐
space. Specify -g 0 to suppress grouping. <Bytes> defaults to 2 in 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
start at <seek> bytes abs. (or rel.) infile offset. + indicates that the seek is relative to the cur‐
rent 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 overlapping.
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 cor‐
rect number of columns. Here anything that looks like a pair of hex-digits is interpreted.
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 differ‐
ence 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
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).
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
<[email protected]>
Distribute freely and credit me,
make money and share with me,
lose money and don't ask me.
Manual page started by Tony Nugent
<[email protected]> <[email protected]>
Small changes by Bram Moolenaar. Edited by Juergen Weigert.
Manual page for xxd August 1996 XXD(1)
Back to main site | Back to man page index