diff options
Diffstat (limited to 'runtime/doc/xxd.man')
| -rw-r--r-- | runtime/doc/xxd.man | 58 |
1 files changed, 29 insertions, 29 deletions
diff --git a/runtime/doc/xxd.man b/runtime/doc/xxd.man index 00d75da41..894dfea35 100644 --- a/runtime/doc/xxd.man +++ b/runtime/doc/xxd.man @@ -82,17 +82,17 @@ OPTIONS allowed anywhere. -seek offset - When used after -r : revert with <offset> added to file posi- - tions found in hexdump. + When used after -r: revert with <offset> added to file positions + found in hexdump. -s [+][-]seek - start at <seek> bytes abs. (or rel.) infile offset. + indicates - that the seek is relative to the current stdin file position - (meaningless when not reading from stdin). - indicates that the - seek should be that many characters from the end of the input - (or if combined with - + : before the current stdin file position). Without -s - option, xxd starts at the current file position. + start at <seek> bytes abs. (or rel.) infile offset. + fRindi- + cates that the seek is relative to the current stdin file posi- + tion (meaningless when not reading from stdin). - indicates + that the seek should be that many characters from the end of the + input (or if combined with +: before the current stdin file + position). Without -s option, xxd starts at the current file + position. -u use upper case hex letters. Default is lower case. @@ -101,20 +101,20 @@ OPTIONS CAVEATS xxd -r has some builtin magic while evaluating line number information. - If the output file is seekable, then the linenumbers at the start of - each hexdump line may be out of order, lines may be missing, or over- - lapping. In these cases xxd will lseek(2) to the next position. If the - output file is not seekable, only gaps are allowed, which will be + If the output file is seekable, then the linenumbers at the start of + each hexdump line may be out of order, lines may be missing, or over- + lapping. In these cases xxd will lseek(2) to the next position. If the + output file is not seekable, only gaps are allowed, which will be filled by null-bytes. xxd -r never generates parse errors. Garbage is silently skipped. - When editing hexdumps, please note that xxd -r skips everything on the + When editing hexdumps, please note that xxd -r skips everything on the input line after reading enough columns of hexadecimal data (see option - -c). This also means, that changes to the printable ascii (or ebcdic) - columns are always ignored. Reverting a plain (or postscript) style - hexdump with xxd -r -p does not depend on the correct number of col- - umns. Here anything that looks like a pair of hex-digits is inter- + -c). This also means, that changes to the printable ascii (or ebcdic) + columns are always ignored. Reverting a plain (or postscript) style + hexdump with xxd -r -p does not depend on the correct number of col- + umns. Here anything that looks like a pair of hex-digits is inter- preted. Note the difference between @@ -122,28 +122,28 @@ CAVEATS and % xxd -i < file - xxd -s +seek may be different from xxd -s seek , as lseek(2) is used to + xxd -s +seek may be different from xxd -s seek, as lseek(2) is used to "rewind" input. A '+' makes a difference if the input source is stdin, - and if stdin's file position is not at the start of the file by the - time xxd is started and given its input. The following examples may + and if stdin's file position is not at the start of the file by the + time xxd is started and given its input. The following examples may help to clarify (or further confuse!)... - Rewind stdin before reading; needed because the `cat' has already read + Rewind stdin before reading; needed because the `cat' has already read to the end of stdin. % sh -c 'cat > plain_copy; xxd -s 0 > hex_copy' < file - Hexdump from file position 0x480 (=1024+128) onwards. The `+' sign + Hexdump from file position 0x480 (=1024+128) onwards. The `+' sign means "relative to the current position", thus the `128' adds to the 1k where dd left off. - % sh -c 'dd of=plain_snippet bs=1k count=1; xxd -s +128 > hex_snippet' + % sh -c 'dd of=plain_snippet bs=1k count=1; xxd -s +128 > hex_snippet' < file Hexdump from file position 0x100 ( = 1024-768) on. % sh -c 'dd of=plain_snippet bs=1k count=1; xxd -s +-768 > hex_snippet' < file - However, this is a rare situation and the use of `+' is rarely needed. - The author prefers to monitor the effect of xxd with strace(1) or + However, this is a rare situation and the use of `+' is rarely needed. + The author prefers to monitor the effect of xxd with strace(1) or truss(1), whenever -s is used. EXAMPLES @@ -187,7 +187,7 @@ EXAMPLES % xxd -s 0x36 -l 13 -c 13 xxd.1 0000036: 3235 7468 204d 6179 2031 3939 36 25th May 1996 - Create a 65537 byte file with all bytes 0x00, except for the last one + Create a 65537 byte file with all bytes 0x00, except for the last one which is 'A' (hex 0x41). % echo '010000: 41' | xxd -r > file @@ -197,7 +197,7 @@ EXAMPLES * 000fffc: 0000 0000 40 ....A - Create a 1 byte file containing a single 'A' character. The number + Create a 1 byte file containing a single 'A' character. The number after '-r -s' adds to the linenumbers found in the file; in effect, the leading bytes are suppressed. % echo '010000: 41' | xxd -r -s -0x10000 > file @@ -239,7 +239,7 @@ SEE ALSO uuencode(1), uudecode(1), patch(1) WARNINGS - The tools weirdness matches its creators brain. Use entirely at your + The tools weirdness matches its creators brain. Use entirely at your own risk. Copy files. Trace it. Become a wizard. VERSION |