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1 .TH XXD 1 "August 1996" "Manual page for xxd"
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2 .\"
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3 .\" 21st May 1996
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4 .\" Man page author:
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5 .\" Tony Nugent <tony@sctnugen.ppp.gu.edu.au> <T.Nugent@sct.gu.edu.au>
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6 .\" Changes by Bram Moolenaar <Bram@vim.org>
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7 .SH NAME
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8 .I xxd
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9 \- make a hexdump or do the reverse.
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10 .SH SYNOPSIS
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11 .B xxd
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12 \-h[elp]
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13 .br
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14 .B xxd
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15 [options] [infile [outfile]]
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16 .br
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17 .B xxd
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18 \-r[evert] [options] [infile [outfile]]
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19 .SH DESCRIPTION
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20 .I xxd
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21 creates a hex dump of a given file or standard input.
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22 It can also convert a hex dump back to its original binary form.
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23 Like
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24 .BR uuencode (1)
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25 and
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26 .BR uudecode (1)
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27 it allows the transmission of binary data in a `mail-safe' ASCII representation,
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28 but has the advantage of decoding to standard output.
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29 Moreover, it can be used to perform binary file patching.
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30 .SH OPTIONS
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31 If no
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32 .I infile
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33 is given, standard input is read.
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34 If
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35 .I infile
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36 is specified as a
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37 .RB \` \- '
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38 character, then input is taken from standard input.
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39 If no
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40 .I outfile
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41 is given (or a
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42 .RB \` \- '
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43 character is in its place), results are sent to standard output.
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44 .PP
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45 Note that a "lazy" parser is used which does not check for more than the first
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46 option letter, unless the option is followed by a parameter.
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47 Spaces between a single option letter and its parameter are optional.
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48 Parameters to options can be specified in decimal, hexadecimal or octal
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49 notation.
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50 Thus
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51 .BR \-c8 ,
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52 .BR "\-c 8" ,
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53 .B \-c 010
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54 and
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55 .B \-cols 8
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56 are all equivalent.
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57 .PP
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58 .TP
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59 .IR \-a " | " \-autoskip
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60 toggle autoskip: A single '*' replaces nul-lines. Default off.
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61 .TP
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62 .IR \-b " | " \-bits
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63 Switch to bits (binary digits) dump, rather than hexdump.
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64 This option writes octets as eight digits "1"s and "0"s instead of a normal
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65 hexadecimal dump. Each line is preceded by a line number in hexadecimal and
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66 followed by an ascii (or ebcdic) representation. The command line switches
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67 \-r, \-p, \-i do not work with this mode.
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68 .TP
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69 .IR "\-c cols " | " \-cols cols"
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70 format
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71 .RI < cols >
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72 octets per line. Default 16 (\-i: 12, \-ps: 30, \-b: 6). Max 256.
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73 .TP
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74 .IR \-E " | " \-EBCDIC
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75 Change the character encoding in the righthand column from ASCII to EBCDIC.
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76 This does not change the hexadecimal representation. The option is
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77 meaningless in combinations with \-r, \-p or \-i.
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78 .TP
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79 .IR "\-g bytes " | " \-groupsize bytes"
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80 separate the output of every
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81 .RI < bytes >
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82 bytes (two hex characters or eight bit-digits each) by a whitespace.
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83 Specify
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84 .I \-g 0
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85 to suppress grouping.
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86 .RI < Bytes "> defaults to " 2
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87 in normal mode and \fI1\fP in bits mode.
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88 Grouping does not apply to postscript or include style.
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89 .TP
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90 .IR \-h " | " \-help
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91 print a summary of available commands and exit. No hex dumping is performed.
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92 .TP
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93 .IR \-i " | " \-include
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94 output in C include file style. A complete static array definition is written
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95 (named after the input file), unless xxd reads from stdin.
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96 .TP
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97 .IR "\-l len " | " \-len len"
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98 stop after writing
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99 .RI < len >
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100 octets.
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101 .TP
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102 .IR \-p " | " \-ps " | " \-postscript " | " \-plain
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103 output in postscript continuous hexdump style. Also known as plain hexdump
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104 style.
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105 .TP
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106 .IR \-r " | " \-revert
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107 reverse operation: convert (or patch) hexdump into binary.
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108 If not writing to stdout, xxd writes into its output file without truncating
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109 it. Use the combination
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110 .I \-r \-p
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111 to read plain hexadecimal dumps without line number information and without a
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112 particular column layout. Additional Whitespace and line-breaks are allowed
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113 anywhere.
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114 .TP
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115 .I \-seek offset
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116 When used after
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117 .IR \-r :
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118 revert with
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119 .RI < offset >
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120 added to file positions found in hexdump.
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121 .TP
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122 .I \-s [+][\-]seek
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123 start at
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124 .RI < seek >
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125 bytes abs. (or rel.) infile offset.
