First, let's talk about the fdisk and sfdisk commands. These tools allow you to view and manage partitions on a disk. 💽

fdisk

To list the partitions of each device, you can use the following commands:

fdisk -l
fdisk -l /dev/sda

sfdisk

Alternatively, you can use sfdisk like this:

sfdisk -l
sfdisk -l /dev/sda

The difference between the two commands is that fdisk is interactive, while sfdisk is not. 🤔 This means that fdisk will prompt you for input, while sfdisk will not.

Here's an example of the output:

Disk /dev/sda: 238.5 GiB, 256060514304 bytes, 500118192 sectors
Disk model: ST1000LM035-1RK172
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x00000000

Now, let's say you want to back up your /dev/sda partition table. You can use the sfdisk command like this:

sfdisk -d /dev/sda > sda.partition.table.2022-12-05.txt

Then, you can copy the file sda.partition.table.12-30-2015.txt to an NFS mounted share or a USB drive. 💾 💻

But what if you want to restore the Linux partition from that file? No problem! Just use the sfdisk command like this:

sfdisk /dev/sda < sda.partition.table.2022-12-05.txt

Or, if the file is on a USB drive:

sfdisk /dev/sda < /path/to/usb/pen/sda.partition.table.2022-12-05.txt

You can also use the -f flag like this:

sfdisk -f /dev/sda < /media/usb/sda.partition.table.2022-12-05.txt

But wait, there's more! You can also replicate a disk partition table from one device to another. This can be useful if you're using Linux-based software RAID. Here's an example:

sfdisk -d /dev/sda | sfdisk -f /dev/sdd

Then, you can verify that the partition tables are the same on both disks like this:

fdisk -l /dev/sda
fdisk -l /dev/sdd

mdadm

You can also use mdadm to manage and rebuild your RAID device:

mdadm --manage /dev/mdX --add /dev/sdd1
mdadm --manage /dev/mdX --add /dev/sdd2
..
..
mdadm --manage /dev/mdX --add /dev/sddN

You can use the watch command to see the progress of the RAID array sync:

watch cat /proc/mdstat

gdisk

But what if your disk uses GPT (GUID Partition Table)? No problem! You can use the gdisk command to manage those disks. The difference between gdisk and fdisk is that gdisk supports GPT partitions, while fdisk does not.

If it's not already installed, install gdisk on a Debian or Ubuntu Linux system like this:

sudo apt-get install gdisk

Then, you can list the partitions on a disk like this:

gdisk -l /dev/sda

Here's an example of the output you might see:

Disk /dev/sda: 500.1 GB, 500107862016 bytes, 976773168 sectors
Disk model: ST500DM002-1BD142
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: 2B0E2B0E-2B0E-2B0E-2B0E-2B0E2B0E2B0E

To backup your partition table with gdisk, you can use the following command:

sudo gdisk -b /path/to/backup/file /dev/sda

To restore the partition table from a backup file, you can use the following command:

sudo gdisk -r /path/to/backup/file /dev/sda

You can also use the gdisk command to copy a partition table from one disk to another. Here's an example:

sudo gdisk -c /dev/sda /dev/sdb

Finally, you can use the gdisk command to create a new partition table on a disk. Here's an example:

sudo gdisk /dev/sda

That's it! Now you know how to manage disk partitions on Linux. 🐧