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Aurimas Liutikasbdbab022017-03-07 09:50:36 -08001.\" Copyright 2011-2013 Roderick W. Smith (rodsmith@rodsbooks.com)
srs5694e7b4ff92009-08-18 13:16:10 -04002.\" May be distributed under the GNU General Public License
Aurimas Liutikasbdbab022017-03-07 09:50:36 -08003.TH "GDISK" "8" "0.8.10" "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 Liutikasbdbab022017-03-07 09:50:36 -0800215is reset to the default (2048 sectors, or 1MB).
srs5694e7b4ff92009-08-18 13:16:10 -0400216
srs5694978041c2009-09-21 20:51:47 -0400217.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400218.B p
219Display basic partition summary data. This includes partition
220numbers, starting and ending sector numbers, partition sizes,
srs5694978041c2009-09-21 20:51:47 -0400221\fBgdisk\fR's partition types codes, and partition names. For
222additional information, use the 'i' command.
srs5694e7b4ff92009-08-18 13:16:10 -0400223
srs5694978041c2009-09-21 20:51:47 -0400224.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400225.B q
srs5694978041c2009-09-21 20:51:47 -0400226Quit from the program \fIwithout saving your changes\fR.
srs56942a9f5da2009-08-26 00:48:01 -0400227Use this option if you just wanted to view information or if you make a
228mistake and want to back out of all your changes.
srs5694e7b4ff92009-08-18 13:16:10 -0400229
srs5694978041c2009-09-21 20:51:47 -0400230.TP
231.B r
232Enter the recovery & transformation menu. This menu includes emergency
233recovery options (to fix damaged GPT data structures) and options to
234transform to or from other partitioning systems, including creating
235hybrid MBRs.
236
237.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400238.B s
239Sort partition entries. GPT partition numbers need not match the order of
240partitions on the disk. If you want them to match, you can use this option.
srs56948bb78762009-11-24 15:43:49 -0500241Note that some partitioning utilities sort partitions whenever they make
242changes. Such changes will be reflected in your device filenames, so you
243may need to edit \fI/etc/fstab\fR if you use this option.
srs5694e7b4ff92009-08-18 13:16:10 -0400244
srs5694978041c2009-09-21 20:51:47 -0400245.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400246.B t
247Change a single partition's type code. You enter the type code using a
srs5694978041c2009-09-21 20:51:47 -0400248two\-byte hexadecimal number, as described earlier. You may also enter a
249GUID directly, if you have one and \fBgdisk\fR doesn't know it.
srs5694e7b4ff92009-08-18 13:16:10 -0400250
srs5694978041c2009-09-21 20:51:47 -0400251.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400252.B v
253Verify disk. This option checks for a variety of problems, such as
254incorrect CRCs and mismatched main and backup data. This option does not
srs5694978041c2009-09-21 20:51:47 -0400255automatically correct most problems, though; for that, you must use
256options on the recovery & transformation menu. If no problems are found,
257this command displays a summary of unallocated disk space.
srs5694e7b4ff92009-08-18 13:16:10 -0400258
srs5694978041c2009-09-21 20:51:47 -0400259.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400260.B w
261Write data. Use this command to save your changes.
262
srs5694978041c2009-09-21 20:51:47 -0400263.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400264.B x
265Enter the experts' menu. Using this option provides access to features you
266can use to get into even more trouble than the main menu allows.
srs5694978041c2009-09-21 20:51:47 -0400267.PP
srs5694e7b4ff92009-08-18 13:16:10 -0400268
srs5694978041c2009-09-21 20:51:47 -0400269.TP
270.B ?
271Print the menu. Type this command (or any other unrecognized command) to
272see a summary of available options.
srs5694e7b4ff92009-08-18 13:16:10 -0400273
srs5694978041c2009-09-21 20:51:47 -0400274.PP
275The second \fBgdisk\fR menu is the recovery & transformation menu, which
276provides access to data recovery options and features related to the
277transformation of partitions between partitioning schemes (converting
278BSD disklabels into GPT partitions or creating hybrid MBRs, for instance).
