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SG3_UTILS(8)                                SG3_UTILS                                SG3_UTILS(8)

NAME
       sg3_utils - a package of utilities for sending SCSI commands

SYNOPSIS
       sg_*  [--dry-run]  [--enumerate]  [--help]  [--hex]  [--in=FN] [--inhex=FN] [--maxlen=LEN]
       [--raw] [--timeout=SECS] [--verbose] [--version] [OTHER_OPTIONS] DEVICE

DESCRIPTION
       sg3_utils is a package of utilities that send SCSI commands to the given DEVICE via a SCSI
       pass through interface provided by the host operating system.

       The names of all utilities start with "sg" and most start with "sg_" often followed by the
       name, or a shortening of the name, of the SCSI command that they  send.  For  example  the
       "sg_verify" utility sends the SCSI VERIFY command. A mapping between SCSI commands and the
       sg3_utils utilities that issue them is shown in the COVERAGE file. The sg_raw utility  can
       be  used to send an arbitrary SCSI command (supplied on the command line) to the given DE-
       VICE.

       sg_decode_sense can be used to decode SCSI sense data given on the command line  or  in  a
       file.  sg_raw  -vvv  will  output  the T10 name of a given SCSI CDB which is most often 16
       bytes or less in length.

       SCSI draft standards can be found at http://www.t10.org . The standards themselves can  be
       purchased  from  ANSI  and other standards organizations.  A good overview of various SCSI
       standards can be seen in http://www.t10.org/scsi-3.htm with the SCSI command sets  in  the
       upper part of the diagram. The highest level (i.e. most abstract) document is the SCSI Ar-
       chitecture Model (SAM) with SAM-5 being the most recent standard  (ANSI  INCITS  515-2016)
       with  the  most recent draft being SAM-6 revision 4 . SCSI commands in common with all de-
       vice types can be found in SCSI Primary Commands (SPC) of which SPC-4 is the  most  recent
       standard (ANSI INCITS 513-2015). The most recent SPC draft is SPC-5 revision 21. Block de-
       vice specific commands (e.g. as used by disks) are in SBC, those for tape drives  in  SSC,
       those for SCSI enclosures in SES and those for CD/DVD/BD drives in MMC.

       It  is becoming more common to control ATA disks with the SCSI command set.  This involves
       the translation of SCSI commands to their corresponding ATA equivalents (and  that  is  an
       imperfect  mapping in some cases). The relevant standard is called SCSI to ATA Translation
       (SAT, SAT-2 and SAT-3) are now standards at INCITS(ANSI) and ISO while  SAT-4  is  at  the
       draft  stage.  The logic to perform the command translation is often called a SAT Layer or
       SATL and may be within an operating system, in host bus adapter firmware or in an external
       device (e.g. associated with a SAS expander). See http://www.t10.org for more information.

       There  is some support for SCSI tape devices but not for their basic operation. The reader
       is referred to the "mt" utility.

       There are two generations of command line option usage. The newer utilities (written since
       July  2004)  use the getopt_long() function to parse command line options. With that func-
       tion, each option has two representations: a short form (e.g.  '-v')  and  a  longer  form
       (e.g. '--verbose'). If an argument is required then it follows a space (optionally) in the
       short form and a "=" in the longer form (e.g. in  the  sg_verify  utility  '-l  2a6h'  and
       '--lba=2a6h'  are  equivalent).  Note  that  with getopt_long(), short form options can be
       elided, for example: '-all' is equivalent to '-a -l -l'.  The DEVICE argument  may  appear
       after, between or prior to any options.

       The  older  utilities,  including  as  sg_inq,  sg_logs,  sg_modes,  sg_opcode,  sg_rbuff,
       sg_readcap, sg_senddiag, sg_start and sg_turs had individual command line processing  code
       typically  based  on  a  single  "-" followed by one or more characters. If an argument is
       needed then it follows a "=" ( e.g. '-p=1f' in sg_modes with its older interface). Various
       options  can  be  elided  as  long as it is not ambiguous (e.g. '-vv' to increase the ver-
       bosity).

       Over time the command line interface of these older utilities became messy and  overloaded
       with options. So in sg3_utils version 1.23 the command line interface of these older util-
       ities was altered to have both a cleaner getopt_long() interface and their older interface
       for  backward  compatibility.   By  default  these older utilities use their getopt_long()
       based interface.  The getopt_long() is a GNU extension (i.e. not yet POSIX certified)  but
       more  recent command line utilities tend to use it. That can be overridden by defining the
       SG3_UTILS_OLD_OPTS environment variable or using '-O' or '--old' as the first command line
       option. The man pages of the older utilities documents the details.

