[prashant]

The fdisk command is a useful Linux tool for listing and changing disk partitions. Keep in mind that modifying or deleting partitions can cause valuable data to be removed, so be sure of your changes before writing them to disk. To use the fdisk command to list information about the partitions on your hard disk, type the following command as root user:

# fdisk –l: List disk partitions for every disk
Disk /dev/sda: 82.3 GB, 82348277760 bytes
255 heads, 63 sectors/track, 10011 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device 	           Boot     Start      End           Blocks       Id 	     System
/dev/sda1	    * 	       1 	  13 	       104391 	   83 	       Linux
/dev/sda2 	               14       9881         79264710 	83	    Linux
/dev/sda3 	               9882   10011        1044225     82 	   Linux swap

This example is for an 80GB hard disk that is divided into three partitions. The first (/dev/sda1) is a small /boot partition that is configured as a Linux ext3 file system (Id 83). Note the asterisk (*), indicating that the first partition is bootable. The next partition is assigned to the root file system and is also ext3. The final partition is Linux swap.

NOTE: In Fedora 7 and later, both IDE and SCSI disks use device names /dev/sd?, where the ? is replaced by a letter (a, b, or c, and so on). In RHEL5 and earlier versions of Fedora, only SCSI disks and USB flash drives used the /dev/sd? names. IDE hard drives used /dev/hd? instead. If multiple disks are present, fdisk -l will list them all unless you indicate the specific disk you want:

# fdisk -l /dev/sdb: List disk partitions for a specific disk

To work with a specific disk with the fdisk command, simply indicate the disk you want with no other options:

# fdisk /dev/sda: Start interactive fdisk session with disk 1
Command (m for help): m: Type m to list help text as shown Command action

a: toggle a bootable flag
b: edit bsd disklabel
c: toggle the dos compatibility flag
d: delete a partition
l: list known partition types
m: print this menu
n: add a new partition
o: create a new empty DOS partition table
p: print the partition table
q: quit without saving changes
s: create a new empty Sun disklabel
t: change a partition’s system id
u: change display/entry units
v: verify the partition table
w: write table to disk and exit
x: extra functionality (experts only)
Command (m for help): With the prompt displayed, you can use any of the commands shown to work with your hard disk. In particular, you can use p (to print the same listing as fdisk -l), n (to create a new partition), d (to delete an existing partition), l (to list known file system types), or t (to change the file system type for a partition). The following examples show some of those fdisk commands in action:

Command (m for help): d: Ask to delete a partition
Partition number (1-4): 4: Type partition number to delete
Command (m for help): n: Create a new disk partition
First cylinder (1-4983, default 1): 1: Select start (or Enter)
Last cylinder ... (default 4983): 4983: Select end (or Enter)
Command (m for help): a: Make a partition bootable
Partition number (1-3): 1: Type bootable partition number
Command (m for help): t: Select a file system type
Partition number (1-3): 3: Select partition to change
Hex code (type L to list codes): 82: Assign partition as swap

Unless you tell it otherwise, fdisk assumes the new partition is a Linux ext3 partition (83). You could have typed L to see the same listing of file system types and hex codes produced from the l command. As noted above, 82 can assign the partition as swap. Other Linux partitions that may interest you include Linux extended (85), Linux LVM (8e), Linux software raid (fd), and EFI/GTP (ee).

For Windows partitions, you can assign a partition as HPFS/NTFS (7), Windows 95 FAT32 (b), FAT 16 (6), or Windows 95 FAT32 LBA (c). Other Unix-type file systems include Minix (be or bf), BSD/OS (e4), FreeBSD (ee), OpenBSD (ef), NeXTSTEP (f0), Darwin UFS (f1), and NetBSD (f4). Any of these file system types might be useful if you have old backup media from those file systems that you want to restore.


So far, you have not made any permanent changes to your partition table. If you are now very sure that your new settings are correct, type w to write those changes to the partition table. To abandon your changes (or quit after writing your changes), type q to quit your fdisk session.