279A few options on this menu duplicate functionality on the main
280menu, for the sake of convenience. The options on this menu are:
281
282.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400283.B b
srs5694978041c2009-09-21 20:51:47 -0400284Rebuild GPT header from backup. You can use the backup GPT header to
srs5694e7b4ff92009-08-18 13:16:10 -0400285rebuild the main GPT header with this option. It's likely to be useful if
286your main GPT header was damaged or destroyed (say, by sloppy use of
srs5694978041c2009-09-21 20:51:47 -0400287\fBdd\fR).
288
289.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400290.B c
srs5694978041c2009-09-21 20:51:47 -0400291Load backup partition table. Ordinarily, \fBgdisk\fR
srs5694e7b4ff92009-08-18 13:16:10 -0400292uses only the main partition table (although the backup's integrity is
293checked when you launch the program). If the main partition table has been
294damaged, you can use this option to load the backup from disk and use it
295instead. Note that this will almost certainly produce no or strange
296partition entries if you've just converted an MBR disk to GPT format, since
297there will be no backup partition table on disk.
298
srs5694978041c2009-09-21 20:51:47 -0400299.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400300.B d
301Use main GPT header and rebuild the backup. This option is likely to be
302useful if the backup GPT header has been damaged or destroyed.
srs5694c0ca8f82009-08-20 21:35:25 -0400303
srs5694978041c2009-09-21 20:51:47 -0400304.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400305.B e
306Load main partition table. This option reloads the main partition table
307from disk. It's only likely to be useful if you've tried to use the backup
308partition table (via 'c') but it's in worse shape then the main partition
309table.
srs5694c0ca8f82009-08-20 21:35:25 -0400310
srs5694978041c2009-09-21 20:51:47 -0400311.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400312.B f
srs5694978041c2009-09-21 20:51:47 -0400313Load MBR and build fresh GPT from it. Use this option if your GPT is corrupt
314or conflicts with the MBR and you want to use the MBR as the basis for a new
315set of GPT partitions.
316
317.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400318.B g
srs569455d92612010-03-07 22:16:07 -0500319Convert GPT into MBR and exit. This option converts as many partitions as possible
srs5694978041c2009-09-21 20:51:47 -0400320into MBR form, destroys the GPT data structures, saves the new MBR, and exits.
321Use this option if you've tried GPT and find that MBR works better for you.
srs569455d92612010-03-07 22:16:07 -0500322Note that this function generates up to four primary MBR partitions or three
323primary partitions and as many logical partitions as can be generated. Each
324logical partition requires at least one unallocated block immediately before
325its first block. Therefore, it may be possible to convert a maximum of four
326partitions on disks with tightly\-packed partitions; however, if free space was
327inserted between partitions when they were created, and if the disk is under
3282 TiB in size, it should be possible to convert all the partitions to MBR form.
329See also the 'h' option.
srs5694c0ca8f82009-08-20 21:35:25 -0400330
srs5694978041c2009-09-21 20:51:47 -0400331.TP
srs5694c0ca8f82009-08-20 21:35:25 -0400332.B h
srs5694978041c2009-09-21 20:51:47 -0400333Create a hybrid MBR. This is an ugly workaround that enables GPT\-unaware
334OSes, or those that can't boot from a GPT disk, to access up to three of
srs5694c0ca8f82009-08-20 21:35:25 -0400335the partitions on the disk by creating MBR entries for them. Note that
srs5694978041c2009-09-21 20:51:47 -0400336these hybrid MBR entries can easily go out of sync with the GPT entries,
337particularly when hybrid\-unaware GPT utilities are used to edit the disk.
