How to mount and unmount disk ISO and DMG images on macOS
Updated 2021-11-03 · Published 2014-05-04

You can use hdiutil to manually mount and unmount disk images, using the commands below. When mounting a file, make sure you replace filename with the correct file name. The same command works for both DMG and ISO files. When unmounting a disk image, be sure to replace disk1s1 with the correct volume identifier that will be shown to you after you mount the image.
Mount a DMG or ISO file
hdiutil attach filename.iso
Unmount the disk image
hdiutil detach /dev/disk1s1