GPT(8)                  NetBSD System Manager's Manual                  GPT(8)

NAME
     gpt -- GUID partition table maintenance utility

SYNOPSIS
     gpt [-nrqv] [-m mediasize] [-s sectorsize] command [command_options]
         device

DESCRIPTION
     The gpt utility provides the necessary functionality to manipulate GUID
     partition tables (GPTs), but see BUGS below for how and where functional-
     ity is missing.  The basic usage model of the gpt tool follows that of
     the cvs(1) tool.  The general options are described in the following
     paragraph.  The remaining paragraphs describe the individual commands
     with their options.  Here we conclude by mentioning that a device is
     either a special file corresponding to a disk-like device or a regular
     file.  The command is applied to each device listed on the command line.

   General Options
     The general options allow the user to change default settings or other-
     wise change the behaviour that is applicable to all commands.  Not all
     commands use all default settings, so some general options may not have
     an effect on all commands.

     -m mediasize
           Override the default media size for the device (obtained from the
           kernel if possible) or defaulting to the file size for plain files.

     -n    Do not update the wedge information that gpt changed.  You need to
           use the dkctl(8) command manually update the device's wedge config-
           uration if you do that.

     -r    Open the device for reading only.  gpt Currently this option is
           primarily useful for the show command, but the intent is to use it
           to implement dry-run behaviour.

     -q    Do not print error messages.  This is not implemented completely
           yet.

     -s sectorsize
           Override the default sector size for the device (obtained from the
           kernel if possible) or 512 for plain files.

     -v    Controls the verbosity level.  The level increases with every
           occurrence of this option.  There is no formalized definition of
           the different levels yet.

   Commands
     gpt add [-a alignment] [-b blocknr] [-i index] [-l label] [-s size] [-t
             type]
             The add command allows the user to add a new partition to an
             existing table.  By default, it will create a UFS partition cov-
             ering the first available block of an unused disk space.  The
             command-specific options can be used to control this behaviour.

             The -a alignment option allows the user to specify an alignment
             for the start and size.  The alignment may have a suffix to indi-
             cate its magnitude.  gpt will attempt to align the partition.

             The -b blocknr option allows the user to specify the starting
             (beginning) sector number of the partition.  The minimum sector
             number is 1, but has to fall inside an unused region of disk
             space that is covered by the GPT.

             The -i index option allows the user to specify which (free) entry
             in the GPT table is to be used for the new partition.  By
             default, the first free entry is selected.

             The -l label option allows the user to specify a label for the
             partition.

             The -s size option allows the user to specify the size of the
             partition.  If there is no suffix, or the suffix is `s' or `S'
             then size is in sectors, otherwise size is in bytes which must be
             a multiple of the device's sector size.  The minimum size is 1
             sector.

             The -t type option allows the user to specify the partition type.
             The type is given as an UUID, but gpt accepts
                   apple             Apple HFS
                   apple-ufs         Apple UFS
                   bios              BIOS Boot
                   efi               EFI System
                   fbsd-legacy       FreeBSD legacy
                   fbsd-swap         FreeBSD swap
                   fbsd-ufs          FreeBSD UFS/UFS2
                   fbsd-vinum        FreeBSD vinum
                   fbsd-zfs          FreeBSD ZFS
                   linux-data        Linux data
                   linux-raid        Linux RAID
                   linux-swap        Linux swap
                   linux-lvm         Linux LVM
                   windows           Windows basic data
                   windows-reserved  Windows reserved
                   ccd               NetBSD ccd component
                   cgd               NetBSD Cryptographic Disk
                   ffs               NetBSD FFSv1/FFSv2
                   lfs               NetBSD LFS
                   raid              NetBSD RAIDFrame component
                   swap              NetBSD swap
             as aliases for the most commonly used partition types.

     gpt backup [-o outfile]
             The backup command dumps the MBR or (PMBR) and GPT partition
             tables to standard output or to a file specified by the outfile
             argument in a format to be used by the restore command.  The for-
             mat is a plist.  It should not be modified.

     gpt biosboot [-A] [-c bootcode] [-i index] [-L label]
             The biosboot command allows the user to configure the partition
             that contains the primary bootstrap program, used during boot(8).

             The -A options sets the PMBR partition active.

             The -c option allows the user to specify the filename that gpt
             should read the bootcode from.  The default is to read from
             /usr/mdec/gptmbr.bin.

             The -i option selects the partition that should contain the pri-
             mary bootstrap code, as installed via installboot(8).  The -L
             option selects the partition by label.  If there are multiple
             partitions with the same label, it will use the first one found.

     gpt create [-AfP] [-p partitions]
             The create command allows the user to create a new (empty) GPT.
             By default, one cannot create a GPT when the device contains a
             MBR, however this can be overridden with the -f option.  If the
             -f option is specified, an existing MBR is destroyed and any par-
             titions described by the MBR are lost.

             The -A options sets the PMBR partition active.

             The -P option tells gpt to create only the primary table and not
             the backup table.  This option is only useful for debugging and
             should not be used otherwise.

