fdisk

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NAME

       fdisk - Partition table manipulator for Linux


SYNOPSIS

       fdisk [ -l ] [ -v ] [ -s partition] [ device ]


DESCRIPTION

       fdisk  is  a  menu  driven program for manipulation of the
       hard disk partition table.  The device is usually  one  of
       the following:

              /dev/hda
              /dev/hdb
              /dev/sda
              /dev/sdb
       The  partition  is  a  device name followed by a partition
       number.  For example, /dev/hda1 is the first partition  on
       the first hard disk in the system.

       If possible, fdisk will obtain the disk geometry automati-
       cally.  This is not necessarily the physical  disk  geome-
       try,  but  is  the  disk geometry that MS-DOS uses for the
       partition table.  If fdisk warns you that you need to  set
       the  disk geometry, please believe this statement, and set
       the geometry.  This should only be necessary with  certain
       SCSI  host  adapters  (the  drivers  for which are rapidly
       being modified to provide geometry  information  automati-
       cally).

       Whenever  a  partition table is printed out, a consistency
       check is performed on the partition table  entries.   This
       check verifies that the physical and logical start and end
       points are identical, and that the  partition  starts  and
       ends  on  a cylinder boundary (except for the first parti-
       tion).

       Old versions of fdisk (all versions prior to 1.1r [includ-
       ing  0.93])  incorrectly  mapped  the cylinder/head/sector
       specification onto absolute sectors.  This may  result  in
       the  first  partition  on  a drive failing the consistency
       check.  If you use LILO to boot,  this  situation  can  be
       ignored.   However,  there  are reports that the OS/2 boot
       manager will not boot a partition with inconsistent  data.

       Some  versions  of  MS-DOS  create a first partition which
       does not begin on a cylinder boundary, but on sector 2  of
       the  first  cylinder.   Partitions beginning in cylinder 1
       cannot begin on a cylinder boundary, but this is  unlikely
       to  cause difficulty unless you have OS/2 on your machine.

       In version 1.1r, a BLKRRPART ioctl() is  performed  before
       exiting when the partition table is updated.  This is pri-
       marily to ensure that removable SCSI disks have their par-
       tition  table information updated.  If the kernel does not
       update its partition table information, fdisk warns you to
       reboot.   If you do not reboot your system after receiving
       such a warning, you may lose or corrupt the  data  on  the
       disk.  Sometimes BLKRRPART fails silently, when installing
       Linux, you should always reboot after editing  the  parti-
       tion table.



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 informa-
       tion in the partition table.  DOS FORMAT expects DOS FDISK
       to  clear the first 512 bytes of the data area of a parti-
       tion 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 dd to zero the first 512 bytes of that  par-
       tition  before  using  DOS FORMAT to format the partition.
       For example, if you were using cfdisk to make a DOS parti-
       tion  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.  BE EXTREMELY CAREFUL if
       you use the dd command, since a small typo can make all of
       the data on your disk useless.

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

       For  best  resutls,  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.



OPTIONS

       -v     Prints version number of fdisk program.

       -l     Lists the partition tables for /dev/hda,  /dev/hdb,
              /dev/sda,  /dev/sdb,  /dev/sdc, /dev/sdd, /dev/sde,
              /dev/sdf, /dev/sdg, /dev/sdh, and then exits.

       -spartition
              If the partition is not a DOS partition (i.e.,  the
              partition  id is greater than 10), then the size of
              that partition is printed on the  standard  output.
              This  value  is normally used as an argument to the
              mkfs(8) program to specify the size of  the  parti-
              tion which will be formatted.


BUGS

       Although  this  man  page (written by faith@cs.unc.edu) is
       poor, there is excellent documentation in the README.fdisk
       file  (written by LeBlanc@mcc.ac.uk) that should always be
       with the fdisk distribution.  If you cannot find this file
       in  the  util-linux-* directory or with the fdisk.c source
       file, then you should write to  the  distributor  of  your
       version  of fdisk and complain that you do not have all of
       the available documentation.


AUTHOR

       A. V. Le Blanc (LeBlanc@mcc.ac.uk)
       v1.0r:  SCSI  and  extfs  support  added  by   Rik   Faith
       (faith@cs.unc.edu)
       v1.1r:   Bug   fixes   and   enhancements   by  Rik  Faith
       (faith@cs.unc.edu),  with  special   thanks   to   Michael
       Bischoff  (i1041905@ws.rz.tu-bs.de  or mbi@mo.math.nat.tu-
       bs.de).
       v1.3: Latest enhancements and bug fixes by A. V. Le Blanc,
       including  the  addition  of  the  -s option.  v2.0: Disks
       larger than 2GB are now fully supported,  thanks  to  Remy
       Card's llseek support.
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