tell the kernel about the new size of a partition
resizepart device partition length
resizepart tells the Linux kernel about the new size of the specified partition. The command is a simple wrapper around the "resize partition" ioctl.
This command doesn't manipulate partitions on a block device.
device The disk device.
partition The partition number.
length The new length of the partition (in 512-byte sectors).
The resizepart command is part of the util-linux package and is available from https://www.kernel.org/pub/linux/utils/util-linux/.