Roderick W. Smithd28495e2014-03-02 11:37:20 -0500338Thus, you may need to re\-create the hybrid MBR if you use such tools. Unlike
srs569455d92612010-03-07 22:16:07 -0500339the 'g' option, this option does not support converting any partitions into
340MBR logical partitions.
srs5694c0ca8f82009-08-20 21:35:25 -0400341
srs5694978041c2009-09-21 20:51:47 -0400342.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400343.B i
344Show detailed partition information. This option is identical to the 'i'
345option on the main menu.
srs5694978041c2009-09-21 20:51:47 -0400346
347.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400348.B l
srs5694978041c2009-09-21 20:51:47 -0400349Load partition data from a backup file. This option is the reverse of the 'b'
350option on the main menu. Note that restoring partition data from anything
351but the original disk is not recommended.
352
353.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400354.B m
srs5694978041c2009-09-21 20:51:47 -0400355Return to the main menu. This option enables you to enter main\-menu commands.
356
357.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400358.B o
359Print protective MBR data. You can see a summary of the protective MBR's
360partitions with this option. This may enable you to spot glaring problems
361or help identify the partitions in a hybrid MBR.
srs5694978041c2009-09-21 20:51:47 -0400362
363.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400364.B p
365Print the partition table. This option is identical to the 'p' option in
366the main menu.
srs5694978041c2009-09-21 20:51:47 -0400367
368.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400369.B q
370Quit without saving changes. This option is identical to the 'q' option in
371the main menu.
srs56942a9f5da2009-08-26 00:48:01 -0400372
srs5694978041c2009-09-21 20:51:47 -0400373.TP
374.B t
375Transform BSD partitions into GPT partitions. This option works on BSD
376disklabels held within GPT (or converted MBR) partitions. Converted
377partitions' type codes are likely to need manual adjustment. \fBgdisk\fR
378will attempt to convert BSD disklabels stored on the main disk when
379launched, but this conversion is likely to produce first and/or last
380partitions that are unusable. The many BSD variants means that the
381probability of \fBgdisk\fR being unable to convert a BSD disklabel is
382high compared to the likelihood of problems with an MBR conversion.
383
384.TP
385.B v
386Verify disk. This option is identical to the 'v' option in the main menu.
387
388.TP
389.B w
390Write table to disk and exit. This option is identical to the 'w' option in
391the main menu.
392
393.TP
394.B x
395Enter the experts' menu. This option is identical to the 'x' option in the
396main menu.
397
398.TP
399.B ?
400Print the menu. This option (or any unrecognized entry) displays a summary
401of the menu options.
402
403.PP
404The third \fBgdisk\fR menu is the experts' menu. This menu provides advanced
405options that aren't closely related to recovery or transformation between
406partitioning systems. Its options are:
407
408.TP
409.B a
410Set attributes. GPT provides a 64\-bit attributes field that can be used to
411set features for each partition. \fBgdisk\fR supports four attributes:
412\fIsystem partition\fR, \fIread\-only\fR, \fIhidden\fR, and
413\fIdo not automount\fR. You can set other attributes, but their numbers
414aren't translated into anything useful. In practice, most OSes seem to
415ignore these attributes.
416
417.TP
418.B c
419Change partition GUID. You can enter a custom unique GUID for a partition
420using this option. (Note this refers to the GUID that uniquely identifies a
421partition, not to its type code, which you can change with the 't' main\-menu
422option.) Ordinarily, \fBgdisk\fR assigns this number randomly; however,
423you might want to adjust the number manually if you've wound up with the
424same GUID on two partitions because of buggy GUID assignments (hopefully
425not in \fBgdisk\fR) or sheer incredible coincidence.
426
srs569455d92612010-03-07 22:16:07 -0500427.TP
srs56941d1448a2009-12-31 21:20:19 -0500428.B d
srs56948a4ddfc2010-03-21 19:05:49 -0400429Display the sector alignment value. See the
430description of the 'l' option for more details.
srs56941d1448a2009-12-31 21:20:19 -0500431
srs569455d92612010-03-07 22:16:07 -0500432.TP
srs56948bb78762009-11-24 15:43:49 -0500433.B e
srs56941d1448a2009-12-31 21:20:19 -0500434Move backup GPT data structures to the end of the disk. Use this command if
435you've added disks to a RAID array, thus creating a virtual disk with space
436that follows the backup GPT data structures. This command moves the backup
437GPT data structures to the end of the disk, where they belong.
srs56948bb78762009-11-24 15:43:49 -0500438
srs56949ba54212010-05-18 23:24:02 -0400439.TP
440.B f
441Randomize the disk's GUID and all partitions' unique GUIDs (but not their
442partition type code GUIDs). This function may be used after cloning a disk
443with another utility in order to render all GUIDs once again unique.
