Do this only right after flashing the image on the SD-Card, so if anything goes wrong you do not lose any data.
sudo fdisk /dev/mmcblk0
In fdisk: Press ‘p’ to print the partition table:
Disk /dev/mmcblk0: 15.9 GB, 15931539456 bytes 4 heads, 16 sectors/track, 486192 cylinders, total 31116288 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00084078 Device Boot Start End Blocks Id System /dev/mmcblk0p1 2048 124927 61440 83 Linux /dev/mmcblk0p2 124928 31116287 15495680 83 Linux
Press ‘d’ to delete a partition: Enter ‘2’ to choose the second partition. Press ‘n’ to create a new partition: Enter ‘p’ to select primary as partition type. Partition number: enter to accept 2 as default partition number. First sector: enter to accept default. This should be 124928 Last sector: enter to accept default. Press ‘w’ to write the new partition table. Reboot to force the kernel to recognise the new partition table.
After the system has come back up you still have to resize the partition.
sudo resize2fs /dev/mmcblk0p2