Usage: sg_unmap [--all=ST,RN[,LA]] [--anchor] [--dry-run] [--force]
                [--grpnum=GN] [--help] [--in=FILE] [--lba=LBA,LBA...]
                [--num=NUM,NUM...] [--timeout=TO] [--verbose] [--version]
                DEVICE
  where:
    --all=ST,RN[,LA]|-A ST,RN[,LA]    start unmaps at LBA ST, RN blocks
                         per unmap until the end of disk, or until
                         and including LBA LA (last)
    --anchor|-a          set anchor field in cdb
    --dry-run|-d         prepare but skip UNMAP call(s)
    --force|-f           don't ask for confirmation before zapping media
    --grpnum=GN|-g GN    GN is group number field (def: 0)
    --help|-h            print out usage message
    --in=FILE|-I FILE    read LBA, NUM pairs from FILE (if FILE is '-'
                         then stdin is read)
    --lba=LBA,LBA...|-l LBA,LBA...    LBA is the logical block address
                                      to start NUM unmaps
    --num=NUM,NUM...|-n NUM,NUM...    NUM is number of logical blocks to
                                      unmap starting at corresponding LBA
    --timeout=TO|-t TO    command timeout (unit: seconds) (def: 60)
    --verbose|-v         increase verbosity
    --version|-V         print version string and exit

Perform a SCSI UNMAP command. LBA, NUM and the values in FILE are assumed
to be decimal. Use '0x' prefix or 'h' suffix for hex values.
Example to unmap LBA 0x12345:
    sg_unmap --lba=0x12345 --num=1 /dev/sdb
Example to unmap starting at LBA 0x12345, 256 blocks per command:
    sg_unmap --all=0x12345,256 /dev/sg2
until the end if /dev/sg2 (assumed to be a storage device)

WARNING: This utility will destroy data on DEVICE in the given range(s)
that will be unmapped. Unmap is also known as 'trim' and is irreversible.