# get UUID for VM using vboxmanage list runningvms # or for stopped VMs vboxmanage list vms # create share vboxmanage sharedfolder add <VM UUID> --name <share name> --hostpath </path/to/host/folder> --transient
sudo mount -t vboxsf <share name> </path/to/guest/mountpoint>
The guest additions includes a service that will do guest-side auto-mounting. You just need to find and start that service. How you do this depends on how the guest additions were installed (from the ISO, or from the guest's package manager), and what guest you are using.