cfdisk.8

一個相當mini的磁碟分割軟體,適合放在嵌入式系統

.B cfdisk
next prompts you for the size of the partition you want to create.
The default size, equal to the entire free space of the current
partition, is display in megabytes.  You can either press the
.I Enter
key to accept the default size or enter a different size at the
prompt.
.B cfdisk
accepts size entries in megabytes
.RB ( M )
[default], kilobytes
.RB ( K ),
cylinders
.RB ( C )
and sectors
.RB ( S )
by entering the number immediately followed by one of
.RB ( M ", " K ", " C " or " S ).
If the partition fills the free space available, the partition is
created and you are returned to the main command line.  Otherwise, the
partition can be created at the beginning or the end of the free
space, and
.B cfdisk
will ask you to choose where to place the partition.  After the
partition is created,
.B cfdisk
automatically adjusts the other partition's partition types if all of
the primary partitions are used.
.TP
.B p
Print the partition table to the screen or to a file. There are
several different formats for the partition that you can choose from:
.sp
.RS
.TP
.B r
Raw data format (exactly what would be written to disk)
.TP
.B s
Partition table in sector order format
.TP
.B t
Partition table in raw format
.RE

.RS
The
.I raw data format
will print the sectors that would be written to disk if a
.BR w rite
command is selected.  First, the primary partition table is printed,
followed by the partition tables associated with each logical
partition.  The data is printed in hex byte by byte with 16 bytes per
line.

The
.I partition table in sector order format
will print the partition table ordered by sector number.  The fields,
from left to right, are the number of the partition, the partition
type, the first sector, the last sector, the offset from the first
sector of the partition to the start of the data, the length of the
partition, the filesystem type (with the hex value in parenthesis),
and the flags (with the hex value in parenthesis).  In addition to the
primary and logical partitions, free and unusable space is printed and
the extended partition is printed before the first logical partition.

If a partition does not start or end on a cylinder boundary or if the
partition length is not divisible by the cylinder size, an asterisks
.RB ( * )
is printed after the non-aligned sector number/count.  This usually
indicates that a partition was created by an operating system that
either does not align partitions to cylinder boundaries or that used
different disk geometry information.  If you know the disk geometry of
the other operating system, you could enter the geometry information
with the change geometry command
.RB ( g ).

For the first partition on the disk and for all logical partitions, if
the offset from the beginning of the partition is not equal to the
number of sectors per track (i.e., the data does not start on the
first head), a number sign
.RB ( # )
is printed after the offset.  For the remaining partitions, if the
offset is not zero, a number sign will be printed after the offset.
This corresponds to the
.I NC
flag in the partitions section of the main display.

The
.I partition table in raw format
will print the partition table ordered by partition number.  It will
leave out all free and unusable space.  The fields, from left to
right, are the number of the partition, the flags (in hex), the
starting head, sector and cylinder, the filesystem ID (in hex), the
ending head, sector and cylinder, the starting sector in the partition
and the number of sectors in the partition.  The information in this
table can be directly translated to the
.IR "raw data format" .

The partition table entries only have 10 bits available to represent
the starting and ending cylinders.  Thus, when the absolute starting
(ending) sector number is on a cylinder greater than 1023, the maximal
values for starting (ending) head, sector and cylinder are printed.
This is the method used by OS/2, and thus fixes the problems
associated with OS/2's fdisk rewriting the partition table when it is
not in this format.  Since Linux and OS/2 use absolute sector counts,
the values in the starting and ending head, sector and cylinder are
not used.
.RE
.TP
.B q
Quit program.  This will exit the program without writing any data to
disk.
.TP
.B t
Change the filesystem type.  By default, new partitions are created as
.I Linux
partitions, but since
.B cfdisk
can create partitions for other operating systems, change partition
type allows you to enter the hex value of the filesystem you desire.
A list of the know filesystem types is displayed.  You can type in the
filesystem type at the prompt or accept the default filesystem type
.RI [ Linux ].
.TP
.B u
Change units of the partition size display.  It will rotate through
megabytes, sectors and cylinders.
.TP
.B W
Write partition table to disk (must enter an upper case W).  Since
this might destroy data on the disk, you must either confirm or deny
the write by entering `yes' or `no'.  If you enter `yes',
.B cfdisk
will write the partition table to disk and the tell the kernel to
re-read the partition table from the disk.  The re-reading of the
partition table works is most cases, but I have seen it fail.  Don't
panic.  It will be correct after you reboot the system.  In all cases,
I still recommend rebooting the system--just to be safe.
.TP
.I Up Arrow
.TP
.I Down Arrow
Move cursor to the previous or next partition.  If there are more
partitions than can be displayed on a screen, you can display the next
(previous) set of partitions by moving down (up) at the last (first)
partition displayed on the screen.
.TP
.I CTRL-L
Redraws the screen.  In case something goes wrong and you cannot read
anything, you can refresh the screen from the main command line.
.TP
.B ?
Print the help screen.

.RE
All of the commands can be entered with either upper or lower case
letters (except for
.BR W rites).
When in a sub-menu or at a prompt to enter a filename, you can hit the
.I ESC
key to return to the main command line.
.SH OPTIONS
.TP
.B \-a
Use an arrow cursor instead of reverse video for highlighting the
current partition.
.TP
.B \-v
Print the version number and copyright.
.TP
.B \-z
Start with zeroed partition table.  This option is useful when you
want to repartition your entire disk.
.I Note:
this option does not zero the partition table on the disk; rather, it
simply starts the program without reading the existing partition
table.
.TP
.BI \-c " cylinders"
.TP
.BI \-h " heads"
.TP
.BI \-s " sectors-per-track"
Override the number of cylinders, heads and sectors per track read
from the BIOS.  If your BIOS or adapter does not supply this
information or if it supplies incorrect information, use these options
to set the disk geometry values.
.TP
.BI \-P " opt"
Prints the partition table in specified formats.
.I opt
can be one or more of "r", "s" or "t".  See the
.BR p rint
command (above) for more information on the print formats.
.SH "SEE ALSO"
fdisk(8)
.SH BUGS
The current version does not support multiple disks (future addition).
.SH AUTHOR
Kevin E. Martin ([e-mail])