tart:tldr:7a7aa

This command is incomplete and not a valid command. It seems to be using the "tart" command to modify some settings of a virtual machine.

The specific purpose of the command cannot be determined without more context or information about the "tart" command and the environment in which it is being used.

However, based on parts of the command, it seems to be setting the display resolution of a virtual machine. The "${vm-name}" placeholder indicates that you would replace it with the name of the virtual machine you want to modify. Similarly, the "${640}x${400}" placeholder suggests that you would replace it with the desired resolution, such as "640x400".

Without further details, it is difficult to provide a more specific explanation or interpretation of the command.