install DMG file using a UNIX command

If you're copying the DMG to the client workstation and opening it, you probably then will need to take control of the workstation and run the installer from there. Most such installers require some manual intervention and so can't be run from a command line.

If the DMG contains the software as a Mac OS X package, use the Install Packages command under the ARD Manage menu and push the package to the workstations that way. If the DMG doesn't have a standard package but you have a number of workstations that you need to install on, you may find it easier to build your own package. You can find some information on this in the ARD Administrator's Guide, and there are third-party tools such as JAMF's Composer that can help you build a package more easily.

Regards.

That might be possible, but that presumes that the DMG only contains something that goes in the Applications folder. Many apps put things in multiple places. If the DMG only contains a single item or folder that can go in the Applications folder and nothing else that needs to go elsewhere, then it will be easier to just open the DMG on your administration computer and just push out the app/folder to each workstations Applications folder rather than copying the DMG to the workstation and then trying to open and copy its contents on each system.

Regards.