1SG_REQUESTS(8)                     SG3_UTILS                    SG_REQUESTS(8)
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NAME

6       sg_requests - send one or more SCSI REQUEST SENSE commands
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SYNOPSIS

9       sg_requests   [--desc]   [--help]  [--hex]  [--maxlen=LEN]  [--num=NUM]
10       [--progress] [--raw] [--status] [--time] [--verbose] [--version] DEVICE
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DESCRIPTION

13       Send SCSI REQUEST SENSE command to DEVICE and output the parameter data
14       response  which  is expected to be in sense data format. Both fixed and
15       descriptor sense data formats are supported.
16
17       Multiple REQUEST SENSE commands can be sent with the --num=NUM  option.
18       This can be used for timing purposes or monitoring the progress indica‐
19       tion.
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OPTIONS

22       Arguments to long options are mandatory for short options as well.
23
24       -d, --desc
25              sets the DESC bit in the REQUEST  SENSE  SCSI  cdb.  The  DEVICE
26              should  return sense data in descriptor (rather than fixed) for‐
27              mat. This will only occur if the  DEVICE  recognizes  descriptor
28              format  (SPC-3  and later). If the device is pre SPC-3 then set‐
29              ting a bit in a reserved field may cause a check condition  sta‐
30              tus  with  an illegal request sense key, but will most likely be
31              ignored.
32
33       -h, --help
34              output the usage message then exit.
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36       -H, --hex
37              output response in ASCII hexadecimal.
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39       -m, --maxlen=LEN
40              where LEN is the (maximum)  response  length  in  bytes.  It  is
41              placed  in the cdb's "allocation length" field. If not given (or
42              LEN is zero) then 252 is used. The maximum value of LEN  is  255
43              (but SPC-4 recommends 252).
44
45       -n, --num=NUM
46              perform  NUM  SCSI  REQUEST SENSE commands, stopping when either
47              NUM is reached or an error occurs. The default value for NUM  is
48              1 .
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50       -p, --progress
51              show   progress  indication  (a  percentage)  if  available.  If
52              --num=NUM is given,  NUM  is  greater  than  1  and  an  initial
53              progress indication was detected then this utility waits 30 sec‐
54              onds before subsequent checks.  Exits when  NUM  is  reached  or
55              there  are  no  more progress indications.  Ignores --hex, --raw
56              and --time options. See NOTES section below.
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58       -r, --raw
59              output response in binary (to stdout).
60
61       -s, --status
62              if the REQUEST SENSE command finished without  error  (as  indi‐
63              cated  by  its  SCSI  status) then the contents of the parameter
64              data are analysed as sense data  and  the  exit  status  is  set
65              accordingly.  The  default  action (i.e. when this option is not
66              given) is to ignore the contents of the parameter data  for  the
67              purposes  of setting the exit status.  Some types of error set a
68              sense key of "NO SENSE" with non-zero information in  the  addi‐
69              tional   sense  code  (e.g.  the  FAILURE  PREDICTION  THRESHOLD
70              EXCEEDED group of codes); this results in an exit  status  value
71              of  10. If the sense key is "NO SENSE" and both asc and ascq are
72              zero then the exit status is set to 0 . See the sg3_utils(8) man
73              page for exit status values.
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75       -t, --time
76              time the SCSI REQUEST SENSE command(s) and calculate the average
77              number of operations per second.
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79       -v, --verbose
80              increase the level of verbosity, (i.e. debug output).  Addition‐
81              ally the response (if received) is output in ASCII-HEX. Use this
82              option multiple times for greater verbosity.
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84       -V, --version
85              print the version string and then exit.
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NOTES

88       In SCSI 1 and 2 the REQUEST SENSE command was very important for  error
89       and  warning processing in SCSI. The autosense capability rendered this
90       command almost superfluous.
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92       However recent SCSI drafts  (e.g.  SPC-4  rev  14  and  SBC-3  rev  14)
93       increase  the  utility  of  the REQUEST SENSE command. Idle and standby
94       (low) power conditions can be detected with this command.
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96       The REQUEST SENSE command is not marked as mandatory in SPC-3 (i.e. for
97       all SCSI devices) but is marked as mandatory in SBC-2 (i.e. for disks),
98       SSC-3 (i.e. for tapes) and MMC-4 (i.e. for CD/DVD/HD-DVD/BD drives).
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100       The progress indication is optionally part of the sense  data.  When  a
101       prior  command  that  takes a long time to complete (and typically pre‐
102       cludes other media access commands) is  still  underway,  the  progress
103       indication  can be used to determine how long before the device returns
104       to its normal state.
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106       The SCSI FORMAT command for disks used with the IMMED  bit  set  is  an
107       example  of  an  operation  that takes a significant amount of time and
108       precludes other media access  during  that  time.  The  IMMED  bit  set
109       instructs  the  FORMAT  command  to  return  control to the application
110       client once the format has commenced (see SBC-3). Several long duration
111       SCSI commands associated with tape drives also use the progress indica‐
112       tion (see SSC-3).
113
114       Early standards suggested that the SCSI TEST UNIT READY command be used
115       for polling the progress indication. More recent standards seem to sug‐
116       gest the SCSI REQUEST SENSE command should be used instead.
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EXIT STATUS

119       The exit status of sg_requests is 0 when it  is  successful.  Otherwise
120       see the sg3_utils(8) man page.
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AUTHORS

123       Written by Douglas Gilbert.
124

REPORTING BUGS

126       Report bugs to <dgilbert at interlog dot com>.
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129       Copyright © 2004-2012 Douglas Gilbert
130       This  software is distributed under a FreeBSD license. There is NO war‐
131       ranty; not even for MERCHANTABILITY or FITNESS FOR  A  PARTICULAR  PUR‐
132       POSE.
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SEE ALSO

135       sg3_utils
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137
138
139sg3_utils-1.35                   December 2012                  SG_REQUESTS(8)
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