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126 \fI+ \fRindicates that the seek is relative to the current stdin file position
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127 (meaningless when not reading from stdin). \fI\- \fRindicates that the seek
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128 should be that many characters from the end of the input (or if combined with
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129 \fI+\fR: before the current stdin file position).
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130 Without \-s option, xxd starts at the current file position.
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131 .TP
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132 .I \-u
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133 use upper case hex letters. Default is lower case.
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134 .TP
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135 .IR \-v " | " \-version
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136 show version string.
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137 .SH CAVEATS
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138 .PP
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139 .I xxd \-r
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140 has some builtin magic while evaluating line number information.
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141 If the output file is seekable, then the linenumbers at the start of each
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142 hexdump line may be out of order, lines may be missing, or overlapping. In
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143 these cases xxd will lseek(2) to the next position. If the output file is not
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144 seekable, only gaps are allowed, which will be filled by null-bytes.
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145 .PP
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146 .I xxd \-r
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147 never generates parse errors. Garbage is silently skipped.
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148 .PP
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149 When editing hexdumps, please note that
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150 .I xxd \-r
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151 skips everything on the input line after reading enough columns of hexadecimal
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152 data (see option \-c). This also means, that changes to the printable ascii (or
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153 ebcdic) columns are always ignored. Reverting a plain (or postscript) style
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154 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.
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155 .PP
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156 Note the difference between
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157 .br
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158 \fI% xxd \-i file\fR
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159 .br
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160 and
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161 .br
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162 \fI% xxd \-i < file\fR
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163 .PP
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164 .I xxd \-s +seek
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165 may be different from
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166 .IR "xxd \-s seek" ,
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167 as lseek(2) is used to "rewind" input. A '+'
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168 makes a difference if the input source is stdin, and if stdin's file position
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169 is not at the start of the file by the time xxd is started and given its input.
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170 The following examples may help to clarify (or further confuse!)...
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171 .PP
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172 Rewind stdin before reading; needed because the `cat' has already read to the
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173 end of stdin.
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174 .br
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175 \fI% sh \-c "cat > plain_copy; xxd \-s 0 > hex_copy" < file\fR
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176 .PP
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177 Hexdump from file position 0x480 (=1024+128) onwards.
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178 The `+' sign means "relative to the current position", thus the `128' adds to
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179 the 1k where dd left off.
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180 .br
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181 \fI% sh \-c "dd of=plain_snippet bs=1k count=1; xxd \-s +128 > hex_snippet" < file\fR
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182 .PP
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183 Hexdump from file position 0x100 ( = 1024\-768) on.
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184 .br
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185 \fI% sh \-c "dd of=plain_snippet bs=1k count=1; xxd \-s +\-768 > hex_snippet" < file\fR
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186 .PP
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187 However, this is a rare situation and the use of `+' is rarely needed.
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188 The author prefers to monitor the effect of xxd with strace(1) or truss(1), whenever \-s is used.
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189 .SH EXAMPLES
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190 .PP
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191 .br
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192 Print everything but the first three lines (hex 0x30 bytes) of
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193 .BR file .
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194 .br
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195 \fI% xxd \-s 0x30 file\fR
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196 .PP
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197 .br
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198 Print 3 lines (hex 0x30 bytes) from the end of
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199 .BR file .
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200 .br
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1125
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201 \fI% xxd \-s \-0x30 file\fR
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202 .PP
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203 .br
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204 Print 120 bytes as continuous hexdump with 20 octets per line.
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205 .br
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206 \fI% xxd \-l 120 \-ps \-c 20 xxd.1\fR
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207 .br
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208 2e54482058584420312022417567757374203139
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209 .br
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210 39362220224d616e75616c207061676520666f72
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211 .br
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212 20787864220a2e5c220a2e5c222032317374204d
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213 .br
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214 617920313939360a2e5c22204d616e2070616765
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215 .br
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216 20617574686f723a0a2e5c2220202020546f6e79
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217 .br
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218 204e7567656e74203c746f6e79407363746e7567
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219 .br
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220
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221 .br
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222 Hexdump the first 120 bytes of this man page with 12 octets per line.
