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SG_OPCODES(8) SG3_UTILS SG_OPCODES(8)

NAME
sg_opcodes - report supported SCSI commands or task management functions

SYNOPSIS
sg_opcodes [--alpha] [--compact] [--enumerate] [--help] [--hex] [--mask] [--mlu] [--no-in‐
quiry] [--opcode=OP[,SA]] [--pdt=DT] [--raw] [--rctd] [--repd] [--sa=SA] [--tmf] [--unsorted]
[--verbose] [--version] DEVICE

sg_opcodes [-a] [-c] [-e] [-H] [-m] [-M] [-n] [-o=OP] [-p=DT] [-q] [-R] [-s=SA] [-t] [-u]
[-v] [-V] [-?] DEVICE

DESCRIPTION
This utility sends a SCSI REPORT SUPPORTED OPERATION CODES or a REPORT SUPPORTED TASK MANAGE‐
MENT FUNCTIONS command to the DEVICE and then outputs the response. The default action is to
report supported operation codes. In this mode it will either list all supported commands or
give detailed information on a specific command identified by the --opcode=OP option (perhaps
with additional information from the --sa=SA option).

The name of a SCSI command depends on its peripheral device type (e.g. a disk). The REPORT
SUPPORTED OPERATION CODES and REPORT SUPPORTED TASK MANAGEMENT FUNCTIONS commands are not
supported in the MMC command set for CD and DVD devices. This utility does an INQUIRY to ob‐
tain the peripheral device type and prints out the vendor, product and revision strings.

A similar facility to query supported operation codes previously was available via the CmdDt
bit in the SCSI INQUIRY command (see sg_inq(8)). However that facility was made obsolete and
replaced by the REPORT SUPPORTED OPERATION CODES command in SPC-3 (revision 4) during Febru‐
ary 2002.

This utility supports two command line syntaxes, the preferred one is shown first in the syn‐
opsis and explained in this section. A later section on the old command line syntax outlines
the second group of options.

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

-a, --alpha
when all supported commands are being listed there is no requirement for the device
server (i.e. the DEVICE) to sort the list of commands. When this option is given the
list of supported commands is sorted by name (alphabetically). When this option and
the --unsorted option are both _not_ given then the list of supported commands is
sorted numerically (first by operation code and then by service action).

-c, --compact
some command names, especially those associated with some service actions, are getting
longer. This may cause line wrap in the one line per command mode on some terminals.
When this option is given the opcode and service action fields are combined into a
single field with the service action, prefixed by a comma shown directly after the op‐
code. If there is no service action associated with the command, then the comma and
the service action are not shown after the opcode. The CDB size field is not shown
when this option is given.

-e, --enumerate
this option prints the name of the SCSI command based on the given opcode, peripheral
device type and optionally the service action. If given, DEVICE is ignored. The op‐
code, peripheral device type and service action default to zero if not given. Thus if
this option is the only option given then "Test Unit ready" is output since its opcode
is 0, it has no service action and it is common to all peripheral device types since
it is defined in the SCSI Primary Commands (SPC) standard(s).

-h, --help
outputs the usage message summarizing command line options then exits. Ignores DEVICE
if given.

-H, --hex
outputs the response in ASCII hexadecimal to stdout.

-m, --mask
additionally prints out the cdb mask in hex. So a 12 byte cdb will have a 12 byte
hexadecimal mask. If the hexadecimal is expanded (mentally) to binary then a "1" means
the corresponding position in the cdb may be set. And "0" means the corresponding po‐
sition in the cdb must not be set. For "0" mask positions that a user tries to set in
a cdb, the device may either ignore it or report an error, typically with a sense key
of "illegal request".

-M, --mlu
additionally prints out an indication (0 or 1) whether the command effects all logical
units in the containing target. MLU (Multiple Logical Units) is a bit in the REPORT
SUPPORTED OPERATION CODES response introduced by proposal 18-045r1 (and possibly in
spc5r20). Without the option, the default output format which lists all opcodes, does
not include a MLU indication.

-n, --no-inquiry
Prior to calling a SCSI REPORT SUPPORTED OPERATION CODES or a REPORT SUPPORTED TASK
MANAGEMENT FUNCTIONS command, a SCSI INQUIRY command is performed. The reason is to
determine the peripheral device type (pdt) of the DEVICE as this is helpful in trans‐
lating operation codes to the command names. By default this utility prints a summary
of INQUIRY command response on stdout. If this option (or the --raw option) is given
then that summary is not printed on stdout.

-O, --old
Switch to older style options. Please use as first option.

-o, --opcode=OP[,SA]
the DEVICE will be queried for the given operation code (i.e. the OP value) which is
the first byte of a SCSI command. Optionally, if a SA value is given, it will be used
as that SCSI command's service action. Note that OP and OP,0 are not the same thing,
as SCSI does allow the service action to be 0 (but it is not comman). OP and SA are
decimal unless prefixed by "0x" or they have a trailing "h". OP should be in the
range 0 to 255 (0xff) inclusive. SA should be in the range 0 to 65535 (0xffff) inclu‐
sive. When this option is not given then all available SCSI commands supported by the
DEVICE are listed.

