# phpman > man > sg_read_attr(8) [SG_READ_ATTR(8)](https://www.chedong.com/phpMan.php/man/SGREADATTR/8/markdown) SG3_UTILS [SG_READ_ATTR(8)](https://www.chedong.com/phpMan.php/man/SGREADATTR/8/markdown) ## NAME sg_read_attr - send SCSI READ ATTRIBUTE command ## SYNOPSIS **sg**___**read**___**attr** [_--cache_] [_--enumerate_] [_--ea=EA_] [_--filter=FL_] [_--first=FAI_] [_--help_] [_--hex_] [_--in=FN_] [_--lvn=LVN_] [_--maxlen=LEN_] [_--pn=PN_] [_--quiet_] [_--raw_] [_--readonly_] [_--sa=SA_] [_--verbose_] [_--version_] _DEVICE_ ## DESCRIPTION Sends a SCSI READ ATTRIBUTE command to _DEVICE_ and outputs the data returned. This command was introduced in SPC-3 revision 1 and thus is applicable to all SCSI devices. In practice it is used mainly for tape systems. This utility is based on the SPC-5 draft standard, revision 17 (spc5r17.pdf). ## OPTIONS Arguments to long options are mandatory for short options as well. ### -c --cache sets the CACHE bit in the READ ATTRIBUTE cdb. This instructs the device server to re‐ turn cached attributes. By default that bit is cleared which instructs the device server not to return cached attributes. ### -e --enumerate enumerates all known attributes and service actions. Attributes include an identifier, length, format and a name as defined by T10. If _DEVICE_ is given then it is ignored. ### -E --ea where _EA_ is an element address which is placed in the READ ATTRIBUTE cdb. This field is only found in SMC-2 and SMC-3 drafts for medium changers usually associated with tape libraries. By default this field is set to zero. ### -f --filter where _FL_ is an attribute identifier in the range 0 to 65535 or -1. Attribute identi‐ fiers are typically given in hexadecimal in which case the hex number should be pre‐ fixed by "0x" or has a trailing "h". "-1" is the default value and means 'match all'; for all other values of _FL_ on the matching attribute is output. ### -F --first where _FAI_ is the "first attribute identifier" field in the cdb. It seems as though the intent of this field is that only attributes whose identifiers are equal to or greater than _FAI_ are returned. The default value of _FAI_ is zero. Attributes are returned in ascending identifier order. ### -h --help output the usage message then exit. ### -H --hex output the response in hexadecimal to stdout. When used once the whole response is output in ASCII hexadecimal with a leading address (starting at 0) on each line. When used twice each attribute descriptor in the response is output separately in hexadeci‐ mal. When used thrice the whole response is output in hexadecimal with no leading ad‐ dress (on each line). Output generated by '-HHH' (or _--hex_ used three times) can be redirected to a file. That file will be in suitable format for _--in=FN_ to use in a later invocation. ### -i --in _FN_ is treated as a file name (or '-' for stdin) which contains ASCII hexadecimal or binary representing the response to a READ ATTRIBUTE command with service action 0x0 (i.e (fetch) attribute values). When this option is given then _DEVICE_ (if also given) is ignored. By default _FN_ is assumed to contain ASCII hexadecimal arranged as bytes which a space, tab or comma delimited. All characters from (and including) "#" to the end of line are ignored. If the _--raw_ option is also given then _FN_ is assumed to contain binary data. When the _--raw_ option is given then after processing the input the internal raw vari‐ able is reset to 0 so it has no effect on the output. Since the READ ATTRIBUTE response does not contain the service action number that it is a response to, then the _--sa=SA_ should be given (if not service action 0 (attribute values) is assumed. ### -l --lvn where _LVN_ is placed in the "logical volume number" field of the cdb. The default value is zero which is required to be the logical volume number if the device only has one volume. ### -m --maxlen where _LEN_ is the (maximum) response length in bytes. It is placed in the cdb's "allo‐ cation length" field. If not given (or _LEN_ is zero) then 8192 is used. The maximum al‐ lowed value of _LEN_ is 1048576. ### -p --pn where _PN_ is placed in the "partition number" field of the cdb. If the _DEVICE_ only has one partition then its partition number must be zero. The default value of _PN_ is zero. ### -q --quiet this option reduces the amount of information output. For example when used once (_SA_=0), it suppresses the header line announcing the output of attributes; when used twice it suppresses the name of each attribute, leaving only the associated attribute values (or strings). ### -r --raw output the SCSI response (i.e. the data-out buffer) 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 --sa where _SA_ is placed on the "service action" field of the cdb. Values of 0 to 63 are ac‐ cepted with a default of 0. spc5r08.pdf defines five service actions: 0 for attributes values ; 1 for an attribute list (names, not values), 2 for the logical volume list; 3 for the partition list; 4 is restricted for SMC-3; and 5 for the supported attribute list. Alternatively an acronym can be given for _SA_. The acronym should be one of "av", "al", "lvl", "pn", "smc" or "sa" for service actions 0 to 5 respectively. The acronyms can also be given in upper case. ### -v --verbose increase the level of verbosity, (i.e. debug output). ### -V --version print the version string and then exit. ## NOTES Only tape systems seem to implement the SCSI READ ATTRIBUTE command. The vast majority of its definition is in the SPC standard so other device types could use it. Much of the information provided by READ ATTRIBUTE can also be found in pages returned by LOG SENSE (see the sg_logs utility) and in the VPD pages returned by the INQUIRY command. ## EXAMPLES To list the attributes of a tape drive whose _DEVICE_ is /dev/sg1 , the following could be used: # sg_read_attr -s al /dev/sg1 Attribute list: Remaining capacity in partition [MiB] Maximum capacity in partition [MiB] TapeAlert flags Load count MAM space remaining [B] Assigning organization Format density code ... To check the number of partitions: # sg_read_attr -s pl /dev/sg1 Partition number list: First partition number: 0 Number of partitions available: 2 And to see the attribute values (which is the default service action): # sg_read_attr /dev/sg1 Attribute values: Remaining capacity in partition [MiB]: 1386103 Maximum capacity in partition [MiB]: 1386103 TapeAlert flags: 0 .... To redirect the attribute values response to a file for later decoding: # sg_read_attr -HHH /dev/sg1 > av.hex And later the response held in the av.hex file could be decoded with: # sg_read_attr -s av --in=av.hex Attribute values: Remaining capacity in partition [MiB]: 1386103 Maximum capacity in partition [MiB]: 1386103 TapeAlert flags: 0 .... ## EXIT STATUS The exit status of sg_read_attr 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 Douglas Gilbert. ## REPORTING BUGS Report bugs to . ## COPYRIGHT Copyright © 2016-2020 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**___**vpd,sg**___**logs(sg3**___**utils)** sg3_utils-1.46 December 2020 [SG_READ_ATTR(8)](https://www.chedong.com/phpMan.php/man/SGREADATTR/8/markdown)