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Aurimas Liutikas74b74902016-05-10 18:53:54 -07001.\" Copyright 2011-2015 Roderick W. Smith (rodsmith@rodsbooks.com)
srs5694e7b4ff92009-08-18 13:16:10 -04002.\" May be distributed under the GNU General Public License
Aurimas Liutikas74b74902016-05-10 18:53:54 -07003.TH "GDISK" "8" "1.0.1" "Roderick W. Smith" "GPT fdisk Manual"
srs5694978041c2009-09-21 20:51:47 -04004.SH "NAME"
srs56940a697312010-01-28 21:10:52 -05005gdisk \- Interactive GUID partition table (GPT) manipulator
srs5694978041c2009-09-21 20:51:47 -04006.SH "SYNOPSIS"
srs5694e7b4ff92009-08-18 13:16:10 -04007.BI "gdisk "
8[ \-l ]
9.I device
srs5694221e0872009-08-29 15:00:31 -040010
srs5694978041c2009-09-21 20:51:47 -040011.SH "DESCRIPTION"
srs5694978041c2009-09-21 20:51:47 -040012GPT fdisk (aka \fBgdisk\fR) is a text\-mode menu\-driven program for
13creation and manipulation of partition tables. It will automatically
14convert an old\-style Master Boot Record (MBR) partition table or BSD
15disklabel stored without an MBR carrier partition to the newer Globally
srs56948bb78762009-11-24 15:43:49 -050016Unique Identifier (GUID) Partition Table (GPT) format, or will load a GUID
srs5694978041c2009-09-21 20:51:47 -040017partition table. When used with the \fI\-l\fR command\-line option, the
18program displays the current partition table and then exits.
srs5694e7b4ff92009-08-18 13:16:10 -040019
srs5694978041c2009-09-21 20:51:47 -040020GPT fdisk operates mainly on the GPT headers and partition tables; however,
srs5694e7b4ff92009-08-18 13:16:10 -040021it can and will generate a fresh protective MBR, when required. (Any boot
22loader code in the protective MBR will not be disturbed.) If you've created
23an unusual protective MBR, such as a hybrid MBR created by
srs5694978041c2009-09-21 20:51:47 -040024\fBgptsync\fR or \fBgdisk\fR's own hybrid MBR creation feature,
srs5694e7b4ff92009-08-18 13:16:10 -040025this should not be disturbed by most ordinary actions. Some advanced data
26recovery options require you to understand the distinctions between the
27main and backup data, as well as between the GPT headers and the partition
srs5694978041c2009-09-21 20:51:47 -040028tables. For information on MBR vs. GPT, as well as GPT terminology and
29structure, see the extended \fBgdisk\fR documentation at
30\fIhttp://www.rodsbooks.com/gdisk/\fR or consult Wikipedia.
srs5694e7b4ff92009-08-18 13:16:10 -040031
srs5694978041c2009-09-21 20:51:47 -040032The \fBgdisk\fR program employs a user interface similar to that of Linux's
srs56948bb78762009-11-24 15:43:49 -050033\fBfdisk\fR, but \fBgdisk\fR modifies GPT partitions. It also has the
34capability of transforming MBR partitions or BSD disklabels into GPT
35partitions. Like the original \fBfdisk\fR program, \fBgdisk\fR does not
36modify disk structures until you explicitly write them to disk, so if you
srs56946aae2a92011-06-10 01:16:51 -040037make a mistake, you can exit from the program with the 'q' option to leave
38your partitions unmodified.
srs5694e7b4ff92009-08-18 13:16:10 -040039
srs5694978041c2009-09-21 20:51:47 -040040Ordinarily, \fBgdisk\fR operates on disk device files, such as
41\fI/dev/sda\fR or \fI/dev/hda\fR under Linux, \fI/dev/disk0\fR under
42Mac OS X, or \fI/dev/ad0\fR or \fI/dev/da0\fR under FreeBSD. The program
43can also operate on disk image files, which can be either copies of whole
44disks (made with \fBdd\fR, for instance) or raw disk images used by
45emulators such as QEMU or VMWare. Note that only \fIraw\fR disk images
46are supported; \fBgdisk\fR cannot work on compressed or other advanced
47disk image formats.
srs5694e7b4ff92009-08-18 13:16:10 -040048
49The MBR partitioning system uses a combination of cylinder/head/sector
50(CHS) addressing and logical block addressing (LBA). The former is klunky
srs5694978041c2009-09-21 20:51:47 -040051and limiting. GPT drops CHS addressing and uses 64\-bit LBA mode
srs5694e7b4ff92009-08-18 13:16:10 -040052exclusively. Thus, GPT data structures, and therefore
srs5694978041c2009-09-21 20:51:47 -040053\fBgdisk\fR, do not need to deal with CHS geometries and all the problems
54they create. Users of \fBfdisk\fR will note that \fBgdisk\fR
srs5694e7b4ff92009-08-18 13:16:10 -040055lacks the options and limitations associated with CHS geometries.
