# phpman > man > sg_read_buffer(8) [SG_READ_BUFFER(8)](https://www.chedong.com/phpMan.php/man/SGREADBUFFER/8/markdown) SG3_UTILS [SG_READ_BUFFER(8)](https://www.chedong.com/phpMan.php/man/SGREADBUFFER/8/markdown) ## NAME sg_read_buffer - send SCSI READ BUFFER command ## SYNOPSIS **sg**___**read**___**buffer** [_--help_] [_--hex_] [_--id=ID_] [_--inhex=FN_] [_--length=LEN_] [_--mode=MO_] [_--off__‐ _set=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 ex‐ pected 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 re‐ sponse 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 this option sets the buffer id field in the cdb. _ID_ is a value between 0 (default) and 255 inclusive. ### -I --inhex _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_ op‐ tions, 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 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 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 this option sets the buffer offset field in the cdb. _OFF_ is a value between 0 (de‐ fault) 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 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)](https://www.chedong.com/phpMan.php/man/sg3utils/8/markdown) man page. ## AUTHORS Written by Luben Tuikov and Douglas Gilbert. ## REPORTING BUGS Report bugs to . ## COPYRIGHT Copyright © 2006-2019 Luben Tuikov and Douglas Gilbert This software is distributed under a FreeBSD license. There is NO warranty; not even for MER‐ CHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. ## SEE ALSO **sg**___**write**___**buffer(sg3**___**utils)** sg3_utils-1.45 May 2019 [SG_READ_BUFFER(8)](https://www.chedong.com/phpMan.php/man/SGREADBUFFER/8/markdown)