       Several sg3_utils utilities are based on the Unix dd command (e.g. sg_dd) and permit copy-
       ing data at the level of SCSI READ and WRITE commands. sg_dd is tightly bound to Linux and
       hence  is  not  ported to other OSes. A more generic utility (than sg_dd) called ddpt in a
       package of the same name has been ported to other OSes.

ENVIRONMENT VARIABLES
       The SG3_UTILS_OLD_OPTS environment variable is explained in the previous  section.  It  is
       only for backward compatibility of the command line options for older utilities.

       The  SG3_UTILS_DSENSE  environment variable may be set to a number. It is only used by the
       embedded SNTL within the library used by the utilities in this library. SNTL is a SCSI  to
       NVMe  Translation  Layer.  This  environment variable defaults to 0 which will lead to any
       utility that issues a SCSI command that is translated to a NVMe command (by  the  embedded
       SNTL)  that fails at the NVMe dvice, to return SCSI sense in 'fixed' format. If this vari-
       able is non-zero then then the returned SCSI sense will be in 'descriptor' format.

       Several utilities have their  own  environment  variable  setting  (e.g.   sg_persist  has
       SG_PERSIST_IN_RDONLY). See individual utility man pages for more information.

       There is a Linux specific environment variable called SG3_UTILS_LINUX_NANO that if defined
       and the sg driver in the system is  4.0.30  or  later,  will  show  command  durations  in
       nanoseconds  rather  than  the default milliseconds.  Command durations are typically only
       shown if --verbose is used 3 or more times. Due to an interface problem (a 32 bit  integer
       that  should  be  64  bits with the benefit of hindsight) the maximum duration that can be
       represented in nanoseconds is about 4.2 seconds. If longer durations may occur then  don't
       define this environment variable (or undefine it).

LINUX DEVICE NAMING
       Most  disk block devices have names like /dev/sda, /dev/sdb, /dev/sdc, etc.  SCSI disks in
       Linux have always had names like that but in recent Linux kernels it has become more  com-
       mon  for  many other disks (including SATA disks and USB storage devices) to be named like
       that. Partitions within a disk are specified by a number  appended  to  the  device  name,
       starting at 1 (e.g. /dev/sda1 ).

       Tape  drives are named /dev/st<num> or /dev/nst<num> where <num> starts at zero. Addition-
       ally one letter from this list: "lma" may be appended to the name. CD, DVD and BD  readers
       (and  writers)  are named /dev/sr<num> where <num> start at zero. There are less used SCSI
       device type names, the dmesg and the lsscsi commands may help to find if any are  attached
       to a running system.

       There  is also a SCSI device driver which offers alternate generic access to SCSI devices.
       It uses names of the form /dev/sg<num> where <num> starts at zero. The "lsscsi -g" command
       may  be  useful  in finding these and which generic name corresponds to a device type name
       (e.g. /dev/sg2 may correspond to /dev/sda). In the lk 2.6  series  a  block  SCSI  generic
       driver was introduced and its names are of the form /dev/bsg/<h:c:t:l> where h, c, t and l
       are numbers. Again see the lsscsi command to find the correspondence between that SCSI tu-
       ple (i.e. <h:c:t:l>) and alternate device names.

       Prior  to  the Linux kernel 2.6 series these utilities could only use generic device names
       (e.g. /dev/sg1 ). In almost all cases in the Linux kernel 2.6 series, any device name  can
       be used by these utilities.

       Very little has changed in Linux device naming in the Linux kernel 3 and 4 series.

WINDOWS DEVICE NAMING
       Storage  and  related devices can have several device names in Windows.  Probably the most
       common in the volume name (e.g. "D:"). There are also  a  "class"  device  names  such  as
       "PhysicalDrive<n>", "CDROM<n>" and "TAPE<n>". <n> is an integer starting at 0 allocated in
       ascending order as devices are discovered (and sometimes rediscovered).

       Some storage devices have a SCSI lower level device name which starts with a SCSI (pseudo)
       adapter  name  of  the  form  "SCSI<n>:". To this is added sub-addressing in the form of a
       "bus" number, a "target" identifier and a LUN (Logical Unit Number). The "bus"  number  is
       also  known  as  a  "PathId".   These  are  assembled  to  form a device name of the form:
       "SCSI<n>:<bus>,<target>,<lun>". The trailing ",<lun>" may be omitted in which case  a  LUN
       of  zero is assumed. This lower level device name cannot often be used directly since Win-
       dows blocks attempts to use it if a class driver has "claimed" the device. There are  SCSI
       device  types  (e.g.  Automation/Drive interface type) for which there is no class driver.
       At least two transports ("bus types" in Windows jargon): USB and IEEE 1394 do not  have  a
       "scsi" device names of this form.

