Macintosh Terminal Pocket Guide

Name

diskutil — stdin  stdout  - file  -- opt  --help  --version

Synopsis

diskutil action [options]

The diskutil command operates on disk partitions: mounting and unmounting, getting information, renaming, erasing, and more. Read-only operations can be done by any user, but writing and mounting require an administrator. For example, if you have a portable USB drive mounted:

➜ df -h /Volumes/MyUSB
Filesystem      Size   Used  Avail Capacity  Mounted on
/dev/disk1s2   1.8Ti  813Mi  1.8Ti     1%    /Volumes/MyUSB

you can unmount it with either of these diskutil commands, by providing the directory where it’s mounted:

➜ sudo diskutil unmount /Volumes/MyUSB
Volume MyUSB on disk1s2 unmounted

or the associated device in the /dev directory:

➜ sudo diskutil unmount /dev/disk1s2
Volume MyUSB on disk1s2 unmounted

and since it’s a portable drive, even eject it for safe unplugging from the Mac:

➜ sudo diskutil eject /dev/disk1s2
Disk /dev/disk1s2 ejected

Then you can remount it by its device name:

➜ sudo diskutil mount /dev/disk1s2
Volume MyUSB on /dev/disk1s2 mounted

diskutil does many other tricks, such as getting information about a partition:

➜ diskutil info /Volumes/MyUSB
Device Node:       /dev/disk1s2
File System:       HFS+
Name:              Mac OS Extended
Bootable:          Is bootable
Protocol:          USB
Total Size:        2.0 TB (2000054960128 Bytes)
Ejectable:         Yes
...

renaming a partition:

➜ sudo diskutil rename /dev/disk1s2 OtherName
Volume on disk1s2 renamed to OtherName

and checking its internal structure for errors:^[16]

➜ sudo diskutil verifyVolume /dev/disk1s2 ...