             The -p option changes the default number of partitions the GPT
             can accommodate.  This is used whenever a new GPT is created.  By
             default, the gpt utility will create space for 128 partitions (or
             32 sectors of 512 bytes).

     gpt destroy [-r]
             The destroy command allows the user to destroy an existing, pos-
             sibly not empty GPT.

             The -r option instructs gpt to destroy the table in a way that it
             can be recovered.

     gpt header
             The header command displays size information about the media and
             information from the GPT header if it exists.

     gpt label [-a] <-f file | -l label>

     gpt label [-b blocknr] [-i index] [-L label] [-s sectors] [-t type] <-f
             file | -l label>
             The label command allows the user to label any partitions that
             match the selection.  At least one of the following selection
             options must be specified.

             The -a option specifies that all partitions should be labeled.
             It is mutually exclusive with all other selection options.

             The -b blocknr option selects the partition that starts at the
             given block number.

             The -i index option selects the partition with the given parti-
             tion number.

             The -L label option selects all partitions that have the given
             label.  This can cause multiple partitions to be relabeled.

             The -s sectors option selects all partitions that have the given
             size.  This can cause multiple partitions to be labeled.

             The -t type option selects all partitions that have the given
             type.  The type is given as an UUID or by the aliases that the
             add command accepts.  This can cause multiple partitions to be
             labeled.

             The -f file or -l label options specify the new label to be
             assigned to the selected partitions.  The -f file option is used
             to read the label from the specified file.  Only the first line
             is read from the file and the trailing newline character is
             stripped.  If the file name is the dash or minus sign (-), the
             label is read from the standard input.  The -l label option is
             used to specify the label in the command line.  The label is
             assumed to be encoded in UTF-8.

     gpt migrate [-Afs] [-p partitions]
             The migrate command allows the user to migrate an MBR-based disk
             partitioning into a GPT-based partitioning.  By default, the MBR
             is not migrated when it contains partitions of an unknown type.
             This can be overridden with the -f option.  Specifying the -f
             option will cause unknown partitions to be ignored and any data
             in it to be lost.

             The -A options sets the PMBR partition active.

             The -s option prevents migrating BSD disk labels into GPT parti-
             tions by creating the GPT equivalent of a slice.  Note that the
             -s option is not applicable to NetBSD partitions.

             The -p option changes the default number of partitions the GPT
             can accommodate.  This is used whenever a new GPT is created.  By
             default, the gpt utility will create space for 128 partitions (or
             32 sectors of 512 bytes).

             The migrate command requires space at the beginning and the end
             of the device outside any partitions to store the GPTs.  Space is
             required for the GPT header (which takes one sector) and the GPT
             partition table.  See the -p option for the size of the GPT par-
             tition table.  By default, just about all devices have a minimum
             of 62 sectors free at the beginning of the device, but do not
             have any free space at the end.  For the default GPT partition
             table size on a 512 byte sector size device, 33 sectors at the
             end of the device would need to be freed.

     gpt recover
             The recover command tries to restore the GPT partition label from
             the backup near the end of the disk.  It is very useful in case
             the primary label was deleted.

     gpt remove [-a]

     gpt remove [-b blocknr] [-i index] [-L label] [-s sectors] [-t type]
             The remove command allows the user to remove any and all parti-
             tions that match the selection.  It uses the same selection
             options as the label command.  See above for a description of
             these options.  Partitions are removed by clearing the partition
             type.  No other information is changed.

     gpt resize -i index [-a alignment] [-s size]
             The resize command allows the user to resize a partition.  The
             partition may be shrunk and if there is sufficient free space
             immediately after it then it may be expanded.  The -s option
             allows the new size to be specified, otherwise the partition will
             be increased to the maximum available size.  If there is no suf-
             fix, or the suffix is `s' or `S' then size is in sectors, other-
             wise size is in bytes which must be a multiple of the device's
             sector size.  The minimum size is 1 sector.  If the -a option is
             specified then the size will be adjusted to be a multiple of
             alignment if possible.

     gpt resizedisk [-s size]
             The resizedisk command allows the user to resize a disk.  With
             GPTs, a backup copy is stored at the end of the disk.  If the
             underlying medium changes size (or is going to change size), then
             the backup copy needs to be moved to the new end of the disk, and
             the last sector available for data storage needs to be adjusted.
             This command does that.  If the backup copy no longer exists due
             to the medium shrinking, then a new backup copy will be created
             using the primary copy.