       In  keeping with DOS file system conventions, the various device names can be given in up-
       per, lower or mixed case. Since "PhysicalDrive<n>" is tedious to write, a  shortened  form
       of "PD<n>" is permitted by all utilities in this package.

       A  single  device (e.g. a disk) can have many device names. For example: "PD0" can also be
       "C:", "D:" and "SCSI0:0,1,0". The two volume names reflect that the disk  has  two  parti-
       tions  on  it.  Disk partitions that are not recognized by Windows are not usually given a
       volume name. However Vista does show a volume name for a disk which has no partitions rec-
       ognized  by  it  and  when selected invites the user to format it (which may be rather un-
       friendly to other OSes).

       These utilities assume a given device name is in the Win32 device namespace.  To make that
       explicit  "\\.\"  can  be  prepended to the device names mentioned in this section. Beware
       that backslash is an escape character in Unix like shells and the C programming  language.
       In a shell like Msys (from MinGW) each backslash may need to be typed twice.

       The  sg_scan  utility within this package lists out Windows device names in a form that is
       suitable for other utilities in this package to use.

FREEBSD DEVICE NAMING
       SCSI disks have block names of the form /dev/da<num> where <num> is an integer starting at
       zero.  The  "da"  is  replaced  by  "sa"  for SCSI tape drives and "cd" for SCSI CD/DVD/BD
       drives. Each SCSI device  has  a  corresponding  pass-through  device  name  of  the  form
       /dev/pass<num>  where  <num> is an integer starting at zero. The "camcontrol devlist" com-
       mand may be useful for finding out which SCSI device names are available  and  the  corre-
       spondence between class and pass-through names.

       FreeBSD  allows device names to be given without the leading "/dev/" (e.g.  da0 instead of
       /dev/da0). That worked in this package up until version 1.43  when  the  unadorned  device
       name  (e.g.  "da0")  gave  an  error.  The original action (i.e. allowing unadorned device
       names) has been restored in version 1.46 . Also note that symlinks (to device  names)  are
       followed before prepending "/dev/" if the resultant name doesn't start with a "/".

SOLARIS DEVICE NAMING
       SCSI  device  names  below  the /dev directory have a form like: c5t4d3s2 where the number
       following "c" is the controller (HBA) number, the number following "t" is the target  num-
       ber  (from the SCSI parallel interface days) and the number following "d" is the LUN. Fol-
       lowing the "s" is the slice number which is related to a partition and by convention  "s2"
       is the whole disk.

       OpenSolaris  also  has a c5t4d3p2 form where the number following the "p" is the partition
       number apart from "p0" which is the whole disk. So a whole disk may be referred to as  ei-
       ther c5t4d3, c5t4d3s2 or c5t4d3p0 .

       And  these device names are duplicated in the /dev/dsk and /dev/rdsk directories. The for-
       mer is the block device name and the latter is for "raw" (or char device) access which  is
       what  sg3_utils needs. So in OpenSolaris something of the form 'sg_inq /dev/rdsk/c5t4d3p0'
       should work.  If it doesn't work then add a '-vvv'  option  for  more  debug  information.
       Trying  this form 'sg_inq /dev/dsk/c5t4d3p0' (note "rdsk" changed to "dsk") will result in
       an "inappropriate ioctl for device" error.

       The device names within the /dev directory are typically symbolic  links  to  much  longer
       topological names in the /device directory. In Solaris cd/dvd/bd drives seem to be treated
       as disks and so are found in the /dev/rdsk directory. Tape drives appear in  the  /dev/rmt
       directory.

       There is also a sgen (SCSI generic) driver which by default does not attach to any device.
       See the /kernel/drv/sgen.conf file to control what is attached. Any attached  device  will
       have a device name of the form /dev/scsi/c5t4d3 .

       Listing  available SCSI devices in Solaris seems to be a challenge. "Use the 'format' com-
       mand" advice works but seems a very dangerous way to list devices. [It does  prompt  again
       before  doing  any  damage.] 'devfsadm -Cv' cleans out the clutter in the /dev/rdsk direc-
       tory, only leaving what is "live". The "cfgadm -v" command looks promising.

NVME SUPPORT
       NVMe (or NVM Express) is a relatively new storage transport and command set. The level  of
       abstraction of the NVMe command set is somewhat lower the SCSI command sets, closer to the
       level of abstraction of ATA (and SATA) command sets. NVMe claims to be designed with flash
       and  modern  "solid  state" storage in mind, something unheard of when SCSI was originally
       developed in the 1980s.

