sg_requests.8

.TH SG_REQUESTS "8" "January 2007" "sg3_utils\-1.23" SG3_UTILS
.SH NAME
sg_requests \- send one or more SCSI REQUEST SENSE commands
.SH SYNOPSIS
.B sg_requests
[\fI\-\-desc\fR] [\fI\-\-help\fR] [\fI\-\-hex\fR] [\fI\-\-num=NUM\fR]
[\fI\-\-raw\fR] [\fI\-\-status\fR] [\fI\-\-time\fR] [\fI\-\-verbose\fR]
[\fI\-\-version\fR] \fIDEVICE\fR
.SH DESCRIPTION
.\" Add any additional description here
.PP
Send REQUEST SENSE command to \fIDEVICE\fR and output the response which is
expected to be in sense data format. Both fixed and descriptor format are
supported.
.SH OPTIONS
Arguments to long options are mandatory for short options as well.
.TP
\fB\-d\fR, \fB\-\-desc\fR
sets the DESC bit in the REQUEST SENSE SCSI cdb. The \fIDEVICE\fR
should return sense data in descriptor (rather than fixed) format. This
will only occur if the \fIDEVICE\fR recognizes descriptor format (SPC\-3
and later). If the device is pre SPC\-3 then setting a bit in a reserved
field may cause a check condition status with an illegal request sense key.
.TP
\fB\-h\fR, \fB\-\-help\fR
output the usage message then exit.
.TP
\fB\-H\fR, \fB\-\-hex\fR
output response in ASCII hexadecimal.
.TP
\fB\-n\fR, \fB\-\-num\fR=\fINUM\fR
perform \fINUM\fR SCSI REQUEST SENSE commands, stopping when either \fINUM\fR
is reached or an error occurs. The default value for \fINUM\fR is 1 .
.TP
\fB\-r\fR, \fB\-\-raw\fR
output response in binary (to stdout).
.TP
\fB\-s\fR, \fB\-\-status\fR
if the last REQUEST SENSE finished without error (from SCSI status or
autosense) then the contents of the parameter data are analysed as
sense data and the exit status is set accordingly. The default
action (when this option is not given) is to ignore the contents
of the parameter data for the purposes of setting the exit status.
Some types of error set a sense key of "NO SENSE" with non\-zero
information in the additional sense code (e.g. the FAILURE PREDICTION
THRESHOLD EXCEEDED group of codes); this results in an exit status
value of 10. If the sense key is "NO SENSE" and both asc and ascq are
zero then the exit status is set to 0 . See the sg3_utils(8) man page
for exit status values.
.TP
\fB\-t\fR, \fB\-\-time\fR
time the SCSI REQUEST SENSE command(s) and calculate the average number
of operations per second.
.TP
\fB\-v\fR, \fB\-\-verbose\fR
increase the level of verbosity, (i.e. debug output).
Additionally the response (if received) is output in ASCII-HEX. Use
this option multiple times for greater verbosity.
.TP
\fB\-V\fR, \fB\-\-version\fR
print the version string and then exit.
.SH NOTES
In SCSI 1 and 2 the REQUEST SENSE command was very important for error
and warning processing in SCSI. The autosense capability rendered this
command almost superfluous.
.PP
However recent SCSI drafts (e.g. SPC\-3 rev 23 and SBC\-2 rev 16) increase
the utility of the REQUEST SENSE command. Idle and standby power
conditions can now be detected with this command; a progress indication
is given during FORMAT (when that command was started with with IMMED=1
in its parameter header); and the Filemark, ILI and EOM bits may be
set (e.g. by a tape drive). Interestingly the sense key is set 
to "no sense" while the asc/ascq code convey the information (e.g.
0x5e/0x4 "Standby condition activated by command").
.PP
The REQUEST SENSE command is not marked as mandatory in SPC\-3 (i.e. for
all SCSI devices) but is marked as mandatory in SBC\-2 (i.e. for disks),
SSC\-3 (i.e. for tapes) and MMC\-4 (i.e. for CD/DVD drives).
.SH EXIT STATUS
The exit status of sg_requests is 0 when it is successful. Otherwise see
the sg3_utils(8) man page.
.SH AUTHORS
Written by Douglas Gilbert.
.SH "REPORTING BUGS"
Report bugs to <dgilbert at interlog dot com>.
.SH COPYRIGHT
Copyright \(co 2004\-2007 Douglas Gilbert
.br
This software is distributed under a FreeBSD license. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
.SH "SEE ALSO"
.B sg3_utils