open .dmg with Terminal

When you open a disk image (.dmg file), whether through the Finder (double-click) or via Terminal.app (open /path/to/your.dmg) then encapsulated disk is mounted on your file system, just like any other disk.

From Terminal.app's perspective, this means that the disk image will be mounted under /Volumes and you can traverse the volume just like you would in any other shell:

/ % cd /Volumes
/Volumes % ls
Macintosh HD
/Volumes % open /Users/me/Downloads/some.dmg
/Volumes % ls
Macintosh HD	My Disk Image
/Volumes % cd My\ Disk\ Image
My Disk Image % ls
...

Use the open command.

1) Type

"open "

without the quotes, but WITH a trailing space; do NOT press enter.

2) Drag the dmg file and drop it on the Terminal window

3) Press enter

Note: opening a dmg file will mount it. The above process is equivalent to double-clicking it in the Finder

You had not mentioned anything about installing a printer driver, you asked how to open a dmg using Terminal, and that is what I answered. FWIW, there is no advantage in doing it via Terminal, you might as well just double-click the dmg file and it will do the same thing.

8Macs wrote:

Helpful way to open but doesn’t seem to help Monterey to install the printer driver.

Does double-clicking the installer in the mounted disk image install the printer driver?