       The SCSI command sets' advantage is the length of time they have been in place and the ex-
       isting  tools  (like  these) to support it. Plus SCSI command sets level of abstraction is
       both and advantage and disadvantage. Recently the NVME-MI (Management Interface) designers
       decide  to  use  the SCSI Enclosure Services (SES-3) standard "as is" with the addition of
       two tunnelling NVME-MI commands: SES Send and SES Receive. This means after the OS  inter-
       face  differences  are  taken  into  account, the sg_ses, sg_ses_microcode and sg_senddiag
       utilities can be used on a NVMe device that supports a newer version of NVME-MI.

       The NVME-MI SES Send and SES Receive commands correspond to the SCSI SEND  DIAGNOSTIC  and
       RECEIVE  DIAGNOSTIC RESULTS commands respectively.  There are however a few other commands
       that need to be translated, the most important of which is the SCSI INQUIRY command to the
       NVMe  Identify  controller/namespace.  Starting  in version 1.43 these utilities contain a
       small SNTL (SCSI to NVMe Translation Layer) to take care of these details.

       As a side effect of this "juggling" if the sg_inq utility is used (without the --page= op-
       tion) on a NVMe DEVICE then the actual NVMe Identifier (controller and possibly namespace)
       responses are decoded and output. However if 'sg_inq --page=sinq <device>'  is  given  for
       the  same  DEVICE  then  parts  of the NVMe Identify controller and namespace response are
       translated to a SCSI standard INQUIRY response which is then decoded and output.

       Apart from the special case with the sg_inq, all other utilities  in  the  package  assume
       they  are  talking  to a SCSI device and decode any response accordingly. One easy way for
       users to see the underlying device is a NVMe device is the standard INQUIRY response  Ven-
       dor  Identification  field  of "NVMe    " (an 8 character long string with 4 spaces to the
       right).

       The following SCSI commands are currently supported by the SNTL library: INQUIRY, MODE SE-
       LECT(10),  MODE  SENSE(10), READ(10,16), READ CAPACITY(10,16), RECEIVE DIAGNOSTIC RESULTS,
       REQUEST SENSE, REPORT LUNS, REPORT SUPPORTED OPERATION CODES, REPORT SUPPORTED  TASK  MAN-
       AGEMENT  FUNCTIONS, SEND DIAGNOSTICS, START STOP UNIT, SYNCHRONIZE CACHE(10,16), TEST UNIT
       READY, VERIFY(10,16), WRITE(10,16) and WRITE SAME(10,16).

EXIT STATUS
       To aid scripts that call these utilities, the exit status is set to indicate  success  (0)
       or  failure  (1  or more). Note that some of the lower values correspond to the SCSI sense
       key values.

       The exit status values listed below can be given to the sg_decode_sense utility (which  is
       found in this package) as follows:
         sg_decode_sense --err=<exit_status>
       and a short explanatory string will be output to stdout.

       The exit status values are:

       0      success.  Also  used for some utilities that wish to return a boolean value for the
              "true" case (and that no error has occurred). The false case is  conveyed  by  exit
              status 36.

       1      syntax  error. Either illegal command line options, options with bad arguments or a
              combination of options that is not permitted.

       2      the DEVICE reports that it is not ready for the operation  requested.   The  DEVICE
              may be in the process of becoming ready (e.g.  spinning up but not at speed) so the
              utility may work after a wait. In Linux the DEVICE may be temporarily blocked while
              error recovery is taking place.

       3      the  DEVICE  reports  a medium or hardware error (or a blank check). For example an
              attempt to read a corrupted block on a disk will yield this value.

       5      the DEVICE reports an "illegal request" with an additional sense  code  other  than
              "invalid  command  operation  code". This is often a supported command with a field
              set requesting an unsupported capability. For commands that require a "service  ac-
              tion" field this value can indicate that the command with that service action value
              is not supported.

       6      the DEVICE reports a "unit attention" condition. This usually indicates that  some-
              thing  unrelated to the requested command has occurred (e.g. a device reset) poten-
              tially before the current SCSI command was sent. The requested command has not been
              executed  by  the  device. Note that unit attention conditions are usually only re-
              ported once by a device.

       7      the DEVICE reports a "data protect" sense key.  This  implies  some  mechanism  has
              blocked writes (or possibly all access to the media).

       9      the  DEVICE  reports  an  illegal request with an additional sense code of "invalid
              command operation code" which means that it doesn't support the requested command.

       10     the DEVICE reports a "copy aborted". This implies another command or device problem
              has stopped a copy operation. The EXTENDED COPY family of commands (including WRITE
              USING TOKEN) may return this sense key.

       11     the DEVICE reports an aborted command. In some cases aborted commands  can  be  re-
              tried immediately (e.g. if the transport aborted the command due to congestion).

