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Mount or Unmount a Volume with diskutil mount

Re-attach a stubborn external volume or detach one without ejecting, using diskutil's mount and unmount verbs.

macOSFilesdiskdiskutilMedium risk
Run diskutil mount /Volumes/MyUSB to re-attach the volume, or diskutil unmount /Volumes/MyUSB to detach it while leaving the drive powered.

01Command

Command
$ diskutil mount /Volumes/MyUSB

02What it does

Unlike diskutil eject, which spins the drive down and removes the whole device, unmount only detaches the volume from the file system while the disk stays powered on. That makes it the right tool for unmounting a Time Machine partition while keeping other partitions available, or for scripting safe access to a drive. When a volume fails to mount after an unsafe unplug, diskutil mount on its /Volumes path usually re-attaches it without a reboot.

03Risk

RiskMedium risk
!Warning: Unmounting is not the same as safe removal — unplug the cable only after unmount or eject completes, or you can corrupt files that were still being written.

04Undo

Undo
$ diskutil unmount /Volumes/MyUSB

05Sources

  • DISKUTIL(8) - macOS manual page
    Apple (Xcode man pages mirror) · vendor-doc · 2026-09-17
    Evidence: The manual page documents 'diskutil mount' and 'diskutil unmount' as mounting and unmounting a single volume.
  • diskutil - Modify, verify and repair local disks
    SS64 · technical · 2026-09-17
    Evidence: Lists diskutil's mount and unmount verbs, including 'diskutil unmount /Volumes/MyUSB' as an example, for attaching and detaching volumes without ejecting them.

Last verified: 2026-09-19 · Category: Files & Folders

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