397 lines
11 KiB
Groff
397 lines
11 KiB
Groff
.\" $OpenBSD: fdisk.8,v 1.119 2023/11/10 15:41:11 krw Exp $
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.\"
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.\"
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.\" Copyright (c) 1997 Tobias Weingartner
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.\"
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.\" Permission to use, copy, modify, and distribute this software for any
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.\" purpose with or without fee is hereby granted, provided that the above
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.\" copyright notice and this permission notice appear in all copies.
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.\"
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.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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.\"
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.Dd $Mdocdate: November 10 2023 $
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.Dt FDISK 8
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.Os
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.Sh NAME
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.Nm fdisk
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.Nd partition table maintenance program
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.Sh SYNOPSIS
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.Nm fdisk
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.Op Fl evy
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.Op Fl A | g | i | u
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.Op Fl b Ar blocks Ns Op @ Ns Ar offset Ns Op : Ns Ar type
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.Op Fl l Ar blocks | Fl c Ar cylinders Fl h Ar heads Fl s Ar sectors
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.Op Fl f Ar file
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.Ar disk
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.Sh DESCRIPTION
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.Nm fdisk
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creates and edits MBR and GPT partition tables.
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These tables are used by the boot process of some
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platforms to find the
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.Ox
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kernel and, when present, are used by the kernel to find the
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.Xr disklabel 5 .
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.Pp
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Caution is advised when editing these tables since some platforms
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rely on specific configurations created at install time.
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.Pp
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The options are as follows:
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.Bl -tag -width Ds
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.It Fl A
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Modifies the GPT partition table entries on
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.Ar disk
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to put all available space not taken by
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.Fl b
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into a single
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.Ox
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partition.
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The available space is maximized by deleting all existing partition
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entries except for partition types APFS ISC, APFS, APFS Recovery, BIOS Boot,
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HiFive FSBL, HiFive BBL and partitions with the
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.Sq Required
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GPT attribute set.
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.Pp
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If
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APFS ISC, APFS, or APFS Recovery
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partitions are detected then existing
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EFI system
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partitions are also preserved.
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If the preserved EFI system partition has fewer blocks
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than the number requested with
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.Fl b ,
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the modified GPT is discarded.
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.It Fl b Ar blocks Ns Op @ Ns Ar offset Ns Op : Ns Ar type
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Creates a partition table entry of the specified number of blocks, offset
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and type.
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.Ar offset
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defaults to the first available block, and
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.Ar type
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defaults to
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.Sq EF .
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.Pp
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.Fl b
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is only available in combination with
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.Fl A ,
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.Fl g ,
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or
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.Fl i .
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.Pp
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If
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.Fl A
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or
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.Fl g
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is specified, only the
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.Ar blocks
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value is used.
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.It Xo
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.Fl c Ar cylinders
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.Fl h Ar heads
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.Fl s Ar sectors
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.Xc
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Specifies a geometry for
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.Nm
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to use.
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By default the disk size and geometry are obtained
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from the default
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.Xr disklabel 5
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constructed by the kernel for
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.Ar disk .
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See
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.Xr disklabel 5
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and
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.Xr disklabel 8 .
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.It Fl e
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Invokes the interactive partition table editor.
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See
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.Sx COMMAND MODE
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below.
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.It Fl f Ar file
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Specifies a file containing the bootcode for an MBR.
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The default file is
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.Pa /usr/mdec/mbr .
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.It Fl g
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Writes a default GPT, including a protective MBR, to
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.Ar disk .
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The GPT has a single
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.Ox
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partition containing all available space not taken by
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.Fl b .
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.It Fl i
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Writes a default MBR to
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.Ar disk .
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The MBR has a single
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.Ox
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partition containing all the available space not taken by
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.Fl b .
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The bootcode is initialized as described in
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.Fl u .
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.It Fl l Ar count
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Treat
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.Ar disk
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as though it has a size of
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.Ar count
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blocks.
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.It Fl u
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Updates the MBR bootcode.
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If a bootcode file is present (see
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.Fl f )
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the MBR, except for the partition entries, is replaced by
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the first block of the file.
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If no bootcode file is present, zeros are used.