       14     the  DEVICE  reports  a miscompare sense key. VERIFY and COMPARE AND WRITE commands
              may report this.

       15     the utility is unable to open, close or use the given DEVICE or  some  other  file.
              The  given file name could be incorrect or there may be permission problems. Adding
              the '-v' option may give more information.

       17     a SCSI "Illegal request" sense code received with a flag indicating the Info  field
              is valid. This is often a LBA but its meaning is command specific.

       18     the  DEVICE reports a medium or hardware error (or a blank check) with a flag indi-
              cating the Info field is valid. This is often a LBA (of the first  encountered  er-
              ror) but its meaning is command specific.

       20     the DEVICE reports it has a check condition but "no sense" and non-zero information
              in its additional sense codes. Some polling commands (e.g. REQUEST SENSE)  can  re-
              ceive  this  response.  There may be useful information in the sense data such as a
              progress indication.

       21     the DEVICE reports a "recovered error". The requested command was successful.  Most
              likely  a  utility  will  report a recovered error to stderr and continue, probably
              leaving the utility with an exit status of 0 .

       22     the DEVICE reports that the current command or its parameters imply a logical block
              address  (LBA) that is out of range. This happens surprisingly often when trying to
              access the last block on a storage device; either a classic "off by one" logic  er-
              ror  or  a misreading of the response from READ CAPACITY(10 or 16) in which the ad-
              dress of the last block rather than the number of blocks on the DEVICE is returned.
              Since LBAs are origin zero they range from 0 to n-1 where n is the number of blocks
              on the DEVICE, so the LBA of the last block is one less than the  total  number  of
              blocks.

       24     the  DEVICE  reports  a SCSI status of "reservation conflict". This means access to
              the DEVICE with the current command has been blocked because another  machine  (HBA
              or  SCSI  "initiator")  holds  a reservation on this DEVICE. On modern SCSI systems
              this is related to the use of the PERSISTENT RESERVATION family of commands.

       25     the DEVICE reports a SCSI status of "condition met". Currently only  the  PRE-FETCH
              command (see SBC-4) yields this status.

       26     the  DEVICE reports a SCSI status of "busy". SAM-6 defines this status as the logi-
              cal unit is temporarily unable to process a command. It is recommended to  re-issue
              the command.

       27     the DEVICE reports a SCSI status of "task set full".

       28     the  DEVICE  reports  a  SCSI status of "ACA active". ACA is "auto contingent alle-
              giance" and is seldom used.

       29     the DEVICE reports a SCSI status of "task aborted". SAM-5 says: "This status  shall
              be returned if a command is aborted by a command or task management function on an-
              other I_T nexus and the Control mode page TAS bit is set to one".

       31     error involving two or more command line options. They may be contradicting, select
              an unsupported mode, or a required option (given the context) is missing.

       32     there  is  a  logic  error  in  the  utility.  It corresponds to code comments like
              "shouldn't/can't get here". Perhaps the author should be informed.

       33     the command sent to DEVICE has timed out.

       34     this is a Windows only exit status and indicates that the Windows error number  (32
              bits)  cannot meaningfully be mapped to an equivalent Unix error number returned as
              the exit status (7 bits).

       36     no error has occurred plus the utility wants to convey a boolean  value  of  false.
              The corresponding true value is conveyed by a 0 exit status.

       40     the  command sent to DEVICE has received an "aborted command" sense key with an ad-
              ditional sense code of 0x10. This value is related to problems with protection  in-
              formation  (PI  or DIF). For example this error may occur when reading a block on a
              drive that has never been written (or is unmapped) if that drive was formatted with
              type 1, 2 or 3 protection.

       41     the  command sent to DEVICE has received an "aborted command" sense key with an ad-
              ditional sense code of 0x10 (as with error code) plus a flag  indicating  the  Info
              field is valid.

       48     this  is an internal message indicating a NVMe status field (SF) is other than zero
              after a command has been executed (i.e. something went wrong).  Work in  this  area
              is currently experimental.

       49     low level driver reports a response's residual count (i.e. number of bytes actually
              received by HBA is 'requested_bytes - residual_count') that is nonsensical.

       50     OS system calls that fail often return a small integer  number  to  help.  In  Unix
              these  are  called  "errno"  values where 0 implies no error. These error codes set
              aside 51 to 96 for mapping these errno values  but  that  may  not  be  sufficient.
              Higher errno values that cannot be mapped are all mapped to this value (i.e. 50).
              Note that an errno value of 0 is mapped to error code 0.

