Inside of Terminal.app, I'm trying to format a thumb drive and I'm getting the following "error":

does not appear to be a whole disk

The line I typed in was the following:

sudo diskutil partitionDisk /dev/disk1s2 GPT JHFS+ HighSierra R

What might I be typing in wrong? Why is it stating this?


You're asking it to partition a whole disk - it wipes existing volumes, and creates the ones you specify.

But, you're giving it /dev/disk1s2, which is itself a partition.

If you're trying to reformat the whole drive, you should be using /dev/disk1

Also, typically, people use eraseDisk to wipe and reformat it -

diskutil eraseDisk Usage: diskutil eraseDisk format name [APM[Format]|MBR[Format]|GPT[Format]] MountPoint|DiskIdentifier|DeviceNode (Re)-partition a whole disk (create a new partition map). This completely erases any existing data on the given whole disk; all volumes on this disk will be destroyed. Format is the specific file system name you want to erase it as (HFS+, etc.). Name is the (new) volume name (subject to file system naming restrictions), or can be specified as %noformat% to skip initialization (newfs). You cannot erase the boot disk. Ownership of the affected disk is required. Example: diskutil eraseDisk JHFS+ UntitledUFS disk3

  • ok yeah. i did a diskutil list and i see it now as disk1. man that was confusing! – The Angry Yeti Feb 9 at 19:29
  • diskX are the actual disks, and diskXsY are the partitions on them. – Alex Feb 9 at 19:34
  • @TheAngryYeti As I understand it, the "s" stands for "slice", which is (sort of) another name for partition. Thus, you can think of diskX as meaning "disk #X", and diskXsY as meaning "the Y'th slice (partition) of disk #X". – Gordon Davisson Feb 9 at 23:12

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