path: root/doc/sg_read_buffer.8

.TH SG_READ_BUFFER "8" "May 2019" "sg3_utils\-1.45" SG3_UTILS
.SH NAME
sg_read_buffer \- send SCSI READ BUFFER command
.SH SYNOPSIS
.B sg_read_buffer
[\fI\-\-help\fR] [\fI\-\-hex\fR] [\fI\-\-id=ID\fR] [\fI\-\-inhex=FN\fR]
[\fI\-\-length=LEN\fR] [\fI\-\-mode=MO\fR] [\fI\-\-offset=OFF\fR]
[\fI\-\-raw\fR] [\fI\-\-readonly\fR] [\fI\-\-specific=MS\fR]
[\fI\-\-verbose\fR] [\fI\-\-version\fR] \fIDEVICE\fR
.SH DESCRIPTION
.\" Add any additional description here
.PP
Sends a SCSI READ BUFFER command to the \fIDEVICE\fR, and if there
is a response either decodes it, prints it in hexadecimal or sends
it in binary to stdout. If a response is received for a "descriptor"
mode then, in the absence of \fI\-\-hex\fR and \fI\-\-raw\fR, it is
decoded. Response for non\-descriptor modes are output in hexadecimal
unless the \fI\-\-raw\fR option is given.
.PP
This utility may be called without a \fIDEVICE\fR but with a
\fI\-\-inhex=FN\fR option instead. \fIFN\fR is expected to be a file
name (or '\-' for stdin). The contents of the file (or stdin stream)
is assumed to be hexadecimal (or binary) data that represents a SCSI
READ BUFFER command response and is decoded as such.
.SH OPTIONS
Arguments to long options are mandatory for short options as well.
.TP
\fB\-h\fR, \fB\-\-help\fR
output the usage message then exit. If used multiple times also prints
the mode names and their acronyms.
.TP
\fB\-H\fR, \fB\-\-hex\fR
output the response in hexadecimal. When given twice the response is
output in hex with the corresponding representation in ASCII to the
right of each line.
.TP
\fB\-i\fR, \fB\-\-id\fR=\fIID\fR
this option sets the buffer id field in the cdb. \fIID\fR is a value between
0 (default) and 255 inclusive.
.TP
\fB\-I\fR, \fB\-\-inhex\fR=\fIFN\fR
\fIFN\fR is expected to be a file name (or '\-' for stdin) which contains
ASCII hexadecimal or binary representing a READ BUFFER response. If known
this utility will then decode that response. It is preferable to also
supply the \fI\-\-mode=MO\fR and \fI\-\-specific=MS\fR options, since these
are not present in the response. The hexadecimal should be arranged as 1 or
2 digits representing a byte each of which is whitespace or comma separated.
Anything from and including a hash mark to the end of line is ignored. If the
\fI\-\-raw\fR option is also given then \fIFN\fR is treated as binary.
.TP
\fB\-l\fR, \fB\-\-length\fR=\fILEN\fR
where \fILEN\fR is the length, in bytes, that is placed in the "allocation
length" field in the cdb. The default value is 4 (bytes). The device may
respond with less bytes.
.TP
\fB\-m\fR, \fB\-\-mode\fR=\fIMO\fR
this option sets the mode field in the cdb. \fIMO\fR is a value between
0 (default) and 31 inclusive. Alternatively an abbreviation can be given.
See the MODES section below. To list the available mode abbreviations use
an invalid one (e.g. '\-\-mode=xxx'). As an example, to fetch the read
buffer descriptor give '\-\-mode=desc' .
.TP
\fB\-o\fR, \fB\-\-offset\fR=\fIOFF\fR
this option sets the buffer offset field in the cdb. \fIOFF\fR is a value
between 0 (default) and 2**24\-1 . It is a byte offset.
.TP
\fB\-r\fR, \fB\-\-raw\fR
if a response is received then it is sent in binary to stdout.
.TP
\fB\-R\fR, \fB\-\-readonly\fR
open the \fIDEVICE\fR read\-only (e.g. in Unix with the O_RDONLY flag).
The default is to open it read\-write.
.TP
\fB\-S\fR, \fB\-\-specific\fR=\fIMS\fR
this option sets the mode specific field in the cdb. \fIMS\fR is a value
between 0 and 7 as this is a 3 bit field.
.TP
\fB\-v\fR, \fB\-\-verbose\fR
increase the level of verbosity, (i.e. debug output).
.TP
\fB\-V\fR, \fB\-\-version\fR
print the version string and then exit.
.SH MODES
Following is a list of READ BUFFER command settings for the MODE field.
First is an acronym accepted by the \fIMO\fR argument of this utility.
Following the acronym in square brackets are the corresponding decimal and
hex values that may also be given for \fIMO\fR. The following are listed
in numerical order.
.TP
hd  [0, 0x0]
Combined header and data (obsolete in SPC\-4).
.TP
vendor  [1, 0x1]
Vendor specific.
.TP
data  [2, 0x2]
Data.
.TP
desc  [3, 0x3]
Descriptor: yields 4 bytes that contain an offset boundary field (1 byte)
and buffer capacity (3 bytes).
.TP
echo  [10, 0xa]
Read data from echo buffer (was called "Echo buffer" in SPC\-3).
.TP
echo_desc  [11, 0xb]
Echo buffer descriptor: yields 4 bytes of which the last (lowest) 13 bits
represent the echo buffer capacity. The maximum echo buffer size is 4096
bytes.
.TP
rd_microc_st  [15, 0xf]
Read microcode status. Added in spc5r20 .
.TP
en_ex  [26, 0x1a]
Enable expander communications protocol and Echo buffer. Made obsolete in
SPC\-4.
.TP
err_hist  [28, 0x1c]
Error history. Introduced in SPC\-4.
.SH NOTES
All numbers given with options are assumed to be decimal.
Alternatively numerical values can be given in hexadecimal preceded by
either "0x" or "0X" (or has a trailing "h" or "H").
.SH EXIT STATUS
The exit status of sg_read_buffer is 0 when it is successful. Otherwise
see the sg3_utils(8) man page.
.SH AUTHORS
Written by Luben Tuikov and Douglas Gilbert.
.SH "REPORTING BUGS"
Report bugs to <dgilbert at interlog dot com>.
.SH COPYRIGHT
Copyright \(co 2006\-2019 Luben Tuikov and Douglas Gilbert
.br
This software is distributed under a FreeBSD license. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
.SH "SEE ALSO"
.B sg_write_buffer(sg3_utils)