       50 + <os_error_number>
              OS system calls that fail often return a small integer number to help indicate what
              the error is. For example in Unix the inability of a system call to allocate memory
              returns  (in  'errno')  ENOMEM which often is associated with the integer 12. So 62
              (i.e. '50 + 12') may be returned by a utility in this case.  It  is  also  possible
              that a utility in this package reports 50+ENOMEM when it can't allocate memory, not
              necessarily from an OS system call. In recent versions of Linux  the  file  showing
              the  mapping between symbolic constants (e.g. ENOMEM) and the corresponding integer
              is in the kernel source code file: include/uapi/asm-generic/errno-base.h
              Note that errno values that are greater than or equal to 47  cannot  fit  in  range
              provided. Instead they are all mapped to 50 as discussed in the previous entry.

       97     a SCSI command response failed sanity checks.

       98     the  DEVICE  reports it has a check condition but the error doesn't fit into any of
              the above categories.

       99     any errors that can't be categorized into values 1 to 98 may yield this value. This
              includes  transport  and operating system errors after the command has been sent to
              the device.

       100-125
              these error codes are used by the ddpt utility which uses  the  sg3_utils  library.
              They are mainly specialized error codes associated with offloaded copies.

       126    the utility was found but could not be executed. That might occur if the executable
              does not have execute permissions.

       127    This is the exit status for utility not found. That might occur when a script calls
              a  utility  in this package but the PATH environment variable has not been properly
              set up, so the script cannot find the executable.

       128 + <signum>
              If a signal kills a utility then the exit status is 128 plus the signal number. For
              example  if  a  segmentation  fault  occurs  then  a utility is typically killed by
              SIGSEGV which according to 'man 7 signal' has an associated signal number of 11; so
              the exit status will be 139 .

       255    the utility tried to yield an exit status of 255 or larger. That should not happen;
              given here for completeness.

       Most of the error conditions reported above will be repeatable (an example of one that  is
       not is "unit attention") so the utility can be run again with the '-v' option (or several)
       to obtain more information.

COMMON OPTIONS
       Arguments to long options are mandatory for short options as well. In the  short  form  an
       argument  to  an  option uses zero or more spaces as a separator (i.e. the short form does
       not use "=" as a separator).

       If an option takes a numeric argument then that argument is assumed to be  decimal  unless
       otherwise  indicated  (e.g.  with  a leading "0x", a trailing "h" or as noted in the usage
       message).

       Some options are used uniformly in most of the utilities in this  package.  Those  options
       are listed below. Note that there are some exceptions.

       -d, --dry-run
              utilities that can cause lots of user data to be lost or overwritten sometimes have
              a --dry-run option. Device modifying actions are typically bypassed (or skipped) to
              implement  a  policy of "do no harm".  This allows complex command line invocations
              to be tested before the action required (e.g. format  a  disk)  is  performed.  The
              --dry-run  option  has become a common feature of many command line utilities (e.g.
              the Unix 'patch' command), not just those from this package.
              Note that most hyphenated option names in this package also can be  given  with  an
              underscore rather than a hyphen (e.g.  --dry_run).

       -e, --enumerate
              some  utilities (e.g. sg_ses and sg_vpd) store a lot of information in internal ta-
              bles. This option will output that information in some readable form  (e.g.  sorted
              by  an  acronym  or by page number) then exit. Note that with this option DEVICE is
              ignored (as are most other options) and no SCSI IO takes place, so the invoker does
              not need any elevated permissions.

       -h, -?, --help
              output  the  usage  message then exit. In a few older utilities the '-h' option re-
              quests hexadecimal output. In these cases the '-?' option  will  output  the  usage
              message then exit.

       -H, --hex
              for  SCSI  commands  that  yield a non-trivial response, print out that response in
              ASCII hexadecimal. To produce hexadecimal that can be  parsed  by  other  utilities
              (e.g.  without  a relative address to the left and without trailing ASCII) use this
              option three or four times.

       -i, --in=FN
              many SCSI commands fetch a significant amount of data (returned in the data-in buf-
              fer) which several of these utilities decode (e.g. sg_vpd and sg_logs). To separate
              the two steps of fetching the data from a SCSI device and then  decoding  it,  this
              option  has  been  added.  The first step (fetching the data) can be done using the
              --hex or --raw option and redirecting the command line output to a file (often done
              with  ">"  in Unix based operating systems). The difference between --hex and --raw
              is that the former produces output in ASCII hexadecimal while  --raw  produces  its
              output in "raw" binary.
              The  second  step  (i.e. decoding the SCSI response data now held in a file) can be
              done using this --in=FN option where the file name is FN. If "-"  is  used  for  FN
              then  stdin is assumed, again this allows for command line redirection (or piping).
              That file (or stdin) is assumed to contain ASCII hexadecimal unless the  --raw  op-
              tion  is also given in which case it is assumed to be binary. Notice that the mean-
              ing of the --raw option is "flipped" when used with --in=FN to act  on  the  input,
              typically it acts on the output data.
              Since  the structure of the data returned by SCSI commands varies considerably then
              the usage information or the manpage of the utility being used should  be  checked.
              In  some  cases  --hex may need to be used multiple times (and is more conveniently
              given as '-HH' or '-HHH).

