xxd

topic - Kurzbeschreibung

Syntax

Exit-Status

  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

Siehe auch

1. uuencode(1)
2. uudecode(1)
3. patch(1)

Unterseiten

• Xxd

Testfragen

Testfrage 1

Antwort1

Testfrage 2

Antwort2

Testfrage 3

Antwort3

Testfrage 4

Antwort4

Testfrage 5

Antwort5

TMP

Datei in Hexa

$ echo Guten Tag | xxd
00000000: 4775 7465 6e20 5461 670a                 Guten Tag.

Datei in Binär

$ echo Guten Tag | xxd -b                                                                                                                                                                                                                                                                                                                                                                                    
00000000: 01000111 01110101 01110100 01100101 01101110 00100000  Guten 
00000006: 01010100 01100001 01100111 00001010                    Tag.

Manpage

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 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) 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. No maxmimum for -ps. With -ps, 0 results in one long line of output.

-C | -capitalize Capitalize variable names in C include file style, when using -i.

-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 hexdump, 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 suppress grouping. <Bytes> defaults to 2 in normal mode, 4 in little-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 definition is written (named after the input file), unless xxd reads from stdin.

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

-n name | -name name Override the variable name output when -i is used. The array is named name and the length is named name_len.

-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 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.

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 correct 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 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.

WARNINGS

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