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1 .TH XXD 1 "August 1996" "Manual page for xxd"
2 .\"
3 .\" 21st May 1996
4 .\" Man page author:
5 .\" Tony Nugent <tony@sctnugen.ppp.gu.edu.au> <T.Nugent@sct.gu.edu.au>
6 .\" Changes by Bram Moolenaar <Bram@vim.org>
7 .SH NAME
8 .I xxd
9 \- make a hexdump or do the reverse.
10 .SH SYNOPSIS
11 .B xxd
12 \-h[elp]
13 .br
14 .B xxd
15 [options] [infile [outfile]]
16 .br
17 .B xxd
18 \-r[evert] [options] [infile [outfile]]
19 .SH DESCRIPTION
20 .I xxd
21 creates a hex dump of a given file or standard input.
22 It can also convert a hex dump back to its original binary form.
23 Like
24 .BR uuencode (1)
25 and
26 .BR uudecode (1)
27 it allows the transmission of binary data in a `mail-safe' ASCII representation,
28 but has the advantage of decoding to standard output.
29 Moreover, it can be used to perform binary file patching.
30 .SH OPTIONS
31 If no
32 .I infile
33 is given, standard input is read.
34 If
35 .I infile
36 is specified as a
37 .RB \` \- '
38 character, then input is taken from standard input.
39 If no
40 .I outfile
41 is given (or a
42 .RB \` \- '
43 character is in its place), results are sent to standard output.
44 .PP
45 Note that a "lazy" parser is used which does not check for more than the first
46 option letter, unless the option is followed by a parameter.
47 Spaces between a single option letter and its parameter are optional.
48 Parameters to options can be specified in decimal, hexadecimal or octal
49 notation.
50 Thus
51 .BR \-c8 ,
52 .BR "\-c 8" ,
53 .B \-c 010
54 and
55 .B \-cols 8
56 are all equivalent.
57 .PP
58 .TP
59 .IR \-a " | " \-autoskip
60 Toggle autoskip: A single '*' replaces nul-lines. Default off.
61 .TP
62 .IR \-b " | " \-bits
63 Switch to bits (binary digits) dump, rather than hexdump.
64 This option writes octets as eight digits "1"s and "0"s instead of a normal
65 hexadecimal dump. Each line is preceded by a line number in hexadecimal and
66 followed by an ascii (or ebcdic) representation. The command line switches
67 \-r, \-p, \-i do not work with this mode.
68 .TP
69 .IR "\-c cols " | " \-cols cols"
70 Format
71 .RI < cols >
72 octets per line. Default 16 (\-i: 12, \-ps: 30, \-b: 6). Max 256.
73 .TP
74 .IR \-C " | " \-capitalize
75 Capitalize variable names in C include file style, when using \-i.
76 .TP
77 .IR \-E " | " \-EBCDIC
78 Change the character encoding in the righthand column from ASCII to EBCDIC.
79 This does not change the hexadecimal representation. The option is
80 meaningless in combinations with \-r, \-p or \-i.
81 .TP
82 .IR \-e
83 Switch to little-endian hexdump.
84 This option treats byte groups as words in little-endian byte order.
85 The default grouping of 4 bytes may be changed using
86 .RI "" \-g .
87 This option only applies to hexdump, leaving the ASCII (or EBCDIC)
88 representation unchanged.
89 The command line switches
90 \-r, \-p, \-i do not work with this mode.
91 .TP
92 .IR "\-g bytes " | " \-groupsize bytes"
93 Separate the output of every
94 .RI < bytes >
95 bytes (two hex characters or eight bit-digits each) by a whitespace.
96 Specify
97 .I \-g 0
98 to suppress grouping.
99 .RI < Bytes "> defaults to " 2
100 in normal mode, \fI4\fP in little-endian mode and \fI1\fP in bits mode.
101 Grouping does not apply to postscript or include style.
102 .TP
103 .IR \-h " | " \-help
104 Print a summary of available commands and exit. No hex dumping is performed.
105 .TP
106 .IR \-i " | " \-include
107 Output in C include file style. A complete static array definition is written
108 (named after the input file), unless xxd reads from stdin.
109 .TP
110 .IR "\-l len " | " \-len len"
111 Stop after writing
112 .RI < len >
113 octets.
114 .TP
115 .I \-o offset
116 Add
117 .RI < offset >
118 to the displayed file position.
119 .TP
120 .IR \-p " | " \-ps " | " \-postscript " | " \-plain
121 Output in postscript continuous hexdump style. Also known as plain hexdump
122 style.
123 .TP
124 .IR \-r " | " \-revert
125 Reverse operation: convert (or patch) hexdump into binary.
126 If not writing to stdout, xxd writes into its output file without truncating
127 it. Use the combination
128 .I \-r \-p
129 to read plain hexadecimal dumps without line number information and without a
130 particular column layout. Additional Whitespace and line-breaks are allowed
131 anywhere.
