SG_MODES(8) SG3_UTILS SG_MODES(8)
NAME
sg_modes - reads mode pages with SCSI MODE SENSE command
SYNOPSIS
sg_modes [--all] [--control=PC] [--dbd] [--dbout] [--examine] [--flexi-
ble] [--help] [--hex] [--list] [--llbaa] [--maxlen=LEN]
[--page=PG[,SPG]] [--raw] [-R] [--readwrite] [--six] [--verbose]
[--version] [DEVICE]
sg_modes [-6] [-a] [-A] [-c=PC] [-d] [-D] [-e] [-f] [-h] [-H] [-l] [-L]
[-m=LEN] [-p=PG[,SPG]] [-r] [-subp=SPG] [-v] [-V] [-w] [-?] [DEVICE]
DESCRIPTION
This utility sends a MODE SENSE SCSI command to the DEVICE and outputs
the response. There is a 6 byte and 10 byte (cdb) variant of the MODE
SENSE command, this utility defaults to the 10 byte variant. The SPC-4
standard (and SPC-5 drafts) include a note stating that implementers
should migrate away from the SCSI MODE SELECT(6) and MODE SENSE(6) com-
mands in favour of the 10 byte variants (e.g. MODE SENSE(10)).
This utility decodes mode page headers and block descriptors but out-
puts the contents of each mode page in hex. It also has no facility to
change the mode page contents or block descriptor data. Mode page con-
tents are decoded and can be changed by the sdparm utility.
This utility supports two command line syntaxes, the preferred one is
shown first in the synopsis and explained in this section. A later sec-
tion on the old command line syntax outlines the second group of op-
tions.
If no page is given (and --list is not selected) then --all is assumed.
The --all option requests all mode pages (but not subpages) in a single
response.
OPTIONS
Arguments to long options are mandatory for short options as well.
-a, --all
output all the mode pages reported by the DEVICE. This is what
the page code 63 (0x3f) is defined to do. When used once, mode
subpages are not fetched. When used twice (e.g. '-aa'), all mode
pages and subpages are requested which is equivalent to
'--page=63,255'.
-c, --control=PC
PC is the page control value. Up to four different versions of
each page are held by the device:
0 : current values (i.e. those active at present)
1 : changeable values
2 : default values (i.e. the manufacturer's settings)
3 : saved values
The changeable values are bit masks showing which fields could
be changed with a MODE SELECT. The saved values will be re-in-
stated the next time the device is power cycled or reset. If
this option is not given then current values [0] are assumed.
-d, --dbd
disable block descriptors. By default, block descriptors (usu-
ally one (for disks) or none) are returned in a MODE SENSE re-
sponse. This option sets the "disable block descriptors" (DBD)
bit in the cdb which instructs the device not to return any
block descriptors in its response. Older devices may not support
this setting and may return an "illegal request" sense key; al-
ternatively they may ignore it. Oddly the Reduced Block Command
set (RBC) requires this bit set.
-D, --dbout
disable outputting block descriptors. Irrespective of whether
block descriptors are present in the response or not, they are
not output.
-e, --examine
examine each mode page in the range 0 through to 62 (inclusive).
If some response is given then print out the mode page name or
number (in hex) if the name is not known.
The sdparm utility which lists mode and VPD pages also has a
--examine option will similar functionility.
-f, --flexible
Some devices, bridges and/or drivers attempt crude translations
between MODE SENSE 6 and 10 byte commands without correcting the
response. This will cause the response to be mis-interpreted
(usually with an error saying the response is malformed). With
this option, the length of the response is checked, and if it
looks wrong, the response is then decoded as if the other mode
sense (cdb length) was sent.
-h, --help
print out the usage message then exit.
-H, --hex
The default action is to decode known mode page numbers (and
subpage numbers) into text. When this option is used once, the
response is output in hexadecimal to stdout. When this option is
used twice, mode page numbers and page control values are output
in hex.
When this option is used three times, the full response to the
MODE SENSE command is output in hex to stdout without any decod-
ing. This form can be redirected to a file (or piped) and then
used 'sdparm --inhex=' to decode.
-l, --list
lists all common page and subpage codes and their names that are
found in the command set that matches the peripheral type of the
given DEVICE. If no DEVICE and no --page=PG is given then the
common page and subpage codes and their names are listed for SBC
(e.g. a disk). If no DEVICE is given and a --page=PG is given
then the common page and subpage codes and their names are
listed for the command set whose peripheral device type matches
the value given to PG. For example 'sg_mode --list --page=1'
lists the command mode pages and subpages for tape devices. Ad-
ditionally if a sub_page_code is given then it is interpreted as
a transport identifier and command transport specific mode page
codes and their names are listed following the main mode page
list. Other options are ignored.
-L, --llbaa
set the Long LBA Accepted (LLBAA) bit in the MODE SENSE (10)
cdb. This bit is not defined in the MODE SENSE (6) cdb so set-
ting the '-L' and '--six' options is reported as an error. When
set the DEVICE may respond with 16 byte block descriptors as in-
dicated by the 'LongLBA' field in the response. In most cases
setting this option is not needed.
-m, --maxlen=LEN
The LEN argument is the maximum response length in bytes. It is
the 'allocation length' field in the cdb. When not given (or LEN
is zero) then the allocation length field is set to 4096 for
MODE SENSE (10) or 252 for MODE SENSE (6). The LEN argument must
be non-negative and no greater than 65535 for MODE SENSE (10)
and not greater than 255 for MODE SENSE (6).
-O, --old
Switch to older style options. Please use as first option.