444
srs5694978041c2009-09-21 20:51:47 -0400445.TP
446.B g
447Change disk GUID. Each disk has a unique GUID code, which \fBgdisk\fR
448assigns randomly upon creation of the GPT data structures. You can generate
449a fresh random GUID or enter one manually with this option.
450
srs56949ba54212010-05-18 23:24:02 -0400451.TP
452.B h
453Recompute CHS values in protective or hybrid MBR. This option can sometimes
454help if a disk utility, OS, or BIOS doesn't like the CHS values used by the
455partitions in the protective or hybrid MBR. In particular, the GPT
456specification requires a CHS value of 0xFFFFFF for over-8GiB partitions,
457but this value is technically illegal by the usual standards. Some BIOSes
458hang if they encounter this value. This option will recompute a more normal
459CHS value -- 0xFEFFFF for over-8GiB partitions, enabling these BIOSes to
460boot.
461
srs5694978041c2009-09-21 20:51:47 -0400462.TP
463.B i
464Show detailed partition information. This option is identical to the 'i'
465option on the main menu.
466
srs569455d92612010-03-07 22:16:07 -0500467.TP
srs56941d1448a2009-12-31 21:20:19 -0500468.B l
srs56948a4ddfc2010-03-21 19:05:49 -0400469Change the sector alignment value. Disks with more logical sectors per
srs5694a17fe692011-09-10 20:30:20 -0400470physical sectors (such as modern Advanced Format drives), some RAID
471configurations, and many SSD devices, can suffer performance problems if
472partitions are not aligned properly for their internal data structures. On
Aurimas Liutikasbdbab022017-03-07 09:50:36 -0800473new disks, GPT fdisk attempts to align partitions on 2048\-sector (1MiB)
474boundaries by default, which optimizes performance for all of these disk
475types. On pre\-partitioned disks, GPT fdisk attempts to identify the
476alignment value used on that disk, but will set 8-sector alignment on disks
477larger than 300 GB even if lesser alignment values are detected. In either
478case, it can be changed by using this option.
srs56941d1448a2009-12-31 21:20:19 -0500479
srs5694978041c2009-09-21 20:51:47 -0400480.TP
481.B m
482Return to the main menu. This option enables you to enter main\-menu commands.
483
484.TP
485.B n
486Create a new protective MBR. Use this option if the current protective MBR
487is damaged in a way that \fBgdisk\fR doesn't automatically detect and
488correct, or if you want to convert a hybrid MBR into a "pure" GPT with a
489conventional protective MBR.
490
491.TP
492.B o
493Print protective MBR data. You can see a summary of the protective MBR's
494partitions with this option. This may enable you to spot glaring problems
495or help identify the partitions in a hybrid MBR.
496
497.TP
498.B p
499Print the partition table. This option is identical to the 'p' option in
500the main menu.
501
502.TP
503.B q
504Quit without saving changes. This option is identical to the 'q' option in
505the main menu.
506
507.TP
508.B r
509Enter the recovery & transformations menu. This option is identical to
510the 'r' option on the main menu.
511
512.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400513.B s
srs56942a9f5da2009-08-26 00:48:01 -0400514Resize partition table. The default partition table size is 128 entries.
515Officially, sizes of less than 16KB (128 entries, given the normal entry
516size) are unsupported by the GPT specification; however, in practice they
517seem to work, and can sometimes be useful in converting MBR disks. Larger
518sizes also work fine. OSes may impose their own limits on the number of
519partitions, though.
