make a hexdump or do the reverse.
xxd -h[elp] xxd [options] [infile [outfile]] xxd -r[evert] [options] [infile [outfile]]
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.
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
-c cols | -cols cols
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.
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
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
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.
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
uuencode(1), uudecode(1), patch(1)
(c) 1990-1997 by Juergen Weigert