56
srs5694978041c2009-09-21 20:51:47 -040057For best results, you should use an OS\-specific partition table
58program whenever possible. For example, you should make Mac OS X
59partitions with the Mac OS X Disk Utility program and Linux partitions
60with the Linux \fBgdisk\fR or GNU Parted program.
srs5694221e0872009-08-29 15:00:31 -040061
srs56948bb78762009-11-24 15:43:49 -050062Upon start, \fBgdisk\fR attempts to identify the partition type in use on
63the disk. If it finds valid GPT data, \fBgdisk\fR will use it. If
64\fBgdisk\fR finds a valid MBR or BSD disklabel but no GPT data, it will
65attempt to convert the MBR or disklabel into GPT form. (BSD disklabels are
66likely to have unusable first and/or final partitions because they overlap
67with the GPT data structures, though.) GPT fdisk can identify, but not use
68data in, Apple Partition Map (APM) disks, which are used on 680x0\- and
69PowerPC\-based Macintoshes. Upon exiting with the 'w' option, \fBgdisk\fR
70replaces the MBR or disklabel with a GPT. \fIThis action is potentially
71dangerous!\fR Your system may become unbootable, and partition type codes
72may become corrupted if the disk uses unrecognized type codes. Boot
73problems are particularly likely if you're multi\-booting with any
74GPT\-unaware OS. If you mistakenly launch \fBgdisk\fR on an MBR disk, you
75can safely exit the program without making any changes by using the 'q'
76option.
srs5694e7b4ff92009-08-18 13:16:10 -040077
srs5694978041c2009-09-21 20:51:47 -040078The MBR\-to\-GPT conversion will leave at least one gap in the partition
srs5694e7b4ff92009-08-18 13:16:10 -040079numbering if the original MBR used logical partitions. These gaps are
80harmless, but you can eliminate them by using the 's' option, if you like.
srs5694978041c2009-09-21 20:51:47 -040081(Doing this may require you to update your \fI/etc/fstab\fR file.)
srs5694e7b4ff92009-08-18 13:16:10 -040082
83When creating a fresh partition table, certain considerations may be in
84order:
85
srs5694978041c2009-09-21 20:51:47 -040086.TP
srs5694e7b4ff92009-08-18 13:16:10 -040087.B *
srs5694978041c2009-09-21 20:51:47 -040088For data (non\-boot) disks, and for boot disks used on BIOS\-based computers
srs5694e7b4ff92009-08-18 13:16:10 -040089with GRUB as the boot loader, partitions may be created in whatever order
90and in whatever sizes are desired.
91
srs5694978041c2009-09-21 20:51:47 -040092.TP
srs5694e7b4ff92009-08-18 13:16:10 -040093.B *
srs5694978041c2009-09-21 20:51:47 -040094Boot disks for EFI\-based systems require an \fIEFI System
95Partition\fR (\fBgdisk\fR internal code 0xEF00) formatted as FAT\-32.
srs5694a17fe692011-09-10 20:30:20 -040096The recommended size of this partition is between 100 and 300 MiB.
srs5694978041c2009-09-21 20:51:47 -040097Boot\-related files are stored here. (Note that GNU Parted identifies
98such partitions as having the "boot flag" set.)
srs5694e7b4ff92009-08-18 13:16:10 -040099
srs5694978041c2009-09-21 20:51:47 -0400100.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400101.B *
srs5694978041c2009-09-21 20:51:47 -0400102Some boot loaders for BIOS\-based systems make use of a \fIBIOS Boot
srs56948bb78762009-11-24 15:43:49 -0500103Partition\fR (\fBgdisk\fR internal code 0xEF02), in which the secondary
srs569455d92612010-03-07 22:16:07 -0500104boot loader is stored, possibly without the benefit of a filesystem. (GRUB2
105may optionally use such a partition.) This partition can typically be quite
106small (roughly 32 to 200 KiB), but you should consult your boot loader
107documentation for details.
srs56942a9f5da2009-08-26 00:48:01 -0400108
srs5694978041c2009-09-21 20:51:47 -0400109.TP
srs56942a9f5da2009-08-26 00:48:01 -0400110.B *
srs5694978041c2009-09-21 20:51:47 -0400111If Windows is to boot from a GPT disk, a partition of type \fIMicrosoft
112Reserved\fR (\fBgdisk\fR
srs5694e7b4ff92009-08-18 13:16:10 -0400113internal code 0x0C01) is recommended. This partition should be about 128 MiB
114in size. It ordinarily follows the EFI System Partition and immediately
srs56948a4ddfc2010-03-21 19:05:49 -0400115precedes the Windows data partitions. (Note that old versions of GNU Parted
116create all FAT partitions as this type, which actually makes the partition
117unusable for normal file storage in both Windows and Mac OS X.)
srs5694e7b4ff92009-08-18 13:16:10 -0400118
srs5694978041c2009-09-21 20:51:47 -0400119.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400120.B *
121Some OSes' GPT utilities create some blank space (typically 128 MiB) after
122each partition. The intent is to enable future disk utilities to use this
123space. Such free space is not required of GPT disks, but creating it may
srs5694e4ac11e2009-08-31 10:13:04 -0400124help in future disk maintenance. You can use GPT fdisk's relative partition
125positioning option (specifying the starting sector as '+128M', for
126instance) to simplify creating such gaps.
srs5694e7b4ff92009-08-18 13:16:10 -0400127
srs5694978041c2009-09-21 20:51:47 -0400128.SH "OPTIONS"
129.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400130.B \-l
Roderick W. Smithaf39cb42013-08-06 15:23:46 -0400131List the partition table for the specified device and then exits.