132 .TP
133 .I \-seek offset
134 When used after
135 .IR \-r :
136 revert with
137 .RI < offset >
138 added to file positions found in hexdump.
139 .TP
140 .I \-s [+][\-]seek
141 Start at
142 .RI < seek >
143 bytes abs. (or rel.) infile offset.
144 \fI+ \fRindicates that the seek is relative to the current stdin file position
145 (meaningless when not reading from stdin). \fI\- \fRindicates that the seek
146 should be that many characters from the end of the input (or if combined with
147 \fI+\fR: before the current stdin file position).
148 Without \-s option, xxd starts at the current file position.
149 .TP
150 .I \-u
151 Use upper case hex letters. Default is lower case.
152 .TP
153 .IR \-v " | " \-version
154 Show version string.
155 .SH CAVEATS
156 .PP
157 .I xxd \-r
158 has some builtin magic while evaluating line number information.
159 If the output file is seekable, then the linenumbers at the start of each
160 hexdump line may be out of order, lines may be missing, or overlapping. In
161 these cases xxd will lseek(2) to the next position. If the output file is not
162 seekable, only gaps are allowed, which will be filled by null-bytes.
163 .PP
164 .I xxd \-r
165 never generates parse errors. Garbage is silently skipped.
166 .PP
167 When editing hexdumps, please note that
168 .I xxd \-r
169 skips everything on the input line after reading enough columns of hexadecimal
170 data (see option \-c). This also means, that changes to the printable ascii (or
171 ebcdic) columns are always ignored. Reverting a plain (or postscript) style
172 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.
173 .PP
174 Note the difference between
175 .br
176 \fI% xxd \-i file\fR
177 .br
178 and
179 .br
180 \fI% xxd \-i < file\fR
181 .PP
182 .I xxd \-s +seek
183 may be different from
184 .IR "xxd \-s seek" ,
185 as lseek(2) is used to "rewind" input. A '+'
186 makes a difference if the input source is stdin, and if stdin's file position
187 is not at the start of the file by the time xxd is started and given its input.
188 The following examples may help to clarify (or further confuse!)...
189 .PP
190 Rewind stdin before reading; needed because the `cat' has already read to the
191 end of stdin.
192 .br
193 \fI% sh \-c "cat > plain_copy; xxd \-s 0 > hex_copy" < file\fR
194 .PP
195 Hexdump from file position 0x480 (=1024+128) onwards.
196 The `+' sign means "relative to the current position", thus the `128' adds to
197 the 1k where dd left off.
198 .br
199 \fI% sh \-c "dd of=plain_snippet bs=1k count=1; xxd \-s +128 > hex_snippet" < file\fR
200 .PP
201 Hexdump from file position 0x100 ( = 1024\-768) on.
202 .br
203 \fI% sh \-c "dd of=plain_snippet bs=1k count=1; xxd \-s +\-768 > hex_snippet" < file\fR
204 .PP
205 However, this is a rare situation and the use of `+' is rarely needed.
206 The author prefers to monitor the effect of xxd with strace(1) or truss(1), whenever \-s is used.
207 .SH EXAMPLES
208 .PP
209 .br
210 Print everything but the first three lines (hex 0x30 bytes) of
211 .BR file .
212 .br
213 \fI% xxd \-s 0x30 file\fR
214 .PP
215 .br
216 Print 3 lines (hex 0x30 bytes) from the end of
217 .BR file .