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.Pp
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Not available when editing a GPT.
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.It Fl v
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Prints detailed information about the MBR, the Primary GPT and the
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Secondary GPT.
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.It Fl y
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New or modified partition table is written to disk without
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asking for confirmation.
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.It Ar disk
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.Nm
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creates or modifies the partition table of
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.Ar disk .
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.Ar disk
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can be a full pathname,
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e.g.
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.Pa /dev/rsd0c ,
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a raw partition name, e.g.
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.Pa sd0c ,
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or just the disk name, e.g.
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.Pa sd0 .
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.El
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.Sh TYPICAL LAYOUT
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When called without options
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.Nm
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prints the partition table of
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.Ar disk .
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.Pp
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If
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.Ar disk
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has a GPT a terse version of its contents is printed:
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.Bd -literal -offset 1n
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# fdisk sd0
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Disk: sd0 Usable LBA: 64 to 500118128 [500118192 Sectors]
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#: type [ start: size ]
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------------------------------------------------------------------------
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1: EFI Sys [ 64: 960 ]
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3: OpenBSD [ 1024: 500117105 ]
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.Ed
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.Pp
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When
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.Ar disk
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does not have a GPT, the first block of
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.Ar disk
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is printed as an MBR:
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.Bd -literal -offset 1n
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# fdisk sd0
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Disk: sd0 geometry: 121601/255/63 [1953525168 Sectors]
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Offset: 0 Signature: 0xAA55
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Starting Ending LBA Info:
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#: id C H S - C H S [ start: size ]
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------------------------------------------------------------------------
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0: 0B 0 1 1 - 26108 0 63 [ 63: 419425020 ] FAT32
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1: 00 0 0 0 - 0 0 0 [ 0: 0 ] unused
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2: 00 0 0 0 - 0 0 0 [ 0: 0 ] unused
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*3: A6 26108 1 1 - 121600 254 63 [ 419425083: 1534094982 ] OpenBSD
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.Ed
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.Pp
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.Em NOTE :
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Partition entry #3 of this MBR is flagged as bootable.
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.Pp
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.Em NOTE :
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The
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.Em S
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field in the C/H/S values is
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.Dq 1 based ,
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but the LBA "start" field is
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.Dq 0 based .
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.Pp
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The
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.Fl v
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option causes more information to be printed:
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.Bd -literal -offset 1n
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# fdisk -v sd0
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Primary GPT:
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Disk: sd0 Usable LBA: 64 to 500118128 [500118192 Sectors]
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GUID: f0418899-4976-4604-a783-3ebe135a8f12
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#: type [ start: size ]
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guid name
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------------------------------------------------------------------------
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1: EFI Sys [ 64: 960 ]
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d0834013-dab8-44df-a5e4-123148f17e03 EFI System Area
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3: OpenBSD [ 1024: 500117105 ]
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cd356d77-8369-44b4-996e-79e8b9a47bfe OpenBSD Area
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Secondary GPT:
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Disk: sd0 Usable LBA: 64 to 500118128 [500118192 Sectors]
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GUID: f0418899-4976-4604-a783-3ebe135a8f12
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#: type [ start: size ]
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guid name
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------------------------------------------------------------------------
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1: EFI Sys [ 64: 960 ]
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d0834013-dab8-44df-a5e4-123148f17e03 EFI System Area
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3: OpenBSD [ 1024: 500117105 ]
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cd356d77-8369-44b4-996e-79e8b9a47bfe OpenBSD Area
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MBR:
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Disk: sd0 geometry: 31130/255/63 [500118192 Sectors]
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Offset: 0 Signature: 0xAA55
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Starting Ending LBA Info:
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#: id C H S - C H S [ start: size ]
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-------------------------------------------------------------------------------
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0: EE 0 0 2 - 31130 233 63 [ 1: 500118191 ] EFI GPT
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1: 00 0 0 0 - 0 0 0 [ 0: 0 ] unused
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2: 00 0 0 0 - 0 0 0 [ 0: 0 ] unused
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3: 00 0 0 0 - 0 0 0 [ 0: 0 ] unused
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.Ed
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.Sh COMMAND MODE
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When
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.Nm
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enters interactive command mode
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it copies the partition table from
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.Ar disk
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into memory and performs all edits on
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that copy.