srs5694978041c2009-09-21 20:51:47 -0400132.PP
srs5694e7b4ff92009-08-18 13:16:10 -0400133
srs5694978041c2009-09-21 20:51:47 -0400134Most interactions with \fBgdisk\fR
135occur with its interactive text\-mode menus. Three menus exist: the main
136menu, the recovery & transformation menu, and the experts' menu. The main
137menu provides the functions that are most likely to be useful for typical partitioning tasks, such as creating and deleting partitions, changing partition type codes, and so on. Specific functions are:
srs5694e7b4ff92009-08-18 13:16:10 -0400138
srs5694978041c2009-09-21 20:51:47 -0400139.TP
srs5694221e0872009-08-29 15:00:31 -0400140.B b
srs56948bb78762009-11-24 15:43:49 -0500141Save partition data to a backup file. You can back up your current
srs569455d92612010-03-07 22:16:07 -0500142in\-memory partition table to a disk file using this option. The resulting
srs56948bb78762009-11-24 15:43:49 -0500143file is a binary file consisting of the protective MBR, the main GPT
144header, the backup GPT header, and one copy of the partition table, in that
srs569455d92612010-03-07 22:16:07 -0500145order. Note that the backup is of the current in\-memory data structures, so
srs56948bb78762009-11-24 15:43:49 -0500146if you launch the program, make changes, and then use this option, the
147backup will reflect your changes. Note also that the restore option is on
148the recovery & transformation menu; the backup option is on the main menu
149to encourage its use.
srs5694221e0872009-08-29 15:00:31 -0400150
srs5694978041c2009-09-21 20:51:47 -0400151
152.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400153.B c
srs5694978041c2009-09-21 20:51:47 -0400154Change the GPT name of a partition. This name is encoded as a UTF\-16
srs5694699941e2011-03-21 21:33:57 -0400155string, but proper entry and display of anything beyond basic ASCII values
156requires suitable locale and font support. For the most part, Linux ignores
157the partition name, but it may be important in some OSes. GPT fdisk sets a
158default name based on the partition type code. Note that the GPT partition
159name is different from the filesystem name, which is encoded in the
160filesystem's data structures.
srs5694e7b4ff92009-08-18 13:16:10 -0400161
srs5694978041c2009-09-21 20:51:47 -0400162.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400163.B d
164Delete a partition. This action deletes the entry from the partition table
165but does not disturb the data within the sectors originally allocated to
srs5694e4ac11e2009-08-31 10:13:04 -0400166the partition on the disk. If a corresponding hybrid MBR partition exists,
srs5694978041c2009-09-21 20:51:47 -0400167\fBgdisk\fR deletes it, as well, and expands any adjacent 0xEE (EFI GPT)
168MBR protective partition to fill the new free space.
srs5694e7b4ff92009-08-18 13:16:10 -0400169
srs5694978041c2009-09-21 20:51:47 -0400170.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400171.B i
172Show detailed partition information. The summary information produced by
173the 'p' command necessarily omits many details, such as the partition's
srs5694978041c2009-09-21 20:51:47 -0400174unique GUID and the translation of \fBgdisk\fR's
srs5694e7b4ff92009-08-18 13:16:10 -0400175internal partition type code to a plain type name. The 'i' option
176displays this information for a single partition.
177
srs5694978041c2009-09-21 20:51:47 -0400178.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400179.B l
srs569400b6d7a2011-06-26 22:40:06 -0400180Display a summary of partition types. GPT uses a GUID to identify partition
181types for particular OSes and purposes. For ease of data entry, \fBgdisk\fR
182compresses these into two\-byte (four\-digit hexadecimal) values that are
183related to their equivalent MBR codes. Specifically, the MBR code is
184multiplied by hexadecimal 0x0100. For instance, the code for Linux swap
185space in MBR is 0x82, and it's 0x8200 in \fBgdisk\fR. A one\-to\-one
186correspondence is impossible, though. Most notably, the codes for all
187varieties of FAT and NTFS partition correspond to a single GPT code
188(entered as 0x0700 in \fBsgdisk\fR). Some OSes use a single MBR code but
189employ many more codes in GPT. For these, \fBgdisk\fR adds code numbers
190sequentially, such as 0xa500 for a FreeBSD disklabel, 0xa501 for FreeBSD
191boot, 0xa502 for FreeBSD swap, and so on. Note that these two\-byte codes
192are unique to \fBgdisk\fR.
srs5694e7b4ff92009-08-18 13:16:10 -0400193
srs5694978041c2009-09-21 20:51:47 -0400194.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400195.B n
196Create a new partition. This command is modelled after the equivalent
srs5694978041c2009-09-21 20:51:47 -0400197\fBfdisk\fR option, although some differences exist. You enter a partition
198number, starting sector, and an ending sector. Both start and end sectors
srs56948bb78762009-11-24 15:43:49 -0500199can be specified in absolute terms as sector numbers or as positions
srs56940873e9d2010-10-07 13:00:45 -0400200measured in kibibytes (K), mebibytes (M), gibibytes (G), tebibytes (T), or
201pebibytes (P); for instance, \fI\fB40M\fR\fR specifies a position 40MiB
202from the start of the disk. You can specify locations relative to the start
srs56944307ef22012-05-30 12:30:48 -0400203or end of the specified default range by preceding the number by a '+' or '\-'
204symbol, as in \fI\fB+2G\fR\fR to specify a point 2GiB after the
srs56940873e9d2010-10-07 13:00:45 -0400205default start sector, or \fI\fB\-200M\fR\fR to specify a point 200MiB
206before the last available sector. Pressing the Enter key with no input
207specifies the default value, which is the start of the largest available
208block for the start sector and the end of the same block for the end
209sector.
