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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 hexacecimal 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 .IR "\-c cols " | " \-cols cols"
71 format
72 .RI < cols >
73 octets per line. Default 16 (\-i: 12, \-ps: 30, \-b: 6). Max 256.
74 .TP
75 .IR \-E " | " \-EBCDIC
76 Change the character encoding in the righthand column from ASCII to EBCDIC.
77 This does not change the hexadecimal representation. The option is
78 meaningless in combinations with \-r, \-p or \-i.
79 .TP
80 .IR "\-g bytes " | " \-groupsize bytes"
81 seperate the output of every
82 .RI < bytes >
83 bytes (two hex characters or eight bit-digits each) by a whitespace.
84 Specify
85 .I \-g 0
86 to suppress grouping.
87 .RI < Bytes "> defaults to " 2
88 in normal mode and \fI1\fP in bits mode.
89 Grouping does not apply to postscript or include style.
90 .TP
91 .IR \-h " | " \-help
92 print a summary of available commands and exit. No hex dumping is performed.
93 .TP
94 .IR \-i " | " \-include
95 output in C include file style. A complete static array definition is written
96 (named after the input file), unless xxd reads from stdin.
97 .TP
98 .IR "\-l len " | " \-len len"
99 stop after writing
100 .RI < len >
101 octets.
102 .TP
103 .IR \-p " | " \-ps " | " \-postscript " | " \-plain
104 output in postscript continuous hexdump style. Also known as plain hexdump
105 style.
106 .TP
107 .IR \-r " | " \-revert
108 reverse operation: convert (or patch) hexdump into binary.
109 If not writing to stdout, xxd writes into its output file without truncating
110 it. Use the combination
111 .I \-r \-p
112 to read plain hexadecimal dumps without line number information and without a
113 particular column layout. Additional Whitespace and line-breaks are allowed
114 anywhere.
115 .TP
116 .I \-seek offset
117 When used after
118 .I \-r
119 : revert with
120 .RI < offset >
121 added to file positions found in hexdump.
122 .TP
123 .I \-s [\+][\-]seek
124 start at
125 .RI < seek >
126 bytes abs. (or rel.) infile offset.
127 \fI\+ \fRindicates that the seek is relative to the current stdin file position
128 (meaningless when not reading from stdin). \fI\- \fRindicates that the seek
129 should be that many characters from the end of the input (or if combined with
130 \fI \+ \fR: before the current stdin file position).
131 Without \-s option, xxd starts at the current file position.
132 .TP
133 .I \-u
134 use upper case hex letters. Default is lower case.
135 .TP
136 .IR \-v " | " \-version
137 show version string.
138 .SH CAVEATS
139 .PP
140 .I xxd \-r
141 has some builtin magic while evaluating line number information.
142 If the ouput file is seekable, then the linenumbers at the start of each
143 hexdump line may be out of order, lines may be missing, or overlapping. In
144 these cases xxd will lseek(2) to the next position. If the output file is not
145 seekable, only gaps are allowed, which will be filled by null-bytes.
146 .PP
147 .I xxd \-r
148 never generates parse errors. Garbage is silently skipped.
149 .PP
150 When editing hexdumps, please note that
151 .I xxd \-r
152 skips everything on the input line after reading enough columns of hexadecimal
153 data (see option \-c). This also means, that changes to the printable ascii (or
154 ebcdic) columns are always ignored. Reverting a plain (or postscript) style
155 hexdump with xxd \-r \-p does not depend on the correct number of columns. Here an thing that looks like a pair of hex-digits is interpreted.
156 .PP
157 Note the difference between
158 .br
159 \fI% xxd \-i file\fR
160 .br
161 and
162 .br
163 \fI% xxd \-i \< file\fR
164 .PP
165 .I xxd \-s \+seek
166 may be different from
167 .I xxd \-s seek
168 , as lseek(2) is used to "rewind" input. A '+'
169 makes a difference if the input source is stdin, and if stdin's file position
170 is not at the start of the file by the time xxd is started and given its input.
171 The following examples may help to clarify (or further confuse!)...
172 .PP
173 Rewind stdin before reading; needed because the `cat' has already read to the
174 end of stdin.
175 .br
176 \fI% sh \-c 'cat > plain_copy; xxd \-s 0 > hex_copy' < file
177 .PP
178 Hexdump from file position 0x480 (=1024+128) onwards.
179 The `+' sign means "relative to the current position", thus the `128' adds to
180 the 1k where dd left off.
181 .br
182 \fI% sh \-c 'dd of=plain_snippet bs=1k count=1; xxd \-s +128 > hex_snippet' < file
183 .PP
184 Hexdump from file position 0x100 ( = 1024-768) on.
185 .br
186 \fI% sh \-c 'dd of=plain_snippet bs=1k count=1; xxd \-s +-768 > hex_snippet' < file
187 .PP
188 However, this is a rare situation and the use of `+' is rarely needed.
189 the author prefers to monitor the effect of xxd with strace(1) or truss(1), whenever \-s is used.
190 .SH EXAMPLES
191 .PP
192 .br
193 Print everything but the first three lines (hex 0x30 bytes) of
194 .B file
195 \.
196 .br
197 \fI% xxd \-s 0x30 file
198 .PP
199 .br
200 Print 3 lines (hex 0x30 bytes) from the end of
201 .B file
202 \.
