I am running Gnome. I would like to execute a shortcut key combination from the command line. For example, type a command that generates the key codes for Ctrl+Alt+Left.
Does anyone know of a way to do this?
You can use xdotool to manufacture keyboard events. See the manual and the examples for how to target a specific window.
If this is to trigger a functionality of Gnome or the window manager, there may be a separate command line tool for that. For example wmctrl gets and changes window parameters such as titles, position, etc.
Similarly, if this to trigger a functionality of a specific application, there may be a way to do this directly. Of course that entirely depends on the application.