       -i, --inhex=FN
              This option has the same or similar functionality as --in=FN. And  perhaps  'inhex'
              is more descriptive since by default, ASCII hexadecimal is expected in the contents
              of file: FN. Alternatively the short form option may be -I or -X. See  the  "FORMAT
              OF FILES CONTAINING ASCII HEX" section below for more information.

       -m, --maxlen=LEN
              several important SCSI commands (e.g. INQUIRY and MODE SENSE) have response lengths
              that vary depending on many factors, only some of which these utilities  take  into
              account.  The  maximum  response  length  is typically specified in the 'allocation
              length' field of the cdb. In the absence of this option, several  utilities  use  a
              default  allocation length (sometimes recommended in the SCSI draft standards) or a
              "double fetch" strategy.  See sg_logs(8) for its description of  a  "double  fetch"
              strategy. These techniques are imperfect and in the presence of faulty SCSI targets
              can cause problems (e.g. some USB mass storage devices freeze if  they  receive  an
              INQUIRY  allocation  length  other  than  36). Also use of this option disables any
              "double fetch" strategy that may have otherwise been used.

       -r, --raw
              for SCSI commands that yield a non-trivial response, output that response in binary
              to  stdout.  If any error messages or warning are produced they are usually sent to
              stderr so as to not interfere with the output from this option.
              Some utilities that consume data to send to the DEVICE along with the SCSI command,
              use  this  option. Alternatively the --in=FN option causes DEVICE to be ignored and
              the response data (to be decoded) fetched from a file named FN. In these cases this
              option  may  indicate  that  binary data can be read from stdin or from a nominated
              file (e.g. FN).

       -t, --timeout=SECS
              utilities that issue potentially long-running SCSI commands often  have  a  --time-
              out=SECS  option.  This  typically instructs the operating system to abort the SCSI
              command in question once the timeout expires. Aborting SCSI commands is typically a
              messy  business  and  in the case of format like commands may leave the device in a
              "format corrupt" state requiring another long-running re-initialization command  to
              be sent. The argument, SECS, is usually in seconds and the short form of the option
              may be something other than -t since the timeout option was typically  added  later
              as storage devices grew in size and initialization commands took longer. Since many
              utilities had relatively long internal command timeouts before this option was  in-
              troduced,  the  actual command timeout given to the operating systems is the higher
              of the internal timeout and SECS.
              Many long running SCSI commands have an IMMED bit which causes the command to  fin-
              ish  relatively  quickly  but the initialization process to continue. In such cases
              the REQUEST SENSE command can be used to monitor progress with its progress indica-
              tion  field  (see the sg_requests and sg_turs utilities).  Utilities that send such
              SCSI command either have an --immed option or a --wait option which is the  logical
              inverse of the "immediate" action.

       -v, --verbose
              increase the level of verbosity, (i.e. debug output). Can be used multiple times to
              further increase verbosity. The additional output caused by this option  is  almost
              always sent to stderr.

       -V, --version
              print the version string and then exit. Each utility has its own version number and
              date of last code change.

NUMERIC ARGUMENTS
       Many utilities have command line options that take numeric arguments. These numeric  argu-
       ments can be large values (e.g. a logical block address (LBA) on a disk) and can be incon-
       venient to enter in the default decimal representation. So various  other  representations
       are permitted.

       Multiplicative  suffixes  are accepted. They are one, two or three letter strings appended
       directly after the number to which they apply:

          c C         *1
          w W         *2
          b B         *512
          k K KiB     *1024
          KB kB       *1000
          m M MiB     *1048576
          MB mB       *1000000
          g G GiB     *(2^30)
          GB gB       *(10^9)
          t T TiB     *(2^40)
          TB          *(10^12)
          p P PiB     *(2^50)
          PB          *(10^15)

       An example is "2k" for 2048. The large tera and peta suffixes are only available  for  nu-
       meric arguments that might require 64 bits to represent internally.

       These  multiplicative  suffixes  are  compatible  with GNU's dd command (since 2002) which
       claims compliance with SI and with IEC 60027-2.

       A suffix of the form "x<n>" multiplies the preceding number by <n>. An example  is  "2x33"
       for  "66". The left argument cannot be '0' as '0x' will be interpreted as hexadecimal num-
       ber prefix (see below). The left argument to the multiplication must end in a  hexadecimal
       digit  (i.e.   0  to f) and the whole expression cannot have any embedded whitespace (e.g.
       spaces). An ugly example: "0xfx0x2" for 30.

