A slick script or method to compile the apps listed in the world file, from an existing system to the new system, all together at once, rather that typing in all of those application names into one giant emerge command. emerge -av $(cat /path/to/oldworld)

This command will install all of the files in the old_world_file (/var/lib/portage/world) while also adding them to the world of the new machine. The –noreplace was added in case some packages had already been installed, in order to avoid repeating one’s self. emerge -va –noreplace $(cat old_world_file)