1XXD(1) General Commands Manual XXD(1) 2 3 4 5NAME 6 xxd - make a hexdump or do the reverse. 7 8SYNOPSIS 9 xxd -h[elp] 10 xxd [options] [infile [outfile]] 11 xxd -r[evert] [options] [infile [outfile]] 12 13DESCRIPTION 14 xxd creates a hex dump of a given file or standard input. It can also 15 convert a hex dump back to its original binary form. Like uuencode(1) 16 and uudecode(1) it allows the transmission of binary data in a `mail- 17 safe' ASCII representation, but has the advantage of decoding to stan‐ 18 dard output. Moreover, it can be used to perform binary file patching. 19 20OPTIONS 21 If no infile is given, standard input is read. If infile is specified 22 as a `-' character, then input is taken from standard input. If no 23 outfile is given (or a `-' character is in its place), results are sent 24 to standard output. 25 26 Note that a "lazy" parser is used which does not check for more than 27 the first option letter, unless the option is followed by a parameter. 28 Spaces between a single option letter and its parameter are optional. 29 Parameters to options can be specified in decimal, hexadecimal or octal 30 notation. Thus -c8, -c 8, -c 010 and -cols 8 are all equivalent. 31 32 -a | -autoskip 33 toggle autoskip: A single '*' replaces nul-lines. Default off. 34 35 -b | -bits 36 Switch to bits (binary digits) dump, rather than hexdump. This 37 option writes octets as eight digits "1"s and "0"s instead of a 38 normal hexadecimal dump. Each line is preceded by a line number 39 in hexadecimal and followed by an ascii (or ebcdic) representa‐ 40 tion. The command line switches -r, -p, -i do not work with this 41 mode. 42 43 -c cols | -cols cols 44 format <cols> octets per line. Default 16 (-i: 12, -ps: 30, -b: 45 6). Max 256. 46 47 -E | -EBCDIC 48 Change the character encoding in the righthand column from ASCII 49 to EBCDIC. This does not change the hexadecimal representation. 50 The option is meaningless in combinations with -r, -p or -i. 51 52 -e Switch to little-endian hexdump. This option treats byte groups 53 as words in little-endian byte order. The default grouping of 4 54 bytes may be changed using -g. This option only applies to hex‐ 55 dump, leaving the ASCII (or EBCDIC) representation unchanged. 56 The command line switches -r, -p, -i do not work with this mode. 57 58 -g bytes | -groupsize bytes 59 separate the output of every <bytes> bytes (two hex characters 60 or eight bit-digits each) by a whitespace. Specify -g 0 to sup‐ 61 press grouping. <Bytes> defaults to 2 in normal mode, 4 in lit‐ 62 tle-endian mode and 1 in bits mode. Grouping does not apply to 63 postscript or include style. 64 65 -h | -help 66 print a summary of available commands and exit. No hex dumping 67 is performed. 68 69 -i | -include 70 output in C include file style. A complete static array defini‐ 71 tion is written (named after the input file), unless xxd reads 72 from stdin. 73 74 -l len | -len len 75 stop after writing <len> octets. 76 77 -o offset 78 add <offset> to the displayed file position. 79 80 -p | -ps | -postscript | -plain 81 output in postscript continuous hexdump style. Also known as 82 plain hexdump style. 83 84 -r | -revert 85 reverse operation: convert (or patch) hexdump into binary. If 86 not writing to stdout, xxd writes into its output file without 87 truncating it. Use the combination -r -p to read plain hexadeci‐ 88 mal dumps without line number information and without a particu‐ 89 lar column layout. Additional Whitespace and line-breaks are 90 allowed anywhere. 91 92 -seek offset 93 When used after -r: revert with <offset> added to file positions 94 found in hexdump. 95 96 -s [+][-]seek 97 start at <seek> bytes abs. (or rel.) infile offset. + indicates 98 that the seek is relative to the current stdin file position 99 (meaningless when not reading from stdin). - indicates that the 100 seek should be that many characters from the end of the input 101 (or if combined with +: before the current stdin file position). 102 Without -s option, xxd starts at the current file position. 103 104 -u use upper case hex letters. Default is lower case. 105 106 -v | -version 107 show version string. 108 109CAVEATS 110 xxd -r has some builtin magic while evaluating line number information. 111 If the output file is seekable, then the linenumbers at the start of 112 each hexdump line may be out of order, lines may be missing, or over‐ 113 lapping. In these cases xxd will lseek(2) to the next position. If the 114 output file is not seekable, only gaps are allowed, which will be 115 filled by null-bytes. 116 117 xxd -r never generates parse errors. Garbage is silently skipped. 118 119 When editing hexdumps, please note that xxd -r skips everything on the 120 input line after reading enough columns of hexadecimal data (see option 121 -c). This also means, that changes to the printable ascii (or ebcdic) 122 columns are always ignored. Reverting a plain (or postscript) style 123 hexdump with xxd -r -p does not depend on the correct number of col‐ 124 umns. Here anything that looks like a pair of hex-digits is inter‐ 125 preted. 