sg_raw(8) send arbitrary SCSI command to a device




This utility sends an arbitrary SCSI command (between 6 and 256 bytes) to the DEVICE. There may be no associated data transfer; or data may be read from a file and sent to the DEVICE; or data may be received from the DEVICE and then displayed or written to a file. If supported by the pass through, bidirectional commands may be sent (i.e. containing both data to be sent to the DEVICE and received from the DEVICE).

The SCSI command may be between 6 and 256 bytes long. Each command byte is specified in plain hex format (00..FF) without a prefix or suffix. See EXAMPLES section below.

The commands pass through a generic SCSI interface which is implemented for several operating systems including Linux, FreeBSD and Windows.


Arguments to long options are mandatory for short options as well.
-b, --binary
Dump data in binary form, even when writing to stdout.
-h, --help
Display usage information and exit.
-i, --infile=IFILE
Read data from IFILE instead of stdin. This option is ignored if --send is not specified.
-k, --skip=LEN
Skip the first LEN bytes of the input file or stream. This option is ignored if --send is not specified.
-n, --nosense
Don't display SCSI Sense information.
-o, --outfile=OFILE
Write data received from the DEVICE to OFILE. The data is written in binary. By default, data is dumped in hex format to stdout. If OFILE is '-' then data is dumped in binary to stdout. This option is ignored if --request is not specified.
-r, --request=RLEN
Expect to receive up to RLEN bytes of data from the DEVICE. RLEN may be suffixed with 'k' to use kilobytes (1024 bytes) instead of bytes. RLEN is decimal unless it has a leading '0x' or a trailing 'h'.
If RLEN is too small (i.e. either smaller than indicated by the cdb (typically the "allocation length" field) and/or smaller than the DEVICE tries to send back) then the HBA driver may complain. Making RLEN larger than required should cause no problems. Most SCSI "data-in" commands return a data block that contains (in its early bytes) a length that the DEVICE would "like" to send back if the "allocation length" field in the cdb is large enough. In practice, the DEVICE will return no more bytes than indicated in the "allocation length" field of the cdb.
-R, --readonly
Open DEVICE read-only. The default (without this option) is to open it read-write.
-s, --send=SLEN
Read SLEN bytes of data, either from stdin or from a file, and send them to the DEVICE. In the SCSI transport, SLEN becomes the length (in bytes) of the "data-out" buffer. SLEN is decimal unless it has a leading '0x' or a trailing 'h'.
It is the responsibility of the user to make sure that the "data-out" length implied or stated in the cdb matches SLEN. Note that some common SCSI commands such as WRITE(10) have a "transfer length" field whose units are logical blocks (which are often 512 bytes long).
-t, --timeout=SEC
Wait up to SEC seconds for command completion (default: 20). Note that if a command times out the operating system may start by aborting the command and if that is unsuccessful it may attempt to reset the device.
-v, --verbose
Increase level of verbosity. Can be used multiple times.
-V, --version
Display version and license information and exit.


The sg_inq utility can be used to send an INQUIRY command to a device to determine its peripheral device type (e.g. '1' for a streaming device (tape drive)) which determines which SCSI command sets a device should support (e.g. SPC and SSC). The sg_vpd utility probes the Vital Product Pages of a devices which may contain useful information.

The ability to send more than a 16 byte CDB (in some cases 12 byte CDB) may be restricted by the pass-through interface, the low level driver or the transport. In the Linux series 3 kernels, the bsg driver can handle longer CDBs, block devices (e.g. /dev/sdc) accessed via the SG_IO ioctl cannot handle CDBs longer than 16 bytes, and the sg driver can handle longer CDBs from lk 3.17 .

The CDB command name defined by T10 for the given CDB is shown if the '-vv' option is given. The command line syntax still needs to be correct, so /dev/null may be used for the DEVICE since the CDB command name decoding is done before the DEVICE is checked.


These examples, apart from the last one, use Linux device names. For suitable device names in other supported Operating Systems see the sg3_utils(8) man page.
sg_raw /dev/scd0 1b 00 00 00 02 00
Eject the medium in CD drive /dev/scd0.
sg_raw -r 1k /dev/sg0 12 00 00 00 60 00
Perform an INQUIRY on /dev/sg0 and dump the response data (up to 1024 bytes) to stdout.
sg_raw -s 512 -i i512.bin /dev/sda 3b 02 00 00 00 00 00 02 00 00
Showing an example of writing 512 bytes to a sector on a disk is a little dangerous. Instead this example will read i512.bin (assumed to be 512 bytes long) and use the SCSI WRITE BUFFER command to send it to the "data" buffer (that is mode 2). This is a safe operation.
sg_raw -r 512 -o o512.bin /dev/sda 3c 02 00 00 00 00 00 02 00 00
This will use the SCSI READ BUFFER command to read 512 bytes from the "data" buffer (i.e. mode 2) then write it to the o512.bin file. When used in conjunction with the previous example, if both commands work then 'cmp i512.bin o512.bin' should show a match.
sg_raw --infile=urandom.bin --send=512 --request=512 --outfile=out.bin "/dev/bsg/7:0:0:0" 53 00 00 00 00 00 00 00 01 00
This is a bidirectional XDWRITEREAD(10) command being sent via a Linux bsg device. Note that data is being read from "urandom.bin" and sent to the device (data-out) while resulting data (data-in) is placed in the "out.bin" file. Also note the length of both is 512 bytes which corresponds to the transfer length of 1 (block) in the cdb (i.e. the second last byte).
sg_raw.exe PhysicalDrive1 a1 0c 0e 00 00 00 00 00 00 e0 00 00
This example is from Windows and shows a ATA STANDBY IMMEDIATE command being sent to PhysicalDrive1. That ATA command is contained within the SCSI ATA PASS-THROUGH(12) command (see the SAT or SAT-2 standard at Notice that the STANDBY IMMEDIATE command does not send or receive any additional data, however if it fails sense data should be returned and displayed.


The exit status of sg_raw is 0 when it is successful. Otherwise see the sg3_utils(8) man page.


Written by Ingo van Lil


Report bugs to <inguin at gmx dot de>.


Copyright © 2001-2015 Ingo van Lil
This software is distributed under the GPL version 2. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.