520
srs569455d92612010-03-07 22:16:07 -0500521.TP
srs569408bb0da2010-02-19 17:19:55 -0500522.B t
523Swap two partitions' entries in the partition table. One partition may be
524empty. For instance, if partitions 1\-4 are defined, transposing 1 and 5
525results in a table with partitions numbered from 2\-5. Transposing
526partitions in this way has no effect on their disk space allocation; it
527only alters their order in the partition table.
528
srs56949ddc14b2010-08-22 22:44:42 -0400529.TP
530.B u
531Replicate the current device's partition table on another device. You will
532be prompted to type the new device's filename. After the write operation
533completes, you can continue editing the original device's partition table.
534Note that the replicated partition table is an exact copy, including all
535GUIDs; if the device should have its own unique GUIDs, you should use the
536\fBf\fR option on the new disk.
537
srs5694978041c2009-09-21 20:51:47 -0400538.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400539.B v
540Verify disk. This option is identical to the 'v' option in the main menu.
srs5694c0ca8f82009-08-20 21:35:25 -0400541
srs5694978041c2009-09-21 20:51:47 -0400542.TP
srs5694c0ca8f82009-08-20 21:35:25 -0400543.B z
srs5694978041c2009-09-21 20:51:47 -0400544Zap (destroy) the GPT data structures and exit. Use this option if you want to
545repartition a GPT disk using \fBfdisk\fR or some other GPT\-unaware program.
srs5694c0ca8f82009-08-20 21:35:25 -0400546You'll be given the choice of preserving the existing MBR, in case it's a
srs5694978041c2009-09-21 20:51:47 -0400547hybrid MBR with salvageable partitions or if you've already created new MBR
548partitions and want to erase the remnants of your GPT partitions. \fIIf you've
549already created new MBR partitions, it's conceivable that this option will
550damage the first and/or last MBR partitions!\fR Such an event is unlikely, but
551could occur if your new MBR partitions overlap the old GPT data structures.
srs5694c0ca8f82009-08-20 21:35:25 -0400552
srs5694978041c2009-09-21 20:51:47 -0400553.TP
554.B ?
555Print the menu. This option (or any unrecognized entry) displays a summary
556of the menu options.
srs5694e7b4ff92009-08-18 13:16:10 -0400557
srs5694978041c2009-09-21 20:51:47 -0400558.PP
srs5694e7b4ff92009-08-18 13:16:10 -0400559In many cases, you can press the Enter key to select a default option when
srs5694978041c2009-09-21 20:51:47 -0400560entering data. When only one option is possible, \fBgdisk\fR
srs5694e7b4ff92009-08-18 13:16:10 -0400561usually bypasses the prompt entirely.
562
srs5694978041c2009-09-21 20:51:47 -0400563.SH "BUGS"
Aurimas Liutikasbdbab022017-03-07 09:50:36 -0800564As of March 2014 (version 0.8.10), \fBgdisk\fR
565should be considered beta software. Known bugs and limitations include:
srs5694e7b4ff92009-08-18 13:16:10 -0400566
srs5694978041c2009-09-21 20:51:47 -0400567.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400568.B *
srs569455d92612010-03-07 22:16:07 -0500569The program compiles correctly only on Linux, FreeBSD, Mac OS X, and Windows.
570Linux versions for x86\-64 (64\-bit), x86 (32\-bit), and PowerPC (32\-bit) have been
srs56948a4ddfc2010-03-21 19:05:49 -0400571tested, with the x86\-64 version having seen the most testing. Under FreeBSD,
57232\-bit (x86) and 64\-bit (x86\-64) versions have been tested. Only 32\-bit
srs5694df9d3632011-01-08 18:33:24 -0500573versions for Mac OS X and Windows have been tested by the author, although
574I've heard of 64-bit versions being successfully compiled.