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The partition table on
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.Ar disk
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is modified only by
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.Em write
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or
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.Em quit
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commands.
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.Pp
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The prompt contains information about the state of the edit
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process.
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.Pp
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.Dl Ar disk Ns *:1>
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.Pp
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Where
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.Ar disk
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is the name of the disk being edited,
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.Sq *
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means that the partition table has been modified, but
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not yet written to disk and
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1 is the edit level when operating on the MBR or GPT.
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This number is 2 when editing an extended partition in the MBR,
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3 when editing an extended partition within the edit level 2
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extended partition, and so on.
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.Pp
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The list of commands and their functions is
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given below.
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Commands may be abbreviated.
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The first command matching the abbreviation is selected.
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.Bl -tag -width Ds
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.It Cm ?\&
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A synonym for
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.Cm help .
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.It Cm help
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Displays a short summary of available commands.
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.It Cm manual
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Displays this manual page.
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.It Cm reinit Op Cm gpt | Cm mbr
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Initializes the partition table.
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.Pp
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By default an MBR partition table is initialized.
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If
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.Cm gpt
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is specified a GPT partition table is initialized, including the
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protective MBR.
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.It Cm setpid Ar #
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Sets the identifier of the partition table entry.
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.It Cm edit Ar #
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Edit an entry in the partition table.
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The offset and size of the entry may be specified in CHS mode (MBR only),
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by using sector offsets and sizes, or by using
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the units
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.Sq b ,
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.Sq k ,
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.Sq m ,
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.Sq g ,
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or
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.Sq t
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to indicate bytes, kilobytes, megabytes, gigabytes, or terabytes.
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The special size value
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.Sq *
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causes the partition to be sized to use the remainder of the disk.
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.It Cm flag Ar # Op Ar value
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Set the partition's flag (MBR) or attribute (GPT) value.
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.Ar value
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can be a positive integer or a hex string.
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An MBR partition will accept values from 0 to 0xff.
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A GPT partition will accept values from 0 to 0xfffffffffffffff.
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If
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.Ar value
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is not provided the partition's bootable flag is set
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and all other partitions have their bootable flags reset.
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MBR partitions with the bootable flag set are printed with a
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.Sq *
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prefix.
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GPT partitions with the bootable flag set display 'bootable' in
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their attributes list.
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.It Cm update
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Updates the MBR bootcode.
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If a bootcode file is present (see
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.Fl f )
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the MBR, except for the partition entries, is replaced by
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the first block of the file.
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If no bootcode file is present, zeros are used.
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.Pp
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Not available when editing a GPT.
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.It Cm select Ar #
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Selects an extended partition entry, increasing the edit level by 1.
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.Pp
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Not available when editing a GPT.
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.It Cm swap Ar # Ar #
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Swaps two partition entries.
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.It Cm print Op Ar unit
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Prints the partition table.
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If
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.Ar unit
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is
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.Sq b ,
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.Sq k ,
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.Sq m ,
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.Sq g ,
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or
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.Sq t
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partition sizes are shown in bytes,
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kilobytes, megabytes, gigabytes, or terabytes.
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If
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.Ar unit
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is not provided, sizes are shown in sectors.
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.It Cm write
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Writes the partition table to disk.
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.It Cm exit
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Discards outstanding changes and exits the current edit level.
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If the edit level is 1,
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.Nm
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terminates.
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.It Cm quit
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Writes outstanding changes to disk and exits the current edit
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level.
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If the edit level is 1,
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.Nm
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terminates.
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.It Cm abort
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Discards outstanding changes and terminates
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.Nm .
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.El
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.Sh FILES
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.Bl -tag -width /usr/mdec/mbr -compact
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.It Pa /usr/mdec/mbr
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default MBR bootcode
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.El
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.Sh SEE ALSO
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.Xr disklabel 5 ,
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.Xr boot 8 ,
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.Xr boot_amd64 8 ,
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.Xr boot_i386 8 ,
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.Xr boot_macppc 8 ,
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.Xr disklabel 8
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