.CD "fdisk \(en partition a hard disk [IBM]"
.SX "fdisk\fR [\fB\(enh\fIm\fR]\fR [\fB\(ens\fIn\fR]\fR [\fIfile\fR]"
.FL "\fB\(enh" "Number of disk heads is \fIm\fR"
.FL "\fB\(ens" "Number of sectors per track is \fIn\fR"
.EX "fdisk /dev/hd0" "Examine disk partitions"
.EX "fdisk \(enh9 /dev/hd0" "Examine disk with 9 heads"
.PP
When \fIfdisk\fR starts up, it reads in the partition table and displays 
it.
It then presents a menu to allow the user to modify partitions, store the
partition table on a file, or load it from a file.  Partitions can be marked
as 
.MX ,
DOS or other, as well as active or not.
Using \fIfdisk\fR is self-explanatory.  
However, be aware that
repartitioning a disk will cause information on it to be lost.  
Rebooting the system \fIimmediately\fR 
is mandatory after changing partition sizes and parameters.
.MX , 
\&\s-2XENIX\s0, \s-2PC-IX\s0, and \s-2MS-DOS\s0 all have different 
partition numbering schemes.
Thus when using multiple systems on the same disk, be careful.
.PP
Note that
.MX ,
unlike
.SY MS-DOS ,
cannot access the last sector in a partition with an odd number of sectors.
The reason that odd partition sizes do not cause a problem with
\s-2MS-DOS\s0 is that \s-2MS-DOS\s0 allocates disk space in units of
512-byte sectors, whereas 
.MX
uses 1K blocks.
\fIFdisk\fR has a variety of other features that can be seen by typing \fIh\fR.
.PP
.I Fdisk
normally knows the geometry of the device by asking the driver.  You can use
the \fB\(enh\fP and \fB\(ens\fP options to override the numbers found.