• create a file of the partition size with dd command
• associate it to a loop device with losetup command
• partition it with fdisk

dd command

utility to copy files/partition create a file named my-hd-file

Create a 100Mo file filed with 0 from /dev/zero:

touch my-hd-file
dd if=/dev/zero of=my-hd-file bs=1024000 count=1
1+0 records in
1+0 records out
1024000 bytes (1.0 MB, 1000 KiB) copied, 0.0318375 s, 32.2 MB/s
root@raspbeeerry:~# dd if=/dev/zero of=my-hd-file bs=1024000 count=100
100+0 records in
100+0 records out
102400000 bytes (102 MB, 98 MiB) copied, 0.749057 s, 137 MB/s

Loop device

In Unix-like operating systems, a loop device, vnd (vnode disk), or lofi (loop file interface) is a pseudo-device that makes a file accessible as a block device.

• losetup -f to identify next available loop device number => /dev/loop0

• losetup -a: list all loop devices

  root@raspbeeerry:~# losetup -a root@raspbeeerry:~# losetup -f /dev/loop0 root@raspbeeerry:~# losetup /dev/loop0 my-hd-file root@raspbeeerry:~# losetup -a /dev/loop0: [2049]:2752537 (/root/my-hd-file) root@raspbeeerry:~#