srs5694e7b4ff92009-08-18 13:16:10 -0400210
srs5694978041c2009-09-21 20:51:47 -0400211.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400212.B o
213Clear out all partition data. This includes GPT header data,
srs56948a4ddfc2010-03-21 19:05:49 -0400214all partition definitions, and the protective MBR. The sector alignment
Aurimas Liutikas74b74902016-05-10 18:53:54 -0700215is reset to the default (1MB, or 2048 sectors on a disk with 512-byte
216sectors).
srs5694e7b4ff92009-08-18 13:16:10 -0400217
srs5694978041c2009-09-21 20:51:47 -0400218.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400219.B p
220Display basic partition summary data. This includes partition
221numbers, starting and ending sector numbers, partition sizes,
srs5694978041c2009-09-21 20:51:47 -0400222\fBgdisk\fR's partition types codes, and partition names. For
223additional information, use the 'i' command.
srs5694e7b4ff92009-08-18 13:16:10 -0400224
srs5694978041c2009-09-21 20:51:47 -0400225.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400226.B q
srs5694978041c2009-09-21 20:51:47 -0400227Quit from the program \fIwithout saving your changes\fR.
srs56942a9f5da2009-08-26 00:48:01 -0400228Use this option if you just wanted to view information or if you make a
229mistake and want to back out of all your changes.
srs5694e7b4ff92009-08-18 13:16:10 -0400230
srs5694978041c2009-09-21 20:51:47 -0400231.TP
232.B r
233Enter the recovery & transformation menu. This menu includes emergency
234recovery options (to fix damaged GPT data structures) and options to
235transform to or from other partitioning systems, including creating
236hybrid MBRs.
237
238.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400239.B s
240Sort partition entries. GPT partition numbers need not match the order of
241partitions on the disk. If you want them to match, you can use this option.
srs56948bb78762009-11-24 15:43:49 -0500242Note that some partitioning utilities sort partitions whenever they make
243changes. Such changes will be reflected in your device filenames, so you
244may need to edit \fI/etc/fstab\fR if you use this option.
srs5694e7b4ff92009-08-18 13:16:10 -0400245
srs5694978041c2009-09-21 20:51:47 -0400246.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400247.B t
248Change a single partition's type code. You enter the type code using a
srs5694978041c2009-09-21 20:51:47 -0400249two\-byte hexadecimal number, as described earlier. You may also enter a
250GUID directly, if you have one and \fBgdisk\fR doesn't know it.
srs5694e7b4ff92009-08-18 13:16:10 -0400251
srs5694978041c2009-09-21 20:51:47 -0400252.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400253.B v
254Verify disk. This option checks for a variety of problems, such as
255incorrect CRCs and mismatched main and backup data. This option does not
srs5694978041c2009-09-21 20:51:47 -0400256automatically correct most problems, though; for that, you must use
257options on the recovery & transformation menu. If no problems are found,
258this command displays a summary of unallocated disk space.
srs5694e7b4ff92009-08-18 13:16:10 -0400259
srs5694978041c2009-09-21 20:51:47 -0400260.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400261.B w
262Write data. Use this command to save your changes.
263
srs5694978041c2009-09-21 20:51:47 -0400264.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400265.B x
266Enter the experts' menu. Using this option provides access to features you
267can use to get into even more trouble than the main menu allows.
srs5694978041c2009-09-21 20:51:47 -0400268.PP
srs5694e7b4ff92009-08-18 13:16:10 -0400269
srs5694978041c2009-09-21 20:51:47 -0400270.TP
271.B ?
272Print the menu. Type this command (or any other unrecognized command) to
273see a summary of available options.
srs5694e7b4ff92009-08-18 13:16:10 -0400274
srs5694978041c2009-09-21 20:51:47 -0400275.PP
276The second \fBgdisk\fR menu is the recovery & transformation menu, which
277provides access to data recovery options and features related to the
278transformation of partitions between partitioning schemes (converting
279BSD disklabels into GPT partitions or creating hybrid MBRs, for instance).
280A few options on this menu duplicate functionality on the main
281menu, for the sake of convenience. The options on this menu are:
282
283.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400284.B b
srs5694978041c2009-09-21 20:51:47 -0400285Rebuild GPT header from backup. You can use the backup GPT header to
srs5694e7b4ff92009-08-18 13:16:10 -0400286rebuild the main GPT header with this option. It's likely to be useful if
287your main GPT header was damaged or destroyed (say, by sloppy use of
srs5694978041c2009-09-21 20:51:47 -0400288\fBdd\fR).
289
290.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400291.B c
srs5694978041c2009-09-21 20:51:47 -0400292Load backup partition table. Ordinarily, \fBgdisk\fR
srs5694e7b4ff92009-08-18 13:16:10 -0400293uses only the main partition table (although the backup's integrity is
294checked when you launch the program). If the main partition table has been
295damaged, you can use this option to load the backup from disk and use it
296instead. Note that this will almost certainly produce no or strange
297partition entries if you've just converted an MBR disk to GPT format, since
298there will be no backup partition table on disk.
299
srs5694978041c2009-09-21 20:51:47 -0400300.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400301.B d
302Use main GPT header and rebuild the backup. This option is likely to be
303useful if the backup GPT header has been damaged or destroyed.
srs5694c0ca8f82009-08-20 21:35:25 -0400304
srs5694978041c2009-09-21 20:51:47 -0400305.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400306.B e
307Load main partition table. This option reloads the main partition table
308from disk. It's only likely to be useful if you've tried to use the backup
309partition table (via 'c') but it's in worse shape then the main partition
310table.
srs5694c0ca8f82009-08-20 21:35:25 -0400311
srs5694978041c2009-09-21 20:51:47 -0400312.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400313.B f
srs5694978041c2009-09-21 20:51:47 -0400314Load MBR and build fresh GPT from it. Use this option if your GPT is corrupt
315or conflicts with the MBR and you want to use the MBR as the basis for a new
316set of GPT partitions.