-p, --page=PG
page code to fetch. The PG is assumed to be a decimal value un-
less prefixed by '0x' or has a trailing 'h'. It should be a
value between 0 and 63 (inclusive). When not given and a default
is required then a value of 63 (0x3f), which fetches all mode
pages, is used.
Alternatively an acronym for the mode page can be given. The
available acronyms can be listed out with the --page=xxx option.
They are almost the same as the acronyms used for mode pages in
the sdparm utility.
-p, --page=PG,SPG
page code and subpage code values to fetch. Both arguments are
assumed to be decimal unless flagged as hexadecimal. The page
code should be between 0 and 63 inclusive. The subpage code
should be between 0 and 255 inclusive. The default value for the
subpage code is 0.
-r, --raw
output the response in binary to stdout. Error messages and
warnings, if any, are sent to stderr. When this option is used
twice (e.g. '-rr') then has the same action as '-R'
-R output the selected mode page to stdout a byte per line. Each
line contains two hexadecimal digits (e.g. "3e"). Useful as in-
put (after editing) to the sg_wr_mode(8) utility.
-w, --readwrite
open DEVICE in "read-write" mode. Default is to open it in
read-only mode.
-6, -s, --six
by default this utility sends a 10 byte MODE SENSE command to
the DEVICE. However some SCSI devices only support 6 byte MODE
SENSE commands (e.g. SCSI-2 tape drives). This parameter forces
the use of 6 byte MODE SENSE commands.
-v, --verbose
increase level of verbosity. Can be used multiple times.
-V, --version
print out version string then exit.
NOTES
If the normal sg_modes utility fails with "illegal command operation
code" then try the '--six' (or '-6') option.
This utility performs a SCSI INQUIRY command to determine the periph-
eral type of the device (e.g. 0 -> Direct Access Device (disk)) prior
to sending a MODE SENSE command. This helps in decoding the block de-
scriptor and mode pages.
This utility opens DEVICE in read-only mode (e.g. in Unix, with the
O_RDONLY flag) by default. It will open DEVICE in read-write mode if
the --readwrite option is given.
In the 2.4 series of Linux kernels the DEVICE must be a SCSI generic
(sg) device. In the 2.6 series block devices (e.g. SCSI disks and DVD
drives) can also be specified. For example "sg_modes -a /dev/sda" will
work in the 2.6 series kernels.
EXIT STATUS
The exit status of sg_modes is 0 when it is successful. Otherwise see
the sg3_utils(8) man page.
OLDER COMMAND LINE OPTIONS
The options in this section were the only ones available prior to
sg3_utils version 1.23 . Since then this utility defaults to the newer
command line options which can be overridden by using --old (or -O) as
the first option. See the ENVIRONMENT VARIABLES section for another way
to force the use of these older command line options.
-6 by default this utility sends a 10 byte MODE SENSE command to
the DEVICE. This parameter forces the use of 6 byte MODE SENSE
commands. See --six in the main description.
-a see --all in the main description.
-A output all the mode pages and subpages supported by the DEVICE.
Same as '--all --all' in the new syntax.
-c=PC PC is the page control value. See --control=PC in the main de-
scription.
-d see --dbd in the main description.
-D see --dbout in the main description.
-e see --examine in the main description.
-f see --flexible in the main description.
-h The default action is to decode known mode page numbers (and
subpage numbers) into text. With this option mode page numbers
(and subpage numbers) are output in hexadecimal.
-H same action as the '-h' option.
-l see --list in the main description.
-L see --llbaa in the main description.
-N, --new
Switch to the newer style options.
-m=LEN see --maxlen=LEN in the main description.
-p=PG PG is page code to fetch. Should be a hexadecimal number between
0 and 3f inclusive (0 to 63 decimal). The default value when re-
quired is 3f (fetch all mode pages). Note that an acronym for
the page and/or subpage values is not accepted in this older
format (because any acronym starting with the letters 'a' to 'f'
is ambiguous; it could either be a hex number or an acronym).
-p=PG,SPG
page code and subpage code values to fetch. The page code should
be a hexadecimal number between 0 and 3f inclusive. The subpage
code should be a hexadecimal number between 0 and ff inclusive.
The default value for the subpage code is 0.
-r output the selected mode page to stdout a byte per line. Each
line contains two hexadecimal digits (e.g. "3e"). Useful as in-
put (after editing) to the sg_wr_mode(8) utility.
-subp=SPG
sub page code to fetch. Should be a hexadecimal number between 0
and 0xff inclusive. The default value is 0.
-v increase verbosity of output.
-V print out version string then exit.
-w see --readwrite in the main description.
-? output usage message then exit. Ignore all other parameters.
ENVIRONMENT VARIABLES
Since sg3_utils version 1.23 the environment variable
SG3_UTILS_OLD_OPTS can be given. When it is present this utility will
expect the older command line options. So the presence of this environ-
ment variable is equivalent to using --old (or -O) as the first command
line option.
AUTHOR
Written by Douglas Gilbert
REPORTING BUGS
Report bugs to <dgilbert at interlog dot com>.
COPYRIGHT
Copyright © 2000-2020 Douglas Gilbert
This software is distributed under the GPL version 2. There is NO war-
ranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PUR-
POSE.
SEE ALSO
sdparm(8), sg_wr_mode(8), sginfo(8), sgmode(scsirastools), scsi-
info(net), scu(net), seatools(seagate)
All these utilities offer some facility to change mode page (or block
descriptor) parameters.
sg3_utils-1.45 September 2020 SG_MODES(8)
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