ah ok........ try: umount /dev/mmcblk1 sfdisk -uM /dev/mmcblk1 << EOF ,2100,C ,,L ,, ,, EOF and then : umount /dev/mmcblk1 mkfs.vfat /dev/mmcblk1p1 -n sdcard mke2fs -j -m0 /dev/mmcblk1p2