317
318.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400319.B g
srs569455d92612010-03-07 22:16:07 -0500320Convert GPT into MBR and exit. This option converts as many partitions as possible
srs5694978041c2009-09-21 20:51:47 -0400321into MBR form, destroys the GPT data structures, saves the new MBR, and exits.
322Use this option if you've tried GPT and find that MBR works better for you.
srs569455d92612010-03-07 22:16:07 -0500323Note that this function generates up to four primary MBR partitions or three
324primary partitions and as many logical partitions as can be generated. Each
325logical partition requires at least one unallocated block immediately before
326its first block. Therefore, it may be possible to convert a maximum of four
327partitions on disks with tightly\-packed partitions; however, if free space was
328inserted between partitions when they were created, and if the disk is under
3292 TiB in size, it should be possible to convert all the partitions to MBR form.
330See also the 'h' option.
srs5694c0ca8f82009-08-20 21:35:25 -0400331
srs5694978041c2009-09-21 20:51:47 -0400332.TP
srs5694c0ca8f82009-08-20 21:35:25 -0400333.B h
srs5694978041c2009-09-21 20:51:47 -0400334Create a hybrid MBR. This is an ugly workaround that enables GPT\-unaware
335OSes, or those that can't boot from a GPT disk, to access up to three of
srs5694c0ca8f82009-08-20 21:35:25 -0400336the partitions on the disk by creating MBR entries for them. Note that
srs5694978041c2009-09-21 20:51:47 -0400337these hybrid MBR entries can easily go out of sync with the GPT entries,
338particularly when hybrid\-unaware GPT utilities are used to edit the disk.
Roderick W. Smithd28495e2014-03-02 11:37:20 -0500339Thus, you may need to re\-create the hybrid MBR if you use such tools. Unlike
srs569455d92612010-03-07 22:16:07 -0500340the 'g' option, this option does not support converting any partitions into
341MBR logical partitions.
srs5694c0ca8f82009-08-20 21:35:25 -0400342
srs5694978041c2009-09-21 20:51:47 -0400343.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400344.B i
345Show detailed partition information. This option is identical to the 'i'
346option on the main menu.
srs5694978041c2009-09-21 20:51:47 -0400347
348.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400349.B l
srs5694978041c2009-09-21 20:51:47 -0400350Load partition data from a backup file. This option is the reverse of the 'b'
351option on the main menu. Note that restoring partition data from anything
352but the original disk is not recommended.
353
354.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400355.B m
srs5694978041c2009-09-21 20:51:47 -0400356Return to the main menu. This option enables you to enter main\-menu commands.
357
358.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400359.B o
360Print protective MBR data. You can see a summary of the protective MBR's
361partitions with this option. This may enable you to spot glaring problems
362or help identify the partitions in a hybrid MBR.
srs5694978041c2009-09-21 20:51:47 -0400363
364.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400365.B p
366Print the partition table. This option is identical to the 'p' option in
367the main menu.
srs5694978041c2009-09-21 20:51:47 -0400368
369.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400370.B q
371Quit without saving changes. This option is identical to the 'q' option in
372the main menu.
srs56942a9f5da2009-08-26 00:48:01 -0400373
srs5694978041c2009-09-21 20:51:47 -0400374.TP
375.B t
376Transform BSD partitions into GPT partitions. This option works on BSD
377disklabels held within GPT (or converted MBR) partitions. Converted
378partitions' type codes are likely to need manual adjustment. \fBgdisk\fR
379will attempt to convert BSD disklabels stored on the main disk when
380launched, but this conversion is likely to produce first and/or last
381partitions that are unusable. The many BSD variants means that the
382probability of \fBgdisk\fR being unable to convert a BSD disklabel is
383high compared to the likelihood of problems with an MBR conversion.
384
385.TP
386.B v
387Verify disk. This option is identical to the 'v' option in the main menu.
388
389.TP
390.B w
391Write table to disk and exit. This option is identical to the 'w' option in
392the main menu.
393
394.TP
395.B x
396Enter the experts' menu. This option is identical to the 'x' option in the
397main menu.
398
399.TP
400.B ?
401Print the menu. This option (or any unrecognized entry) displays a summary
402of the menu options.
403
404.PP
405The third \fBgdisk\fR menu is the experts' menu. This menu provides advanced
406options that aren't closely related to recovery or transformation between
407partitioning systems. Its options are:
408
409.TP
410.B a
411Set attributes. GPT provides a 64\-bit attributes field that can be used to
412set features for each partition. \fBgdisk\fR supports four attributes:
413\fIsystem partition\fR, \fIread\-only\fR, \fIhidden\fR, and
414\fIdo not automount\fR. You can set other attributes, but their numbers
415aren't translated into anything useful. In practice, most OSes seem to
416ignore these attributes.
417
418.TP
419.B c
420Change partition GUID. You can enter a custom unique GUID for a partition
421using this option. (Note this refers to the GUID that uniquely identifies a
422partition, not to its type code, which you can change with the 't' main\-menu
423option.) Ordinarily, \fBgdisk\fR assigns this number randomly; however,
424you might want to adjust the number manually if you've wound up with the
425same GUID on two partitions because of buggy GUID assignments (hopefully
426not in \fBgdisk\fR) or sheer incredible coincidence.