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223 .br
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224 \fI% xxd \-l 120 \-c 12 xxd.1\fR
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225 .br
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226 0000000: 2e54 4820 5858 4420 3120 2241 .TH XXD 1 "A
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227 .br
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228 000000c: 7567 7573 7420 3139 3936 2220 ugust 1996"
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229 .br
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230 0000018: 224d 616e 7561 6c20 7061 6765 "Manual page
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231 .br
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232 0000024: 2066 6f72 2078 7864 220a 2e5c for xxd"..\\
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233 .br
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234 0000030: 220a 2e5c 2220 3231 7374 204d "..\\" 21st M
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235 .br
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236 000003c: 6179 2031 3939 360a 2e5c 2220 ay 1996..\\"
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237 .br
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238 0000048: 4d61 6e20 7061 6765 2061 7574 Man page aut
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239 .br
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240 0000054: 686f 723a 0a2e 5c22 2020 2020 hor:..\\"
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241 .br
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242 0000060: 546f 6e79 204e 7567 656e 7420 Tony Nugent
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243 .br
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244 000006c: 3c74 6f6e 7940 7363 746e 7567 <tony@sctnug
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245 .PP
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246 .br
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247 Display just the date from the file xxd.1
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248 .br
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249 \fI% xxd \-s 0x36 \-l 13 \-c 13 xxd.1\fR
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250 .br
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251 0000036: 3231 7374 204d 6179 2031 3939 36 21st May 1996
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252 .PP
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253 .br
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254 Copy
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255 .B input_file
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256 to
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257 .B output_file
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258 and prepend 100 bytes of value 0x00.
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259 .br
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260 \fI% xxd input_file | xxd \-r \-s 100 > output_file\fR
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261 .br
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262
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263 .br
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264 Patch the date in the file xxd.1
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265 .br
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266 \fI% echo "0000037: 3574 68" | xxd \-r \- xxd.1\fR
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267 .br
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268 \fI% xxd \-s 0x36 \-l 13 \-c 13 xxd.1\fR
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269 .br
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270 0000036: 3235 7468 204d 6179 2031 3939 36 25th May 1996
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271 .PP
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272 .br
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273 Create a 65537 byte file with all bytes 0x00,
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274 except for the last one which is 'A' (hex 0x41).
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275 .br
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276 \fI% echo "010000: 41" | xxd \-r > file\fR
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277 .PP
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278 .br
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279 Hexdump this file with autoskip.
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280 .br
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281 \fI% xxd \-a \-c 12 file\fR
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282 .br
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283 0000000: 0000 0000 0000 0000 0000 0000 ............
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284 .br
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285 *
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286 .br
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287 000fffc: 0000 0000 40 ....A
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288 .PP
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289 Create a 1 byte file containing a single 'A' character.
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290 The number after '\-r \-s' adds to the linenumbers found in the file;
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291 in effect, the leading bytes are suppressed.
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292 .br
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293 \fI% echo "010000: 41" | xxd \-r \-s \-0x10000 > file\fR
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294 .PP
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295 Use xxd as a filter within an editor such as
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296 .B vim(1)
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297 to hexdump a region marked between `a' and `z'.
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298 .br
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299 \fI:'a,'z!xxd\fR
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300 .PP
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301 Use xxd as a filter within an editor such as
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302 .B vim(1)
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303 to recover a binary hexdump marked between `a' and `z'.
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304 .br
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305 \fI:'a,'z!xxd \-r\fR
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306 .PP
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307 Use xxd as a filter within an editor such as
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308 .B vim(1)
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309 to recover one line of a hexdump. Move the cursor over the line and type:
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310 .br
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311 \fI!!xxd \-r\fR
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312 .PP
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313 Read single characters from a serial line
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314 .br
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315 \fI% xxd \-c1 < /dev/term/b &\fR
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316 .br
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317 \fI% stty < /dev/term/b \-echo \-opost \-isig \-icanon min 1\fR
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318 .br
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319 \fI% echo \-n foo > /dev/term/b\fR
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320 .PP
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321 .SH "RETURN VALUES"
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322 The following error values are returned:
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323 .TP
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324 0
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325 no errors encountered.
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326 .TP
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327 \-1
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328 operation not supported (
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329 .I xxd \-r \-i
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330 still impossible).
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331 .TP
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332 1
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333 error while parsing options.
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334 .TP
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335 2
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336 problems with input file.
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337 .TP
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338 3
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339 problems with output file.
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340 .TP
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341 4,5
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342 desired seek position is unreachable.
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343 .SH "SEE ALSO"
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344 uuencode(1), uudecode(1), patch(1)
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345 .br
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346 .SH WARNINGS
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347 The tools weirdness matches its creators brain.
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348 Use entirely at your own risk. Copy files. Trace it. Become a wizard.
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349 .br
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350 .SH VERSION
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351 This manual page documents xxd version 1.7
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352 .SH AUTHOR
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353 .br
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354 (c) 1990-1997 by Juergen Weigert
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355 .br
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356 <jnweiger@informatik.uni\-erlangen.de>
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357 .LP
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358 Distribute freely and credit me,
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359 .br
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360 make money and share with me,
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361 .br
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362 lose money and don't ask me.
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363 .PP
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364 Manual page started by Tony Nugent
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365 .br
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366 <tony@sctnugen.ppp.gu.edu.au> <T.Nugent@sct.gu.edu.au>
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367 .br
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368 Small changes by Bram Moolenaar.
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369 Edited by Juergen Weigert.
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370 .PP
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