Usage: sg_readcap [--10] [--16] [--brief] [--help] [--hex] [--inhex-FN]
                  [--json[=JO]] [--js-file=JFN] [--lba=LBA] [--long] [--pmi]
                  [--raw] [--readonly] [--verbose] [--version] [--zbc]
                  DEVICE
  where:
    --10            use READ CAPACITY (10) cdb (this is the default)
    --16            use READ CAPACITY (16) cdb (same as --long)
    --brief|-b      brief, two hex numbers: number of blocks and block size
    --help|-h       print this usage message and exit
    --hex|-H        output response in hexadecimal to stdout
    --inhex=FN|-i FN    contents of file FN treated as hex and used
                        instead of DEVICE which is ignored
    --json[=JO]|-j[=JO]    output in JSON instead of plain text
                           Use --json=? for JSON help
    --js-file=JFN|-J JFN    JFN is a filename to which JSON output is
                            written (def: stdout); truncates then writes
    --lba=LBA|-L LBA    yields the last block prior to (head movement) delay
                        after LBA [in decimal (def: 0) valid with '--pmi']
    --long|-l       use READ CAPACITY (16) cdb (def: use 10 byte cdb)
    --old|-O        use old interface (use as first option)
    --pmi|-p        partial medium indicator (without this option shows
                    total disk capacity) [made obsolete in sbc3r26]
    --raw|-r        output response in binary to stdout
    --readonly|-R    open DEVICE read-only (def: RCAP(16) read-write)
    --verbose|-v    increase verbosity
    --version|-V    print version string and exit
    --zbc|-z        show rc_basis ZBC field (implies --16)

Perform a SCSI READ CAPACITY (10 or 16) command