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GPT(8)                    BSD 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 functionality is missing.  The basic usage model of the gpt tool fol-lows follows
     lows 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 mention-ing mentioning
     ing 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 otherwise 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 count option allows the user to change the 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 parti-tions partitions
     tions (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 [-b number] [-i index] [-s count] [-t type] device ...
             The add command allows the user to add a new partition to an existing table.  By default, it
             will create an HFS partition covering the first available block of an unused disk space.  The
             command-specific options can be used to control this behaviour.

             The -b number 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 -s count option allows the user to specify the size of the partition in sectors.  The mini-mum minimum
             mum size is 1.

             The -t type option allows the user to specify the partition type.  The type is given as an
             UUID, but gpt accepts efi, hfs, linux and windows as aliases for the most commonly used parti-tion partition
             tion types.

     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 partitions 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, possibly 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 number] [-i index] [-s count] [-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 number option selects the partition that starts at the given block number.

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

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

             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
             removed.

             The -f file or -l label options specify the new label to be assigned to the selected parti-tions. partitions.
             tions.  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 recover device ...
             The recover command allows the user to recover the GPT from the backup table.

     gpt remove [-a] device ...

     gpt remove [-b number] [-i index] [-s count] [-t type] device ...
             The remove command allows the user to remove any and all partitions 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 show [-l] device ...
             The show command displays the current partitioning on the listed devices and gives an overall
             view of the disk contents.  With the -l option the GPT partition label will be displayed
             instead of the GPT partition type.  The option has no effect on non-GPT partitions.

SEE ALSO
     fdisk(8), mount(8), newfs(8), pdisk(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 necessary features are missing or
     partially implemented.  In practice this means that the manual page, supposed to describe these fea-tures, features,
     tures, is farther removed from being complete or useful.  As such, missing functionality 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 possible that future versions will
     not be compatible in the strictest sense of the word.  For example, the -p count 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 primar-ily primarily
     ily 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.

BSD                               May 7, 2012                              BSD

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