sfdisk

• Scripting version of fdisk

--list

• List partition

sfdisk /dev/diskN -l

--list-free

• List free (unallocated space)

sfdisk /dev/diskN -F

--move-data

• Use the output of --list-free empty sectors to know how many sectors to shift left/right

# Move the 1st partition by NUM sectors to the right
echo '+NUM' | sfdisk --move-data /dev/diskN -N 1

# Move the 2nd partition by NUM sectors to the left
echo '-NUM' | sfdisk --move-data /dev/diskN -N 2

resize

echo ", +" | sfdisk -N 1 /dev/diskN