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updated for version 7.0061
author vimboss
date Fri, 18 Mar 2005 20:25:31 +0000
parents 125e80798a85
children 9f345c48220b
comparison
equal deleted inserted replaced
215:a4029d1d83df 216:da182deebec7
19 .SH DESCRIPTION 19 .SH DESCRIPTION
20 .I xxd 20 .I xxd
21 creates a hex dump of a given file or standard input. 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. 22 It can also convert a hex dump back to its original binary form.
23 Like 23 Like
24 .BR uuencode(1) 24 .BR uuencode (1)
25 and 25 and
26 .BR uudecode(1) 26 .BR uudecode (1)
27 it allows the transmission of binary data in a `mail-safe' ASCII representation, 27 it allows the transmission of binary data in a `mail-safe' ASCII representation,
28 but has the advantage of decoding to standard output. 28 but has the advantage of decoding to standard output.
29 Moreover, it can be used to perform binary file patching. 29 Moreover, it can be used to perform binary file patching.
30 .SH OPTIONS 30 .SH OPTIONS
31 If no 31 If no
112 particular column layout. Additional Whitespace and line-breaks are allowed 112 particular column layout. Additional Whitespace and line-breaks are allowed
113 anywhere. 113 anywhere.
114 .TP 114 .TP
115 .I \-seek offset 115 .I \-seek offset
116 When used after 116 When used after
117 .I \-r 117 .IR \-r :
118 : revert with 118 revert with
119 .RI < offset > 119 .RI < offset >
120 added to file positions found in hexdump. 120 added to file positions found in hexdump.
121 .TP 121 .TP
122 .I \-s [\+][\-]seek 122 .I \-s [+][\-]seek
123 start at 123 start at
124 .RI < seek > 124 .RI < seek >
125 bytes abs. (or rel.) infile offset. 125 bytes abs. (or rel.) infile offset.
126 \fI\+ \fRindicates that the seek is relative to the current stdin file position 126 \fI+ fRindicates that the seek is relative to the current stdin file position
127 (meaningless when not reading from stdin). \fI\- \fRindicates that the seek 127 (meaningless when not reading from stdin). \fI\- \fRindicates that the seek
128 should be that many characters from the end of the input (or if combined with 128 should be that many characters from the end of the input (or if combined with
129 \fI \+ \fR: before the current stdin file position). 129 \fI+\fR: before the current stdin file position).
130 Without \-s option, xxd starts at the current file position. 130 Without \-s option, xxd starts at the current file position.
131 .TP 131 .TP
132 .I \-u 132 .I \-u
133 use upper case hex letters. Default is lower case. 133 use upper case hex letters. Default is lower case.
134 .TP 134 .TP
157 .br 157 .br
158 \fI% xxd \-i file\fR 158 \fI% xxd \-i file\fR
159 .br 159 .br
160 and 160 and
161 .br 161 .br
162 \fI% xxd \-i \< file\fR 162 \fI% xxd \-i < file\fR
163 .PP 163 .PP
164 .I xxd \-s \+seek 164 .I xxd \-s \+seek
165 may be different from 165 may be different from
166 .I xxd \-s seek 166 .IR "xxd \-s seek" ,
167 , as lseek(2) is used to "rewind" input. A '+' 167 as lseek(2) is used to "rewind" input. A '+'
168 makes a difference if the input source is stdin, and if stdin's file position 168 makes a difference if the input source is stdin, and if stdin's file position
169 is not at the start of the file by the time xxd is started and given its input. 169 is not at the start of the file by the time xxd is started and given its input.
170 The following examples may help to clarify (or further confuse!)... 170 The following examples may help to clarify (or further confuse!)...
171 .PP 171 .PP
172 Rewind stdin before reading; needed because the `cat' has already read to the 172 Rewind stdin before reading; needed because the `cat' has already read to the
178 The `+' sign means "relative to the current position", thus the `128' adds to 178 The `+' sign means "relative to the current position", thus the `128' adds to
179 the 1k where dd left off. 179 the 1k where dd left off.
180 .br 180 .br
181 \fI% sh \-c 'dd of=plain_snippet bs=1k count=1; xxd \-s +128 > hex_snippet' < file 181 \fI% sh \-c 'dd of=plain_snippet bs=1k count=1; xxd \-s +128 > hex_snippet' < file
182 .PP 182 .PP
183 Hexdump from file position 0x100 ( = 1024-768) on. 183 Hexdump from file position 0x100 ( = 1024\-768) on.
184 .br 184 .br
185 \fI% sh \-c 'dd of=plain_snippet bs=1k count=1; xxd \-s +-768 > hex_snippet' < file 185 \fI% sh \-c 'dd of=plain_snippet bs=1k count=1; xxd \-s +-768 > hex_snippet' < file
186 .PP 186 .PP
187 However, this is a rare situation and the use of `+' is rarely needed. 187 However, this is a rare situation and the use of `+' is rarely needed.
188 The author prefers to monitor the effect of xxd with strace(1) or truss(1), whenever \-s is used. 188 The author prefers to monitor the effect of xxd with strace(1) or truss(1), whenever \-s is used.