427
srs569455d92612010-03-07 22:16:07 -0500428.TP
srs56941d1448a2009-12-31 21:20:19 -0500429.B d
srs56948a4ddfc2010-03-21 19:05:49 -0400430Display the sector alignment value. See the
431description of the 'l' option for more details.
srs56941d1448a2009-12-31 21:20:19 -0500432
srs569455d92612010-03-07 22:16:07 -0500433.TP
srs56948bb78762009-11-24 15:43:49 -0500434.B e
srs56941d1448a2009-12-31 21:20:19 -0500435Move backup GPT data structures to the end of the disk. Use this command if
436you've added disks to a RAID array, thus creating a virtual disk with space
437that follows the backup GPT data structures. This command moves the backup
438GPT data structures to the end of the disk, where they belong.
srs56948bb78762009-11-24 15:43:49 -0500439
srs56949ba54212010-05-18 23:24:02 -0400440.TP
441.B f
442Randomize the disk's GUID and all partitions' unique GUIDs (but not their
443partition type code GUIDs). This function may be used after cloning a disk
444with another utility in order to render all GUIDs once again unique.
445
srs5694978041c2009-09-21 20:51:47 -0400446.TP
447.B g
448Change disk GUID. Each disk has a unique GUID code, which \fBgdisk\fR
449assigns randomly upon creation of the GPT data structures. You can generate
450a fresh random GUID or enter one manually with this option.
451
srs56949ba54212010-05-18 23:24:02 -0400452.TP
453.B h
454Recompute CHS values in protective or hybrid MBR. This option can sometimes
455help if a disk utility, OS, or BIOS doesn't like the CHS values used by the
456partitions in the protective or hybrid MBR. In particular, the GPT
457specification requires a CHS value of 0xFFFFFF for over-8GiB partitions,
458but this value is technically illegal by the usual standards. Some BIOSes
459hang if they encounter this value. This option will recompute a more normal
460CHS value -- 0xFEFFFF for over-8GiB partitions, enabling these BIOSes to
461boot.
462
srs5694978041c2009-09-21 20:51:47 -0400463.TP
464.B i
465Show detailed partition information. This option is identical to the 'i'
466option on the main menu.
467
srs569455d92612010-03-07 22:16:07 -0500468.TP
srs56941d1448a2009-12-31 21:20:19 -0500469.B l
srs56948a4ddfc2010-03-21 19:05:49 -0400470Change the sector alignment value. Disks with more logical sectors per
srs5694a17fe692011-09-10 20:30:20 -0400471physical sectors (such as modern Advanced Format drives), some RAID
472configurations, and many SSD devices, can suffer performance problems if
473partitions are not aligned properly for their internal data structures. On
Aurimas Liutikas74b74902016-05-10 18:53:54 -0700474new disks, GPT fdisk attempts to align partitions on 1MiB boundaries
475(2048\-sectors on disks with 512-byte sectors) by default, which optimizes
476performance for all of these disk types. On pre\-partitioned disks, GPT
477fdisk attempts to identify the alignment value used on that disk, but will
478set 8-sector alignment on disks larger than 300 GB even if lesser alignment
479values are detected. In either case, it can be changed by using this
480option.
srs56941d1448a2009-12-31 21:20:19 -0500481
srs5694978041c2009-09-21 20:51:47 -0400482.TP
483.B m
484Return to the main menu. This option enables you to enter main\-menu commands.
485
486.TP
487.B n
488Create a new protective MBR. Use this option if the current protective MBR
489is damaged in a way that \fBgdisk\fR doesn't automatically detect and
490correct, or if you want to convert a hybrid MBR into a "pure" GPT with a
491conventional protective MBR.
492
493.TP
494.B o
495Print protective MBR data. You can see a summary of the protective MBR's
496partitions with this option. This may enable you to spot glaring problems
497or help identify the partitions in a hybrid MBR.
498
499.TP
500.B p
501Print the partition table. This option is identical to the 'p' option in
502the main menu.
503
504.TP
505.B q
506Quit without saving changes. This option is identical to the 'q' option in
507the main menu.
508
509.TP
510.B r
511Enter the recovery & transformations menu. This option is identical to
512the 'r' option on the main menu.
513
514.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400515.B s
srs56942a9f5da2009-08-26 00:48:01 -0400516Resize partition table. The default partition table size is 128 entries.
517Officially, sizes of less than 16KB (128 entries, given the normal entry
518size) are unsupported by the GPT specification; however, in practice they
519seem to work, and can sometimes be useful in converting MBR disks. Larger
520sizes also work fine. OSes may impose their own limits on the number of
521partitions, though.
522
srs569455d92612010-03-07 22:16:07 -0500523.TP
srs569408bb0da2010-02-19 17:19:55 -0500524.B t
525Swap two partitions' entries in the partition table. One partition may be
526empty. For instance, if partitions 1\-4 are defined, transposing 1 and 5
527results in a table with partitions numbered from 2\-5. Transposing
528partitions in this way has no effect on their disk space allocation; it
529only alters their order in the partition table.
530
srs56949ddc14b2010-08-22 22:44:42 -0400531.TP
532.B u
533Replicate the current device's partition table on another device. You will
534be prompted to type the new device's filename. After the write operation
535completes, you can continue editing the original device's partition table.