126 127 Note the difference between 128 % xxd -i file 129 and 130 % xxd -i < file 131 132 xxd -s +seek may be different from xxd -s seek, as lseek(2) is used to 133 "rewind" input. A '+' makes a difference if the input source is stdin, 134 and if stdin's file position is not at the start of the file by the 135 time xxd is started and given its input. The following examples may 136 help to clarify (or further confuse!)... 137 138 Rewind stdin before reading; needed because the `cat' has already read 139 to the end of stdin. 140 % sh -c "cat > plain_copy; xxd -s 0 > hex_copy" < file 141 142 Hexdump from file position 0x480 (=1024+128) onwards. The `+' sign 143 means "relative to the current position", thus the `128' adds to the 1k 144 where dd left off. 145 % sh -c "dd of=plain_snippet bs=1k count=1; xxd -s +128 > hex_snippet" 146 < file 147 148 Hexdump from file position 0x100 ( = 1024-768) on. 149 % sh -c "dd of=plain_snippet bs=1k count=1; xxd -s +-768 > hex_snippet" 150 < file 151 152 However, this is a rare situation and the use of `+' is rarely needed. 153 The author prefers to monitor the effect of xxd with strace(1) or 154 truss(1), whenever -s is used. 155 156EXAMPLES 157 Print everything but the first three lines (hex 0x30 bytes) of file. 158 % xxd -s 0x30 file 159 160 Print 3 lines (hex 0x30 bytes) from the end of file. 161 % xxd -s -0x30 file 162 163 Print 120 bytes as continuous hexdump with 20 octets per line. 164 % xxd -l 120 -ps -c 20 xxd.1 165 2e54482058584420312022417567757374203139 166 39362220224d616e75616c207061676520666f72 167 20787864220a2e5c220a2e5c222032317374204d 168 617920313939360a2e5c22204d616e2070616765 169 20617574686f723a0a2e5c2220202020546f6e79 170 204e7567656e74203c746f6e79407363746e7567 171 172 Hexdump the first 120 bytes of this man page with 12 octets per line. 173 % xxd -l 120 -c 12 xxd.1 174 0000000: 2e54 4820 5858 4420 3120 2241 .TH XXD 1 "A 175 000000c: 7567 7573 7420 3139 3936 2220 ugust 1996" 176 0000018: 224d 616e 7561 6c20 7061 6765 "Manual page 177 0000024: 2066 6f72 2078 7864 220a 2e5c for xxd"..\ 178 0000030: 220a 2e5c 2220 3231 7374 204d "..\" 21st M 179 000003c: 6179 2031 3939 360a 2e5c 2220 ay 1996..\" 180 0000048: 4d61 6e20 7061 6765 2061 7574 Man page aut 181 0000054: 686f 723a 0a2e 5c22 2020 2020 hor:..\" 182 0000060: 546f 6e79 204e 7567 656e 7420 Tony Nugent 183 000006c: 3c74 6f6e 7940 7363 746e 7567 <tony@sctnug 184 185 Display just the date from the file xxd.1 186 % xxd -s 0x36 -l 13 -c 13 xxd.1 187 0000036: 3231 7374 204d 6179 2031 3939 36 21st May 1996 188 189 Copy input_file to output_file and prepend 100 bytes of value 0x00. 190 % xxd input_file | xxd -r -s 100 > output_file 191 192 Patch the date in the file xxd.1 193 % echo "0000037: 3574 68" | xxd -r - xxd.1 194 % xxd -s 0x36 -l 13 -c 13 xxd.1 195 0000036: 3235 7468 204d 6179 2031 3939 36 25th May 1996 196 197 Create a 65537 byte file with all bytes 0x00, except for the last one 198 which is 'A' (hex 0x41). 199 % echo "010000: 41" | xxd -r > file 200 201 Hexdump this file with autoskip. 202 % xxd -a -c 12 file 203 0000000: 0000 0000 0000 0000 0000 0000 ............ 204 * 205 000fffc: 0000 0000 40 ....A 206 207 Create a 1 byte file containing a single 'A' character. The number 208 after '-r -s' adds to the linenumbers found in the file; in effect, the 209 leading bytes are suppressed. 210 % echo "010000: 41" | xxd -r -s -0x10000 > file 211 212 Use xxd as a filter within an editor such as vim(1) to hexdump a region 213 marked between `a' and `z'. 214 :'a,'z!xxd 215 216 Use xxd as a filter within an editor such as vim(1) to recover a binary 217 hexdump marked between `a' and `z'. 218 :'a,'z!xxd -r 219 220 Use xxd as a filter within an editor such as vim(1) to recover one line 221 of a hexdump. Move the cursor over the line and type: 222 !!xxd -r 223 224 Read single characters from a serial line 225 % xxd -c1 < /dev/term/b & 226 % stty < /dev/term/b -echo -opost -isig -icanon min 1 227 % echo -n foo > /dev/term/b 228 229RETURN VALUES 230 The following error values are returned: 231 232 0 no errors encountered. 233 234 -1 operation not supported ( xxd -r -i still impossible). 235 236 1 error while parsing options. 237 238 2 problems with input file. 239 240 3 problems with output file. 241 242 4,5 desired seek position is unreachable. 243 244SEE ALSO 245 uuencode(1), uudecode(1), patch(1) 246 247WARNINGS 248 The tools weirdness matches its creators brain. Use entirely at your 249 own risk. Copy files. Trace it. Become a wizard. 250 251VERSION 252 This manual page documents xxd version 1.7 253 254AUTHOR 255 (c) 1990-1997 by Juergen Weigert 256 <[email protected]> 257 258 Distribute freely and credit me, 259 make money and share with me, 260 lose money and don't ask me. 261 262 Manual page started by Tony Nugent 263 <[email protected]> <[email protected]> 264 Small changes by Bram Moolenaar. Edited by Juergen Weigert. 265 266Manual page for xxd August 1996 XXD(1) 267