Fix SDCards and disks #
Sometimes you need to reformat a disk and DiskUtility isn't cutting it. I had a recent case of an SD card I'd used
to install Linux. Disk Utility could see the drive but not read the linux partitions nor erase the partitions to turn it back
into a plain MS-Dos (FAT) drive. The key is to use diskutil, the command line counterpart.
List the partitions
diskutil list
Find the id for the disk you are erasing. disk4 in my case.
diskutil eraseDisk FAT32 RASPBIAN MBRFormat disk4