             The -s option allows the new size to be specified, otherwise the
             backup copy will automatically be placed at the current end of
             the disk.  If there is no suffix, or the suffix is `s' or `S'
             then size is in sectors, otherwise size is in bytes which must be
             a multiple of the device's sector size.  Using the -s option
             allows you to move the backup copy prior to resizing the medium.
             This is primarily useful when shrinking the medium.

     gpt restore [-F] [-i infile]
             The restore command restores a partition table that was previ-
             ously saved using the backup command.  The partition table is
             read from standard input or a file specified in the infile argu-
             ment and is expected to be in the format of a plist.  It assumes
             an empty disk.  The -F option can be used to blank the disk.  The
             new disk does not have to be the same size as the old disk as
             long as all the partitions fit, as restore will automatically
             adjust.  However, the new disk must use the same sector size as
             the old disk.

     gpt set -a attribute -i index

     gpt set -l
             The set command sets various partition attributes.  The -l flag
             lists all available attributes.  The -a option specifies which
             attributes to set and may be specified more than once, or the
             attributes can be comma-separated.  The -i option specifies which
             entry to update.  The possible attributes are ``biosboot'',
             ``bootme'', ``bootonce'', ``bootfailed'', ``noblockio'', and
             ``required''.  The biosboot flag is used to indicate which parti-
             tion should be booted by legacy BIOS boot code.  See the biosboot
             command for more information.  The other attributes are for com-
             patibility with FreeBSD and are not currently used by any NetBSD
             code.  They may be used by NetBSD code in the future.

     gpt show [-aglu] [-i index]
             The show command displays the current partitioning on the listed
             devices and gives an overall view of the disk contents.  With the
             -g option the GPT partition GUID will be displayed instead of the
             GPT partition type.  With the -l option the GPT partition label
             will be displayed instead of the GPT partition type.  With the -u
             option the GPT partition type is displayed as an UUID instead of
             in a user friendly form.  With the -i option, all the details of
             a particular GPT partition will be displayed.  The format of this
             display is subject to change.  With the -a option, all informa-
             tion for all GPT partitions (just like with -i index) will be
             printed.  None of the options have any effect on non-GPT parti-
             tions.  The order of precedence for the options are: -a, -i, -l,
             -g, -u.

     gpt type [-a] -T newtype

     gpt type [-b blocknr] [-i index] [-L label] [-s sectors] [-t type] -T
             newtype

     gpt type -l
             The type command allows the user to change the type of any and
             all partitions that match the selection.  It uses the same selec-
             tion options as the label command.  See above for a description
             of these options.  The -l flag lists available types.

     gpt unset -a attribute -i index

     gpt unset -l
             The unset command unsets various partition attributes.  The -l
             flag lists all available attributes.  The -a option specifies
             which attributes to unset and may be specified more than once.
             The -i option specifies which entry to update.  The possible
             attributes are ``biosboot'', ``bootme'', ``bootonce'',
             ``bootfailed'', ``noblockio'', and ``required''.  The biosboot
             flag is used to indicate which partition should be booted by
             legacy BIOS boot code.  See the biosboot command for more infor-
             mation.  The other attributes are for compatibility with FreeBSD
             and are not currently used by any NetBSD code.  They may be used
             by NetBSD code in the future.

EXAMPLES
     nas# gpt show wd3
            start        size  index  contents
                0           1         PMBR
                1  3907029167
     nas# gpt create wd3
     nas# gpt show wd3
            start        size  index  contents
                0           1         PMBR
                1           1         Pri GPT header
                2          32         Pri GPT table
               34  3907029101
       3907029135          32         Sec GPT table
       3907029167           1         Sec GPT header
     nas# gpt add -s 10486224 -t swap -i 1 wd3
     nas# gpt label -i 1 -l swap_1 wd3
     parition 1 on rwd3d labeled swap_1
     nas# gpt show wd3
            start        size  index  contents
                0           1         PMBR
                1           1         Pri GPT header
                2          32         Pri GPT table
               34    10486224      1  GPT part - NetBSD swap
         10486258  3896542877
       3907029135          32         Sec GPT table
       3907029167           1         Sec GPT header
     nas# gpt show -l wd3
            start        size  index  contents
                0           1         PMBR
                1           1         Pri GPT header
                2          32         Pri GPT table
               34    10486224      1  GPT part - "swap_1"
         10486258  3896542877
       3907029135          32         Sec GPT table
       3907029167           1         Sec GPT header
     nas#

SEE ALSO
     boot(8), dkctl(8), fdisk(8), installboot(8), mount(8), newfs(8),
     swapon(8)

HISTORY
     The gpt utility appeared in FreeBSD 5.0 for ia64.  gpt utility first
     appeared in NetBSD 5.0.

BUGS
     The development of the gpt utility is still work in progress.  Many nec-
     essary features are missing or partially implemented.  In practice this
     means that the manual page, supposed to describe these features, is far-
     ther removed from being complete or useful.  As such, missing functional-
     ity is not even documented as missing.  However, it is believed that the
     currently present functionality is reliable and stable enough that this
     tool can be used without bullet-proof footware if one thinks one does not
     make mistakes.

     It is expected that the basic usage model does not change, but it is pos-
     sible that future versions will not be compatible in the strictest sense
     of the word.  Also, options primarily intended for diagnostic or debug
     purposes may be removed in future versions.

     Another possibility is that the current usage model is accompanied by
     other interfaces to make the tool usable as a back-end.  This all depends
     on demand and thus feedback.

NetBSD 7.0                     November 1, 2016                     NetBSD 7.0

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