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