srs5694e4ac11e2009-08-31 10:13:04 -0400575
srs5694978041c2009-09-21 20:51:47 -0400576.TP
srs5694e4ac11e2009-08-31 10:13:04 -0400577.B *
578The FreeBSD version of the program can't write changes to the partition
579table to a disk when existing partitions on that disk are mounted. (The
580same problem exists with many other FreeBSD utilities, such as
srs56947dbb9322010-01-20 16:56:30 -0500581\fBgpt\fR, \fBfdisk\fR, and \fBdd\fR.) This limitation can be overcome
582by typing \fBsysctl kern.geom.debugflags=16\fR at a shell prompt.
srs5694e4ac11e2009-08-31 10:13:04 -0400583
srs5694978041c2009-09-21 20:51:47 -0400584.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400585.B *
srs5694e7b4ff92009-08-18 13:16:10 -0400586The fields used to display the start and end sector numbers for partitions
587in the 'p' command are 14 characters wide. This translates to a limitation
588of about 45 PiB. On larger disks, the displayed columns will go out of
589alignment.
590
srs5694978041c2009-09-21 20:51:47 -0400591.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400592.B *
srs5694699941e2011-03-21 21:33:57 -0400593In the Windows version, only ASCII characters are supported in the
594partition name field. If an existing partition uses non\-ASCII UTF\-16
595characters, they're likely to be corrupted in the 'i' and 'p' menu options'
596displays; however, they should be preserved when loading and saving
597partitions. Binaries for Linux, FreeBSD, and OS X support full UTF-16
598partition names.
srs5694e7b4ff92009-08-18 13:16:10 -0400599
srs5694978041c2009-09-21 20:51:47 -0400600.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400601.B *
srs5694978041c2009-09-21 20:51:47 -0400602The program can load only up to 128 partitions (4 primary partitions and
603124 logical partitions) when converting from MBR format. This limit can
604be raised by changing the \fI#define MAX_MBR_PARTS\fR line in the
srs5694bf8950c2011-03-12 01:23:12 -0500605\fIbasicmbr.h\fR source code file and recompiling; however, such a change
srs56948bb78762009-11-24 15:43:49 -0500606will require using a larger\-than\-normal partition table. (The limit
srs5694978041c2009-09-21 20:51:47 -0400607of 128 partitions was chosen because that number equals the 128 partitions
srs56948bb78762009-11-24 15:43:49 -0500608supported by the most common partition table size.)
srs5694e7b4ff92009-08-18 13:16:10 -0400609
srs5694978041c2009-09-21 20:51:47 -0400610.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400611.B *
612Converting from MBR format sometimes fails because of insufficient space at
613the start or (more commonly) the end of the disk. Resizing the partition
614table (using the 's' option in the experts' menu) can sometimes overcome
615this problem; however, in extreme cases it may be necessary to resize a
srs5694978041c2009-09-21 20:51:47 -0400616partition using GNU Parted or a similar tool prior to conversion with
617\fBgdisk\fR.
srs5694e7b4ff92009-08-18 13:16:10 -0400618
srs5694978041c2009-09-21 20:51:47 -0400619.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400620.B *
srs5694e7b4ff92009-08-18 13:16:10 -0400621MBR conversions work only if the disk has correct LBA partition
622descriptors. These descriptors should be present on any disk over 8 GiB in
623size or on smaller disks partitioned with any but very ancient software.
624
srs5694978041c2009-09-21 20:51:47 -0400625.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400626.B *
srs5694e4ac11e2009-08-31 10:13:04 -0400627BSD disklabel support can create first and/or last partitions that overlap
628with the GPT data structures. This can sometimes be compensated by
629adjusting the partition table size, but in extreme cases the affected
630partition(s) may need to be deleted.
srs5694e7b4ff92009-08-18 13:16:10 -0400631
srs5694978041c2009-09-21 20:51:47 -0400632.TP
srs5694e7b4ff92009-08-18 13:16:10 -0400633.B *
srs5694e4ac11e2009-08-31 10:13:04 -0400634Because of the highly variable nature of BSD disklabel structures,
srs5694978041c2009-09-21 20:51:47 -0400635conversions from this form may be unreliable \-\- partitions may be dropped,
srs5694e4ac11e2009-08-31 10:13:04 -0400636converted in a way that creates overlaps with other partitions, or
637converted with incorrect start or end values. Use this feature with
638caution!
