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SG_DECODE_SENSE(8)		   SG3_UTILS		    SG_DECODE_SENSE(8)

NAME
       sg_decode_sense - decode	SCSI sense and related data

SYNOPSIS
       sg_decode_sense [--binary=BFN] [--cdb] [--err=ES] [--file=HFN] [--help]
       [--hex] [--nospace] [--status=SS] [--verbose] [--version] [--write=WFN]
       [H1 H2 H3 ...]

DESCRIPTION
       This  utility takes SCSI	sense data in binary or	as a sequence of ASCII
       hexadecimal bytes and decodes it. The primary reference for the	decod-
       ing is SPC-4 ANSI INCITS	513-2015 and the most recent draft SPC-5 revi-
       sion 19 which can be found at http://www.t10.org	and other locations on
       the internet.

       SCSI sense data is often	found in kernel	log files as a result of some-
       thing going wrong or may	be an informative warning. It is  often	 shown
       as a sequence of	hexadecimal bytes, starting with 70, 71, 72, 73, f0 or
       f1.  Sense data could be	up to 252 bytes	long  but  typically  is  much
       shorter	than  that, 18 bytes long is often seen	and is usually associ-
       ated with the older "fixed" format sense	data.

       The sense data can be provided on the command line or  in  a  file.  If
       given  on the command line the sense data should	be a sequence of hexa-
       decimal bytes separated by space. Alternatively a  file	can  be	 given
       with the	contents in binary or ASCII hexadecimal	bytes. The latter form
       can contain several lines each with none, one or	more ASCII hexadecimal
       bytes separated by space	(comma or tab).	The hash symbol	may appear and
       it and the rest of the line is ignored making it	useful for comments.

       If the --cdb option is given then rather	than viewing the given hex ar-
       guments	as sense data, it is viewed as a SCSI command descriptor block
       (CDB). In this case the command name is printed out. That name is based
       on  the first hex byte given (know as the opcode) and optionally	on an-
       other field called the "service action".

       Another alternate action	is when	the --err=ES is	given. ES  is  assumed
       to  be  an "exit	status"	value between 0	and 255	from one of the	utili-
       ties in this package. A descriptive string is  printed.	Other  options
       are ignored apart from --verbose.

OPTIONS
       Arguments to long options are mandatory for short options as well.

       -b, --binary=BFN
	      the sense	data is	read in	binary from a file called BFN.

       -c, --cdb
	      treat  the  given	string of hex arguments	as bytes in a SCSI CDB
	      and decode the command name.

       -e, --err=ES
	      ES should	be an "exit status" value between 0 and	 255  that  is
	      available	 from the shell	(i.e. the utility's execution context)
	      after the	utility	is finished. By	default	 an  indicative	 error
	      message  is  printed  to	stdout;	and if the --verbose option is
	      given once (or an	odd number of times) then the message  is  in-
	      stead printed to stderr. If --verbose is given two or more times
	      a	longer form of the message is output. In all cases the message
	      is  less	than  128 characters long with one trailing line feed.
	      All other	command	line options and arguments are ignored.

       -f, --file=HFN
	      the sense	data is	read in	ASCII hexadecimal from a  file	called
	      HFN.   The sense data should appear as a sequence	of bytes sepa-
	      rated by space, comma, tab or newline. Everything	from  and  in-
	      cluding  a  hash	symbol	to the end of that line	is ignored. If
	      --nospace	is set then no separator is required between the ASCII
	      hexadecimal digits in HFN	with bytes decoded from	pairs of ASCII
	      hexadecimal digits.

       -h, --help
	      output the usage message then exit.

       -H, --hex
	      this option is used in conjunction with --write=WFN in order  to
	      change  the  output  written  to WFN to lines of ASCII hex bytes
	      suitable for a C language	compiler. Each line contains up	to  16
	      bytes (e.g. a line starting with "0x3b,0x07,0x00,0xff").

       -n, --nospace
	      expect  ASCII  hexadecimal  to be	a string of hexadecimal	digits
	      with no spaces between them. Bytes are  decoded  by  taking  two
	      hexadecimal digits at a time, so an even number of digits	is ex-
	      pected. The string of hexadecimal	digits may be on  the  command
	      line  (replacing "H1 H2 H3") or spread across multiple lines the
	      HFN given	to --file=.  On	the command  line,  spaces  (or	 other
	      whitespace  characters)  between sequences of hexadecimal	digits
	      are ignored; the maximum command line hex	string is 1023 charac-
	      ters long.

       -s, --status=SS
	      where  SS	is a SCSI status byte value, given in hexadecimal. The
	      SCSI status byte is related to, but distinct from, sense data.

       -v, --verbose
	      increase the degree of verbosity (debug messages).

       -V, --version
	      output version string then exit.

       -w, --write=WFN
	      writes the sense data out	to a file called WFN. If necessary WFN
	      is  created. If WFN exists then it is truncated prior to writing
	      the sense	data to	it. If the --hex option	 is  also  given  then
	      ASCII  hex is written to WFN (see	the --hex option description);
	      otherwise	binary is written to WFN. This option is a convenience
	      and may be helpful in converting the ASCII hexadecimal represen-
	      tation of	sense data (or anything	else) into the equivalent  bi-
	      nary or a	compilable ASCII hex form.

NOTES
       Unlike  most  utilities in this package,	this utility does not access a
       SCSI device (logical unit). This	utility	accesses a library  associated
       with  this package. Amongst other things	the library decodes SCSI sense
       data.

       The sg_raw utility takes	a ASCII	hexadecimal  sequence  representing  a
       SCSI  CDB.  When	 sg_raw	is given the '-vvv' option, it will attempt to
       decode the CDB name.

EXAMPLES
       Sense data is often printed out in kernel logs  and  sometimes  on  the
       command line when verbose or debug flags	are given. It will be at least
       8 bytes long, often 18 bytes long but  may  be  longer.	A  sense  data
       string might look like this:

       f0 00 03	00 00 12 34 0a	00 00 00 00 11 00 00 00
       00 00

       Cut and paste it	after the sg_decode_sense command:

	 sg_decode_sense f0 00 03 00 00	12 34 0a 00 00 00 00 11	00 00 00 00 00

       and for this sense data the output should look like this:

	Fixed format, current;	Sense key: Medium Error
	Additional sense: Unrecovered read error
	 Info fld=0x1234 [4660]

       For a medium error the Info field is the	logical	block address (LBA) of
       the lowest numbered block that the associated SCSI command was not able
       to read (verify or write).

EXIT STATUS
       The  exit  status of sg_decode_sense is 0 when it is successful.	Other-
       wise see	the sg3_utils(8) man page.

AUTHORS
       Written by Douglas Gilbert.

REPORTING BUGS
       Report bugs to <dgilbert	at interlog dot	com>.

COPYRIGHT
       Copyright (C) 2010-2019 Douglas Gilbert
       This software is	distributed under a FreeBSD license. There is NO  war-
       ranty;  not  even  for MERCHANTABILITY or FITNESS FOR A PARTICULAR PUR-
       POSE.

SEE ALSO
       sg_requests,sg_raw(sg3_utils)

sg3_utils-1.45			   June	2019		    SG_DECODE_SENSE(8)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | NOTES | EXAMPLES | EXIT STATUS | AUTHORS | REPORTING BUGS | COPYRIGHT | SEE ALSO

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