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 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 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 accomodate. 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 −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 a UFS 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 minimum 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, swap, ufs, linux and windows as aliases for the most commonly used partition types.
gpt create [−p] device ...
The create command allows the user to create a new (empty) GPT.
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 migrate [−k] [−s] device ...
The migrate command allows the user to migrate an MBR-based disk partitioning into a GPT-based partitioning.
The −k option instructs gpt to not destroy the current MBR. This option is primarily useful for debugging and should not be used by users.
The −s option prevents migrating BSD disk labels into GPT partitions by creating the GPT equivalent of a slice.
gpt remove [−b number] [−i index] [−s count] [−t type] device ...
The remove command allows the user to remove any partitions that match the selection. BEWARE: when no options are given, all GPT partitions will match and thus will be deleted.
The −b number option selects the partitions that starts at the given 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.
gpt show device ...
The show command displays the current partitioning on the listed devices and gives an overall view of the disk contents.
SEE ALSO
fdisk(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 necessary features are missing or partially implemented. In practice this means that the manual page, supposed to describe these features, 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 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.
BSD August 7, 2004 BSD