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

NAME
     gpt -- GUID partition table maintenance utility

SYNOPSIS
     gpt [general_options] 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.

     The -p partitions option allows the user to change the number of parti-
     tions the GPT can accommodate.  This is used whenever a new GPT is cre-
     ated.  By default, the gpt utility will create space for 128 partitions
     (or 32 sectors of 512 bytes).

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

     The -v option 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] device ...
             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 efi, swap, ufs,
             hfs, linux, raid, lfs, ccd, cgd, bios, ffs, and windows as
             aliases for the most commonly used partition types.

     gpt backup device ...
             The backup command dumps the MBR or (PMBR) and GPT partition
             tables to standard output in a format to be used by the restore
             command.  The format is a plist.  It should not be modified.

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

             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).

     gpt create [-fp] device ...
             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 -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.

     gpt destroy [-r] device ...
             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 label [-a] <-f file | -l label> device ...

     gpt label [-b blocknr] [-i index] [-s sectors] [-t type] <-f file | -l
             label> device ...
             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 -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 [-fs] device ...
             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 -s option prevents migrating BSD disk labels into GPT parti-
             tions by creating the GPT equivalent of a slice.  Note that the
             -s option isn't applicable to NetBSD partitions.

             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 don't 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 device ...
             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] device ...

     gpt remove [-b blocknr] [-i index] [-s sectors] [-t type] device ...
             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] device ...
             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 set -a attribute -i index device ...
             The set command sets various partition attributes.  The -a option
             specifies which attributes to set and may be specified more than
             once.  The -i option specifies which entry to update.  The possi-
             ble attributes are ``biosboot'', ``bootme'', ``bootonce'', and
             ``bootfailed''.  The biosboot flag is used to indicate which par-
             tition should be booted by legacy BIOS boot code.  See the
             biosboot command for more information.  The other three
             attributes are for compatibility with FreeBSD and are not cur-
             rently used by any NetBSD code.  They may be used by NetBSD code
             in the future.

     gpt show [-glu] [-i index] device ...
             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.  None of the options have any
             effect on non-GPT partitions.  The order of precedence for the
             options are: -i, -l, -g, -u.

     gpt unset -a attribute -i index device ...
             The unset command unsets various partition 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'', and ``bootfailed''.  The biosboot flag is used to
             indicate which partition should be booted by legacy BIOS boot
             code.  See the biosboot command for more information.  The other
             three 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
     Partition added, use:
             dkctl rwd3d addwedge dk<N> 34 10486224 <type>
     to create a wedge for it
     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), fdisk(8), installboot(8), mount(8), newfs(8), swapon(8)

HISTORY
     The gpt utility appeared in FreeBSD 5.0 for ia64.

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.  For example, the -p partitions option may be changed to a
     command option rather than a generic option.  There are only two commands
     that use it so there is a chance that the natural tendency for people is
     to use it as a command option.  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                     December 19, 2013                    NetBSD 7.0

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©1996-2014 Modified for NetBSD by Kimmo Suominen