639
srs5694978041c2009-09-21 20:51:47 -0400640.TP
srs5694e4ac11e2009-08-31 10:13:04 -0400641.B *
642Booting after converting an MBR or BSD disklabel disk is likely to be
srs5694978041c2009-09-21 20:51:47 -0400643disrupted. Sometimes re\-installing a boot loader will fix the problem, but
644other times you may need to switch boot loaders. Except on EFI\-based
srs569455d92612010-03-07 22:16:07 -0500645platforms, Windows through at least Windows 7 doesn't support booting
srs5694978041c2009-09-21 20:51:47 -0400646from GPT disks. Creating a hybrid MBR (using the 'h' option on the recovery &
647transformation menu) or abandoning GPT in favor of MBR may be your only
648options in this case.
srs5694c0ca8f82009-08-20 21:35:25 -0400649
srs5694978041c2009-09-21 20:51:47 -0400650.PP
srs5694e7b4ff92009-08-18 13:16:10 -0400651
srs5694978041c2009-09-21 20:51:47 -0400652.SH "AUTHORS"
srs5694e7b4ff92009-08-18 13:16:10 -0400653Primary author: Roderick W. Smith (rodsmith@rodsbooks.com)
654
655Contributors:
656
657* Yves Blusseau (1otnwmz02@sneakemail.com)
658
srs56947f244ba2009-08-18 14:22:12 -0400659* David Hubbard (david.c.hubbard@gmail.com)
srs5694e7b4ff92009-08-18 13:16:10 -0400660
srs569461768bc2010-07-04 01:54:00 -0400661* Justin Maggard (justin.maggard@netgear.com)
662
Aurimas Liutikasbdbab022017-03-07 09:50:36 -0800663* Dwight Schauer (dschauer@ti.com)
srs5694659eaf12010-08-23 11:26:12 -0400664
srs569464cbd172011-03-01 22:03:54 -0500665* Florian Zumbiehl (florz@florz.de)
666
srs56948f1b2d62010-05-23 13:07:19 -0400667
srs5694e7b4ff92009-08-18 13:16:10 -0400668.SH "SEE ALSO"
srs5694978041c2009-09-21 20:51:47 -0400669\fBcfdisk (8)\fR,
srs5694a17fe692011-09-10 20:30:20 -0400670\fBcgdisk (8)\fR,
srs5694978041c2009-09-21 20:51:47 -0400671\fBfdisk (8)\fR,
672\fBmkfs (8)\fR,
673\fBparted (8)\fR,
674\fBsfdisk (8)\fR
srs569455d92612010-03-07 22:16:07 -0500675\fBsgdisk (8)\fR
srs5694bf8950c2011-03-12 01:23:12 -0500676\fBfixparts (8)\fR
srs5694e7b4ff92009-08-18 13:16:10 -0400677
srs5694978041c2009-09-21 20:51:47 -0400678\fIhttp://en.wikipedia.org/wiki/GUID_Partition_Table\fR
srs5694e7b4ff92009-08-18 13:16:10 -0400679
srs5694978041c2009-09-21 20:51:47 -0400680\fIhttp://developer.apple.com/technotes/tn2006/tn2166.html\fR
srs5694e7b4ff92009-08-18 13:16:10 -0400681
srs5694978041c2009-09-21 20:51:47 -0400682\fIhttp://www.rodsbooks.com/gdisk/\fR
srs5694e7b4ff92009-08-18 13:16:10 -0400683
srs5694978041c2009-09-21 20:51:47 -0400684.SH "AVAILABILITY"
685The \fBgdisk\fR command is part of the \fIGPT fdisk\fR package and is
686available from Rod Smith.