sg_requests man page on YellowDog
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SG_REQUESTS(8) SG3_UTILS SG_REQUESTS(8)
NAME
sg_requests - send one or more SCSI REQUEST SENSE commands
SYNOPSIS
sg_requests [--desc] [--help] [--hex] [--num=NUM] [--raw] [--status]
[--time] [--verbose] [--version] DEVICE
DESCRIPTION
Send REQUEST SENSE command to DEVICE and output the response which is
expected to be in sense data format. Both fixed and descriptor format
are supported.
OPTIONS
Arguments to long options are mandatory for short options as well.
-d, --desc
sets the DESC bit in the REQUEST SENSE SCSI cdb. The DEVICE
should return sense data in descriptor (rather than fixed) for‐
mat. This will only occur if the DEVICE recognizes descriptor
format (SPC-3 and later). If the device is pre SPC-3 then set‐
ting a bit in a reserved field may cause a check condition sta‐
tus with an illegal request sense key.
-h, --help
output the usage message then exit.
-H, --hex
output response in ASCII hexadecimal.
-n, --num=NUM
perform NUM SCSI REQUEST SENSE commands, stopping when either
NUM is reached or an error occurs. The default value for NUM is
1 .
-r, --raw
output response in binary (to stdout).
-s, --status
if the last REQUEST SENSE finished without error (from SCSI sta‐
tus 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 val‐
ues.
-t, --time
time the SCSI REQUEST SENSE command(s) and calculate the average
number of operations per second.
-v, --verbose
increase the level of verbosity, (i.e. debug output). Addition‐
ally the response (if received) is output in ASCII-HEX. Use this
option multiple times for greater verbosity.
-V, --version
print the version string and then exit.
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.
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").
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).
EXIT STATUS
The exit status of sg_requests is 0 when it is successful. Otherwise
see the sg3_utils(8) man page.
AUTHORS
Written by Douglas Gilbert.
REPORTING BUGS
Report bugs to <dgilbert at interlog dot com>.
COPYRIGHT
Copyright © 2004-2007 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
sg3_utils
sg3_utils-1.23 January 2007 SG_REQUESTS(8)
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