-p, --pdt=DT
where DT is the peripheral device type. This is used together with the --enumerate to
differentiate when a command opcode (and perhaps service action) is shared by multiple
device types.
This option may also be used with the --no-inquiry option to suppress this utility do‐
ing an INQUIRY command since the main reason for doing that is to find the peripheral
device type of the DEVICE.

-r, --raw
output the response in binary to stdout. Error messages and warnings, if any, are sent
to stderr.

-R, --rctd
set report command timeout descriptor (RCTD) bit in the cdb. The response may or may
not contain command timeout descriptors. If available they are output. If supported
there are two values: a nominal command timeout and a recommended command timeout.
Both have units of seconds. A value of zero means that no timeout is indicated and
this is shown in the corresponding decoded output as "-".

-q, --repd
set read extended parameter data (REPD) bit in the report task management functions
cdb. 16 bytes rather than the default 4 bytes expected in the response. This was added
in SPC-4 (revision 26).

-s, --sa=SA
the DEVICE will be queried for a command with the given service action (i.e. the SA
value). Used in conjunction with the --opcode=OP option. If this option is not given,
--opcode=OP is given and the command in question does have a service action then a
value of 0 will be assumed. SA is decimal and expected to be in the range 0 to 65535
(0xffff) inclusive.

-t, --tmf
list supported task management functions. This is done with the SCSI REPORT SUPPORTED
TASK MANAGEMENT FUNCTIONS command. When this option is chosen the --alpha, --op‐
code=OP, --rctd, --sa=SA and --unsorted options are ignored.

-u, --unsorted
when all supported commands are being listed there is no requirement for the device
server (i.e. the DEVICE) to sort the list of commands. When this option is given the
list of supported commands is in the order given by the DEVICE. When this option is
not given the supported commands are sorted numerically (first by operation code and
then by service action).

-v, --verbose
increase level of verbosity. Can be used multiple times.

-V, --version
print out version string then exit.

NOTES
As of SPC-5 revision 8 the recognized task management functions are: abort set, abort task
set, clear ACA, clear task set, logical unit reset, query task, query asynchronous event,
query task set, and I_T nexus reset. In SPC-4 revision 26 target reset and wakeup task man‐
agement functions were made obsolete.

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_opcodes /dev/sda" will work in the 2.6 series kernels.

EXIT STATUS
The exit status of sg_opcodes 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.

-a sort command alphabetically. Equivalent to --alpha in main description.

-c see the --compact option above.

-e see the --enumerate option above.

-H see the --hex option above.

-m see the --mask option above.

-n don't print a summary of the SCSI INQUIRY response on stdout.

-N, --new
Switch to the newer style options.

-o=OP the DEVICE will be queried for the given operation code (i.e. OP) which is the first
byte of a SCSI command. OP is hexadecimal and expected to be in the range 0 to ff in‐
clusive. When this option is not given then all available SCSI commands supported by
the DEVICE are listed.

-p=DT see the --pdt=DT option above.

-q set the read extended parameter data (REPD) bit in report TMF cdb. Equivalent to
--repd in main description.

-R set the report command timeout descriptor (RCTD) bit in cdb. Equivalent to --rctd in
main description.

-s=SA the DEVICE will be queried for a command with the given service action (i.e. SA). Used
in conjunction with the -o=OP option. If this option is not given, -o=OP is given and
the command in question does have a service action then a value of 0 will be assumed.
SA is hexadecimal and expected to be in the range 0 to ffff inclusive.

-t list supported task management functions. Equivalent to --tmf in the main description.

-u output all supported commands in the order given by DEVICE. Equivalent to --unsorted
in main description.

-v increase level of verbosity. Can be used multiple times.

-V print out version string then exit.

-? output usage message. Ignore all other parameters.

EXAMPLES
The examples in this page use Linux device names. For suitable device names in other sup‐
ported Operating Systems see the sg3_utils(8) man page.

To see the information about a specific command give its operation code to the '--op=' op‐
tion. A command line invocation is shown first followed by a typical response:

# sg_opcodes --op=93h /dev/sdb

Opcode=0x93
Command_name: Write same(16)
Command supported [conforming to SCSI standard]
Usage data: 93 e2 00 00 00 00 ff ff ff ff 00 00 ff ff 00 00

The next example shows the supported task management functions:

# sg_opcodes --tmf -n /dev/sdb

Task Management Functions supported by device:
Abort task
Abort task set
Clear ACA
Clear task set
Logical unit reset
Query task

Enumerate can be used to look up a SCSI command name in the absence of a device that supports
that command. The opcode and service action (if required) should be supplied:

# sg_opcodes --enumerate --op=0x9b,0xa

SCSI command:
Read buffer(16), read data from echo buffer

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 environment variable is equivalent to using --old (or -O) as the first command line op‐
tion.

AUTHOR
Written by Douglas Gilbert

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