536Note that the replicated partition table is an exact copy, including all
537GUIDs; if the device should have its own unique GUIDs, you should use the
538\fBf\fR option on the new disk.
539
srs5694978041c2009-09-21 20:51:47 -0400540.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400541.B v
542Verify disk. This option is identical to the 'v' option in the main menu.
srs5694c0ca8f82009-08-20 21:35:25 -0400543
srs5694978041c2009-09-21 20:51:47 -0400544.TP
srs5694c0ca8f82009-08-20 21:35:25 -0400545.B z
srs5694978041c2009-09-21 20:51:47 -0400546Zap (destroy) the GPT data structures and exit. Use this option if you want to
547repartition a GPT disk using \fBfdisk\fR or some other GPT\-unaware program.
srs5694c0ca8f82009-08-20 21:35:25 -0400548You'll be given the choice of preserving the existing MBR, in case it's a
srs5694978041c2009-09-21 20:51:47 -0400549hybrid MBR with salvageable partitions or if you've already created new MBR
550partitions and want to erase the remnants of your GPT partitions. \fIIf you've
551already created new MBR partitions, it's conceivable that this option will
552damage the first and/or last MBR partitions!\fR Such an event is unlikely, but
553could occur if your new MBR partitions overlap the old GPT data structures.
srs5694c0ca8f82009-08-20 21:35:25 -0400554
srs5694978041c2009-09-21 20:51:47 -0400555.TP
556.B ?
557Print the menu. This option (or any unrecognized entry) displays a summary
558of the menu options.
srs5694e7b4ff92009-08-18 13:16:10 -0400559
srs5694978041c2009-09-21 20:51:47 -0400560.PP
srs5694e7b4ff92009-08-18 13:16:10 -0400561In many cases, you can press the Enter key to select a default option when
srs5694978041c2009-09-21 20:51:47 -0400562entering data. When only one option is possible, \fBgdisk\fR
srs5694e7b4ff92009-08-18 13:16:10 -0400563usually bypasses the prompt entirely.
564
srs5694978041c2009-09-21 20:51:47 -0400565.SH "BUGS"
Aurimas Liutikas74b74902016-05-10 18:53:54 -0700566Known bugs and limitations include:
srs5694e7b4ff92009-08-18 13:16:10 -0400567
srs5694978041c2009-09-21 20:51:47 -0400568.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400569.B *
srs569455d92612010-03-07 22:16:07 -0500570The program compiles correctly only on Linux, FreeBSD, Mac OS X, and Windows.
571Linux versions for x86\-64 (64\-bit), x86 (32\-bit), and PowerPC (32\-bit) have been
srs56948a4ddfc2010-03-21 19:05:49 -0400572tested, with the x86\-64 version having seen the most testing. Under FreeBSD,
57332\-bit (x86) and 64\-bit (x86\-64) versions have been tested. Only 32\-bit
srs5694df9d3632011-01-08 18:33:24 -0500574versions for Mac OS X and Windows have been tested by the author, although
575I've heard of 64-bit versions being successfully compiled.
srs5694e4ac11e2009-08-31 10:13:04 -0400576
srs5694978041c2009-09-21 20:51:47 -0400577.TP
srs5694e4ac11e2009-08-31 10:13:04 -0400578.B *
579The FreeBSD version of the program can't write changes to the partition
580table to a disk when existing partitions on that disk are mounted. (The
581same problem exists with many other FreeBSD utilities, such as
srs56947dbb9322010-01-20 16:56:30 -0500582\fBgpt\fR, \fBfdisk\fR, and \fBdd\fR.) This limitation can be overcome
583by typing \fBsysctl kern.geom.debugflags=16\fR at a shell prompt.
srs5694e4ac11e2009-08-31 10:13:04 -0400584
srs5694978041c2009-09-21 20:51:47 -0400585.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400586.B *
srs5694e7b4ff92009-08-18 13:16:10 -0400587The fields used to display the start and end sector numbers for partitions
588in the 'p' command are 14 characters wide. This translates to a limitation
589of about 45 PiB. On larger disks, the displayed columns will go out of
590alignment.
591
srs5694978041c2009-09-21 20:51:47 -0400592.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400593.B *
srs5694699941e2011-03-21 21:33:57 -0400594In the Windows version, only ASCII characters are supported in the
595partition name field. If an existing partition uses non\-ASCII UTF\-16
596characters, they're likely to be corrupted in the 'i' and 'p' menu options'
597displays; however, they should be preserved when loading and saving
598partitions. Binaries for Linux, FreeBSD, and OS X support full UTF-16
599partition names.
srs5694e7b4ff92009-08-18 13:16:10 -0400600
srs5694978041c2009-09-21 20:51:47 -0400601.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400602.B *
srs5694978041c2009-09-21 20:51:47 -0400603The program can load only up to 128 partitions (4 primary partitions and
604124 logical partitions) when converting from MBR format. This limit can
605be raised by changing the \fI#define MAX_MBR_PARTS\fR line in the
srs5694bf8950c2011-03-12 01:23:12 -0500606\fIbasicmbr.h\fR source code file and recompiling; however, such a change
srs56948bb78762009-11-24 15:43:49 -0500607will require using a larger\-than\-normal partition table. (The limit
srs5694978041c2009-09-21 20:51:47 -0400608of 128 partitions was chosen because that number equals the 128 partitions
srs56948bb78762009-11-24 15:43:49 -0500609supported by the most common partition table size.)
