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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 represen-
tation, but has the advantage of decoding to standard out-
put. Moreover, it can be used to perform binary file patch-
ing.
OPTIONS
If no infile is given, standard input is read. If infile is
specified as a `-' character, then input is taken from stan-
dard 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 fol-
lowed 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 hex-
dump. This option writes octets as eight digits "1"s
and "0"s instead of a normal hexacecimal dump. Each
line is preceded by a line number in hexadecimal 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
-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 hexade-
cimal representation. The option is meaningless in com-
binations 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 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 |
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 hexadecimal dumps without line
number information and without a particular column lay-
out. 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 ouput 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 every-
thing on the input line after reading enough columns of hex-
adecimal 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
columns. Here an thing 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 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 40 octets per
line.
% xxd -l 120 -ps -c 20 xxd.1
2e544820585844203120224d616e75616c207061
676520666f7220787864220a2e5c220a2e5c2220
32317374204d617920313939360a2e5c22204d61
6e207061676520617574686f723a0a2e5c222020
2020546f6e79204e7567656e74203c746f6e7940
7363746e7567656e2e7070702e67752e6564752e
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 ony@sctnugen
000006c: 2e70 7070 2e67 752e 6564 752e .ppp.gu.edu.
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
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 '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 as vim(1) to hex-
dump 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
<[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.
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