Fdisk

Fdisk is the command line utility in linux systems which is used to manage partitions in linux using the CLI commands and it is one of the most popular tool for managing partitions by the linux administrators.

sudo fdisk /dev/xxx

Replace the xxx with the target partition which we are about to change

Here is the basic manual of fdisk utility :

Help:

  GPT
   M   enter protective/hybrid MBR

  Generic
   d   delete a partition
   F   list free unpartitioned space
   l   list known partition types
   n   add a new partition
   p   print the partition table
   t   change a partition type
   v   verify the partition table
   i   print information about a partition

  Misc
   m   print this menu
   x   extra functionality (experts only)

  Script
   I   load disk layout from sfdisk script file
   O   dump disk layout to sfdisk script file

  Save & Exit
   w   write table to disk and exit
   q   quit without saving changes

  Create a new label
   g   create a new empty GPT partition table
   G   create a new empty SGI (IRIX) partition table
   o   create a new empty DOS partition table
   s   create a new empty Sun partition table

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Use-Case 1 : Creating the partition using fdisk in ubuntu

Here we can see there are two physical disks allocated on the system sda & sdb where the sda partition is mounted as the main primary disk and OS is mounted on the 3 partitions on it. Now we will add the sdb as the secondary partition on the linux.

We will enter the fdisk console with the target disk sdb

sudo fdisk /dev/sdb

Type n to create the new partition on the physical disk and select the primary option and then enter the partition number & pass the other parameters to keep the value default and make a primary partition of full disk.

Upon successful execution we can see that sdb1 is created with the volume size of 5G and now we will format it as ext4 partition type to make it usable in linux

Now we will format this partition as ext4 using :

sudo fdisk /dev/sdb

Type p to check the current partition table the output should look like :

Now we will use the following command :

sudo mkfs.ext4 /dev/sdXn

The ourput should look like :

Here we have successfully created the ext4 partition and the output should reflect in lsblk

Now we will need to mount the partition to make it usable , The steps to mount the partition is as follows :

sudo mkdir -p /mnt/extended

Now we will mount the partition on the path we just created

sudo mount <disk_voulme> <mount_point>
# sudo mount /dev/sdb1 /mnt/extended

Now the disk is mounted and we can confirm it using lsblk

There is a slight issue the partition mount will be lost in case the machine it restarted, to make it mounted on startup we will need to make following changes :

Mounting disk on startup

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