cfdisk.8

一個相當mini的磁碟分割軟體,適合放在嵌入式系統

.\" cfdisk.8 -- man page for cfdisk
.\" Copyright 1994 Kevin E. Martin ([e-mail])
.\"
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
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.\" " for hilit mode
.TH CFDISK 8 "3 June 1995" "The BOGUS Linux Release" "Linux Programmer's Manual"
.SH NAME
cfdisk \- Curses based disk partition table manipulator for Linux
.SH SYNOPSIS
.BI "cfdisk [ \-avz ] [ \-c " cylinders " ] [ \-h " heads " ]"
.BI "[ \-s " sectors-per-track " ] [ -P " opt " ] [ " device " ]"
.SH DESCRIPTION
.B cfdisk
is a curses based program for partitioning a hard disk drive.  The
.I device
can be any one of the following:
.sp
.nf
.RS
/dev/hda [default]
/dev/hdb
/dev/sda
/dev/sdb
/dev/sdc
/dev/sdd
.RE
.fi

.B cfdisk
first tries to read the geometry of the hard disk.  If it fails, an
error message is displayed and
.B cfdisk
exits.  This should only happen when partitioning a SCSI drive on an
adapter without a BIOS.  To correct this problem, you can set the
.IR cylinders ", " heads " and " sectors-per-track
on the command line.  Next,
.B cfdisk
tries to read the current partition table from the disk drive.  If it
is unable to figure out the partition table, an error is displayed and
the program will exit.  This might also be caused by incorrect
geometry information, and can be overridden on the command line.
Another way around this problem is with the
.B \-z
option.  This will ignore the partition table on the disk.

The main display is composed of four sections, from top to bottom: the
header, the partitions, the command line and a warning line.  The
header contains the program name and version number followed by the
disk drive and its geometry.  The partitions section always displays
the current partition table.  The command line is the place where
commands and text are entered.  The available commands are usually
displayed in brackets.  The warning line is usually empty except when
there is important information to be displayed.  The current partition
is highlighted with reverse video (or an arrow if the
.B \-a
option is given).  All partition specific commands apply to the
current partition.

The format of the partition table in the partitions section is, from
left to right: Name, Flags, Partition Type, Filesystem Type and Size.
The name is the partition device name.  The flags can be
.IR Boot ,
which designates a bootable partition or
.IR NC ,
which stands for "Not Compatible with DOS or OS/2".  DOS, OS/2 and
possibly other operating systems require the first sector of the first
partition on the disk and all logical partitions to begin on the
second head.  This wastes the second through the last sector of the
first track of the first head (the first sector is taken by the
partition table itself).
.B cfdisk
allows you to recover these "lost" sectors with the maximize command
.RB ( m ).
.I Note:
.BR fdisk (8)
and some early versions of DOS create all partitions with the number
of sectors already maximized.  For more information, see the maximize
command below.  The partition type can be one of
.IR Primary " or " Logical .
For unallocated space on the drive, the partition type can also be
.IR Pri/Log ,
or empty (if the space is unusable).  The filesystem type section
displays the name of the filesystem used on the partition, if known.
If it is unknown, then
.I Unknown
and the hex value of the filesystem type are displayed.  A special
case occurs when there are sections of the disk drive that cannot be
used (because all of the primary partitions are used).  When this is
detected, the filesystem type is displayed as
.IR Unusable .
The size field displays the size of the partition in megabytes (by
default).  It can also display the size in sectors and cylinders (see
the change units command below).  If an asterisks
.RB ( * )
appears after the size, this means that the partition is not aligned
on cylinder boundaries.
.SH "DOS 6.x WARNING"

The DOS 6.x FORMAT command looks for some information in the first
sector of the data area of the partition, and treats this information
as more reliable than the information in the partition table.  DOS
FORMAT expects DOS FDISK to clear the first 512 bytes of the data area
of a partition whenever a size change occurs.  DOS FORMAT will look at
this extra information even if the /U flag is given -- we consider
this a bug in DOS FORMAT and DOS FDISK.

The bottom line is that if you use cfdisk or fdisk to change the size of a
DOS partition table entry, then you must also use
.B dd
to zero the first 512 bytes of that partition before using DOS FORMAT to
format the partition.  For example, if you were using cfdisk to make a DOS
partition table entry for /dev/hda1, then (after exiting fdisk or cfdisk
and rebooting Linux so that the partition table information is valid) you
would use the command "dd if=/dev/zero of=/dev/hda1 bs=512 count=1" to zero
the first 512 bytes of the partition. Note:

.B BE EXTREMELY CAREFUL
if you use the
.B dd
command, since a small typo can make all of the data on your disk useless.

For best results, you should always use an OS-specific partition table
program.  For example, you should make DOS partitions with the DOS FDISK
program and Linux partitions with the Linux fdisk or Linux cfdisk program.

.SH COMMANDS
.B cfdisk
commands can be entered by pressing the desired key (pressing
.I Enter
after the command is not necessary).  Here is a list of the available
commands:
.TP
.B b
Toggle bootable flag of the current partition.  This allows you to
select which primary partition is bootable on the drive.
.TP
.B d
Delete the current partition.  This will convert the current partition
into free space and merge it with any free space immediately
surrounding the current partition.  A partition already marked as free
space or marked as unusable cannot be deleted.
.TP
.B g
Change the disk geometry (cylinders, heads, or sectors-per-track).
.B WARNING:
This option should only be used by people who know what they are
doing.  A command line option is also available to change the disk
geometry.  While at the change disk geometry command line, you can
choose to change cylinders
.RB ( c ),
heads
.RB ( h ),
and sectors per track
.RB ( s ).
The default value will be printed at the prompt which you can accept
by simply pressing the
.I Enter
key, or you can exit without changes by pressing the
.I ESC
key.  If you want to change the default value, simply enter the
desired value and press
.IR Enter .
The altered disk parameter values do not take effect until you return
the main menu (by pressing
.IR Enter " or " ESC
at the change disk geometry command line.  If you change the geometry
such that the disk appears larger, the extra sectors are added at the
end of the disk as free space.  If the disk appears smaller, the
partitions that are beyond the new last sector are deleted and the
last partition on the drive (or the free space at the end of the
drive) is made to end at the new last sector.
.TP
.B h
Print the help screen.
.TP
.B m
Maximize disk usage of the current partition.  This command will
recover the the unused space between the partition table and the
beginning of the partition, but at the cost of making the partition
incompatible with DOS, OS/2 and possibly other operating systems.
This option will toggle between maximal disk usage and DOS, OS/2,
etc. compatible disk usage.  The default when creating a partition is
to create DOS, OS/2, etc. compatible partitions.
.TP
.B n
Create new partition from free space.  If the partition type is
.IR Primary " or " Logical ,
a partition of that type will be created, but if the partition type is
.IR Pri/Log ,
you will be prompted for the type you want to create.  Be aware that
(1) there are only four slots available for primary partitions and (2)
since there can be only one extended partition, which contains all of
the logical drives, all of the logical drives must be contiguous (with
no intervening primary partition).