we erased the disk signature as the following ( this is after we performed umount )
wipefs -a /dev/sde
/dev/sde: 2 bytes were erased at offset 0x00000438 (ext4): 53 ef
then we check that disk is without file system as the following
lsblk -f
sde ext4 20eba791-c9c9-4462-aa23-74c40a41b8a0
but in spite we erase the filesystem , lsblk still show the ext4 filesystem on sde disk
From the man page of wipefs (emphasis mine):
DESCRIPTION
wipefs can erase filesystem, raid or partition-table signatures (magic strings) from the specified device to make the signatures invisible for libblkid. wipefs does not erase the filesystem itself nor any other data from the device.
So, the only thing it guarantees is that after wipefs, the blkid command (or anything else that uses libblkid for identifying contents of block devices) will no longer detect that filesystem, RAID set, or partition table.
lsblk does use libblkid, but apparently that is not its only way to detect filesystems.
