|
xxd − make a hexdump or do the reverse. |
|
xxd −h[elp] |
|
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 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) 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 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 | −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 hexadecimal dumps without line number information and without a particular 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. |
|
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 correct number of columns. Here anything that looks like a pair of hex-digits is interpreted. Note the difference between 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. 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. Hexdump from file position 0x100 ( = 1024−768)
on. 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. Print 3 lines (hex 0x30 bytes) from the end of
file. Print 120 bytes as continuous hexdump with 20 octets per
line. Hexdump the first 120 bytes of this man page with 12
octets per line. Display just the date from the file xxd.1 Copy input_file to output_file and prepend
100 bytes of value 0x00. Patch the date in the file xxd.1 Create a 65537 byte file with all bytes 0x00, except for
the last one which is ’A’ (hex 0x41). Hexdump this file with autoskip. 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. Use xxd as a filter within an editor such as
vim(1) to hexdump a region marked between
‘a’ and ‘z’. Use xxd as a filter within an editor such as
vim(1) to recover a binary hexdump marked between
‘a’ and ‘z’. 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: Read single characters from a serial line |
|
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. |
|
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, Manual page started by Tony Nugent |