SG_READ_BUFFER(8)

NAME
sg_read_buffer - send SCSI READ BUFFER command

SYNOPSIS
sg_read_buffer [--help] [--hex] [--id=ID] [--inhex=FN] [--length=LEN] [--mode=MO] [--offset=OFF] [--raw] [--readonly] [--specific=MS] [--verbose] [--version] DEVICE

DESCRIPTION

Sends a SCSI READ BUFFER command to the DEVICE, 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 --hex and --raw, it is decoded. Response for non-descriptor modes are output in hexadecimal unless the --raw option is given.

This utility may be called without a DEVICE but with a --inhex=FN option instead. FN 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.

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

-h, --help
    output the usage message then exit. If used multiple times also prints the mode names and their acronyms.

-H, --hex
    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.

-i, --id=ID
    this option sets the buffer id field in the cdb. ID is a value between 0 (default) and 255 inclusive.

-I, --inhex=FN
    FN 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 --mode=MO and --specific=MS 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 --raw option is also given then FN is treated as binary.

-l, --length=LEN
    where LEN 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.

-m, --mode=MO
    this option sets the mode field in the cdb. MO 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' .

-o, --offset=OFF
    this option sets the buffer offset field in the cdb. OFF is a value between 0 (default) and 2**24-1 . It is a byte offset.

-r, --raw
    if a response is received then it is sent in binary to stdout.

-R, --readonly
    open the DEVICE read-only (e.g. in Unix with the O_RDONLY flag). The default is to open it read-write.

-S, --specific=MS
    this option sets the mode specific field in the cdb. MS is a value between 0 and 7 as this is a 3 bit field.

-v, --verbose
    increase the level of verbosity, (i.e. debug output).

-V, --version
    print the version string and then exit.

MODES
Following is a list of READ BUFFER command settings for the MODE field. First is an acronym accepted by the MO argument of this utility. Following the acronym in square brackets are the corresponding decimal and hex values that may also be given for MO. The following are listed in numerical order.

hd  [0, 0x0]
    Combined header and data (obsolete in SPC-4).

vendor  [1, 0x1]
    Vendor specific.

data  [2, 0x2]
    Data.

desc  [3, 0x3]
    Descriptor: yields 4 bytes that contain an offset boundary field (1 byte) and buffer capacity (3 bytes).

echo  [10, 0xa]
    Read data from echo buffer (was called "Echo buffer" in SPC-3).

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.

rd_microc_st  [15, 0xf]
    Read microcode status. Added in spc5r20 .

en_ex  [26, 0x1a]
    Enable expander communications protocol and Echo buffer. Made obsolete in SPC-4.

err_hist  [28, 0x1c]
    Error history. Introduced in SPC-4.

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").

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

AUTHORS
Written by Luben Tuikov and Douglas Gilbert.

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

COPYRIGHT
Copyright © 2006-2019 Luben Tuikov and Douglas Gilbert
This software is distributed under a FreeBSD license. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

SEE ALSO
sg_write_buffer(sg3_utils)