FDISK(8)FDISK(8)NAMEfdisk - examine or change DOS partitioning information
SYNOPSIS
/usr/etc/fdisk <raw-device> [ inquiry ] [ action ] [ flags ]
DESCRIPTIONfdisk displays or changes the DOS partition table found in the
bootsector of i386 bootable disks. If no inquiry or action is
specified, it is run in interactive mode, allowing multiple changes to
the partition table to be made. If an inquiry is specified, the result
is displayed to standard output but no changes to the partition table
are made. If an action is requested, the partition table will usually
be modified and fdisk immediately returns. When fdisk is run in
interactive mode, no changes to the partition table are effected until
the user explicitly writes the changes.
fdisk modifies only the bootsector and (unless the -bootsectorOnly flag
is specified) the first sector of newly allocated partitions; it does
not modify other contents of the disk in any way. However, it is used
to redefine the allocation of the disk; deleting a partition makes the
partition inaccessible and should be considered tantamount to erasing
the partition.
Flags
-useAllSectors
For compatibility with the DOS version, fdisk by default
recognizes only those sectors that are bios-accessible. However,
if fdisk is passed the -useAllSectors flag, it will recognize all
sectors physically present. Data allocated in the extra sectors
may not be bios accessible, and certain fields in the partition
table might overflow, which might cause problems with some
operating systems. Bios inaccessible sectors could prevent
NEXTSTEP from booting, though once booted NEXTSTEP is unaffected
by bios limitations or partition table overflows.
-useBoot0
Reads in /usr/standalone/i386/boot0 to be used as the partition
boot program. If this option is not specified, the existing boot
program is retained.
-bootsectorOnly
Tells fdisk to modify only the bootsector when saving changes.
Otherwise, the default behavior is to zero the first sector of
newly-created partitions to ensure that extant data is not
treated as a boot program or meaningful partition information.
Interactive mode
When fdisk is run in interactive mode, it displays the defined
partitions and unallocated disk space, then displays a menu.
Information on defined partitions includes:
Type The type of data the partition is said to contain.
rt The starting address of the partition, in megabytes.
e The size of the partition, in megabytes.
tus If the partition is marked as active, the partition will be
booted from when the selected device is the boot device.
All unused blocks on the disk are also displayed, with their sizes
rounded to the nearest megabyte.
Interactive mode main menu options
a new partition
Allocates space on the disk for use by NEXTSTEP or another
operating system. The space is allocated from the first adequate
free block. The partition table structure only allows for 4
partitions per disk.
te partition
Deallocates the space occupied by the specified partition.
the active partition
Specifies which partition is to be booted from if the selected
device is the boot device.
w disk information
Displays the layout of the disk, both according to the driver and
accoring to the rom bios. For compatibility with the DOS
verstion, fdisk by default only recognizes those sectors that are
bios-accessible. However, if fdisk is passed the -useAllSectors
flag, it will recognize all sectors physically present.
Non-interactive mode
For the benefit of installation scripts, fdisk can be given one inquiry
or one action to effect partitioning. Inquiries do not modify the
partition table, but actions usually do.
The following inquiries are allowed:
-isDiskPartitioned
Outputs "Yes" if the disk contains 1 or more valid partitions,
"No" otherwise.
-isThereExtendedPartition
Outputs "Yes" if the disk has a DOS extended partition, "No"
otherwise.
-isThereNeXTPartition
Outputs "Yes" if the disk has a NEXTSTEP partition, "No"
otherwise.
-freeSpace
Outputs the size (in megabytes) of the largest free block on the
disk.
-freeWONeXT
Outputs the size (in megabytes) of the largest free block on the
disk if the NEXTSTEP partition were deleted.
-freeWONeXTorExt
Outputs the size (in megabytes) of the largest free block on the
disk if the NEXTSTEP and extended partitions were deleted.
-sizeofExtended
Outputs the size (in megabytes) of the extended partition.
-diskSize
Outputs the size of the disk in megabytes.
-installSize
Outputs the size that NEXTSTEP would install to on the current
disk; effectively the size of the NEXTSTEP partition if the disk
is partitioned, otherwise the size of the disk.
The following actions are allowed:
-removePartitioning
Zeros out the bootsector, eliminating the partition table and
boot program. Prepares the disk so that NEXTSTEP will install on
the entire disk.
-dosPlusNeXT <megsForDos>
Partitions the disk with <megsForDos> reserved for DOS and the
remainder used for NEXTSTEP.
-setAvailableToNeXT
Deletes the current NEXTSTEP partition, then reserves the largest
free space for NEXTSTEP; doesn't destroy other partitions.
-setExtAndAvailableToNeXT
Deletes the current NEXTSTEP and extended partitions, then
reserves the largest free space for NEXTSTEP; doesn't destroy
other partitions.
-setExtendedToNeXT
Changes the current extended partition to NEXTSTEP.
-setNeXTActive
Makes the NEXTSTEP partition active, but doesn't affect the size
of any partition.
SEE ALSOdisk(8)BUGS
When creating a partition, fdisk's idea of a megabyte is sometimes
different than other versions; fdisk is not guaranteed to locate the
partition where another version would.
fdisk knows nothing about logical partitions, which are sub-partitions
of an extended partition. Nor perhaps should it, as these are gross
kludges from the Evil OS Company of the North.
fdisk does not tolerate inconsistent partitions; a partition that
overlaps another will not be included in the partition table when it is
written out, and the cylinder/head/sector bios values are derived from
the absolute sector numbers. Upon writing, the partition table entries
are ordered the same as the actual partitions.
4th Berkeley Distribution Mar 30, 1993 FDISK(8)
