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fdisk command in linux with examples

The fdisk command in Linux is used to create, delete, modify, and manage disk partitions. It is one of the most commonly used tools for partitioning storage devices.

Summary of fdisk Commands

Command Description
fdisk -l List partitions
fdisk /dev/sdb Open partition manager for /dev/sdb
p Print partition table
n Create a new partition
d Delete a partition
t Change partition type
w Write changes and exit
q Quit without saving

The fdisk command is powerful for managing disk partitions. However, be cautious while modifying partitions to avoid data loss.

1. Display Partition Table (-l option)

To list all available disks and their partitions:

sudo fdisk -l

Example Output:

Disk /dev/sda: 500GB
Device Boot Start End Sectors Size Id Type
/dev/sda1 * 2048 2099199 2097152 1G 83 Linux
/dev/sda2 2099200 976773119 974673920 499G 83 Linux

🔹 Explanation:

  • Device column shows the partitions (/dev/sda1, /dev/sda2).
  • Boot column (*) marks the bootable partition.
  • Size column shows partition sizes.

2. Enter fdisk Interactive Mode

To modify partitions, open fdisk for a specific disk:

sudo fdisk /dev/sdb

🔹 This opens an interactive mode where you can create, delete, and modify partitions.

3. View Current Partition Table

Inside fdisk, press:


🔹 Displays partition details of /dev/sdb.

4. Create a New Partition

Step 1: Enter fdisk

sudo fdisk /dev/sdb

Step 2: Create a New Partition

Press n → Enter (for new partition).

🔹 It will ask for the partition type:

  • Press p for Primary partition.
  • Press e for Extended partition.

Then, specify the partition number, starting sector, and size (e.g., +10G for a 10GB partition).

Step 3: Save and Exit

Press:


🔹 This writes the changes and exits fdisk.

5. Delete a Partition

Inside fdisk:

  1. Press d → Enter (Deletes a partition).
  2. Enter the partition number to delete.
  3. Press w to save and exit.

6. Change Partition Type

Inside fdisk:

  1. Press t → Enter (Change partition type).
  2. Enter the partition number.
  3. Enter the type code (e.g., 82 for Swap, 83 for Linux).
  4. Press w to save changes.

7. Format the New Partition

After creating a partition, format it before use:

sudo mkfs.ext4 /dev/sdb1

🔹 Formats /dev/sdb1 with ext4 filesystem.

For Swap Partition:

sudo mkswap /dev/sdb1
sudo swapon /dev/sdb1

8. Mount the New Partition

To use the new partition, mount it:

sudo mount /dev/sdb1 /mnt

To make it permanent, add to /etc/fstab:

echo "/dev/sdb1 /mnt ext4 defaults 0 2" | sudo tee -a /etc/fstab

9. Resize a Partition (Requires resize2fs)

If you extend a partition, resize the filesystem:

sudo resize2fs /dev/sdb1

🔹 This resizes the filesystem to match the new partition size.