srs5694e7b4ff92009-08-18 13:16:10 -0400610
srs5694978041c2009-09-21 20:51:47 -0400611.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400612.B *
613Converting from MBR format sometimes fails because of insufficient space at
614the start or (more commonly) the end of the disk. Resizing the partition
615table (using the 's' option in the experts' menu) can sometimes overcome
616this problem; however, in extreme cases it may be necessary to resize a
srs5694978041c2009-09-21 20:51:47 -0400617partition using GNU Parted or a similar tool prior to conversion with
618\fBgdisk\fR.
srs5694e7b4ff92009-08-18 13:16:10 -0400619
srs5694978041c2009-09-21 20:51:47 -0400620.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400621.B *
srs5694e7b4ff92009-08-18 13:16:10 -0400622MBR conversions work only if the disk has correct LBA partition
623descriptors. These descriptors should be present on any disk over 8 GiB in
624size or on smaller disks partitioned with any but very ancient software.
625
srs5694978041c2009-09-21 20:51:47 -0400626.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400627.B *
srs5694e4ac11e2009-08-31 10:13:04 -0400628BSD disklabel support can create first and/or last partitions that overlap
629with the GPT data structures. This can sometimes be compensated by
630adjusting the partition table size, but in extreme cases the affected
631partition(s) may need to be deleted.
srs5694e7b4ff92009-08-18 13:16:10 -0400632
srs5694978041c2009-09-21 20:51:47 -0400633.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400634.B *
srs5694e4ac11e2009-08-31 10:13:04 -0400635Because of the highly variable nature of BSD disklabel structures,
srs5694978041c2009-09-21 20:51:47 -0400636conversions from this form may be unreliable \-\- partitions may be dropped,
srs5694e4ac11e2009-08-31 10:13:04 -0400637converted in a way that creates overlaps with other partitions, or
638converted with incorrect start or end values. Use this feature with
639caution!
640
srs5694978041c2009-09-21 20:51:47 -0400641.TP
srs5694e4ac11e2009-08-31 10:13:04 -0400642.B *
643Booting after converting an MBR or BSD disklabel disk is likely to be
srs5694978041c2009-09-21 20:51:47 -0400644disrupted. Sometimes re\-installing a boot loader will fix the problem, but
645other times you may need to switch boot loaders. Except on EFI\-based
srs569455d92612010-03-07 22:16:07 -0500646platforms, Windows through at least Windows 7 doesn't support booting
srs5694978041c2009-09-21 20:51:47 -0400647from GPT disks. Creating a hybrid MBR (using the 'h' option on the recovery &
648transformation menu) or abandoning GPT in favor of MBR may be your only
649options in this case.
srs5694c0ca8f82009-08-20 21:35:25 -0400650
srs5694978041c2009-09-21 20:51:47 -0400651.PP
srs5694e7b4ff92009-08-18 13:16:10 -0400652
srs5694978041c2009-09-21 20:51:47 -0400653.SH "AUTHORS"
srs5694e7b4ff92009-08-18 13:16:10 -0400654Primary author: Roderick W. Smith (rodsmith@rodsbooks.com)
655
656Contributors:
657
658* Yves Blusseau (1otnwmz02@sneakemail.com)
659
srs56947f244ba2009-08-18 14:22:12 -0400660* David Hubbard (david.c.hubbard@gmail.com)
srs5694e7b4ff92009-08-18 13:16:10 -0400661
srs569461768bc2010-07-04 01:54:00 -0400662* Justin Maggard (justin.maggard@netgear.com)
663
Aurimas Liutikas74b74902016-05-10 18:53:54 -0700664* Dwight Schauer (dschauer@gmail.com)
srs5694659eaf12010-08-23 11:26:12 -0400665
srs569464cbd172011-03-01 22:03:54 -0500666* Florian Zumbiehl (florz@florz.de)
667
srs56948f1b2d62010-05-23 13:07:19 -0400668
srs5694e7b4ff92009-08-18 13:16:10 -0400669.SH "SEE ALSO"
srs5694978041c2009-09-21 20:51:47 -0400670\fBcfdisk (8)\fR,
srs5694a17fe692011-09-10 20:30:20 -0400671\fBcgdisk (8)\fR,
srs5694978041c2009-09-21 20:51:47 -0400672\fBfdisk (8)\fR,
673\fBmkfs (8)\fR,
674\fBparted (8)\fR,
675\fBsfdisk (8)\fR
srs569455d92612010-03-07 22:16:07 -0500676\fBsgdisk (8)\fR
srs5694bf8950c2011-03-12 01:23:12 -0500677\fBfixparts (8)\fR
srs5694e7b4ff92009-08-18 13:16:10 -0400678
srs5694978041c2009-09-21 20:51:47 -0400679\fIhttp://en.wikipedia.org/wiki/GUID_Partition_Table\fR
srs5694e7b4ff92009-08-18 13:16:10 -0400680
srs5694978041c2009-09-21 20:51:47 -0400681\fIhttp://developer.apple.com/technotes/tn2006/tn2166.html\fR
srs5694e7b4ff92009-08-18 13:16:10 -0400682
srs5694978041c2009-09-21 20:51:47 -0400683\fIhttp://www.rodsbooks.com/gdisk/\fR
srs5694e7b4ff92009-08-18 13:16:10 -0400684
srs5694978041c2009-09-21 20:51:47 -0400685.SH "AVAILABILITY"
686The \fBgdisk\fR command is part of the \fIGPT fdisk\fR package and is
687available from Rod Smith.