I'm trying to format my usb drive that is partitioned with FAT32 by the following command in Terminal:

$ diskutil eraseDisk JHFS+ UntitledUFS disk1

However, I get this output:

Started erase on disk1
Unmounting disk
Error: 12: POSIX reports: Cannot allocate memory

1 Answer 1


It could be likely that you are not running the command as admin (Unix root) user.

To run a command with administrator privileges use the sudo command so:

$ sudo diskutil eraseDisk JHFS+ UntitledUFS disk1

The error message can lead one astray giving the impression that something else is wrong but it is likely a permissions issue.

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