203 .br
204 \fI% xxd \-s \-0x30 file
205 .PP
206 .br
207 Print 120 bytes as continuous hexdump with 40 octets per line.
208 .br
209 \fI% xxd \-l 120 \-ps \-c 20 xxd.1\fR
210 .br
211 2e544820585844203120224d616e75616c207061
212 .br
213 676520666f7220787864220a2e5c220a2e5c2220
214 .br
215 32317374204d617920313939360a2e5c22204d61
216 .br
217 6e207061676520617574686f723a0a2e5c222020
218 .br
219 2020546f6e79204e7567656e74203c746f6e7940
220 .br
221 7363746e7567656e2e7070702e67752e6564752e
222 .br
224 .br
225 Hexdump the first 120 bytes of this man page with 12 octets per line.
226 .br
227 \fI% xxd \-l 120 \-c 12 xxd.1\fR
228 .br
229 0000000: 2e54 4820 5858 4420 3120 224d .TH XXD 1 "M
230 .br
231 000000c: 616e 7561 6c20 7061 6765 2066 anual page f
232 .br
233 0000018: 6f72 2078 7864 220a 2e5c 220a or xxd"..\\".
234 .br
235 0000024: 2e5c 2220 3231 7374 204d 6179 .\\" 21st May
236 .br
237 0000030: 2031 3939 360a 2e5c 2220 4d61 1996..\\" Ma
238 .br
239 000003c: 6e20 7061 6765 2061 7574 686f n page autho
240 .br
241 0000048: 723a 0a2e 5c22 2020 2020 546f r:..\\" To
242 .br
243 0000054: 6e79 204e 7567 656e 7420 3c74 ny Nugent <t
244 .br
245 0000060: 6f6e 7940 7363 746e 7567 656e ony@sctnugen
246 .br
247 000006c: 2e70 7070 2e67 752e 6564 752e .ppp.gu.edu.
248 .PP
249 .br
250 Display just the date from the file xxd.1
251 .br
252 \fI% xxd \-s 0x28 \-l 12 \-c 12 xxd.1\fR
253 .br
254 0000028: 3231 7374 204d 6179 2031 3939 21st May 199
255 .PP
256 .br
257 Copy
258 .B input_file
259 to
260 .B output_file
261 and prepend 100 bytes of value 0x00.
262 .br
263 \fI% xxd input_file | xxd \-r \-s 100 \> output_file\fR
264 .br
266 .br
267 Patch the date in the file xxd.1
268 .br
269 \fI% echo '0000029: 3574 68' | xxd \-r \- xxd.1\fR
270 .br
271 \fI% xxd \-s 0x28 \-l 12 \-c 12 xxd.1\fR
272 .br
273 0000028: 3235 7468 204d 6179 2031 3939 25th May 199
274 .PP
275 .br
276 Create a 65537 byte file with all bytes 0x00,
277 except for the last one which is 'A' (hex 0x41).
278 .br
279 \fI% echo '010000: 41' | xxd \-r \> file\fR
280 .PP
281 .br
282 Hexdump this file with autoskip.
283 .br
284 \fI% xxd \-a \-c 12 file\fR
285 .br
286 0000000: 0000 0000 0000 0000 0000 0000 ............
287 .br
288 *
289 .br
290 000fffc: 0000 0000 40 ....A
291 .PP
292 Create a 1 byte file containing a single 'A' character.
293 The number after '\-r \-s' adds to the linenumbers found in the file;
294 in effect, the leading bytes are suppressed.
295 .br
296 \fI% echo '010000: 41' | xxd \-r \-s \-0x10000 \> file\fR
297 .PP
298 Use xxd as a filter within an editor such as
299 .B vim(1)
300 to hexdump a region marked between `a' and `z'.
301 .br
302 \fI:'a,'z!xxd\fR
303 .PP
304 Use xxd as a filter within an editor such as
305 .B vim(1)
306 to recover a binary hexdump marked between `a' and `z'.
307 .br
308 \fI:'a,'z!xxd \-r\fR
309 .PP
310 Use xxd as a filter within an editor such as
311 .B vim(1)
312 to recover one line of a hexdump. Move the cursor over the line and type:
313 .br
314 \fI!!xxd \-r\fR
315 .PP
316 Read single characters from a serial line
317 .br
318 \fI% xxd \-c1 < /dev/term/b &\fR
319 .br
320 \fI% stty < /dev/term/b \-echo \-opost \-isig \-icanon min 1\fR
321 .br
322 \fI% echo \-n foo > /dev/term/b\fR
323 .PP
324 .SH "RETURN VALUES"
325 The following error values are returned:
326 .TP
327 0
328 no errors encountered.
329 .TP
330 \-1
331 operation not supported (
332 .I xxd \-r \-i
333 still impossible).
334 .TP
335 1
336 error while parsing options.
337 .TP
338 2
339 problems with input file.
340 .TP
341 3
342 problems with output file.
343 .TP
344 4,5
345 desired seek position is unreachable.
346 .SH "SEE ALSO"
347 uuencode(1), uudecode(1), patch(1)
348 .br
349 .SH WARNINGS
350 The tools weirdness matches its creators brain.
351 Use entirely at your own risk. Copy files. Trace it. Become a wizard.
352 .br
353 .SH VERSION
354 This manual page documents xxd version 1.7
355 .SH AUTHOR
356 .br
357 (c) 1990-1997 by Juergen Weigert
358 .br
359 <jnweiger@informatik.uni-erlangen.de>
360 .LP
361 Distribute freely and credit me,
362 .br
363 make money and share with me,
364 .br
365 lose money and don't ask me.
366 .PP
367 Manual page started by Tony Nugent
368 .br
369 <tony@sctnugen.ppp.gu.edu.au> <T.Nugent@sct.gu.edu.au>
370 .br
371 Small changes by Bram Moolenaar.
372 Edited by Juergen Weigert.
373 .PP