       A suffix of the form "+<n>" adds the preceding number to <n>. An  example  is  "3+1k"  for
       "1027".  The  left  argument to the addition must end in a hexadecimal digit (i.e. 0 to f)
       and the whole expression cannot have any embedded whitespace (e.g. spaces). Another  exam-
       ple: "0xf+0x2" for 17.

       Alternatively numerical arguments can be given in hexadecimal. There are two syntaxes. The
       number can be preceded by either "0x" or "0X" as found in the C programming language.  The
       second  hexadecimal  representation  is  a trailing "h" or "H" as found in (storage) stan-
       dards. When hex numbers are given, multipliers cannot be used.  For  example  the  decimal
       value "256" can be given as "0x100" or "100h".

FORMAT OF FILES CONTAINING ASCII HEX
       Such  a file is assumed to contain a sequence of one or two digit ASCII hexadecimal values
       separated by whitespace. "Whitespace consists of either spaces, tabs, blank lines, or  any
       combination  thereof". Each one or two digit ASCII hex pair is decoded into a byte (i.e. 8
       bits). The following will be decoded to valid (ascending valued) bytes:  '0',  '01',  '3',
       'c', 'F', '4a', 'cC', 'ff'.  Lines containing only whitespace are ignored. The contents of
       any line containing a hash mark ('#') is ignored from that point until  the  end  of  that
       line.  Users  are encouraged to use hash marks to introduce comments in hex files. The au-
       thor uses the extension'.hex' on such files. Examples can be found in the  'inhex'  direc-
       tory.

MICROCODE AND FIRMWARE
       There  are  two standardized methods for downloading microcode (i.e. device firmware) to a
       SCSI device. The more general  way  is  with  the  SCSI  WRITE  BUFFER  command,  see  the
       sg_write_buffer  utility.  SCSI enclosures have their own method based on the Download mi-
       crocode control/status diagnostic page, see the sg_ses_microcode utility.

SCRIPTS, EXAMPLES and UTILS
       There are several bash shell scripts in the 'scripts' subdirectory  that  invoke  compiled
       utilities  (e.g. sg_readcap). Several of the scripts start with 'scsi_' rather than 'sg_'.
       One purpose of these scripts is to call the same utility (e.g. sg_readcap) on multiple de-
       vices.  Most  of  the  basic compiled utilities only allow one device as an argument. Some
       distributions install these scripts in a more visible directory (e.g. /usr/bin).  Some  of
       these scripts have man page entries. See the README file in the 'scripts' subdirectory.

       There is some example C code plus examples of complex invocations in the 'examples' subdi-
       rectory. There is also a README file. The example C may be a simpler example of how to use
       a  SCSI  pass-through  in Linux than the main utilities (found in the 'src' subdirectory).
       This is due to the fewer abstraction layers (e.g. they don't worry the  MinGW  in  Windows
       may open a file in text rather than binary mode).

       Some  utilities that the author has found useful have been placed in the 'utils' subdirec-
       tory.

WEB SITE
       There is a web page discussing this package at http://sg.danny.cz/sg/sg3_utils.html .  The
       device  naming  used  by  this  package  on  various  operating  systems  is discussed at:
       http://sg.danny.cz/sg/device_name.html   .   There   is   a    git    code    mirror    at
       https://github.com/hreinecke/sg3_utils . The principle code repository uses subversion and
       is on the author's equipment. The author keeps track of this via the  subversion  revision
       number  which is an ascending integer (currently at 774 for this package). The github mir-
       ror gets updated periodically from the author's repository. Depending on the time  of  up-
       date,  the  above  Downloads section at sg.danny.cz may be more up to date than the github
       mirror.

AUTHORS
       Written by Douglas Gilbert. Some utilities have been contributed, see the CREDITS file and
       individual source files (in the 'src' directory).

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

COPYRIGHT
       Copyright (C) 1999-2021 Douglas Gilbert
       Some  utilities  are  distributed under a GPL version 2 license while others, usually more
       recent ones, are under a FreeBSD license. The files that are common to almost  all  utili-
       ties  and  thus contain the most reusable code, namely sg_lib.[hc], sg_cmds_basic.[hc] and
       sg_cmds_extra.[hc] are under a FreeBSD license. There is NO warranty; not  even  for  MER-
       CHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

SEE ALSO
       sdparm(sdparm), ddpt(ddpt), lsscsi(lsscsi), dmesg(1), mt(1)

sg3_utils-1.46                              March 2021                               SG3_UTILS(8)

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