Admin Tips: fdisk

In the next post in the Admin Tips series, we’ll cover fdisk.

fdisk is a Linux command used to create and manipulate a disk’s partition table. It allows you to view, create, delete, change, resize, copy, and move partitions on a hard drive using a dialog interface.

fdisk allows you to create up to four primary partitions, and the number of logical partitions depends on the size of the hard drive being used. fdisk allows the user to:
– create space for new partitions
– organize space for new drives
– reorganize old drives
– copy or move data to new drives (partitions).

fdisk is part of the util-linux package.

Syntax:
Changing the partition table

fdisk [options] DISK

Options:
-b, –sector-size : Physical and logical sector size
-B, –protect-boot : Don’t strip bootbits when creating the label
-c, –compatibility[=] : Compatibility mode: ‘dos’ or ‘nondos’ (default)
-L, –color[=] : Color output (auto, always, or never) Colors are enabled by default
-l, –list : List partitions and exit
-x, –list-details : Like –list, but with more details
-n, –noauto-pt : Don’t create a default partition table on empty devices
-o, –output : Columns to output
-t, –type : Recognize only the specified partition table type
-u, –units[=] : Display units ‘cylinders’ or ‘sectors’ (default)
-s, –getsz : Specify the device size in 512b sectors [OBSOLETE]
–bytes : Print the size in bytes, rather than in a human-readable format
–lock[=] : Use exclusive device locking (yes, no, or nonblock)
-w, –wipe : Wipe signatures (auto, always, or never)
-W, –wipe-partitions : Wipe signatures from new partitions (auto, always, or never)
-C, –cylinders : Specify the number of cylinders
-H, –heads : Specify the number of heads
-S, –sectors : Specify the number of sectors per track

Examples

List all disk partitions
The following command lists the partitions on the system and displays their /dev names. For example, /dev/sda, /dev/sdb, or /dev/sdc.

sudo fdisk -l

View partition on a specific disk
The following command displays all disk partitions on the /dev/sda device.

sudo fdisk -l /dev/sda

View all fdisk commands
To see all the commands available with the fdisk command, you can use the /dev/sda partition with the fdisk command.

sudo fdisk /dev/sda

This will prompt you for a command. Type m to see all the operations that can be performed on /dev/sda.

Create a Hard Disk Partition
Navigate to the hard disk partition, which is /dev/sda.

sudo fdisk /dev/sda

Now you need to type ‘n’ to create a new partition, then type ‘p’ to create a primary partition and ‘e’ to create an extended or logical partition, depending on the partition type you want to create. Use ‘w’ to save changes.

Delete a Hard Disk Partition
To delete a hard disk partition and free up the space occupied by it, for example, /dev/sdb,

sudo fdisk /dev/sda

and then use ‘d’ to access the delete partition menu. You will be prompted for the number of the partition you want to delete (enter the number). Use ‘w’ to save changes.

How to view partition size

sudo fdisk -s /dev/sda

For more information about fdisk, use the following commands:

sudo fdisk –help
man fdisk