218 .br
219 \fI% xxd \-s \-0x30 file\fR
220 .PP
221 .br
222 Print 120 bytes as continuous hexdump with 20 octets per line.
223 .br
224 \fI% xxd \-l 120 \-ps \-c 20 xxd.1\fR
225 .br
226 2e54482058584420312022417567757374203139
227 .br
228 39362220224d616e75616c207061676520666f72
229 .br
230 20787864220a2e5c220a2e5c222032317374204d
231 .br
232 617920313939360a2e5c22204d616e2070616765
233 .br
234 20617574686f723a0a2e5c2220202020546f6e79
235 .br
236 204e7567656e74203c746f6e79407363746e7567
237 .br
239 .br
240 Hexdump the first 120 bytes of this man page with 12 octets per line.
241 .br
242 \fI% xxd \-l 120 \-c 12 xxd.1\fR
243 .br
244 0000000: 2e54 4820 5858 4420 3120 2241 .TH XXD 1 "A
245 .br
246 000000c: 7567 7573 7420 3139 3936 2220 ugust 1996"
247 .br
248 0000018: 224d 616e 7561 6c20 7061 6765 "Manual page
249 .br
250 0000024: 2066 6f72 2078 7864 220a 2e5c for xxd"..\\
251 .br
252 0000030: 220a 2e5c 2220 3231 7374 204d "..\\" 21st M
253 .br
254 000003c: 6179 2031 3939 360a 2e5c 2220 ay 1996..\\"
255 .br
256 0000048: 4d61 6e20 7061 6765 2061 7574 Man page aut
257 .br
258 0000054: 686f 723a 0a2e 5c22 2020 2020 hor:..\\"
259 .br
260 0000060: 546f 6e79 204e 7567 656e 7420 Tony Nugent
261 .br
262 000006c: 3c74 6f6e 7940 7363 746e 7567 <tony@sctnug
263 .PP
264 .br
265 Display just the date from the file xxd.1
266 .br
267 \fI% xxd \-s 0x36 \-l 13 \-c 13 xxd.1\fR
268 .br
269 0000036: 3231 7374 204d 6179 2031 3939 36 21st May 1996
270 .PP
271 .br
272 Copy
273 .B input_file
274 to
275 .B output_file
276 and prepend 100 bytes of value 0x00.
277 .br
278 \fI% xxd input_file | xxd \-r \-s 100 > output_file\fR
279 .br
281 .br
282 Patch the date in the file xxd.1
283 .br
284 \fI% echo "0000037: 3574 68" | xxd \-r \- xxd.1\fR
285 .br
286 \fI% xxd \-s 0x36 \-l 13 \-c 13 xxd.1\fR
287 .br
288 0000036: 3235 7468 204d 6179 2031 3939 36 25th May 1996
289 .PP
290 .br
291 Create a 65537 byte file with all bytes 0x00,
292 except for the last one which is 'A' (hex 0x41).
293 .br
294 \fI% echo "010000: 41" | xxd \-r > file\fR
295 .PP
296 .br
297 Hexdump this file with autoskip.
298 .br
299 \fI% xxd \-a \-c 12 file\fR
300 .br
301 0000000: 0000 0000 0000 0000 0000 0000 ............
302 .br
303 *
304 .br
305 000fffc: 0000 0000 40 ....A
306 .PP
307 Create a 1 byte file containing a single 'A' character.
308 The number after '\-r \-s' adds to the linenumbers found in the file;
309 in effect, the leading bytes are suppressed.
310 .br
311 \fI% echo "010000: 41" | xxd \-r \-s \-0x10000 > file\fR
312 .PP
313 Use xxd as a filter within an editor such as
314 .B vim(1)
315 to hexdump a region marked between `a' and `z'.
316 .br
317 \fI:'a,'z!xxd\fR
318 .PP
319 Use xxd as a filter within an editor such as
320 .B vim(1)
321 to recover a binary hexdump marked between `a' and `z'.
322 .br
323 \fI:'a,'z!xxd \-r\fR
324 .PP
325 Use xxd as a filter within an editor such as
326 .B vim(1)
327 to recover one line of a hexdump. Move the cursor over the line and type:
328 .br
329 \fI!!xxd \-r\fR
330 .PP
331 Read single characters from a serial line
332 .br
333 \fI% xxd \-c1 < /dev/term/b &\fR
334 .br
335 \fI% stty < /dev/term/b \-echo \-opost \-isig \-icanon min 1\fR
336 .br
337 \fI% echo \-n foo > /dev/term/b\fR
338 .PP
339 .SH "RETURN VALUES"
340 The following error values are returned:
341 .TP
342 0
343 no errors encountered.
344 .TP
345 \-1
346 operation not supported (
347 .I xxd \-r \-i
348 still impossible).
349 .TP
350 1
351 error while parsing options.
352 .TP
353 2
354 problems with input file.
355 .TP
356 3
357 problems with output file.
358 .TP
359 4,5
360 desired seek position is unreachable.
361 .SH "SEE ALSO"
362 uuencode(1), uudecode(1), patch(1)
363 .br
364 .SH WARNINGS
365 The tools weirdness matches its creators brain.
366 Use entirely at your own risk. Copy files. Trace it. Become a wizard.
367 .br
368 .SH VERSION
369 This manual page documents xxd version 1.7
370 .SH AUTHOR
371 .br
372 (c) 1990-1997 by Juergen Weigert
373 .br
374 <jnweiger@informatik.uni\-erlangen.de>
375 .LP
376 Distribute freely and credit me,
377 .br
378 make money and share with me,
379 .br
380 lose money and don't ask me.
381 .PP
382 Manual page started by Tony Nugent
383 .br
384 <tony@sctnugen.ppp.gu.edu.au> <T.Nugent@sct.gu.edu.au>
385 .br
386 Small changes by Bram Moolenaar.
387 Edited by Juergen Weigert.
388 .PP